Dissertations / Theses on the topic 'Animal breeding'

This thesis comprises a collection of 39 research papers divided into three groups. The first group is entitled 'Statistical Methods, including variance component estimation with general application'. The second group report on 'Application of statistical methods to animal breeding studies'. The last group 'Experimental Studies' reports on studies on animal breeding data in beef and dairy cattle. The major theme of Group I is variance component estimation and the introduction of a method, now known as REML (Residual Maximum Likelihood) that unifies the area. The method was introduced for the analysis of incomplete block designs with unequal block size but was found to have important applications in the analysis of groups of trials, time-series, multivariate data and detecting outliers. The work on variance components has applications to animal breeding and is discussed in Group II. Papers discuss efficient designs for estimation of genetic parameters, including heritability, maternal and multivariate genetic parameters. These designs can lead to substantial reductions in the variances of the parameters over classical designs. It is shown that REML can be applied in certain circumstances when there is selection of animals. Links between variance estimation and best linear unbiased prediction are explored. Methods of prediction, estimation of genetic parameters and optimal designs are given for non-normal data. The last group includes reports on the comparison of breeds and cross-breeding in beef cattle in Zambia. Other studies include estimating the genetic relationship between beef can dairy characters in british Friesian cattle. The validity of models used in dairy sire evaluation are investigated including the heterogenity of heritability of milk yield at different levels of production and a novel method for taking account of environmental variation within herds.

The interaction effects of genotype and nutrition on the performance of sows during lactation is still poorly understood; this series of experiments explored the factors contributing to breed differences in lactational performance and the development of appropriate feeding strategies. Two extreme types of sow were used in these experiments; lean pure-bred White sows (W: Large White and Landrace) and a prolific but fatter Meishan synthetic damline (M: 50% Meishan genes). M sows had higher numbers of piglets, a different feed intake curve and produced more milk with a higher fat content compared to W breed types. Their response to dietary protein was different for the two breeds; the Meishan sows, with higher initial levels of body fat reserves, used the extra protein to increase milk production. The White sows did not partition the extra protein into milk but used it to conserve their own maternal body reserves and improved their weaning to conception interval. The breed differences in sows performance were found not to be solely due to differences in litter size or piglet genotype or maternal body fat reserves. M sows showed better maternal behaviour with lower activity and shorter suckling intervals. It can be concluded from these experiments that Meishan synthetic sows are inherently better mothers, and the way in which sows of different breed types partition feed nutrients during lactation is very different. A dietary lysine concentration of 9 g/kg (giving daily intakes of 53-61 g/day at 98-111 MJ DE/day) optimised lactational and rebreeding performance in both breed types.

There have been many changes in the United States sheep industry over the years. Decreasing profitability of wool production has shifted the focus of many producers to strictly meat production. In south Texas, extreme high summer temperatures add an additional challenge in raising wool breeds of sheep. Hair sheep are gaining popularity in lamb-only production systems as they are more adapted to hot climates and eliminate shearing costs. The Dorper is the most popular breed of hair sheep throughout Texas due to superior lamb carcasses. Maximizing reproductive efficiency is critical for increasing the profitability of sheep production. Accelerated lambing systems can produce 3 lamb crops every two years versus 1 lamb crop per year. For this to be accomplished, ewes must be capable of breeding early post-partum and at all times of the year. We determined the reproductive characteristics of Dorper ewes. In the absence of a ram, Dorper ewes were anestrous from March until May. We observed considerable variation of ewes when both entering and ending anestrous. During the initial breeding season, 7-d CIDR^® treated ewes, which conceived 1^st service, had a significantly lower mean day of birthing (3.2 ± 2.1 d) compared to (10.1 ± 1.9 d) control ewes, resulting in a shorter lambing duration. During the seasonal anestrous period both CIDR^® treated and control post-partum Dorper ewes were stimulated to ovulate while in the presence of the ram. However, during this time, 9-d CIDR^® treatment significantly shortened both overall ram to lambing interval (152.8 ± 3.2d vs.165.7 ± 3.0 d) and first service ram to lambing interval (149.3 ± 1.3 d vs. 160.7 ± 1.5 d). Fall-born Dorper ewes with known birth dates had a mean age of puberty of 306.5 ± 4.9 d. Fall-born yearlings and spring-born ewe lambs were exposed to a ram during the first fall breeding season following their birth. While no difference was found in overall conception rate, fall-born yearlings had a significantly greater first service conception rate (83.3 %) compared to spring-born lambs (28.6 %). The findings of this study illustrate that Dorper ewes have the potential to be utilized in accelerated lambing systems in south Texas. By achieving a high conception rate post-partum simultaneous to the anestrous season, we were able to maintain an 8 mo lambing interval during the first two breeding season. We conclude that the reproductive attributes of the Dorper ewe makes them an excellent choice for sheep producers throughout South Texas.

The genetic outcome of operating an open nucleus system (ONS) in a population of 1200 sheep divided into individual flocks, was investigatd using simulation techniques, and a comparison to alternative breeding systems was made. Selection was for best linear unbiased prediction of breeding value (EBV) for a trait measurable on individuals before selection. Migration of animals between flocks was based on the EBV. The results of stochastic simulations indicated that, compared to selection within closed flocks (CF), the annual genetic gain could be increased by 25 to 40 per cent if an ONS was operated. The variation in selection response, and the rate of inbreeding were also lower. Simulation results showed that approximately 25 per cent of nucleus sires should be selected from the base flocks. Initial genetic differences between flocks had a short term effect on genetic gain in the ONS. Screening the population to ensure that the nucleus flock was initially composed of the best ewes, also only had a short term effect. The advantage of an ONS over CF selection was effected by flock size but not intitial heritability. The use of dispersed nucleus system and a sire referencing scheme with selection of sires across flocks, was investigated. The outcome of these systems was very similar to the ONS. The higher rate of genetic gain achieved in the ONS, compared to CF selection, was attributed to higher genetic selection differentials and maintenance of genetic variation within flocks. These effects were included in a deterministic model of the ONS. The model described the simulated data well, although changes in genetic variance at the outset of the ONS were underestimated. Failure to account for finite population effects in previous studies has resulted in underestimation of the benefits of an open nucleus system in small populations.

The aim of this work was to study the interaction of melatonin and prolactin in the control of seasonal breeding and coat development in goats. British Saanen goats (n=5) were maintained for 8 weeks in long days (20L: 40) followed by 8 weeks exogenous melatonin. Group treatment was staggered over the year in an attempt to dissociate breeding season advance from advanced coat growth. To assess the effect of prolactin suppression, the 20L:4D treatment from January was repeated in consecutive years but followed in March by melatonin (Year 1) or bromocriptine (Year 2). To study further the interaction of melatonin and prolactin on coat development and reproductive advance, goats (n=5) were maintained as follows: 1) natural photoperiod and temperature, Jul-Juni 2) 16L: 8D, natural temperature, Jul-Deci 3) 16L:8D, 17°C, Jul-Decj 4) 8L:16D, 8°C, Dec-Jun. To study melatonin suppression of prolactin, the secretagogues arginine vasopressin, serotonin and thyrotropin releasing hormone were given to goats (n=6) maintained in sequence under 8L:16D, 20L:4D and simulated short days (20L:4D+melatonin). Depending on long-day Imelatonin treatment onset, the breeding season was advanced from November to May, August or September. With 20L:4D followed by melatonin or bromocriptine the spring prolactin rise was delayed. A corresponding delay in winter coat moulting was observed only under melatonin. However, a winter secondary to primary (SIP) follicle ratio was retained with both treatments. Prolactin may determine coat structure, whilst melatonin influences the duration of fibre retention. Under conditions of summer or winter solstice hold, the seasonal prolactin variation was inhibited and initial SIP follicle ratios were retained. A tendency for a spontaneous change in prolactin secretion suggested existence of an endogenous rhythm. Maintained seasonal temperature did not influence melatonin secretion. Dusk and dawn prolactin peaks corresponded with the rise and fall in nocturnal melatonin. Basal prolactin concentrations and peak responses to the secretagogues altered with photoperiod, being low under 8L:16D and increased under 20L:4D. Exogenous melatonin under 20L:4D did not suppress prolactin to short-day concentrations. Invol vement of another factor mediating photoperiodic changes in prolactin secretion is suggested.

Kyoto University (京都大学)
0048
新制・論文博士
博士(農学)
乙第12591号
論農博第2756号
新制||農||994(附属図書館)
学位論文||H23||N4640(農学部図書室)
29080
京都大学農学研究科応用生物科学専攻
(主査)教授 廣岡 博之, 教授 祝前 博明, 教授 今井 裕
学位規則第４条第２項該当

In Mozambique, 80 per cent of the people rely on farming for their livelihood. The majority of them are small-scale and subsistence farmers. In spite of high GDP and agricultural growth rates, the majority of Mozambicans in rural areas remain below the poverty line.  Even though many subsistence farmers in Ribáuè District own animals, programmes and policies for development are aimed at commercialization in medium- and large-scale sector animal farming. We found a lack of attention given to family sector animal breeding as a development factor in Ribáuè. Over the course of five weeks, we engaged in an ethnographically inspired, qualitative field study in Ribáuè District, the city of Nampula and the capital Maputo. Our gender and animal advocacy viewpoints allowed us to look at development as a holistic concept and determine effects beyond the immediately visible. Applying the Sustainable Rural Livelihoods approach, we identified a serious threat to the farmers’ livelihoods both in the short- and long-term, which we believe needs to receive much greater attention in policy-making. We found that animal breeding fulfils diverse functions, such as diversification of assets and diet, and generating and increasing resilience. It is crucial as mid-term investment and as a live bank. However, it is hugely insecure in all of these functions due to recurring shocks. Animal health issues are a major limitation for farmers. Therefore, animal breeding has little development scope for subsistence farmers at the moment, and is further diminished by commercialization plans for a minority of farmers, which overlook the complexity of the farming system and may negatively impact regional markets.  Development through intensive animal breeding reflects a dangerous short-term thinking. Sustainability and an important livelihood strategy for many are sacrificed for economic development of a few while exploitative systems are reproduced.
Em Moçambique, oitenta por cento da população depende da agricultura para a sua subsistência; sendo que a maioria desse montante é composto por pequenos agricultores. Apesar de altas no PIB e taxa de crescimento agrícola, a maioria dos moçambicanos em áreas rurais permanece abaixo da linha de pobreza. Mesmo que muitos agricultores de subsistência no Distrito Ribáuè – localizada na cidade de Nampula, capital Maputo – possuam seus próprios animais e façam parte de programas de desenvolvimento, políticas de apoio e suporte à comercialização costumam ser destinadas a setores rurais de médio e grande porte. Durante o desenvolvimento deste trabalho, identificamos falta de assistência à criação familiar de animais para o desenvolvimento da região de Ribáuè. Ao longo de cinco semanas, estivemos envolvidos em um estudo de campo qualitativo – com inspiração etnográfica – nesta região.  Nossa tese, baseada na análise de políticas de questão de gênero e animais nos permitiu um olhar para o desenvolvimento desta população com um conceito holístico, determinando efeitos para além do imediatamente visível. Ao aplicar a “Abordagem Sustentável dos Modos de Vida Rurais”, identificamos uma séria ameaça para a subsistência dos agricultores em curto e longo prazo – o que acreditamos necessitar de maior atenção na formulação de políticas públicas. Descobrimos que a criação de animais cumpre diversas funções sociais, tais como a diversificação de ativos financeiros e dieta, gerando e aumentando no poder de resiliência da população estudada. Para isso se manter, percebemos ser fundamental que a população invista em médio prazo, usando seus animais como recurso financeiro. Porém, recorrentes revezes costumam limitar essa iniciativa. Problemas de saúde em animais, por exemplo, são uma grande limitação para os agricultores. Por isso, criação de animais tem pouco espaço no desenvolvimento de agricultores de subsistência e é ainda mais reduzido por causa dos planos de comercialização de uma minoria de agricultores (por causa da complexidade do sistema de produção e a fragilidade dos mercados regionais). Desenvolvimento através da criação intensiva de animais ainda reflete um pensamento perigoso em curto prazo. Sustentabilidade e importantes estratégias de sobrevivência são sacrificadas para o desenvolvimento de curto prazo de uma minoria, reproduzindo a exploração de sistemas.

