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1
McMillan, Allison. "Dairy cattle grouping /." Click here to view, 2009. http://digitalcommons.calpoly.edu/dscisp/7.
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Thesis (B.S.)--California Polytechnic State University, 2009.Project advisor: Edwin Jaster. Title from PDF title page; viewed on Jan. 21, 2010. Includes bibliographical references. Also available on microfiche.
2
Roxström, Anki. "Genetic aspects of fertility and longevity in dairy cattle /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5812-9.pdf.
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3
Wang, Wei. "Plasminogen polymorphism in dairy cattle." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26174.
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A genetic approach to lowering protease (plasmin) levels in milk, requires the presence of polymorphism of bovine plasminogen. This study was conducted to determine to what extent genetic polymorphism exists in dairy cattle. Bovine plasminogen was first purified from Holstein cow plasma by affinity chromatography on Lysine-Sepharose and antibodies to bovine plasminogen were raised by monthly intramuscular injection of the isolated bovine plasminogen into rabbits. For plasminogen phenotyping, blood samples were collected at random from 50 Holstein and Ayrshire cattle, and plasminogen was isolated from the plasma using lysine-Sepharose and then treated with neuraminidase. After separation by isoelectric focusing (pH 3.5-9.5) in polyacrylamide gels, Plasminogen polymorphs were detected immunologically using rabbit anti-bovine plasminogen antibodies. Additionally, the plasminogen isoforms were evaluated with a functional assay (caseinolytic overlay technique) after activation of the plasminogen with urokinase. Six plasminogen phenotypes were identified which represent products of 5 variant alleles. The 5 plasminogen variants were characterized based on their isoelectric points and designated PLG A$ sb2$ (pI 6.5 and 7.0), B$ sb2$ (pI 7.6 and 7.8), C$ sb1$ (pI 6.8), D$ sb2$ (pI 7.8 and 8.0), and E$ sb2$ (pI 6.8 and 7.0). PLG A$ sb2$ and PLG B$ sb2$ were the most common variants in these cattle. The 6 phenotypes were $ rm A sb2A sb2, B sb2B sb2, A sb2B sb2, B sb2C sb1, A sb2D sb2 and D sb2E sb2$. The phenotypic frequencies in Holstein and Ayrshire were very different, $ rm A sb2A sb2 and B sb2B sb2$ being respectively the most frequent phenotype. In addition, DNA polymorphism at bovine plasminogen gene was detected when genomic DNA was digested with the restriction enzyme Msp I and hybridized with mouse plasminogen cDNA. This is the first description of plasminogen polymorphism reported in dairy cattle. If different variants have altered activity, the detrimental effect
4
Tortosa, Christina Suzanne. "Reproductive diseases of dairy cattle /." Click here to view, 2009. http://digitalcommons.calpoly.edu/dscisp/6.
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Thesis (B.S.)--California Polytechnic State University, 2009.Project advisor: Edwin Jaster. Title from PDF title page; viewed on Jan. 21, 2010. Includes bibliographical references. Also available on microfiche.
5
Morton, John. "Determinants of reproductive performance of dairy cows in commercial herds in Australia /." Connect to thesis, 2004. http://eprints.unimelb.edu.au/archive/00000608.
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Puntenney, Steven B. "The effect of prepartum anionic diets on cortisol, adiponectin, and tumour necrosis factor-[alpha] expression at varying levels of body mass index in preparturient dairy cows : implications for insulin resistance /." Connect to this title online, 2006. http://hdl.handle.net/1957/1931.
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Olori, Victor Enishede. "Utilisation of daily milk records in genetic evaluation of dairy cattle." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/12729.
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The aim of this study was to determine how daily yield records might be used to improve the genetic evaluation of dairy cattle, which is currently based on 305-day yield predicted from monthly test day records. Daily milk yield records of 488 first lactation Holstein Friesian cows were obtained from one UK herd and summarised into weekly averages. Weekly fat, protein and lactose content records, from the same herd, were also obtained and each multiplied by test day yield to estimate fat, protein and lactose yields. Analysis of variance indicated that residual standard deviation (RSD) for each trait was lower when season of production was included in the model instead of the season of calving. The difference in RSD was more for fat and protein yields than the other traits. Lactation stage and season were the most important environmental factors affecting daily milk yield and composition while calving age had a small but significant (P<0.05) effect. Pregnancy accounted for 1.4 to 1.7% of the variation in yield traits but less than 0.4% of the variation in content traits. Its effects varied with gestation stage causing daily milk yield to decline by 3kg in the 8th month of gestation. A significant interaction between lactation and gestation stage was observed which suggested that the negative effect of pregnancy was higher in mid than late stages of lactation. Standard models of the lactation curve studied accounted for a substantial proportion of the variation in daily milk yields of typical lactations, which made up about half of the lactations studied. The other half was made up of atypical lactations such as highly persistent animals with almost flat curves whose lactation could not be adequately modelled with the standard curve functions. A regression spline model was derived which was as good as the best 3 parameter model and more flexible. These results indicate that models which make rigid assumptions about the shape of the lactation curve may not be very effective in accounting for the effect of lactation stage on daily yields. Yields of the same trait at different stages of lactation were positively correlated throughout but the correlation between yield and content traits was negative. Average correlation between milk yield and adjacent weeks was 0.93 declining to 0.61 between yields 41 weeks apart. Daily milk yields in mid and late stages of lactation were more highly correlated with 305-day yield than yields in early lactation. Covariance functions, using orthogonal polynomials up to the order of 4, were used to model genetic and permanent environmental covariances in a restricted maximum likelihood (REML) random regression (RR) model. Genetic parameters and breeding values were estimated for yield in every week of lactation. There were compared with estimates from a multivariate model, which considered yield at different stages as different traits, and a repeatability model without random regressions.