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Esta tese compreende quatro diferentes estudos conduzidos a fim de avaliar estratégias alternativas para aumentar a eficiência de seleção genômica (GS) em programas de melhoramento animal. Um primeiro estudo foi desenvolvido com a finalidade de avaliar a performance preditiva de diferentes métodos estatísticos com base na informação de painéis de marcadores densamente distribuídos ao longo do genoma. Cinco diferentes características de uma população real de camundongos foram analisadas. Verificou-se que métodos com grandes diferenças conceituais apresentaram performance preditiva similar em algumas situações, também havendo variação na performance relativa dos métodos em função da característica analisada. O uso de diferentes variáveis resposta (pseudo-fenótipos) para estimação de efeitos de marcadores foi avaliado num segundo estudo, por meio da simulação de uma grande população de bovinos de corte, para a qual predições genômicas foram obtidas usando um procedimento de múltiplas etapas. Houve evidência de que provas desregredidas (dEBV) são mais apropriadas do que valores genéticos preditos (EBV) e médias ajustadas de desempenho da progênie (PYD), tanto para o treinamento de modelos quanto para a validação de predições genômicas. No terceiro estudo, procurou-se avaliar consequências em longo-prazo da aplicação de GS numa população de bovinos de corte sob seleção. Verificou-se grande benefício da aplicação de GS em cenários simulando seleção para características de qualidade de carne e reprodução de fêmeas. Houve evidência de que pode-se esperar maior benefício para GS, quando comparada à seleção por BLUP, no caso de características oligogênicas. Também foi possível inferir que em aplicações de GS, o uso de um critério de seleção em que se atribui maior peso a alelos favoráveis de menor frequência poderia proporcionar...
Improvements in production levels and product quality are needed in livestock systems to meet the growing world demand for animal-source foods. Besides this increasing demand, the productive sector must deal with constraints related to competition for land, greenhouse gas emissions and also due to hardening legislation in the fields of environment and animal welfare (FAO, 2011). In this context, animal breeding has played and will continue to play an important role to improve the efficiency of such production systems, especially in terms of competitiveness, safety, sustainability and biodiversity conservation (Harlizius et al., 2004). The main objective of animal breeding programs is to improve the performance of the next generations, through identification and reproduction of the animals with better genetic pool to efficiently produce in a specific environment (herein, superior animals). In the last decades, animal breeders succeeded in achieving this goal, mostly through the application of statistical tools grounded in quantitative genetics theory, what could be called as 'classical animal breeding'. In this case, the traditional prediction of the genetic merit of individuals (estimated breeding values, EBV) is obtained based on information of pedigree and phenotypes (own records and measures on relatives). With the advent of dense molecular marker panels, the implementation and design of breeding programs, especially in dairy cattle, had changed dramatically as a consequence of incorporating this new information to identify superior animals earlier and more precisely. Pioneer simulation studies drew attention of animal breeders to the possibility of making accurate predictions of the genetic merit of individuals by using genotypic information from dense marker panels, a process known as genomic selection (GS) (Nejati-Javaremi et al., 1997; Meuwissen et al., 2001). Other influential work ...

Orientador: Sandra Aidar de Queiroz
Coorientador: Roberto Carvalheiro
Banca: Fernando Sebastián Baldi Rey
Banca: Rúsbel Raúl Aspilcueta Borquis
Banca: Fernanda Brito
Banca: Fabyano Fonseca e Silva
Resumo: Esta tese compreende quatro diferentes estudos conduzidos a fim de avaliar estratégias alternativas para aumentar a eficiência de seleção genômica (GS) em programas de melhoramento animal. Um primeiro estudo foi desenvolvido com a finalidade de avaliar a performance preditiva de diferentes métodos estatísticos com base na informação de painéis de marcadores densamente distribuídos ao longo do genoma. Cinco diferentes características de uma população real de camundongos foram analisadas. Verificou-se que métodos com grandes diferenças conceituais apresentaram performance preditiva similar em algumas situações, também havendo variação na performance relativa dos métodos em função da característica analisada. O uso de diferentes variáveis resposta (pseudo-fenótipos) para estimação de efeitos de marcadores foi avaliado num segundo estudo, por meio da simulação de uma grande população de bovinos de corte, para a qual predições genômicas foram obtidas usando um procedimento de múltiplas etapas. Houve evidência de que provas desregredidas (dEBV) são mais apropriadas do que valores genéticos preditos (EBV) e médias ajustadas de desempenho da progênie (PYD), tanto para o treinamento de modelos quanto para a validação de predições genômicas. No terceiro estudo, procurou-se avaliar consequências em longo-prazo da aplicação de GS numa população de bovinos de corte sob seleção. Verificou-se grande benefício da aplicação de GS em cenários simulando seleção para características de qualidade de carne e reprodução de fêmeas. Houve evidência de que pode-se esperar maior benefício para GS, quando comparada à seleção por BLUP, no caso de características oligogênicas. Também foi possível inferir que em aplicações de GS, o uso de um critério de seleção em que se atribui maior peso a alelos favoráveis de menor frequência poderia proporcionar ...
Abstract: Improvements in production levels and product quality are needed in livestock systems to meet the growing world demand for animal-source foods. Besides this increasing demand, the productive sector must deal with constraints related to competition for land, greenhouse gas emissions and also due to hardening legislation in the fields of environment and animal welfare (FAO, 2011). In this context, animal breeding has played and will continue to play an important role to improve the efficiency of such production systems, especially in terms of competitiveness, safety, sustainability and biodiversity conservation (Harlizius et al., 2004). The main objective of animal breeding programs is to improve the performance of the next generations, through identification and reproduction of the animals with better genetic pool to efficiently produce in a specific environment (herein, superior animals). In the last decades, animal breeders succeeded in achieving this goal, mostly through the application of statistical tools grounded in quantitative genetics theory, what could be called as 'classical animal breeding'. In this case, the traditional prediction of the genetic merit of individuals (estimated breeding values, EBV) is obtained based on information of pedigree and phenotypes (own records and measures on relatives). With the advent of dense molecular marker panels, the implementation and design of breeding programs, especially in dairy cattle, had changed dramatically as a consequence of incorporating this new information to identify superior animals earlier and more precisely. Pioneer simulation studies drew attention of animal breeders to the possibility of making accurate predictions of the genetic merit of individuals by using genotypic information from dense marker panels, a process known as genomic selection (GS) (Nejati-Javaremi et al., 1997; Meuwissen et al., 2001). Other influential work ...
Doutor

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The nutrient requirements for breeding ostriches are currently not well-defined. Quantification of the nutrient requirements will improve the financial wellbeing of the industry. A study of the growth of the reproductive organs and liver, together with various production studies, were therefore undertaken in order to gain knowledge about the nutrition of breeding ostriches, thereby quantifying the nutrient requirements of breeding ostriches. Various studies were conducted to determine the influence of dietary protein, amino acids and energy on production levels of breeding ostriches. In a first study, five diets, varying in crude protein (CP) but with a constant energy content of 9.2 MJ ME/kg feed, were provided at a feed intake level of 2.5 kg/bird/day. The dietary CP levels were 7.5%, 9.1%, 10.8%, 12.3% and 14.0%. No differences (P>0.05) between treatments (total eggs per female per season) were found for number of unfertilized eggs (eggs per female per season; 8.9±0.8), dead-in-shell chicks (8.0±0.5), number of chicks hatched (19.1±1.1) and change in mass of females (-16.2±1.6kg). A tendency was observed for a difference in total egg production (mean and standard error; 39.1±3.6; P=0.08). The 12.3% CP diet caused the lowest (P<0.05) change in live mass (-3.8±2kg) for male birds. No interaction (P>0.05) occurred between the genotype of the bird and the dietary protein concentration for both egg and chick production. In a second study, six diets varying in ME (MJ ME/kg feed), were provided at an average feed intake level of 3.4 kg/bird/day. The levels were 7.5, 8.0, 8.5, 9.0, 9.5 and 10.0 MJ ME/kg feed respectively. No differences (P>0.05) were observed for total eggs produced per female per season (44.8±7.8), number of chicks hatched (15.4±4.1), number of infertile eggs (11.5±3.8), number of dead-in-shell eggs (12.1±3.2) and change in mass of females (10.7±3.6kg). Males increased linearly (y=2.4x + 2.45; R2=0.09; P<0.05) in live mass as the dietary energy content increased. Two eggs per diet per month were analyzed for crude protein, crude fat and trace elements, and one egg per diet per month was analyzed for fatty acid composition. Eggs from the first and last month of the season were subjected to amino acid analysis. Analysis of variance showed no difference in crude protein and fat (P>0.05) content of eggs between the experimental diets, as well as for the calcium content of eggshells. The proline content differed (P<0.05) between the diets. The C18:3n-3 (linoleic acid) content of the eggs increased (P<0.05) amongst the dietary treatments. Crude protein, fat and C18:3n-3 content in eggs increased (P<0.05) for the number of the egg in the laying cycle. In a third study, the feed intake of breeding ostriches, as affected by dietary energy content was investigated. Average feed intake (kg feed/bird/day) was not affected (P>0.05) at any dietary energy level when levels of 8.0, 8.7, 9.4, 10.1, 10.8 and 11.5 MJ ME/kg feed were provided. The mean and standard error was 3.7±0.2kg. The production of breeding female ostriches was not influenced by dietary ME and protein at these feed intake levels. Ostrich birds do not have the ability to regulate their feed intake at any dietary energy level as used in this study. The amount of nutrients deposited in the eggs had no influence on the reproductive efficiency of the breeding female ostrich. The experiments also revealed that female breeding ostriches were independent of dietary energy and protein as used in this study for the mean frequency of egg laying at various dietary protein and energy levels (P>0.05). In a fourth study, the growth and development of the reproductive organs of female birds at the onset of the breeding season were investigated. The amount of nutrients needs to be determined in order to support the growth of the reproductive organs during the breeding season, due to the fact that these organs are linked to egg production. It was thus necessary to investigate whether the reproductive organs grew and developed during a season. The first slaughter interval was conducted at the start of the breeding season. The ovary, oviduct and liver were collected, weighed after each slaughter and analyzed. Ovary and oviduct were analyzed for crude protein and fat. No differences (P>0.05) were observed between the different slaughter intervals for the mass, crude protein and fat content of both organs. No trend (P>0.05) in the weight of the oviduct could be observed over the 49-day period, this weight being highly correlated with body weight; whereas the ovary weight tended to be correlated with the time after the onset of the breeding period, although the variation in weights, both within and between weighings, was very high. The variation in the weight of the ovary probably reflects differences in the laying pattern of individuals. The number of follicles were not affected (P>0.05) by the number of days after mating. Livers were assessed for crude protein and fat, but no difference (P>0.05) was detected between the intervals, but the weight difference amongst the slaughter intervals was significant (P<0.05), suggesting that the ostriches used liver reserves to supplement nutrients that obtained from the diet for the development of the reproductive organs. This data will be used in an optimising model (Brand & Gous, 2006) to predict the nutrient requirements of female breeding ostriches. This study suggests that the female breeding ostrich might need additional protein during the first 7 weeks of the breeding season. Results from Chapter 4 and previous studies were used to calculate the energy, protein and amino acid requirements for the egg production and maintenance of the breeding female ostrich. Two methods were used to determine the energy requirement for egg production. The Metabolisable Energy requirement for egg production (MEe) and efficiency of ME utilization for energy deposition in the egg (ko) was calculated as 12.2 MJ (for an average size egg of 1.4kg) and 0.8 respectively. The Effective Energy requirement for egg production (EEe) and maintenance (EEm) was calculated as 15.9 MJ/day and 17.1 MJ/day respectively. Average total daily protein requirement (TPt) was calculated as 175g day. The amino acid requirements for maintenance and egg production is also provided, which is lower than previous studies. This study also provides evidence that the nutrient requirements are different for every month of the breeding season.
AFRIKAANSE OPSOMMING: Tans heers daar onsekerheid oor die voedingsbehoeftes van volstruis broeivolstruise. Kwantifisering van die voedingsbehoeftes sal ‘n finansiële hupstoot aan die industrie gee. ‘n Groeistudie van die reproduksie-organe en lewer, tesame met ‘n aantal produksie-studies, is uitgevoer om inligting oor die voedingsbehoeftes van volstruis broeivoëls te versamel. Daarby is die voedingsbehoeftes teoreties bereken. ‘n Aantal studies was uitgevoer om die invloed van dieët proteïen en aminosure en energie op produksie-data te bepaal. Eerstens is vyf diëte, wisselend in ru-proteïen (RP) en beperk tot ‘n inname van 2.5 kg/voël/dag, aan broeivolstruise gevoer. Die RP van elke dieët was 7.5%, 9.1%, 10.8%, 12.3% en 14.0%. Die energiewaarde van die voer is konstant by 9.2 MJ ME/kg voer gehou. Geen verskille (P>0.05) was tussen die behandelings waargeneem vir aantal geil eiers (totale eiers geproduseer per voël per seisoen; 8.9±0.8), aantal dood-in-dop (8.0±0.5), aantal kuikens (19.1±1.1) en verandering in massa van wyfies (-16.2±1.6kg) nie. ‘n Neiging (P=0.08) is wel waargeneem vir totale aantal eiers geproduseer. Die gemiddelde en standaard fout was 39.1±3.6. Die 12.3% dieët het tot die laagste verandering (P<0.05) in lewendige massa (-3.8±2kg) vir die mannetjies gelei. Geen interaksie (P>0.05) was tussen die genotipe en dieët proteïen konsentrasie vir beide eier- en kuikenproduksie opgemerk nie. In ‘n tweede studie is ses diëte, variërend in ME (MJ ME/kg voer), by ‘n gemiddelde tempo van 3.4 kg/voël/dag gevoer. Die verskillende ME-vlakke was 7.5, 8.0, 8.5, 9.0, 9.5 en 10.0 MJ ME/kg voer. Geen betekenisvolle verskille (P>0.05) is vir totale eiers geproduseer per voël per seisoen (44.8±7.8), aantal kuikens uitgebroei (15.4±4.1), aantal geil eiers (11.5±3.8), aantal dood-in-dop eiers (12.1±3.2) en massa verandering van wyfies (10.7±3.6kg) opgemerk nie. Die mannetjies het toegeneem in liggaamsmassa (P<0.05) soos daar ‘n toename was in die energievlak van die dieët. Twee eiers per dieët per maand is vir ru-proteïen, vet en spoorelemente, en een eier per diet per maand vir vetsure ontleed. Eiers van die eerste en laaste maand van die seisoen is ontleed vir aminosure. Analise van variansie het aangetoon dat daar geen verskille (P>0.05) bestaan vir die ru-proteïen en vetinhoud van die eiers by die verskillende eksperimentele diëte, asook die kalsiuminhoud van die eierdoppe. Prolien vlakke het tussen die diëte verskil (P<0.05). Die C18:3n-3 (linoleïensuur) inhoud van die eiers het verskil (P<0.05) tussen die dieët behandelilngs. Vir die hoeveelste eier in die lê siklus het die ru-proteïen-, vet- en C18:3n-3 inhoud van die eiers verhoog (P<0.05). In ‘n derde studie is ondersoek ingestel na die voerinname van die broeivolstruise soos moontlik beïnvloed deur die energievlak van die dieët. Gemiddelde voerinname (kg voer/voël/dag) is nie (P>0.05) deur die verskillende dieët energie vlakke van 8.0, 8.7, 9.4, 10.1, 10.8 en 11.5 MJ ME/kg voer beïnvloed nie. Die gemiddelde en standaardfout was 3.7±0.2kg. Die produksie van broeivolstruise nie deur verskillende dieëtvlakke van proteïen en energie by vlakke soos gevoer in hierdie studie geraak nie. Broeivolstruise in hierdie studie het nie die vermoë gehad om hul voerinname te beheer by enige dieët energievlak soos gebruik nie. Die aantal nutriënte wat in die eiers neergelê is, het geen bydrae tot die reproduksievermoë van die wyfie gehad nie. Die studie het verder bewys dat die gemiddelde frekwensie van eier-lê by wyfies onafhanklik was by dieët-energie en -proteïenvlakke (P>0.05) soos in hierdie studie gebruik. In ‘n vierde studie is die groei en ontwikkeling van die reproduksie-organe van die wyfies bestudeer tydens die aanvang van die broeiseisoen. Die hoeveelheid of konsentrasie van voedingstowwe moes bepaal word om die groei van die reproduksie-organe te ondersteun tydens die broeiseisoen, omdat hierdie organe aan eierproduksie gekoppel is. ‘n Studie is derhalwe uitgevoer om te bepaal tot watter mate die reproduksie organe groei en ontwikkel tydens die broeiseisoen. Die eerste slagting is uitgevoer op die dag van afkamp. Die ovaria, ovidukt en lewer is versamel, geweeg en ontleed. Die ovaria en ovidukt is ontleed vir ru-proteïen en vet. Geen verskille (P>0.05) is tussen die verskillende slagtings vir die gewig, ru-proteïen en vetinhoud vir beide organe opgemerk nie. Geen betekenisvolle tendens in die gewig van die ovidukt is waargeneem oor die 49-dae periode nie, maar die gewig was hoogs gekorreleerd met liggaamsmassa. Ovaria-gewig het geneig om gekorreleerd te wees met die aantal dae na afkamp. Variasie binne en buite die gewigte was baie hoog. Die aantal follikels teenwoordig is nie beïnvloed (P>0.05) deur die aantal dae na paring. Die lewers is ontleed vir ruproteïen en vet, maar geen verskille (P>0.05) is tussen die intervalle opgemerk nie, maar die gewigte van dag 0 en 49 na paring het verskil (P<0.05). Dit kan aangevoer word dat die voëls moontlik lewer reserwes gebruik het om die voedingstowwe van die dieët te supplementeer vir die ontwikkeling van die reproduksie-organe. Data uit hierdie studie kan gebruik word in ‘n optimiseringsmodel (Brand & Gous, 2006) om die voedingsbehoeftes van broeivolstruise te bepaal. Hierdie studie beveel aan dat die broeiwyfie moontlik addisionele proteïen tydens die eerste sewe weke van die broeiseisoen benodig. Resultate van Hoofstuk 4 en vorige studies is gebruik om die energie- proteïen- en aminosuurbehoefte vir eierproduksie en onderhoud van broeivolstruise te bereken. Twee metodes is gebruik om die energiebehoefte vir eierproduksie te bereken. Metaboliseerbare Energie behoefte vir eierproduksie (MEe) en effektiwiteit van ME benutting vir energie deponering in eier (ko) is onderskeidelik as 12.2 MJ (vir ‘n eier wat gemiddeld 1.4kg weeg) en 0.8 bereken. Effektiewe Energie behoefte vir eierproduksie (EEe) en onderhoud (EEm) was onderskeidelik as 15.9 MJ/dag en 17.1 MJ/dag bereken. Die gemiddelde daaglikse proteïenbehoefte (TPt) is as 175g proteïen/dag bereken. ‘n Aanduiding van die aminosuur behoefte vir onderhoud en eierproduksie word ook gegee, wat laer is as vorige studies.

English pastoral husbandry has been largely neglected by previous historians. It is generally agreed that the mid-eighteenth century saw a revolution in breeding practices, moving livestock husbandry from hopeless confusion to a controlled, 'scientific' selection for marketable traits. The academicians, mostly economic historians, who have developed this model of pastoral history rely heavily upon farming manuals dating from the fifteenth to the eighteenth centuries for evidence of the changes they claim to perceive. Agricultural manuals are complex literary documents. However, in the current historiography, the manuals are quoted as simple records of contemporaneous agricultural practice, the intricacies of authorship, audience and motive for publication being almost entirely ignored. A critical survey of the manuals which deal with pastoral husbandry beginning with the thirteenth, rather than the fifteenth, century reveals flaws in the use which has been made of the manuals and, therefore, in the conclusions which have been drawn from them. In order to accomplish a reconsideration of English pastoral husbandry, it is necessary to reincorporate the extant medieval farming manuals and to examine all didactic agricultural texts as representative of a single genre. Discussion of livestock husbandry was carried out in terms of generation and nutrition of animals. Therefore, any intimations of procedural changes or scientific influence upon breeding and feeding in the discussions of manuals which deal most extensively with pastoral husbandry should be noted as of particular interest. Finally, the manuals must be considered within a social context. It is here that the interaction of science and agriculture becomes particularly important, though as a tool for understanding the manuals as documents rather than solely as the motor for late eighteenth-century changes in livestock husbandry. Such an analysis reveals an amazing continuity of actual information in the agricultural manual genre. There are no changes in the depictions of practices of breeding and feeding. However, especially in the late seventeenth and eighteenth century texts, a preoccupation with attracting the attention of institutional science, particularly the Royal Society, emerges as a new trend. Yet there is no indication in the textual record that livestock husbandry was ever affected by 'Natural Philosophy'. Far from simply recording contemporary practice, agricultural manuals, especially those which expressed a desire to ally with institutional science, reveal themselves more as vehicles for their authors' social aspirations than as exemplars of agricultural practice. Once this is recognized, the prevailing models of pastoral husbandry lose credibility. Eighteenth-century animal breeding was no more nor less 'scientific' or intellectually sophisticated than preceeding breeding programs. In short, the use of farming manuals to corroborate economic models of agrarian development has been, at best, somewhat spurious. Studying livestock husbandry and its relationship to institutional science in medieval and early modern England can be peculiarly helpful in assisting to rectify this error.
Arts, Faculty of
History, Department of
Graduate

Methods of superovulation, embryo recovery and embryo transfer were adapted and developed for application to Welsh Black cattle in a Group Breeding scheme. Three methods of oestrus detection in early postpartum suckling beef cows were evaluated. None was entirely reliable although a probe for the measurement of the electrical resistance of vaginal mucus was the most effective and the least stressful. The postpartum interval to superovulation did not affect the responses to treatment. The effect of suckling on embryo quality from superovulated Welsh Black cows was investigated. Three groups of cows (one dry and two suckling) were superovulated and their embryos recovered in two seasons; summer and autumn. Significant effects of season (P=O.016) and suckling (P=O.015) on embryo quality were detected. Season significantly affected the number of viable embryos (P=O.004). There were no effects on ovarian responses or on the numbers of embryos recovered. Nutritional supplementation and the administration of heG failed to improve embryo quality. Examination of the data from three years of superovulation and embryo recovery revealed significant monthly variations in % viable embryos (P=O.006) and in the numbers of viable embryos (P=O.02) recovered. Embryo recovery was not affected by the catheter used or by the side of uterus being flushed. The number of pari ties of the donor affected the ovulation rate (P=O.009) and the numbers of embryos recovered (P=O.028) but not the embryo recovery rate (%). No differences were detected in the superovulatory responses of cows bred by 3 methods nor from the method of oestrus synchronisation. Embryo transfers were performed by surgical and nonsurgical methods. Fresh and frozen embryos were successfully transferred by the surgical technique but no embryos transferred nonsurgically continued development. A measurement of cervical diameter was successful in identifying animals which were unsuitable for non-surgical embryo transfer and recovery procedures. n-Alkanes as nutritional markers for intake estimation were applied'to cattl~ in a performance test and to cows at pasture. The results obtained indicate that the method may be useful in the future development of selection methodologies for beef cattle. The findings of both series of investigations are discussed in relation to beef cattle improvement through Group Breeding schemes.