8
Pong-Wong, Ricardo. "Milk protein polymorphisms in dairy cattle." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/11270.
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This study covered two main areas of major genes affecting quantitative traits: (i) the estimation of their effects with emphasis on the milk protein loci and (ii) the use of genotype information on major genes as part of the selection criteria. In a situation in which only a subset of the population has known genotypes for a major gene, the estimated effects of this gene obtained with a method using performance information on all the individuals (with and without known genotype) were compared with those estimates obtained with a method using information on only individuals with known genotype. The first method used a Gibbs sampling approach to infer genotypes of individuals with unknown value. The results from a simulation study showed that, in absence of selection, both methods yielded unbiased estimates of the major gene effects. However, the inclusion of performance information of individuals without genotype decreased the error variance of the estimates by 12 to 69% of the reduction there would be if all individuals had known genotype, depending on the gene frequency, and the mode of action of the major locus. In the population undergoing selection the use of such information also substantially reduced the bias of estimates. This methodology was applied to estimation of the effects of the β-lactoglobulin and the κ-casein loci on lactation traits (milk yield, fat and protein yield and content), using data from 1452 Holstein Friesian cows of two experimental herds and a MOET nucleus in the UK, and available progeny test of sires. There were no significant effects of these loci on any of the traits considered. To study the use of genotype information as part of the selection criteria, a deterministic model for predicting response to selection when a single locus is segregating was defined. It was used to compare the traditional phenotypic selection with other methods of combining performance information with either the genotype of the major locus or only its Mendelian sampling term (i.e. the effect due to the major locus expressed as deviation from family mean).
9
Dhaliwal, G. S. "Leptospirosis and subfertility in dairy cattle." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240458.
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10
Meyer, Joseph Patrick. "Evaluation of estrus synchronization protocols for first and second insemination in dairy cows and heifers /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426088.
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11
Fitzgerald, Tracey. "The effect of long-term supplementation with biotin on lameness, milk production and reproductive performance in pasture fed dairy cows /." [St Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16283.pdf.
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12
Brown, Timothy P. (Timothy Phillip). "Selection indices in retrospect for dairy cattle." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59266.
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Selection differentials and selection indices in retrospect were calculated to determine the relative emphasis placed on production and type traits through bull selection. Indices in retrospect including only production traits indicated that, for Holsteins, fat yield was the trait most heavily selected for between 1978 and 1987, followed by protein percent and then milk yield. Fat percent and protein yield had negative index weights throughout the nine year period. In Ayrshires, similar weights were observed except that milk yield index weights were negative throughout the nine year period. It was found that the relative weight placed on type was small and did not affect the relative weights place on production traits. Within Holsteins, differences in bull selection when multiple services were required to successfully service a cow indicated that selection for overall size was reduced in later services. Within Ayrshires, there were no differences in any production or type trait within multiple services.
13
Margerison, Jean K. "Restricted suckling and nutrition of dairy cattle." Thesis, Bangor University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296323.
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14
Lambert, Helen Susan. "Identifying measures of emotion in dairy cattle." Thesis, University of Portsmouth, 2018. https://researchportal.port.ac.uk/portal/en/theses/identifying-measures-of-emotion-in-dairy-cattle(16e6b385-9877-44f3-927f-856099dad349).html.
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The following commentary discusses the six papers submitted for evaluation for the award of PhD by Publication (chapters 1-6). To give context to my contribution to the field of animal welfare science, I have also included several published reviews and extended abstracts as appendices (appendices 1- 6). The research considered in this commentary examined the potential of ear postures, eye whites, and nasal temperatures as measures of both positive and negative emotions in cattle. Three papers focussed on measuring a positive, low arousal emotional state. The paper; "Can ear postures reliably measure the positive emotional state of cows?" (chapter 1, page 44), which was published in Applied Animal Behaviour Science, demonstrated that cows perform two ear postures for significantly longer when they are in a positive, low arousal emotional state, compared with before and after. The second paper; "Nasal temperatures in dairy cows are influenced by positive emotional state" (chapter 2, page 53), which was published in Physiology & Behavior, showed that cow's nasal temperature drops significantly when they are stroked to induce a positive, low arousal emotional state, compared with before and after. The paper; "Measuring positive emotions in cows: Do visible eye whites tell us anything?" (chapter 3, page 59), also published in Physiology & Behavior, revealed that the percentage of visible eye white is significantly decreased when cows are in a positive, low arousal emotional state, compared with before and after. Papers 4-6 focussed on measuring both positive and negative high arousal emotional states in dairy cows. The paper "Can changes in nasal temperature be used as an indicator of emotional state in cows?" was published in Applied Animal Behaviour Science (chapter 4), page 66), and showed a significant decrease in nasal temperature in cows, in response to stimuli intended to elicit positive and negative high arousal states, compared with a neutral stimulus. Paper 5; "Looking into the eyes of a cow: Can eye whites be used as a measure of emotional state?" (chapter 5, page 73), was also published in Applied Animal Behaviour Science, and found that visible eye white in cows increased significantly in response to the emotional states of excitement and frustration, compared with a neutral stimulus. Finally, paper 6; "Positive and negative emotions in dairy cows: Can ear postures be used as a measure?" (chapter 6, page 80) which has been submitted to Behavioural Processes, demonstrated that cows are more likely to perform certain ear postures in response to positive or negative, high arousal emotional states. Taken together, these findings show that there is potential for ear postures to be used as a measure of emotional state in cattle, although further research is required to explore the effects of other contexts and stimuli. In addition, nasal temperatures and eye whites are not purely the result of arousal levels, as they did not mirror the heart rate measurements, and so further research is needed to explore the complex relationship between arousal and valence. Throughout the whole of the commentary these papers will be referred to, and so it is recommended that the publications are read first.