PALA, AKIN. Effects of Three Twice-a-Year Breeding Schedules in Four Breeds of Sheep. (Under the direction of ODIS WAYNE ROBISON and ROGER LEE McCRAW).Straightbred populations of Dorset, Finnsheep, Composite I (50% Finnsheep, 25% Dorset, and 25% Rambouillet), and Composite II (50% Finnsheep, 25% Suffolk, and 25% Targhee) sheep were evaluated under three different twice-a-year breeding schedules. Ewes were exposed for 32 d starting on August 13 and February 5 for schedule I, on September 15 and March 10 for schedule II, and on October 22 and April 11 for schedule III. Approximately 100 ewes of each breed were exposed to rams during each breeding season. The experiment was conducted for five complete cycles starting with matings in the fall of 1984 and ending with matings in the spring of 1989. Data were obtained on 9419 lambs produced from 2334 ewes and 257 rams. Traits of primary interest were conception rate, litter size at birth, weaning weight, weaning weight adjusted for conception rate, litter weaning weight and litter weaning weight per ewe exposed. Lactation status had a significant effect on conception rate and litter size while number of lambs suckling did not have a significant effect on conception rate. Composite I ewes had the highest conception rates and litter size (P 0.10), both had larger litters (P < 0.01) than the other two breeds. Ewes giving birth in spring had the highest conception rate and heaviest lambs (P < 0.01). Animals bred in schedule I had the heaviest and largest litters, highest conception rate, heaviest lambs and highest litter weaning weight per ewe exposed (P < 0.01). Efficiency of twice-a-year lambing systems is greatly affected by breeds, breeding schedules and seasons. Twice-a-year lambing programs must use the correct breeding schedule. Further, using composite breeds can be of great benefit.Genetic parameters for conception rate, litter size at birth, weaning weight, weaning weight adjusted for conception rate, litter weaning weight and litter weaning weight per ewe exposed were estimated using REML with animal models. Heritability estimates for conception rate were adjusted to a normal scale. Standard errors of heritabilities for conception rate were calculated using three methods, including bootstrapping. Heritabilities were estimated overall and within breed. Estimates of heritability for conception rate ranged from 0.17 ± 0.01 (Dorset) to 0.27 ± 0.01 (Composite I). Heritability estimates for litter size were 0.08 ± 0.01, 0.19 ± 0.01, 0.14 ± 0.01 and 0.13 ± 0.01 for Dorset, Finnsheep, Composite I and Composite II, respectively. Heritabilities for litter weaning weight and litter weaning weight per ewe exposed were similar across breeds and ranged from 0.31 ± 0.01 to 0.36 ± 0.01. Heritability for weaning weight was higher for Dorset (0.65 ± 0.01) than for Composite I (0.57 ± 0.01). Finnsheep and Composite II had similar heritabilities (0.41 ± 0.01). Overall heritabilities for litter weaning weight, litter weaning weight per ewe exposed, weaning weight, weaning weight adjusted for conception rate, conception rate and litter size were 0.33 ± 0.02, 0.35 ± 0.01, 0.64 ± 0.01, 0.64 ± 0.01, 0.24 ± 0.01 and 0.16 ± 0.01, respectively. Overall Spearman rank-order correlations of litter weight traits with conception rate or litter size ranged from 0.81 to 0.88. Correlations within breed were generally high and positive. Genetic correlations between dry and lactating ewes for conception rate and litter size were small (0.009 and 0.108, respectively), indicating that rank of sires was inconsistent under different environments (lactation status). Selection should be practiced among lactating animals for conception rate and litter size in twice-a-year lambing systems.Heritability estimates were moderate to high for weight traits and low to moderate for reproduction traits, indicating that selection in twice-a-year lambing programs is feasible. There was no substantial evidence that heritabilities and rank correlations were different among the four breeds. Litter weaning weight may be increased along with conception rate and litter size in a selection program based on twice-a-year lambing. Small genetic correlation between dry and lactating ewes indicated that grouping sires according to the lactation status of the ewes is necessary in a selection program.

Recent policies on the ban of fishing discards and the closure of open-air landfills are expected to reduce amount of predictable anthropogenic food subsidies (PAFS) for seabirds. To forecast the ecological consequences of these policies, it is necessary to understand the influence that each of these resources has on ecological parameters and how this can be mediated by density-dependent mechanisms. Besides, for those species exploiting both types of resources, it is important to consider whether or not their effects act synergistically. Finally, it is also important to understand how the ecological interactions between seabirds and PAFS can be influenced by other potentially important environmental factors, such as for example, the abundance of natural prey or the one of foraging conditions. In the first chapter of this thesis, I reviewed the current knowledge on the ecological interactions between seabirds and fishery discards, with the aim of identifying the main knowledge gaps and to propose new challenges to improve our understanding of the ecological role of PAFS availability to seabirds. In the second chapter, I assessed the relative role of fishery discards and open-air landfills in the breeding investment of a generalist seabird, investigating the possible interplay with density-dependent mechanisms. In the third chapter I collaborated to investigate the role of PAFS in buffering environmental stochasticity and disrupting the natural synchronous dynamics between two seabirds. Finally, in the last chapter, I assessed the importance of several environmental factors in the breeding investment of three seabirds with contrasting life-history strategies. In particular, I considered local environmental variables (food abundance, competition and sea state) during breeding as well as the influence of winter conditions summarized by a large-scale climatic index, the North Atlantic Oscillation (NAO). Considering these variables simultaneously allowed me to assess the relative importance of natural and anthropogenic food resources, intra- and inter-specific competition and foraging conditions in the form of detectability and accessibility of food. This thesis shows that the main knowledge gaps on seabird-discard ecological interactions are related to survival, dispersal and reproduction, the resilience of their populations against perturbations and the role of individual specialization in the foraging process. Results showed that both fishery discards and open-air landfills can significantly increase seabirds’ breeding investment. However, the landfill effect was weaker than the effect of fishing discards, probably due to the lower quality of waste as food resource. It is also shown that these effects can be masked by density-dependence processes. In addition, the thesis highlights the importance of considering the possible influence of socio-economic factors on the availability of these PAFS depending on the geographic area considered. I showed that PAFS can alter natural stochasticity, increasing the breeding investment of generalist species, which in turn, may alter the community structure. Finally, this thesis makes evident that foraging conditions in the form of detectability and accessibility of food can play a very important role in key demographic parameters such as breeding investment. This implies that in contrast to what is commonly assumed, food abundance does not directly translate into food intake. Finally, the results also suggest that the influence that the winter North Atlantic Oscillation has on breeding investment in some seabirds is limited to winter months and acts in spring as a ‘carry-over’ effect of winter conditions.
Las recientes políticas en materia de prohibición de descartes y cierre de vertederos, supondrán una importante reducción de la disponibilidad de los recursos antropogénicos predecibles (PAFS) para las aves marinas. Para entender mejor las consecuencias ecológicas de esta reducción y proponer nuevos retos futuros, en esta tesis se revisa el conocimiento actual sobre las interacciones ecológicas que se dan entre las aves marinas y los descartes de la pesca. Por otra parte, también se evalúa cómo los PAFS y otros factores ambientales influyen en la inversión que las aves marinas hacen en la reproducción. Los resultados muestran que los principales vacíos de conocimiento en relación a las interacciones entre aves marinas y descartes, son los relacionados con la supervivencia, la dispersión, la reproducción, la resiliencia de las poblaciones frente a las perturbaciones y la especialización individual en el proceso de forrajeo. También se muestra que tanto los descartes de la pesca como la basura de los vertederos incrementan la inversión en la reproducción. Sin embargo, este efecto es menos marcado en los vertederos, probablemente debido a su menor calidad como recurso alimentario. También se ha observado que estos efectos pueden quedar enmascarados por procesos de densodependencia. La tesis también demuestra la importancia de considerar los factores socioeconómicos al evaluar la disponibilidad de los PAFS, dependiendo del área geográfica considerada. También se muestra que los PAFS pueden alterar la estocasticidad natural, incrementando la inversión en reproducción en especies generalistas, lo cual puede alterar la estructura de la comunidad. También se muestra cómo los factores ambientales que condicionan la detectabilidad y accesibilidad del alimento pueden jugar un papel muy importante en la inversión en la reproducción. Esto implica que el hecho de que el alimento sea abundante, no implica que esté disponible para los organismos. Finalmente, los resultados también sugieren que la influencia de la Oscilación del Atlántico Norte en la inversión en la reproducción de algunas aves marinas, se limita a los meses de invierno y se manifiesta en primavera en forma de efectos de tipo carry-over.

Doctor of Philosophy
Department of Animal Sciences and Industry
KC Olson
The objective of this series of studies was to develop and improve methods of production in cow/calf operations of the Great Plains. Ultrasound measures of longissimus muscle depth (LMD) and intramuscular fat (IMF) of Angus × heifers were used to predict lifetime cow productivity. IMF and LMD were categorized into high, medium, and low groups (IMFG and LMDG, respectively). Cows in the high and medium LMDG had greater (P < 0.05) pregnancy rates than cows in the low LMDG. Calf BW at weaning increased (P < 0.05) as dam IMF increased. Angus crossbred cows grazing native range were used to evaluate the effects of pre-partum ruminally-protected choline (RPC) supplementation on postpartum beef cow and calf performance. Under the conditions of our study, RPC supplementation had minimal (P > 0.05) effects on pregnancy rates and performance of beef cows and calves. Lactating crossbred cows with calves and non-pregnant, non-lactating Boer-cross nannies were used to evaluate the effects of co-grazing on herbivory patterns and animal performance while grazing native tallgrass rangeland infested heavily by sericea lespedeza (SL). The proportion of individual SL plants that had been grazed at the end of the trial was greater (P < 0.01) in co-grazed pastures than in single-species pastures. Grazing cows and goats in combination increased (P < 0.01) grazing pressure on SL without negatively affecting beef cow performance, beef calf performance, or residual forage biomass. Angus × cows and heifers grazing native range were used to evaluate the effects of pre-partum corn steep liquor supplementation on postpartum beef cow and calf performance. Under the conditions of our study, CSL supplementation did not generally promote beef cow and calf performance that was equivalent to supplementation with an isonitrogenous, dry, corn-soy alternative. Cow calf pairs were used to evaluate the effects of grazing system (GS) and stocking rate (SR) on cow and calf performance. Late season rest-rotation (LSRR) was compared with continuous (CONT) grazing at low, moderate, and high SR. Under the conditions of our study, CONT produced consistently better (P < 0.01) late-season cow and calf performance than LSRR. Season-long effects of SR on animal performance were minimal; moreover, GS and SR treatments produced equivalent pregnancy rates.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
No primeiro capitulo, foi proposto um estudo de associação genômica para curvas de crescimento de suínos utilizando modelos hierárquicos Bayesianos. Utilizou-se um painel de 237 marcadores SNPs conjuntamente com informações de pedigree objetivando identificar possíveis regiões cromossômicas que afetam os parâmetros da curva de crescimento (dados de peso-idade) de 345 animais (população F2 proveniente do cruzamento Piau vs comercial). Assumiu-se uma trajetória de crescimento individual descrita pela função não linear de Gompertz, de forma que as estimativas de cada parâmetro desta função são influenciadas pelos efeitos sistemáticos, poligênicos aditivos e de marcadores SNPs. O modelo combinando informações de pedigree e marcadores apresentou o melhor ajuste com base no critério de informação da deviance (DIC). As estimativas de herdabilidade variaram de 0,53 a 0,56, e de 0,55 a 0,57 para os parâmetros peso a maturidade (a) e taxa de maturidade (k), respectivamente. A correlação genética entre os parâmetros “a” e “k” foi alta e positiva (0,78). As porcentagens das variâncias genéticas explicadas por cada SNP permitiram identificar as regiões cromossômicas mais relevantes para cada fenótipo (parâmetros da curva de crescimento). Foram identificados três SNPs relevantes (55840514 bp no SSC17, 55814469 bp no SSC17 e 76475804 bp no SSC X) que influenciaram, simultaneamente, os parâmetros “a” e “k”. Também foram reportados três SNPs afetando apenas “a” (292758 bp no SSC1, 67319 bp no SSC8 e 50290193 bp no SSC17) localizados em regiões cromossômicas que ainda não foram previamente descritos como QTL para características de crescimento em suínos. A modelagem utilizada foi efetiva, e resultou na identificação de marcadores SNPs localizados em regiões cromossômicas específicas que apresentam potencial para serem exploradas em programas de melhoramento via seleção assistida por marcadores. No segundo capítulo, comparou-se as metodologias baseadas na utilização de dados censurados de idade ao primeiro parto (IPP) em bovinos Brahman por meio da abordagem Bayesiana. Os dados foram cedidos pela Associação Brasileira dos Criadores de Zebu (ABCZ). Registros censurados foram definidos como valores de IPP que extrapolaram o intervalo entre 731 e 1824 dias. Os registros de IPP (no total de 53.703 informações) foram analisados por meio de quatro diferentes metodologias: método linear convencional (LM); de simulação (SM); de penalidade (PM) e modelos bicaracterístico limiar-linear (TLcens). Os componentes de variância genética aditiva estimados para os métodos LM e PM foram similares. As estimativas de herdabilidade para IPP variaram de 0,09 (TLcens) à 0,20 (LM). De forma geral, as correlações entre os valores genéticos obtidos por meio das diferentes metodologias e a porcentagem de animais selecionados em comum variaram de 0,82 (LM x SM) à 0,97 (LM x PM), e de 32,70% (SM x TLcens) à 89,12% (LM x PM), respectivamente, indicando reordenamento moderado entre os animais. As comparações realizadas via validação cruzada indicaram o método LM como a melhor opção para predição dos valores genéticos dos animais para a característica IPP na população estudada. No terceiro capítulo, foram estimados os parâmetros genéticos para características de escores visuais de estrutura (S), precocidade (P), musculosidade (M) e reprodutiva (idade ao primeiro parto - IPP) em bovinos da raça Brahman utilizando modelos Bayesianos multicaracterístico completo e bicaracterísticos. As estimativas de herdabilidade utilizando o modelo bicaracterístico foram 0,59 (S), 0,44 (P), 0,38 (M) e 0,20 (IPP), e utilizando o modelo multicaracterístico completo foram 0,60 (S), 0,44 (P), 0,40 (M) e 0,20 (IPP). As correlações genéticas foram 0,57 entre estrutura e precocidade, 0,56 entre estrutura e musculosidade e 0,82 entre precocidade e musculosidade no modelo x multicarcterística completo. As correlações genéticas entre os escores visuais e IPP foram de moderada magnitude e negativas (-0,29, -0,24 e -0,31 para S, P e M utilizando o modelo de bicaracterístico) e (-0,29, -0,22 e -0,29 para S, P e M utilizando o modelo multicaracterístico completo). Os resultados indicam que os escores visuais podem ser utilizados como critérios de seleção em programas de melhoramento de bovinos Brahman e que essas características apresentam correlação genética favorável com a idade no primeiro parto.
In the first chapter, we proposed a genome association study for pig growth curves based on Bayesian hierarchical framework. A panel of 237 SNPs markers with the pedigree were used jointly to identify possible chromosomal regions that affect growth curve parameters (weight-age data) of 345 animals (F2 population from the Piau vs. commercial). Under the proposed hierarchical approach, individual growth trajectories were modeled by the nonlinear Gompertz function, so that the parameter estimates were considered to be affected by systematic, additive polygenic and SNP markers effects. The model assuming jointly pedigree and SNP markers presented the best fit based on Deviance Information Criterion. Heritability estimates ranged from 0.53 to 0.56 and from 0.55 to 0.57, respectively, for the parameters mature weight (a) and maturing rate (k). Additionally, we found high and positive genetic correlation (0.78) between “a” and "k". The percentages of the genetic variances explained by each SNP allowed identifying the most relevant chromosome regions for each phenotype (growth curve parameters). We identified three relevant SNPs (55840514 bp at SSC17, 55814469 bp at SSC17 and 76475804 bp at SSC X) affecting "a" and "k" simultaneously, and three SNPs affecting only "a" (292758 bp at SSC1, 67319 bp at SSC8 and 50290193 bp at SSC17), that are located in regions not previously described as QTL for growth traits in pigs. The modeling used was effective, and resulted in the identification of SNPs located in specific chromosomal regions that have the potential to be explored in breeding programs by marker-assisted selection. In the second chapter, we compared different methods for handling censored data of age at first calving (AFC) in Brahman cattle by Bayesian vii models. Data were provided by Brazilian Association of Zebu Cattle Breeders (ABCZ). Censored records were defined as AFC records outside the interval from 731 to 1824 days. Data containing 53,703 AFC records were analyzed using four different methods: conventional linear method (LM), simulation method (SM), penalty method (PM) and a bitrait threshold-linear model considering (TLcens). The additive genetic variance components estimated from LM and PM were similar. Heritability estimates for AFC ranged from 0.09 (TLcens) to 0.20 (LM). In general, genetic breeding values correlations from different methods and the percentage of selected animals in common indicated moderate reranking, ranging from 0.82 (LM x SM) to 0.97 (LM x PM) and 32.70 (SM x TLcens) to 89.12 (LM x PM), respectively. Comparisons based on cross-validation analyses, indicated LM as a suitable alternative for predicting breeding values for AFC in this Brahman population. In the third chapter, we estimated genetic parameters for visual scores of body structure (S), precocity (P), muscularity (M) and reproductive (age at first calving - AFC) traits in Brahman cattle by using Bayesian bitrait and full multitrait models. The heritability estimates obtained using bitrait model were 0.59 (S), 0.44 (P), 0.38 (M), and 0.20 (AFC) and those obtained by full multitrait model were 0.60 (S), 0.44 (P), 0.40 (M) and 0.20 (AFC). Genetic correlations were 0.57 between body structure and precocity, 0.56 between body structure and muscularity and 0.82 between precocity and muscularity (by full multitrait model). Genetic correlations between visual scores and AFC were negatives and moderate magnitude (-0.29, -0.24 and -0.31 to S, P and M by bitrait model) and (-0.29, -0.22 and -0.29 to S, P and M by full multitrait model). These results suggest that visual scores can be used as selection criteria in Brahman cattle breeding programs and that these traits present favorable genetic correlation with age at first calving.

Thesis (Ph.D.)--Tufts University, 2003.
Adviser: J. Michael Reed. Submitted to the Dept. of Biology. Includes bibliographical references (leaves 124-134). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

A study of the inbreeding of UK Holstein cows was undertaken to assess the current levels and trends in inbreeding in this breed. Results showed that inbreeding has increased at a rate of 0.17% per year and it continues to increase in a linear fashion. Optimisation procedures, which have been developed to maximise the rate of genetic gain at a predefined rate of inbreeding, were applied to determine is such procedures would be useful in a dairy cattle context. The results showed that the procedures were able to generate more genetic gain at current rates of inbreeding or alternatively to reduce the rate of inbreeding at the current rate of genetic gain. Many resources have been devoted to the mapping of quantitative trait loci (QTL) of economic importance in most domestic livestock species. In the thesis a method is described to assess the benefits of using DNA tests at the commercial herd level. This method can be used for a variety of situations and two case studies were examined to illustrate the usefulness of the method. The first study dealt with the situation in which a breeder chooses to use a sire that is a carrier for a deleterious allele. The second case dealt with the availability of a DNA test for the A2 variant of the casein milk protein for which a premium is paid. Through a stochastic simulation, it is shown that pleiotropic QTL can result in a QTL segregating at constant frequencies in a population when the estimated polygenic correlation is zero.  This has important implications when, for example, the traits under consideration are production and disease-type traits. Various selection strategies were investigated to determine genetic gain and changes in allele frequency when the underlying genetic model for the QTL was different in both traits.

Abstract This literary review is focused on how conservation breeding programs may influence an animal’s behaviour and communication and if this may affect reintroduction. The expansion of the human population is an increasing threat to all wild animals and their habitats. Animals are forced to survive in smaller areas and the worst case scenario is extinction. Animals communicate with each other using various types of signals to transmit information about their reproductive status, intentions, identity and their state of mind. Sexual selection can benefit these traits which improves the reproductive success in animals. In male species sexual dimorphisms have evolved to enhance a greater reproductive success, whilst secondary sexual characteristics are described as an exaggerated feature which improves success in the forms of body size, skin colour and weaponry. Zoos are being encouraged to conserve endangered species with the hope of a possible reintroduction to their native environment and it is therefore essential that zoo managers have an understanding of the species specific behaviour in order to achieve a higher reproductive success. The breeding of endangered animals in captivity provides a healthy population growth and a higher survival rate than that of their wild conspecifics. Negative impacts that can occur in captive breeding include a reduction in genetic diversity, domestication, inbreeding and a loss of fitness. When provided with enclosures that are designed to resemble their natural environment, thus allowing them to perform natural behaviours, there is a decrease in stereotypes and stress. Environmental enrichment can also provide the essential skills that are needed for their survival when reintroduced into their native habitat. I discovered that when provided with the appropriate management and enclosures animals showed a decrease in abnormal behaviour and an increase in fitness and health which influenced reproductive success.
Den här litteraturstudien är fokuserad på hur bevarandeavelsprogram påverkar ett djurs beteende och dess kommunikation och om de kan påverka återintroduktion. Befolkningsökningen är ett växande hot mot alla vilda djur och deras livsmiljöer. Detta medför att de tvingas överleva på mindre områden och det värsta tänkbara scenariot är utrotning. Djur kommunicerar med varandra med hjälp av olika typer av signaler för att förmedla information om deras reproduktiva tillstånd, avsikter, identitet och sinnestillstånd. Sexuell selektion kan gynna de egenskaper som medför en ökad reproduktion hos djur. Hos hanar har könsdimorfism utvecklats för att förbättra reproduktionsframgång, medan sekundära könskaraktärer beskrivs som en överdriven funktion som förbättrar framgången i form av kroppsstorlek, hudfärg and vapen. Djurparker uppmuntras att bevara hotade arter med hopp om en eventuell återintroduktion till sitt naturliga habitat, och det är därför viktigt att det finns en förståelse för artens specifika beteende i syfte att uppnå en högre reproduktiv framgång. Aveln av utrotningshotade djur i fångenskap medför en välmående populationstillväxt och en större överlevnad jämfört med sina vilda artfränder. Negativa effekter som kan uppstå i bevarandeavel är en minskning av den genetiska mångfalden, domesticering, inavel och en nedgång i fitness. När djur förses med inhägnader som är utformade att likna deras naturliga miljö, vilket tillåter dem att utföra naturliga beteenden, sker det en minskning i stereotyper och stress. Miljöberikning kan även förse djuren med de väsentliga färdigheter som krävs för överlevnad när de återintroduceras till deras naturliga habitat. Jag upptäckte att när djuren var försedda med en lämplig skötsel och inhägnad visades en minskning i avvikandebeteende och en ökning av fitness och hälsa vilket påverkade den reproduktiva framgången.

Two sheep group breeding schemes were considered in this study to examine the genetic progress made over a 20 year period and the success of running such schemes in practice. The data were records of lamb weaning weight in the CAMDA scheme (Welsh Mountain breed) and the Lleyn scheme (Lleyn breed), collected between 1976 and 1996. After the edits, a total of 31,161 records for the CAMDA and 29,090 records for the Lleyn scheme were available for the analyses. The estimates of the heritability of weaning weight for individual flocks were low to moderate. In the CAMDA scheme, the estimates of the direct and maternal heritability values ranged from 0.04 to 0.43, and 0.03 to 0.11, respectively. The ratio of temporary environmental variance over the total variance ranged between 0.13 to 0.35. The estimates of total heritability values in flocks of 12 and 18 weeks of age were in the range of 0.23-0.45 and 0.07-0.18, respectively. In the Lleyn scheme, the estimates of the ratio of temporary environmental variance over the total variance, and the direct and maternal heritability values ranged from 0.15 to 0.39, 0.03 to 0.31, and 0.04 and 0.23, respectively. The estimates of the total heritability values in individual flocks of the scheme ranged from 0.07 to 0.33. The differences in heritability values between the flocks, reflected the differences in the model of analysis fitted, and size and structure of the data available for individual flocks of the scheme. It is concluded that group breeding schemes are a viable means of improving the production of traits of a breed, but that more attention should be paid in the setting up of the schemes, to a scoring system which will accurately reflect the market value of the stock. The application of group breeding schemes in Iran would require taking account of the differences in the social and climatic environments. Much greater attention would be needed to determine the selection objectives and these would need to be properly included in the selection index.