15
Potts, Justin C. "Determining the water needs of dairy cattle." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14176.
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Master of ScienceDepartment of Animal Science and Industry
Micheal J. Brouk
Data obtained from 50 individual published studies recording water intake by dairy cattle were utilized in a meta-analysis to develop a prediction equation for free water intake (FWI). Studies were selected based on quantitative measurements of DMI, diet DM%, water intake (WI), and milk yield. Many of the studies determined FWI on multiple treatments resulting in 116 mean data points from the 50 studies. With the addition of Na in the meta-analysis, 40 data points were available from the studies to examine the effects of Na on FWI. The effects of DMI, ration water intake (RWI), and milk yield (MY) were used to develop a FWI prediction equation from the 116 data points. The effects of DMI, RWI, MY, and sodium intake were used to develop a second prediction equation from the 40 data points. These equations were then compared with five published FWI prediction equations from Castle and Thomas (1975), Dahlborn et al. (1998), Little and Shaw (1978), Murphy et al. (1983) and Stockdale and King (1983). This data set showed that the five published equations either over or under predicted (P < 0.05) FWI when compared the actual FWI calculated from the meta-analysis data points. It also showed that the equation developed from the meta-analysis data points is the more accurate in determining FWI from the data points selected from the studies. A second project was conducted with the fresh water data collected from 13 freestall (FS) and 11 dry lot (DL) Kansas dairies over a 10-year period (2000-2009). Fresh water was recorded from water pumping records. Data were first summarized annually by operation and then converted to a per cow per day basis prior to analysis. Data were then analyzed by using the mixed procedures of SAS. Fixed effects included in the model were dairy type (FS or DL) and year was considered a random effect. The DL dairies averaged 186 L/cow per day and were lower than the FS dairies which averaged 237 L/cow per day. Differences between DL and FS style dairies may have been due to differences in parlor fresh water usage or cow cooling systems.
16
McGill, Tyler R. "Improving the Efficiency of Dairy Cattle Feeding." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/79951.
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Biological functions that use amino acids (AA) are limited by AA supply. This concept was likened to staves in a barrel, where the shortest stave determines the barrel's ability to hold water (Mitchell and Block, 1946). Inaccuracies in models that predict nutrient supply and requirements of dairy cows result in inefficient feeding, as under-prediction of requirements results in deficiency, and over-prediction results in excess. To avoid limitations in production due to AA deficiencies, protein is fed in quantities that likely exceed requirements. Overfeeding of AA results in increased expenses for producers and increased N excretion to the environment, providing economic and environmental incentives to increase N-efficiency. Work presented in the following chapters evaluated the impact of AA supplementation on milk production in dairy cattle, and evaluated the PREP10 and NRC (2001) nutrient requirement model predictions. In two feeding trials (Chapter 2 and Chapter 3), low protein diets did not result in decreased milk production, indicating that protein requirements were overestimated. Although supplementation of AA did not increase milk production, low protein diets resulted in greater N-efficiency, especially when supplemented with Histidine. Evaluation of the PREP10 and NRC (2001) models (Chapter 4) used production data from the literature to identify deficiencies in prediction equations, and found that correction of model bias would considerably reduce prediction errors. Model inaccuracies affect the inefficiency of dairy cow feeding, and must be evaluated to improve feed efficiency. Such improvements could act synergistically with AA supplementation to more closely match nutrient supply to requirements.Master of Science
17
Schadt, Iris. "Feed particle size reduction in dairy cattle." Thesis, Università degli Studi di Catania, 2011. http://hdl.handle.net/10761/159.
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This research was carried out at CoRFiLaC in collaboration with the CoRFiLaC research
group and technical staff.
The understanding of how cows chew their feed might be one fundamental previous step
necessary to study if, and how feed particle size could alter efficient feeding, milk production and
composition and animal health. Our main objective was to learn some rules, of how feed particle
size is reduced during the ingestive mastication in dairy cattle, in order to get an idea about rumen
mat consistency from diet particle size and intake. We measured lengths distributions of feed and
respective bolus particles which are potentially contributing to rumen mat formation, estimated an
approximate dry matter proportion of this sample fraction, and evaluated differences in chewing
behaviour between dry and lactating cows.