This PhD dissertation is framed on a line of research aimed at improving pork quality and, particularly, intramuscular fat (IMF) and monounsaturated fatty acid (MUFA) content as two of the main traits affecting nutritional and sensorial pork attributes. Several strategies have been investigated to enhance IMF and MUFA without increasing the rest of fat depots, but one of the most promising approaches is to find out genetic markers specifically associated to them. There is a variant in the promoter of the stearoyl-CoA desaturase (SCD) gene (AY487830:g.2228T>C used as tag single nucleotide polymorphism) that specifically enhances MUFA. This polymorphism localizes in the core sequence of a putative retinoic acid response element. The primary objective of the thesis was to assess the impact of this SCD polymorphism in different production and commercial scenarios. The thesis comprises four studies. The first one was intended to show whether the effect of this SCD polymorphism is maintained at different market carcass weights. The second and third study examined whether the effect of the SCD polymorphism is still evident in dry-cured products from purebred Duroc and Duroc-sired Iberian crossbreds, respectively. The fourth study investigated the impact of carotenoid intake as a source of dietary retinoic acid on IMF and MUFA in pigs from opposite genotypes at the SCD gene polymorphism. Four experiments, one per objective, were designed. The first consisted of a series of 1-4 repeated samples of m. longissimus thoracis and subcutaneous fat of 214 Duroc barrows collected at 160, 180, 210 and at 220 days of age. The second and third experiments were based, respectively, on 125 dry-cured hams from purebred Duroc pigs (53 traced throughout curation and 72 randomly sampled) and on 74 dry-cured hams from Duroc × Iberian pigs (taken from sliced trays randomly purchased from the same supplier). Dry-cured hams were from barrows and gilts. The fourth experiment consisted of 32 Duroc barrows which were allocated in a 2 x 2 split-plot design consisting of two finishing diets (from 165 to 195 days of age) differing in pro-vitamin A carotenoid content and the two SCD homozygotes. The diets were identical except the corn line used in the feed. The carotenoid-rich diet was formulated with 20% of a carotenoid-fortified corn while the carotenoid-restricted diet used instead 20% of its near isogenic line, which did not contain pro-vitamin A carotenoids. The positive effect of the T allele at the SCD gene on fat desaturation and MUFA content was confirmed throughout the growing-finishing period and after the curing process on both purebred Duroc and Duroc × Iberian dry-cured hams. A strong relationship between MUFA in green and dry-cured samples was found, with TT pigs being more effective in retaining increased MUFA in green hams until the end of the curing period. Moreover, the SCD polymorphism had a greater impact on MUFA than using hams from barrows instead of gilts. The results of the last experiment indicated that pigs fed with the carotenoid-rich diet had 2.8-fold more retinoic acid and 4.5-fold more SCD gene expression in liver, around one fifth less fat and MUFA in liver and one third less IMF in m. gluteus medius. The TT genotype at the SCD gene increased MUFA in all tissues. Liver fat and MUFA content declined non-linearly with liver all-trans retinoic acid, suggesting a saturation point at relatively low all-trans retinoic acid content. The results obtained support that a pro-vitamin A carotenoid restricted diet at finishing and the TT genotype at the SCD gene complement well each other to simultaneously increase IMF and MUFA without increasing total fat content. The leptin receptor (LEPR) NM_001024587:g.1987C>T polymorphism was also segregating in Duroc, with the T allele positively affecting IMF and the saturated fatty acid (SFA) content. Selection for the SCD T allele, particularly in combination with selection for the LEPR C allele, is confirmed as a good strategy to enhance the MUFA/SFA ratio and therefore to produce healthier meat.
Aquesta tesi doctoral s'emmarca en una línia d'investigació dirigida a millorar la qualitat de la carn de porc i, principalment, el greix intramuscular (IMF) i els àcids grassos monoinsaturats (MUFA), per ser dos dels principals trets que afecten els atributs nutricionals i sensorials del porc. S'han investigat diverses estratègies per millorar IMF i MUFA sense augmentar la resta dels dipòsits de greix, i una de les més prometedores és la de trobar marcadors genètics associats específicament a ells. Hi ha una variant en el promotor del gen de la estearoil-CoA desaturasa (SCD) que millora específicament MUFA (AY487830: g.2228T> C, polimorfisme d'un sol nucleòtid utilitzat com a marcador de referència). Aquest polimorfisme es localitza en la seqüència central d'un putatiu element de resposta a l’àcid retinoic. L'objectiu principal de la tesi va ser avaluar l'impacte del polimorfisme SCD en diferents escenaris de producció i comercials. La tesi consta de quatre estudis. El primer tenia per objectiu mostrar si l'efecte del polimorfisme SCD es manté a diferents pesos comercials de la canal. El segon i tercer estudi es dedicaren a examinar si l'efecte del polimorfisme SCD és fa encara evident en productes curats de raça pura Duroc i en els seus creuaments amb Ibèric, respectivament. En el quart estudi es va investigar l'impacte de la ingesta de carotenoides, com a font d'àcid retinoic en la dieta, sobre IMF i MUFA en porcs de genotips oposats en el polimorfisme del gen SCD. Es van dissenyar quatre experiments, un per cada objectiu. El primer experiment consistí en un a sèrie de fins a 4 mostres repetides de m. longissimus thoracis i de greix subcutani presses a 160, 180, 210 i en 220 dies d'edat en 214 mascles castrats Duroc. El segon i tercer experiments es van basar, respectivament, en 125 pernils curats de porcs Duroc de pura raça (53 traçats des de fres fins el final de la curació i 72 escollits a l’atzar) i en 74 pernils curats procedents d’un encreuament Duroc × Ibèric (presos de safates de pernil llescat comprades a l'atzar del mateix proveïdor). Els pernils curats provenien de mascles castrats i femelles. El quart experiment va consistir en 32 mascles castrats Duroc disposats segons un disseny split-plot 2 x 2, amb dues dietes de finalització (des de 165 a 195 dies d'edat) que diferien en el contingut de provitamina A carotenoide i els dos homozigots SCD. Les dietes van ser idèntiques, excepte en la línia genètica de blat de moro utilitzat en el pinso. La dieta rica en carotenoides es va formular amb un 20% de blat de moro fortificat amb carotenoides, mentre que la dieta control va incloure en el seu lloc un 20% de blat de moro d’una línia quasi isogènica sense carotenoides precursors de provitamina A. Els resultats obtinguts confirmen que l'efecte positiu de l'al·lel T del gen SCD sobre la dessaturació del greix i el contingut de MUFA es manté durant tot el període de creixement i d'acabat i al final del procés de curació, tant en els pernils Duroc com en els Duroc × Ibèric. S’ha posat en evidencia una forta relació entre el contingut de MUFA en el pernil fresc i curat, de tal manera que els porcs TT són més eficaços retenint els MUFA fins al final del període de curació. D'altra banda, el polimorfisme SCD ha tingut un major impacte sobre MUFA que la utilització de porcs castrats en lloc de femelles per la producció de pernil. Els porcs alimentats amb una dieta enriquida en carotenoides mostraren 2.8 vegades més àcid retinoic i 4.5 vegades més expressió del gen SCD en fetge, aproximadament un cinquè menys de greix i MUFA en el fetge i un terç menys de IMF en m. gluteus medius. El genotip TT del gen SCD ocasionà un augment de MUFA en tots els teixits. El greix del fetge i el contingut de MUFA disminuïren de forma no lineal amb l'àcid holo-trans retinoic del fetge, el que suggereix l’existència d’un punt de saturació a un nivell relativament baix d'àcid holo-trans retinoic. Els resultats obtinguts han posat de manifest que els efectes d’una dieta restringida en carotenoides precursors de la vitamina A i el genotip TT del gen SCD es complementen bé per augmentar simultàniament IMF i MUFA sense variar el contingut de greix total. S’ha observat que el polimorfisme NM_001024587: g.1987C> T del gen del receptor de la leptina (LEPR) també segrega en Duroc, amb l'al·lel T afectant positivament IMF i el contingut d'àcids grassos saturats (SFA). La selecció a favor de l'al·lel T del gen SCD, particularment en combinació amb la selecció a favor de l'al·lel C de LEPR, es confirma com una bona estratègia per millorar la relació MUFA / SFA i per tant la producció de carn més saludable.
La presente tesis doctoral se enmarca en una línea de investigación dirigida a mejorar la calidad de la carne cerdo y, en particular, su contenido de grasa intramuscular (IMF) y ácidos grasos monoinsaturados (MUFA) al ser dos de los principales caracteres que afectan atributos tanto nutricionales como organolépticos de la carne. A la fecha, diversas estrategias han sido investigadas para mejorar IMF y MUFA sin aumentar el resto de depósitos grasos de la canal, siendo uno de los enfoques más prometedores el encontrar marcadores genéticos asociados específicamente a dichos caracteres. Existe una variante en el promotor del gen de la estearoil-CoA desaturasa (SCD) (AY487830: g.2228T>C ha sido utilizado como polimorfismo de un solo nucleótido de referencia) que mejora MUFA. Este polimorfismo se localiza en el núcleo de la secuencia de un elemento de respuesta putativo al ácido retinoico. El objetivo principal de la tesis fue evaluar el impacto del polimorfismo SCD en diferentes escenarios productivos y comerciales. La tesis está compuesta por cuatro estudios. El primero tuvo como objetivo evaluar si el efecto del polimorfismo SCD se mantiene a diferentes pesos comerciales. El segundo y tercer estudio examinaron si el efecto del polimorfismo SCD es evidente en jamones curados de raza pura Duroc y de Ibéricos cruzados con Duroc. El cuarto estudio investigó el impacto de la ingesta de carotenoides, como fuente de ácido retinoico en la dieta, sobre IMF y MUFA en cerdos de genotipos opuestos para el polimorfismo SCD. Para cada objetivo se diseñó un experimento. El primero consistió en un muestreo repetido (de 1 a 4) de m. longissimus thoracis y grasa subcutánea a las edades de 160, 180, 210 y 220 días en 214 machos castrados Duroc. El segundo y tercer experimento se basaron en 125 jamones curados de cerdos Duroc de raza pura (53 rastreados a lo largo de la curación y 72 muestreados al azar) y en 74 jamones curados Duroc × Ibérico (tomados de bandejas loncheadas compradas aleatoriamente del mismo proveedor), respectivamente. Los jamones curados provenían de machos castrados y hembras. El cuarto experimento consistió en 32 machos castrados Duroc que fueron asignados a un diseño split-plot 2 x 2 consistente en dos dietas de engorde (de 165 a 195 días de edad) que diferían en el contenido de carotenoides precursores de vitamina A y los dos genotipos homocigotos del gen SCD. Las dietas fueron idénticas excepto en la línea de maíz usada en la formulación. La dieta rica en carotenoides se formuló con 20% de maíz fortificado con carotenoides, mientras que la dieta restringida en carotenoides contuvo en su lugar un 20% de una línea casi-isogénica que no contenía carotenoides precursores de vitamina A. El efecto positivo del alelo T del gen SCD sobre la desaturación de la grasa y el contenido de MUFA se confirmó a lo largo del período de crecimiento-engorde así como al final del proceso de curado, tanto en los jamones de raza pura Duroc como en los Duroc × Ibérico. Se encontró una fuerte correlación en el contenido de MUFA entre muestras frescas y curadas, mientras que el genotipo TT fue más efectivo reteniendo el aumento de MUFA observado en los jamones frescos hasta el final del período de curación. Por otra parte, el polimorfismo SCD tuvo un mayor impacto sobre MUFA que el uso de jamones de machos castrados en lugar de hembras. Los resultados del último experimento mostraron que los cerdos alimentados con la dieta rica en carotenoides tuvieron 2.8 veces más ácido retinoico y 4.5 veces más expresión del gen SCD en hígado, alrededor de un quinto menos grasa y MUFA en el hígado, y un tercio menos de IMF en el m. gluteus medius. El genotipo TT del gen SCD aumentó MUFA en todos los tejidos. La grasa hepática y el contenido de MUFA disminuyeron de forma no lineal con el ácido retinoico hepático, sugiriendo un punto de saturación a un nivel relativamente bajo de ácido retinoico. Los resultados obtenidos evidencian que los efectos de una dieta restringida en carotenoides precursores de vitamina A durante el engorde y del genotipo TT del gen SCD se complementan bien para aumentar simultáneamente IMF y MUFA sin alterar el contenido total de grasa. El polimorfismo del gen del receptor de la leptina (LEPR) NM_001024587:g.1987C>T también segrega en esta población Duroc, con el alelo T afectando positivamente IMF y el contenido de ácidos grasos saturados (SFA). La selección del alelo T del gen SCD en combinación con la selección del alelo C de LEPR se confirma como una buena estrategia para aumentar el ratio MUFA / SFA y en consecuencia producir carne más saludable.

Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on October 26, 2007) Includes bibliographical references.

Genetic selection for higher milk production has unavoidably resulted in a decline in fertility of dairy cattle in the UK due to the antagonistic correlation existing between fertility and milk yield. This trend in fertility has necessitated broadening the breeding programme to include fertility traits. However, the heritability of fertility traits currently used in the UK are of low heritability (h2<0.05). Therefore, one approach is to use molecular markers in order to identify animals with the highest genetic merit for fertility. The first aim of this project was therefore to test single nucleotide polymorphisms (SNPs) in candidate genes for their possible associations with fertility PTAs. A group of 408 dairy cows and bulls were genotyped at different loci (GnRH receptor, FSH receptor, LH receptor, activin receptor, and neuropeptide Y receptor Y2 (NPYRY2)). Seven SNPs were identified in the GnRH receptor gene. These were in the promoter and coding regions at positions -331, -108, 206, 260, 341, 383 and 410 relative to the translation start site. Two groups of SNPs were found to be in linkage disequilibrium, the SNPs at positions 206 and 383 being inherited together, as were those at -108, 260, 341 and 410. An association study between these SNPs and fertility PTAs revealed that the -108 SNP group was associated with favourable effects on fertility, reducing PTA for DFS by about 0.4 day. However, when GnRHR gene function was evaluated by measuring circulating LH level after administration of GnRH in pre-pubertal animals, no significant associations of the SNPs with LH levels were detected. Furthermore, five SNPs were identified in the FSHR at residues 502, 669, 596, 658, and 685, four of which (at positions 502, 669, 658, and 685), had deleterious effects on fertility PTAs, increasing CI and DFS, while decreasing NR56. Inaccurate heat detection has been identified as a major contributor to low fertility in dairy cattle, and therefore the second aim of this project was to investigate oestrus expression traits for which BLUP breeding values were estimated. Electronic tags (Fullwood and Lily) were used to measure behavioural activities at oestrus in two separate groups of animals. The first group comprised 103 cows in their first parity. Oestrus behaviour traits were: the number of steps at oestrus (STEPS) and the percentage increase in the number of steps at oestrus (STEPS%) relative to the number of steps over the 10 days preceding oestrus (BASE). Cows in this group were genotyped at 10 genes (GnRHR, LHR, FSHR, oestrogen receptors α and β (ESR), activin receptor, leptin, ghrelin, neuropeptide Y (NPY) and NPYRY2 for SNP identification. Of these SNPs, only those located in the GnRHR, oestrogen receptor α and NPY were found to have statistically significant effects on oestrus traits. The second group consisted of 189 cows with 995 oestrus behaviour records. Oestrus traits were: the number of activity units (AU) at oestrus (ACTIVITY) and the percentage increase in the number of AU at oestrus (ACTIVITY%) over baseline activity (BASE) determined over a 4 day rolling average. In addition to the above mentioned 10 genes, these cows were genotyped at signal transducer and activator of transcription 1 and 5A (STAT1, STAT5A), growth hormone receptor (GHR), prolactin, and prolactin receptor genes. In this study SNPs in the GnRHR, LHR, FSHR, ESRα, GHR, activin receptor, STAT1, and STAT5 were found to have significant effects on oestrus expression. The genetic basis for oestrus behaviour was also investigated applying various animal models in this group. ACTIVITY, ACTIVITY% and BASE had moderate heritabilities of 0.19 to 0.24, 0.16, and 0.25 respectively. The breeding values of the cows were shown to be normally distributed, and ranged between -19 to 27, -18 to 20, and -20 to 28 for ACTIVITY, ACTIVITY%, and BASE respectively. These values are significant in terms of the ability of the stockman to reliably detect cows in heat. There have in the past been few genetic analyses of oestrus behaviour characteristics, and there are few studies of SNP associations with fertility traits of the kind described here. Therefore these studies make a significant contribution to our understanding of the genetics of fertility in dairy cattle, and can be used by breeders as a means to improving fertility in the national dairy herd.

Thesis (MPhil (Animal Sciences))--University of Stellenbosch, 2004.
African Grey Parrots are now being bred on a commercial scale in South Africa, mainly for the export market. In order to produce the best breeding results it is necessary to formulate balanced diets but no research has been done on the feeding value for African Grey parrots of ingredients used in formulating diets. Once the apparent metabolisable energy (AME) of extruded maize for African Greys has been established it will be possible to calculate the AME of other ingredients such as full fat soya, soya oil cake or sunflower oil cake. By feeding an extruded mix containing a known amount of maize mixed with a known amount of soya oil cake and establishing experimentally the AME of the mix, the AME of soya oil cake for African Greys can be calculated by difference. This information will make it possible to decide whether AME results obtained for poultry can be used in formulating diets for African Grey parrots. The study consisted of two parts where the determination of the apparent metabolisable energy (AME) of extruded maize and the practical application thereof in formulating parrot diets, and the economic viability of a commercial African Grey parrot breeding operation was investigated. A reference procedure adopted by several European laboratories for the in vivo determination of metabolisable energy (ME) was used to determine the apparent metabolisable energy (AME) of extruded whole maize for African Grey parrots. The long term goal is to make a well balanced, extruded diet for these birds. Extruded maize is the form in which maize is generally included in commercial parrot diets and was therefore chosen as the experimental feed. Maize can be conveniently extruded with other single ingredients such as full fat soyabean meal, soyabean oil cake meal or sunflower oil cake meal to determine, by difference, the AME of those ingredients. For the first part of the study, ten, 3-year-old African Grey parrots were individually housed and fed in cages designed to facilitate collection of the faeces. Cage design varied between a tall type (n=6) and a low type (n=4). The parrots were acclimatized to their new environment before the trial commenced to ensure normal feeding behaviour. The average AME value established for the ten African Grey Parrots was 16.8 MJ/kg. In the trial it became apparent that it is very difficult to get consistent results with the cages used and a modified cage design is proposed for the future. The second part of the study investigated the economic viability of breeding African Grey parrots commercially, with extruded maize as part of their diet. It was generally concluded that the breeding of African Grey parrots for the pet market can be considered as an economical venture.

Nowadays it is requested more investigations on alternative rearing systems that are able to improve poultry welfare and to warrant high-quality and safe meat products. This thesis work was focused on the evaluation of the oxidative stability of poultry meats, obtained with different rearing systems, diets (supplemented with bioactive compounds), and packaging conditions. The thesis work was divided into the following parts: - Evaluation of the effects of different rearing systems on the quality, fatty acid composition and oxidative stability of poultry thigh and breast meat belonging to different product categories (“rotisserie” and “cut-up” carcasses); - Evaluation of the effects of different rearing systems and packaging conditions on the shelf-life of poultry thigh meat stored at 4°C for 14 days, and the effects of feed supplementation with thymol (control diet and diet with 2 different concentration of thymol) and packaging conditions on lipid oxidation of poultry thigh meat shelf-life (stored at 4°C for 14 days). The oxidative stability of poultry meat was studied by means of the spectrophotometric determinations of peroxide value and thiobarbituric acid reactive substances. - Evaluation of anti-inflammatory effects of different flavonoids (thymol, luteolin, tangeretin, sulforaphane, polymethoxyflavones, curcumin derivates) to detect their biological activity in LPS-stimulated RAW 264.7 macrophage cells in vitro, in order to study more in depth their action mechanisms. It was evaluated the cell vitality (MTT assay), nitrite concentration and protein profile. The study was focused on the identification of potential dietary bioactive compounds in order to investigate their biological activity and possible synergic effects, and to develop new suitable strategies for long-term promotion of human health, in particular against cancer.
Oggigiorno sono sempre più richiesti i lavori di ricerca sullo studio di sistemi di allevamento alternativi in grado di migliorare il benessere degli animali e di migliorare la qualità e la sicurezza delle carni. Il presente elaborato di tesi si è basato sulla valutazione dello stato ossidativo di carni avicole, provenienti da animali allevati con sistemi alternativi ed alimentati con diete integrate con composti bioattivi, e conservate in diverse tipologie di packaging. L’organizzazione della ricerca si è sviluppata nei seguenti punti: - Valutazione dell’effetto di sistemi di allevamento alternativi del pollo da carne sulla qualità, composizione degli acidi grassi e stabilità ossidativa della frazione lipidica muscolare delle carni di petto e coscia ottenute da due categorie commerciali (“Rotisserie” e “Cut-up”); - Studio della stabilità ossidativa condotta mediante prove di shelf-life su carni di coscia ottenute da polli allevati con diversi sistemi di allevamento e alimentati con tre tipi di diete (dieta di controllo e diete arricchite di timolo a due diverse concentrazioni). Queste carni sono state confezionate con diverse modalità (atmosfera ordinaria e protettiva) e conservate in condizioni di refrigerazione (2-4°C) per 14 giorni. La stabilità ossidativa è stata valutata mediante le determinazioni spettrofotometriche del numero di perossidi e delle sostanze reattive all’acido tiobarbiturico; - Valutazione dell’attività anti-infiammatoria di diversi bioflavonoidi (timolo, luteolina, tangeretina, sulforafano, polimetossiflavoni, derivati della curcumina), facendo luce sui meccanismi d’azione di quest’ultimi, su linee cellulari macrofagiche (LPS-stimulated RAW 264.7 cells) in vitro. Sono stati valutati la vitalità cellulare (MTT assay), la determinazione indiretta dell’ossido nitrico e l’identificazione delle proteine. In particolare, il lavoro si è soffermato sull’identificazione di potenziali componenti nutraceutici, caratterizzati da una forte azione sinergica, con lo scopo di indagare sulla loro attività biologica ed i loro possibili effetti sinergici e quindi di sviluppare nuove strategie finalizzate alla prevenzione del cancro, a lungo termine.

Nowadays it is requested more investigations on alternative rearing systems that are able to improve poultry welfare and to warrant high-quality and safe meat products. This thesis work was focused on the evaluation of the oxidative stability of poultry meats, obtained with different rearing systems, diets (supplemented with bioactive compounds), and packaging conditions. The thesis work was divided into the following parts: - Evaluation of the effects of different rearing systems on the quality, fatty acid composition and oxidative stability of poultry thigh and breast meat belonging to different product categories (“rotisserie” and “cut-up” carcasses); - Evaluation of the effects of different rearing systems and packaging conditions on the shelf-life of poultry thigh meat stored at 4°C for 14 days, and the effects of feed supplementation with thymol (control diet and diet with 2 different concentration of thymol) and packaging conditions on lipid oxidation of poultry thigh meat shelf-life (stored at 4°C for 14 days). The oxidative stability of poultry meat was studied by means of the spectrophotometric determinations of peroxide value and thiobarbituric acid reactive substances. - Evaluation of anti-inflammatory effects of different flavonoids (thymol, luteolin, tangeretin, sulforaphane, polymethoxyflavones, curcumin derivates) to detect their biological activity in LPS-stimulated RAW 264.7 macrophage cells in vitro, in order to study more in depth their action mechanisms. It was evaluated the cell vitality (MTT assay), nitrite concentration and protein profile. The study was focused on the identification of potential dietary bioactive compounds in order to investigate their biological activity and possible synergic effects, and to develop new suitable strategies for long-term promotion of human health, in particular against cancer.
Oggigiorno sono sempre più richiesti i lavori di ricerca sullo studio di sistemi di allevamento alternativi in grado di migliorare il benessere degli animali e di migliorare la qualità e la sicurezza delle carni. Il presente elaborato di tesi si è basato sulla valutazione dello stato ossidativo di carni avicole, provenienti da animali allevati con sistemi alternativi ed alimentati con diete integrate con composti bioattivi, e conservate in diverse tipologie di packaging. L’organizzazione della ricerca si è sviluppata nei seguenti punti: - Valutazione dell’effetto di sistemi di allevamento alternativi del pollo da carne sulla qualità, composizione degli acidi grassi e stabilità ossidativa della frazione lipidica muscolare delle carni di petto e coscia ottenute da due categorie commerciali (“Rotisserie” e “Cut-up”); - Studio della stabilità ossidativa condotta mediante prove di shelf-life su carni di coscia ottenute da polli allevati con diversi sistemi di allevamento e alimentati con tre tipi di diete (dieta di controllo e diete arricchite di timolo a due diverse concentrazioni). Queste carni sono state confezionate con diverse modalità (atmosfera ordinaria e protettiva) e conservate in condizioni di refrigerazione (2-4°C) per 14 giorni. La stabilità ossidativa è stata valutata mediante le determinazioni spettrofotometriche del numero di perossidi e delle sostanze reattive all’acido tiobarbiturico; - Valutazione dell’attività anti-infiammatoria di diversi bioflavonoidi (timolo, luteolina, tangeretina, sulforafano, polimetossiflavoni, derivati della curcumina), facendo luce sui meccanismi d’azione di quest’ultimi, su linee cellulari macrofagiche (LPS-stimulated RAW 264.7 cells) in vitro. Sono stati valutati la vitalità cellulare (MTT assay), la determinazione indiretta dell’ossido nitrico e l’identificazione delle proteine. In particolare, il lavoro si è soffermato sull’identificazione di potenziali componenti nutraceutici, caratterizzati da una forte azione sinergica, con lo scopo di indagare sulla loro attività biologica ed i loro possibili effetti sinergici e quindi di sviluppare nuove strategie finalizzate alla prevenzione del cancro, a lungo termine.