Poppi et al. (1985) reported that particles retained on a 1.18 mm screen, using a vertical
sieving technique, are highly resistant to passage from the rumen in cattle. As vertical sieving
techniques divide particles by their widths rather than their lengths and Mertens (1984) reported
constant lengths to widths ratios varying from 3.4:1 for corn silage to 10:1 for alfalfa and
bermudagrass hay, we concluded that particles resistant to passage out of the rumen might have
lengths probably not shorter than 5 mm. We focussed on the analysis of particle lengths > = 5 mm.
Analyses were performed using an image analysis technique. A mean length (ML) was calculated
considering only particle lengths > = 5 mm. In order to determine the mass of particles > = 5 mm, we
found that a screen with 1.6 mm openings, using a horizontal wet sieving technique, separated best
the particles > = 5 mm from those of smaller dimensions. The dry proportion of samples on that
screen was called PROP_1.6.
We performed two experiments. In the first experiment, 6 rye grass hay treatments differing
in particle lengths, one corn silage, one grass silage and one TMR sample were fed to four dry and
four lactating, rumen fistulated, dairy cows after rumen were emptied, and boli, rumen mat and
feces were sampled. Rye grass hay treatments were as follows: rye grass cut at 50 mm lengths and
dried to hay, long rye grass hay, chopped rye grass hay retained on the Penn State Particle Separator
(PSPS) screens of 19 mm, 8 mm, 1.18 mm and on the bottom pan. In the second experiment we
selected 10 total mixed ration (TMR) samples from Sicilian dairy farms. We divided TMRs into
fractions by sieving them through four sequential sieves of 19 mm, 8 mm, 2.5 mm and 1.18 mm.
All fractions and the unprocessed TMRs were fed to three dry dairy, rumen fistulated cows, after
rumen were emptied, and boli were sampled. Feed (with exception of the long rye grass hay, rye
grass cut at 50 mm lengths and dried, chopped rye grass hay retained on the 19 mm and the 8 mm
screen), bolus, rumen mat and feces were sieved through a 1.6 mm screen to obtain PROP_1.6,
particles retained were separated, imaged and ML was calculated. Dry matter (DM) and contents of
crude protein (CP) and neutral detergent insoluble fiber (aNDF) were determined in the feed
samples.
The longest ML of a TMR particle the cows were able to swallow was about 18 mm. This
was nearly twice the longest ML of rye grass hay bolus particles, which could be swallowed at ML
< = 10 to 11 mm.
As a difference to TMR particles, all rye grass hay fractions probably stimulated chewing to
some extent. Even the smallest rye grass hay particles retained on the PSPS bottom pan were
apparently reduced in PROP_1.6 although this fraction is not defined physical effective (Kononoff
and Heinrichs, 2003). Ingestive chewing reduced PROP_1.6 of the unprocessed TMRs. Eating
reduced also PROP_1.6 of TMR fractions retained on screens with openings of at least 2.5 mm, but
not PROP_1.6 of the TMR fractions passing that screen. Eating reduced ML of TMR fractions
retained on screens with openings of at least 8 mm, but neither ML of particles which had passed
the 8 mm screen, nor ML of the unprocessed TMRs were reduced significantly (p > 0.05). The sum
of TMR residues on the two upper PSPS screens with 19 and 8 mm openings might underestimate
TMR physical effective fiber (pef), while the sum of residues from all three PSPS screens might
overestimate TMR pef. We suggest the use of a sequential sieve set containing a 19 mm, a 8 mm
sieve and an additional screen with 2.5 mm openings, instead of the additional screen with 1.18 mm
openings, for diet evaluation on the farm.
Feed and bolus PROP_1.6 were highly correlated (R2 = 0.94, 65 observations), when
unprocessed TMRs and TMR fractions were fed, with y = 0.79x + 0.03 and y being bolus and x
feed PROP_1.6. Rye grass hay particles and most silage samples were apparently chewed more
intensely and having lower bolus PROP_1.6. Feed and bolus ML were highly correlated (R2 = 0.86,
47 observations), when unprocessed TMRs and TMR fractions were fed and feed ML < = 20 mm,
with y = 0.76x + 2.08 and y being bolus and x feed ML. Most silages apparently fitted this
regression, too. When rye grass hay was fed and feed ML < = 20 mm, feed and bolus ML were
correlated with R2 = 0.43 at 21 observations, with y = 0.24x + 6.13 and y being bolus and x feed
ML. Rye grass hay and TMR particles with ML > 20 mm were apparently chewed to constant
lengths, with feed particle size not being related to bolus particle size. Chopped rye grass hay
particles with ML > 20 mm were particles retained on the 19 and the 8 mm PSPS screen, whereas
TMR with ML > 20 mm were retained only on the 19 mm screen. Only particle size of feeds with
ML under this threshold might be able to influence parameters such as rumen retention time, intake
and rumen degradation of feed, if these parameters were related to bolus particle size.
Rye grass hay was chewed more intensely compared to TMR particles. Rye grass hay
particles were dry, while TMR treatments contained 36 to 48% water. Rye grass hay particles
contained 12 to 14 (% DM) CP and 54 to 59 (% DM) aNDF, whereas CP and aNDF of TMRs were
14 to 24 and 20 to 48 (% DM), respectively. During eating, chemical parameters influenced more
reduction of ML of longer compared to shorter particles, but reduction of PROP_1.6 was more
affected in the shorter particles. For each % decrease in sample DM bolus ML increased
approximately 0.2 mm, under the particular condition where feed particles ML ranged between 14.7
and 43.7 mm, CP content ranged between 12.8 and 13 (% DM) and aNDF content ranged between
47.5 and 51 (% DM).
Chewing behaviour of dairy cows was not altered by physiological stage nor by the
interaction of treatment feed by physiological stage. Bolus PROP_1.6 and ML from dry cows were
not different from lactating cows. Even though dry and lactating cows received different diets,
PROP_1.6 and ML of rumen mat and feces were alike. Approximately 26% and 36% dry matter of
rumen mat was retained on a 1.6 mm screen in dry and lactating cows, respectively. Rumen mat
particles retained on that screen and > = 5 mm, had ML of 8.6 mm in dry and 10.3 mm in lactating
cows. There was a trend for higher PROP_1.6 of fecal particles from dry cows compared to
lactating cows (p = 0.105), but ML of 7.4 and 7.9 in dry and lactating cows, respectively, were not
statistically different.
The lengths of the longer particle fraction from TMR, which was retained on a 1.6 mm
screen, were reduced to a higher extent during rumination compared to the longer fraction of
ingested particles from rye grass hay. Only approximately 38% or less of TMR DM is constituted
by particles potentially retained in the rumen. However, these particles might need a longer time for
rumination compared to chewed hay particles.
In both, dry and lactating cows, proportions of rumen mat particles > 4 and > 6 mm,
respectively, at individual lengths, retained on a 1.6 mm screen, were highly correlated to
proportions of bolus particles. Rumen mat ML can be estimated from lengths distribution of bolus
particles retained on a 1.6 mm screen.
18
NICOLAZZI, EZEQUIEL LUIS. "New trends in dairy cattle genetic evaluation." Doctoral thesis, Università Cattolica del Sacro Cuore, 2011. http://hdl.handle.net/10280/966.
Full textAbstract:
I sistemi di valutazione genetica nel mondo sono in rapido sviluppo. Attualmente, i programmi di selezione “tradizionale” basati su fenotipi e rapporti di parentela tra gli animali vengono integrati, e nel futuro potrebbero essere sostituiti, dalle informazioni molecolari. In questo periodo di transizione, questa tesi riguarda ricerche su entrambi i tipi di valutazioni: dall’accertamento sull’accuratezza degli indici genetici internazionali (tradizionali), allo studio di metodi statistici utilizzati per integrare informazioni genomiche nella selezione (selezione genomica). Tre capitoli valutano gli approcci per stimare i valori genetici dai dati genomici riducendo il numero di variabili indipendenti. In modo particolare, la correzione di Bonferroni e il test di permutazioni con regressione a marcatori singoli (Capitolo III), analisi delle componenti principali con BLUP (Capitolo IV) e indice Fst tra razze con BayesA (Capitolo VI). Inoltre, il Capitolo V analizza l’accuratezza dei valori genomici con BLUP, BayesA e Bayesian LASSO includendo tutte le variabili disponibili. I risultati di questa tesi indicano che il progresso genetico atteso dall’analisi dei dati simulati può effettivamente essere ottenuto, anche se ulteriori ricerche sono necessarie per ottimizzare l’utilizzo delle informazioni molecolari in modo da ottimizzare i risultati per tutti i caratteri sotto selezione.Genetic evaluation systems are in rapid development worldwide. In most countries, “traditional” breeding programs based on phenotypes and relationships between animals are currently being integrated and in the future might be replaced by the introduction of molecular information. This thesis stands in this transition period, therefore it covers research on both types of genetic evaluations: from the assessment of the accuracy of (traditional) international genetic evaluations to the study of statistical methods used to integrate genomic information into breeding (genomic selection). Three chapters investigate and evaluate approaches for the estimation of genetic values from genomic data reducing the number of independent variables. In particular, Bonferroni correction and Permutation test combined with single marker regression (Chapter III), principal component analysis combined with BLUP (Chapter IV) and Fst across breeds combined with BayesA (Chapter VI). In addition, Chapter V analyzes the accuracy of direct genomic values with BLUP, BayesA and Bayesian LASSO including all available variables. The results of this thesis indicate that the genetic gains expected from the analysis of simulated data can be obtained on real data. Still, further research is needed to optimize the use of genome-wide information and obtain the best possible estimates for all traits under selection.
19
NICOLAZZI, EZEQUIEL LUIS. "New trends in dairy cattle genetic evaluation." Doctoral thesis, Università Cattolica del Sacro Cuore, 2011. http://hdl.handle.net/10280/966.