Animal movement is a ubiquitous process and can have consequences ranging from an individual’s energy expenditure to ecosystem dynamics. This study uses biologgers, primarily accelerometers, to record and examine the at-sea behaviours of black-legged kittiwakes (Rissa tridactyla) during their breeding period. Accelerometers record the acceleration of an instrumented animal to give an indication of their behaviour and movements, yet their output can be particularly difficult to interpret. As such, this thesis begins with a method developed for the assignation of coarse-scale behaviours to accelerometry data. The method is a simple yet objective approach intended to be widely applicable. Using this method, we construct time-activity budgets for incubating and chick-rearing kittiwakes and apply activity-specific estimates of energy expenditure to these behaviours. We identify how kittiwakes allocate their time and what the energetic consequences of variation in time-allocation are. We present empirical evidence for chick-rearing kittiwakes expending more energy than incubating birds and identify that kittiwakes exhibit behavioural compensation whereby they limit energy expenditure across both foraging trips and days. We also examine the flight behaviour of kittiwakes in relation to extrinsic conditions. We find that wind conditions do not seem to influence broader scale patterns in movements during foraging trips, however kittiwakes do display behavioural plasticity in response to wind conditions by optimising their flight speeds towards maximum range speeds. We also identify that to optimise flight speeds, kittiwakes change the strength at which they flap their wings, rather than the frequency. Finally we present a serendipitous observation of predation of kittiwake chicks by a peregrine falcon. Although not directly related to movement ecology, this study documents novel predatory behaviour and highlights the importance of biological forces other than movement. Overall, the work presented in this thesis demonstrates that by examining the movement of individuals, it is possible to gain insights into various important aspects of their biology.

Foram estudados dados provenientes do experimento de seleção estabelecido na Estação Experimental de Zootecnia de Sertãozinho (IZ - SP), com o objetivo de avaliar a resposta direta no peso ao sobreano de machos e fêmeas e as respostas correlacionadas no tamanho e caracteres reprodutivos das matrizes. O experimento iniciou em 1978, com três rebanhos da raça Nelore, seleção (NeS), tradicional (NeT) e controle (NeC), sendo os dois primeiros selecionados para maior peso ao sobreano e o terceiro para a média deste peso. O NeT diferencia-se de NeS por ter recebido, eventualmente, touros de outros rebanhos, inclusive comerciais. Registros de dias ao parto foram analisados separadamente nas novilhas, vacas e vacas e novilhas sem incluir e incluindo as fêmeas não paridas. Nenhuma diferença significativa (P<0,05) foi detectada entre os desempenhos das fêmeas dos rebanhos selecionados (NeS e NeT) e as do controle (NeC). As herdabilidades variaram de 0,02 a 0,16, sendo as mais altas obtidas em arquivos nos quais foram incluídos os registros das fêmeas não paridas. Os registros repetidos de dias ao parto de vacas e novilhas incluindo as fêmeas não paridas foram também analisados por modelo de regressão aleatória com polinômios ortogonais (Legendre) da idade na monta (em anos) como a covariável independente, para avaliar este caracter longitudinalmente durante a vida produtiva das fêmeas. As herdabilidades estimadas aumentaram de 0,08 a 0,28 da 1 a à 6 a monta. A seleção para peso não alterou o valor genético médio das vacas de NeS e NeT, entretanto os valores genéticos das vacas do NeC mostraram tendência de queda no decorrer dos anos, além de longitudinalmente, com o avanço da idade. Registros de peso ao sobreano dos animais nascidos de 1978 a 1998, e da altura na garupa ao sobreano das fêmeas nascidas a partir de 1985 foram analisados por modelo animal para obter a tendência genética de 1981 a 1996. Médias de peso, altura e escore de condição corporal na entrada da monta, dias ao parto e sucesso ao parto das matrizes nascidas nos últimos 4 anos foram contrastadas entre os selecionados e o NeC, em análise de quadrados mínimos. As tendências genéticas médias obtidas em 16 anos foram 1,7±0,2; 2,3±0,2 e –0,1±0,1 kg/ano nos machos e 1,9±0,2; 2,4±0,2 e –0,1±0,1 kg/ano nas fêmeas para peso, e 0,25±0,03; 0,24±0,04 e –0,04±0,03 cm nas fêmeas para altura ao sobreano, respectivamente em NeS, NeT e NeC. Novilhas e vacas de NeS e NeT foram 19% e 15% mais pesadas e 4% mais altas na entrada da monta, em relação às do NeC. Não foram detectadas diferenças significativas (P<0,05) no desempenho reprodutivo das matrizes selecionadas em relação ao NeC. Os resultados indicaram que a seleção para peso corporal promoveu respostas altas e consistentes nos pesos e alturas ao sobreano e em idades mais tardias, sem comprometer o desempenho reprodutivo das matrizes.
Data from a selection experiment, carried out AT Experimental Station of Sertãozinho, State of São Paulo, Brazil, were analyzed in order to evaluate the direct response of yearling weight and the correlated responses of the size and reproduction traits of cows. The experiment started in 1978, with three lines of Nelore cattle, selection (NeS), traditional (NeT), both selected for greater yearling weight, and control (NeC), selected for mean yearling weight. The NeT line is different from the NeS one because sires from another herds were eventually introduced into the NeT line. Records of days to calving were analyzed separately for heifers, cows and cows and heifers with and without non-calver females. There were no significant differences (P<0.05) between the performance of females from the selection lines (NeS and NeT) and those from the control line (NeC). The heritabilities were between 0.02 and 0.06, and the higher estimates were from data sets including non-calver females. The repeated records of days to calving of cows and heifers with non-calvers, were too analyzed using a random regression model, with orthogonal polynomials (Legendre) of age in the breeding season (in years) as the independent covariable, to order to evaluate this trait longitudinally during the herd life of the females. The estimates of heritability increased from 0.08 to 0.28, from first up to 6 th breeding season. The selection for weight did not alter the average breeding value of cows from NeS and NeT, although the average genetic breeding values of cows declined throughout the years, and too longitudinally, with advancing age. Yearling weight of the animals born from 1978 to 1998, and the yearling hip height of females born from 1985 to 1998, were evaluated using an animal model, in order to obtain the genetic trends for the years 1981 to 1996. The averages for weight, height and body condition score at the start of the breeding season, days to calving and calving success of cows born in the last 4 years, were contrasted between the selected (NeS and NeT) and control lines. The genetic trends obtained after 16 years were 1.7±0.2; 2.3±0.2 and –0.1±0.1 kg/year for males and 1.9±0.2; 2.4±0.2 e –0.1±0.1 kg/year for females with respect to weight, and 0.25±0.03; 0.24±0.04 and –0.04±0.03 cm for females with respect to yearling height for the NeS, NeT and NeC lines, respectively. Heifers and cows from NeS and NeT were 19% and 15% heavier and 4% taller at the start of the breeding season than those from NeC. Significant differences (P<0.05) were not detected with respect to the reproductive performance between selected (NeS and NeT) and control females. The results indicated that the selection according to body weight gave high and consistent responses for weight and height both at the yearling and later ages, without compromised the reproductive performance of the cows.

Die Arbeit beschreibt ein stochastisches Simulationsprogramm zur Modellierung von Honigbienenpopulationen unter Zuchtbedingungen. Dieses Programm wurde neu implementiert um unterschiedliche Selektionsstrategien zu evaluieren und zu optimieren. In einer ersten Studie wurde untersucht, inwiefern die Vorhersagen, die das Programm trifft, vom verwendeten genetischen Modell abhängt. Hierbei wurde festgestellt, dass das Finite-Locus-Modell dem Infinitesimalmodell in Langzeitstudien vorzuziehen ist. Eine zweite Studie beleuchtete die Bedeutung der sicheren Anpaarung auf Belegstellen für die Honigbienenzucht. Hier zeigten die Simulationen, dass die Zucht mit Anpaarungskontrolle derjenigen mit freier Paarung von Königinnen deutlich überlegen ist. Schließlich wurde in einer finalen Studie der Frage nachgegangen, wie erfolgreiche Zuchtprogramme bei der Honigbiene langfristig nachhaltig zu gestalten sind. Hierbei sind kurzfristiger genetischer Zugewinn und langfristige Inzuchtvermeidung gegeneinander abzuwägen. Durch umfangreiche Simulationen konnten für verschiedene Ausgangspopulationen Empfehlungen für eine optimale Zuchtintensität auf mütterlicher und väterlicher Seite gefunden werden.
The present work describes a stochastic simulation program for modelling honeybee populations under breeding conditions. The program was newly implemented to investigate and optimize different selection strategies. A first study evaluated in how far the program's predictions depend on the underlying genetic model. It was found that the finite locus model rather than the infinitesimal model should be used for long-term investigations. A second study shed light into the importance of controlled mating for honeybee breeding. It was found that breeding schemes with controlled mating are far superior to free-mating alternatives. Ultimately, a final study examined how successful breeding strategies can be designed so that they are sustainable in the long term. For this, short-term genetic progress has to be weighed against the avoidance of inbreeding in the long run. By extensive simulations, optimal selection intensities on the maternal and paternal paths could be determined for different sets of population parameters.

Uterine inflammation after breeding is considered necessary for the clearance of excess semen and debris from the uterus. A subpopulation of mares fails to clear the inflammation in a timely fashion, and develops a persistent breeding induced endometritis (PBIE). Experiments were preformed to evaluate correlations of PBIE to endometrial quality and age. Mares of advanced age and poor endometrial quality had a higher incidence of PBIE. In addition, mares fluctuated in susceptibility to PBIE from one season to the next. The uterine inflammatory gene expression in susceptible and resistant mares within the first 24 hours after breeding was investigated. The peak endometrial cytokine gene expression occurred 6 hours after insemination, and susceptible mares were found to have a reduced response of the inflammatory modulating cytokines during this time. Intrauterine accumulation of the inflammatory byproduct nitric oxide (NO) was investigated in resistant and susceptible mares within the first 24 hours after breeding. Susceptible mares had an increase in NO accumulation over time, whereas NO accumulation in resistant mares remained relatively constant. The effects of immunomodulators on uterine inflammatory response and nitric oxide accumulation in susceptible mares was investigated. Immunomodulators decreased expression of the pro-inflammatory cytokine interleukin-1β and nitric oxide accumulation. In conclusion, endometrial quality and age are indicators of susceptibility to PBIE, and susceptibly can change from year to year. Six hours after breeding is a critical time for the development of PBIE, and susceptible and resistant mares have differential endometrial inflammatory gene expression, with susceptible mares appearing to have a defect in the inflammatory modulating immune response. Finally, treatment with immune modulators alters the IL1β gene expression and intrauterine nitric oxide accumulation, which may help to explain how they act to reduce inflammation during PBIE.