Full textAbstract:
I sistemi di valutazione genetica nel mondo sono in rapido sviluppo. Attualmente, i programmi di selezione “tradizionale” basati su fenotipi e rapporti di parentela tra gli animali vengono integrati, e nel futuro potrebbero essere sostituiti, dalle informazioni molecolari. In questo periodo di transizione, questa tesi riguarda ricerche su entrambi i tipi di valutazioni: dall’accertamento sull’accuratezza degli indici genetici internazionali (tradizionali), allo studio di metodi statistici utilizzati per integrare informazioni genomiche nella selezione (selezione genomica). Tre capitoli valutano gli approcci per stimare i valori genetici dai dati genomici riducendo il numero di variabili indipendenti. In modo particolare, la correzione di Bonferroni e il test di permutazioni con regressione a marcatori singoli (Capitolo III), analisi delle componenti principali con BLUP (Capitolo IV) e indice Fst tra razze con BayesA (Capitolo VI). Inoltre, il Capitolo V analizza l’accuratezza dei valori genomici con BLUP, BayesA e Bayesian LASSO includendo tutte le variabili disponibili. I risultati di questa tesi indicano che il progresso genetico atteso dall’analisi dei dati simulati può effettivamente essere ottenuto, anche se ulteriori ricerche sono necessarie per ottimizzare l’utilizzo delle informazioni molecolari in modo da ottimizzare i risultati per tutti i caratteri sotto selezione.Genetic evaluation systems are in rapid development worldwide. In most countries, “traditional” breeding programs based on phenotypes and relationships between animals are currently being integrated and in the future might be replaced by the introduction of molecular information. This thesis stands in this transition period, therefore it covers research on both types of genetic evaluations: from the assessment of the accuracy of (traditional) international genetic evaluations to the study of statistical methods used to integrate genomic information into breeding (genomic selection). Three chapters investigate and evaluate approaches for the estimation of genetic values from genomic data reducing the number of independent variables. In particular, Bonferroni correction and Permutation test combined with single marker regression (Chapter III), principal component analysis combined with BLUP (Chapter IV) and Fst across breeds combined with BayesA (Chapter VI). In addition, Chapter V analyzes the accuracy of direct genomic values with BLUP, BayesA and Bayesian LASSO including all available variables. The results of this thesis indicate that the genetic gains expected from the analysis of simulated data can be obtained on real data. Still, further research is needed to optimize the use of genome-wide information and obtain the best possible estimates for all traits under selection.
20
OMODEI, ZORINI FABIO. "IMPROVEMENT OF FEED EFFICIENCY IN DAIRY CATTLE." Doctoral thesis, Università degli Studi di Milano, 2021. http://hdl.handle.net/2434/859146.
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The improvement of feed efficiency in dairy cattle has traditionally been approached through an increase in production levels. However, the effectiveness of the energy partitioning underlying the dilution of maintenance phenomenon decreases with each successive increment in production relative to body size, and therefore will lose importance in the next years. The selection of more efficient animals (i.e. animals that consume less feed to achieve a fixed production) is limited by the cost and inherent difficulty in recording individual feed intake data, which prove pivotal to improve the accuracy of the estimated breeding values for feed efficiency traits. First aim of my project was to record and collect individual phenotypic data on the dry matter intake of dairy cattle under different dietary conditions and at different production stages. The collected data will become part of a larger collaborative dataset aimed at increasing the prediction power of genomic selection plans including traits related to the feed efficiency. Furthermore, following a multimodal approach essential for an effective improvement of the dairy enterprise efficiency, the effect of feed additives and alternative feed ingredients on the production, health status and efficiency of dairy cattle has been investigated.
In the first trial, the effect of camelina cake – a byproduct of camelina oil rich in proteins and unsaturated fatty acids – on milk fatty acid profile was investigated. Results from the study evidenced a higher concentration of n-3 PUFA (p = 0.02) and a lower n-6/n-3 ratio (p = 0.01) in the milk of cows fed camelina compared to control. The analysis of the ruminal content suggested a moderate effect of camelina on the ruminal environment and biochemistry.
In the second trial, the effect of Saccharomyces cerevisiae (live yeast) on the ruminal environment and its interaction with the production and health status of dairy cows was investigated. Dietary treatment with S. cerevisiae did not affect the investigated ruminal parameters and had only mild effects on blood biochemistry. However, an effect on the ruminal pH was observed when cows were fed low-quality forages, with higher pH values in cows supplemented with S. cerevisiae compared to control (p < 0.05).
In the last trial, the effect of camelina on the ruminal microbial populations and the cumulus-oocyte complexes of growing dairy heifers was evaluated. The inclusion of camelina in the diet was associated with higher expression of all selected molecular markers of oocyte quality (p < 0.05). Moreover, feeding camelina affected the ruminal microbiota, as shown by the significant reduction in the alpha diversity of the treatment group (p < 0.05).
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Kakwaya, Damian Saranga Muhongo. "Canadian/New Zealand genotype-environment interaction trial : comparison of growth traits of Canadian and New Zealand dairy cattle in Canada." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29883.
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This study, being part of a larger project - "Canadian/New Zealand GxE Interaction Trial" - is comparing Canadian and New Zealand sired heifers for growth traits within Canada, since differences for growth traits were found in the Polish strain comparison (Jasiorowski et al., 1987) and due to selection programs in the two countries.
Twenty Canadian Holstein and twenty New Zealand Friesian progeny tested, A.I. bulls were randomly mated to over 1,000 cows in 10 Canadian herds. 3,539 records of weight and wither height from 475 heifers (i.e. 241 Canadian and 234 New Zealand sired) were generated. Subsets of the data for different stages of heifer maturity were analyzed separately. Herd and strain effects least squares means were estimated using analysis of variance. Genetic and phenotypic and correlations and heritability for weight and wither height were estimated by a Derivative-Free Restricted Maximum Likelihood (DFREML) algorithm and an animal model (AM).
No differences were found between sire strains for weight except at 15 and 18 months where sib groups of Canadian (CN) sires were heavier than their New Zealand (NZ) contemporaries (393 vs 386 kg and 447 vs 445 kg,
respectively). CN sired heifers were taller at all ages except at birth, 3 and 9 months of age. At 24 months CN heifers were 136 cm while NZ heifers were 133 cm.
Heritability estimates for weight at birth was 0.62 for the CN strain and 0.59 for the NZ strain. CN estimates (3 to 6 months) and NZ estimates (3 to 9 months) were close to zero. Between 9 to 24 months CN strain estimates ranged from 0.44 to 0.69 while NZ estimates were 0.17 to 0.51. The joint estimates ranged from 0.10 to 0.66.
Heritability estimates for wither height for CN strain at birth and between 9 to 21 months were between 0.34 to 0.66 and close to zero between 3 to 6 and at 24 months. The NZ estimates at birth, 18, 21 and 24 months were between 0.36 to 0.93 but close to zero between 3 to 15 months. The joint estimates ranged from 0.32 to 0.75 between 12 to 24 months.
Genetic correlations between weight and wither height ranged from 0.62 to 1.0 for CN strain and from -0.04 to 0.91 for NZ strain between 4.5 to 21 months. At six months of age the genetic correlation for CN strain was -0.01 and NZ strain was 0.54. At birth, both sire groups had a genetic correlation of 1.0.
At 24 months NZ strain had a genetic correlation of 0.84 while that of the CN strain was 0. Genetic correlations for the joint analysis ranged from 0.61 to 1.0 for all ages except at 6 months (0.18).
Phenotypic correlations between weight and wither height were between 0.33 to 0.60 for CN group and 0.33 to 0.62 for NZ group. The joint estimates were 0.36 to 0.61.
There were no differences in the phenotypic variances except at 9, 12 and 15 months. Genetic variances were different at all ages except at birth for weight.Land and Food Systems, Faculty of
Graduate
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Larcombe, Michael Tinniswood. "The effects of manipulating reproduction on the productivity and profitability of dairy herds which graze pasture /." Connect to thesis, 1989. http://eprints.unimelb.edu.au/archive/00000650.
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Olynk, Nicole J. "Economic analyses of reproduction management strategies and technologies on U.S. dairy farms." Diss., Connect to online resource - MSU authorized users, 2008.
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Thesis (M.S.)--Michigan State University. Dept. of Agricultural, Food, and Resource Economics, 2008.Title from PDF t.p. (viewed on July 28, 2009) Includes bibliographical references (p. 105-108). Also issued in print.
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Gotschi, Manuela. "The use of blood metabolic concentrations as indicators of the metabolic and productive status in dairy cows." Diss., Pretoria : [s.n.], 2000. http://upetd.up.ac.za/thesis/available/etd-01312008-145827.
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Ngo, Van Man. "Better use of local forages for dairy cattle in Vietnam : improving grasses, rice straw and protein rich forages /." Uppsala : Swedish University of Agricultural Sciences, 2001. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=009768639&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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McLachlan, Brenda Patricia. "Peri-partum diet and health in dairy cattle /." [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18167.pdf.
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Olofsson, Jan. "Feed availability and its effects on intake, production and behaviour in dairy cows /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5752-1.pdf.
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Kolath, Sarah Jane. "Ovarian gene expression in heat-stressed dairy cattle /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426077.
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Pryce, Jennie Elizabeth. "Genetics of health and fertility in dairy cattle." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/23523.
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In this study genetic parameters were estimated and the importance of genotype by feeding system interactions investigated for a range of health and fertility traits in dairy cattle. Data were from the Langhill Dairy Cattle Research Centre and two UK recording schemes, one a recording scheme operated by the Scottish Livestock Services Ltd. (SLS) and the other a health and fertility recording and management system, the Dairy Information System (DAISY). Genetic parameters for 305 day yield of milk and its components, health traits (mastitis, somatic cell counts (SCC), lameness and milk fever) and fertility traits (calving interval, days to first service and conception to first service) were estimated using data from DAISY and SLS. Heritabilities and correlations agreed well between the two data sets implying that the nature of the recording scheme had little effect on the parameter estimates obtained. Heritabilities for all health and fertility traits were less than 0.10 with the exception of SCC which had a heritability of 0.15. The genetic correlation between SCC and mastitis was estimated to be 0.65. Genetic correlations of health and fertility traits with production were in all cases unfavourable. Using these estimates, a breeding programme designed to maximise response in production was predicted to increase calving intervals, mastitis and lameness by 0.39, 0.27 and 0.13 genetic standard deviations per unit selection differential. Restricting these traits to zero genetic change was predicted to result in 11% less overall economic response in production than an unrestricted index. Genotype by feeding system interactions were investigated for a wider range of health and fertility traits using data from Langhill. Selection and control line animals housed and managed as one herd were assigned to either a high concentrate or low concentrate feeding system. There were no significant genetic line by feeding system interactions. However, regressions of the traits on pedigree index for fat plus protein yield (PI) were significantly different from zero for six measures of fertility and mastitis. It was concluded that selection for production has led to a deterioration in some health and fertility traits in UK dairy herds. This deterioration could be halted, or the situation improved by direct recording and selection. However, in the absence of a national recording scheme for health and fertility, an alternative would be to use predictor traits, as they are generally easier to measure and record and have higher heritabilities. Results from this study supports the use of SCC as a selection criterion for mastitis (on a small data set), but the regressions on sire predicted transmitting abilities for type were less conclusive. Therefore future research should investigate associations between health, fertility, production, type, SCC and other potential predictor traits more fully and compare the role of direct measurements of these traits or indirect predictions of them in national indices.
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Kamande, George Matiru. "Forage and concentrate protein utilization by dairy cattle." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27970.
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In the first part of this study, the relative in situ rumen degradabilities of some common Kenyan feedstuffs were estimated using two fistulated steers. The second part of the study attempted to manipulate rumen fermentation processes by heat treating dietary protein, and also by varying the hay particle size.
The in situ dacron bag technique was used to estimate the feeding value of some common Kenyan forages. The rate and extent of dry matter (DM) and crude protein (CP) degradation in the rumen was then determined from the incubated samples. Effective DM and CP degradation was also estimated at various rumen digesta flow rates.
Green maize chop, fodder sorghum, napier grass, kikuyu grass, Pennisetum trachyphyllum, rhubarb leaves, banana leaves, sweet potato vines, desmodium and lucerne had moderate to high DM and CP degradability (>50%). These feedstuffs would therefore offer greater potential for conservation for feeding dairy cattle in the dry season. Wheat straw, maize stover, red oats grass and naivasha stargrass had significantly (P<0.05) lower rumen degradability. This last group would require supplemental energy and nitrogen in order to meet the dairy cow's nutrients requirements. Wheat bran had a high DM degradability but its CP degradability was low. The
digestibility and amino acid availability of its protein requires further investigations.
The effects of forage particle length and heat treatment of protein sources on intake, milk yield and composition and, ration digestibility were determined using dairy cows. Normal or heated canola meal and dehydrated alfalfa were fed together with orchard grass hay to 24 lactating Holstein cows. Orchard grass hay was chopped to two mean cut lengths i.e 14.19 and 1.71 mm.
In situ results showed that both canola meal and alfalfa proteins in the supplement was made indigestible by heat.
Heat treatment did not affect in vivo dry matter (DM), crude protein (CP) and acid detergent fibre (ADF) digestibility for the complete canola rations. Milk yield was also not significantly affected by heating canola meal. However, neutral detergent fibre (NDF) digestibility, voluntary feed intake, butter fat and milk protein contents decreased with heat treatment. Reduced forage particle size in combination with heat treatment resulted in significantly lower DM, CP, and ADF digestibility. There was no significant change in voluntary feed intake, milk yield or its components, (except lactose content), with reduced hay particle size. Lactose content was significantly higher with long chop hay.
Heat treatment of "alfalfa and short hay particle size resulted in lower DM and CP digestibility of the complete rations. ADF digestibility and voluntary feed intake were reduced with heat treatment. Hay particle size did not affect voluntary feed intake significantly. Milk yield and its components increased with heat treatment of alfalfa. Only total milk fat increased with the longer chop hay.Land and Food Systems, Faculty of
Graduate
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Holmberg, Mia. "Genetic dissection of functional traits in dairy cattle /." Uppsala : Dept. of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200792.pdf.
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Musa, Lutfi Mohamed Ahmed. "Characterization and utilization of dairy cattle in Sudan /." Berlin : Köster, 2007. http://deposit.d-nb.de/cgi-bin/dokserv?id=3030232&prov=M&dok_var=1&dok_ext=htm.
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Gonzalez, Esquivel Carlos Ernesto. "Evaluation of suitability in dairy cattle production systems." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286689.
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Erdogan, Hidayet Metin. "An epidemiological study of listeriosis in dairy cattle." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246248.
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Veerkamp, Roel Franciscus. "Genetic improvement of economic performance in dairy cattle." Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/11503.
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The aims in this thesis were to investigate more comprehensive breeding goals in dairy cattle, to investigate the possible importance of genotype by environment interaction and to identify possible sources of genetic variation in feed utilisation. On the basis of a literature review, longevity was examined as component of the breeding goal, and four linear type traits (foot angle, udder depth, teat length and angularity) with the closest genetic association with longevity were used as index measurements. Economic values were derived for protein, fat and milk yield and for longevity using dynamic programming. The derived values were in genetic standard deviations relative to protein yield 1.0, 0.2, -0.2 and 0.8, respectively. Three completely additive indices were derived, assuming that the breeding goal was for: (i) yield only (YIN), (ii) longevity only (LIN) or (iii) yield and longevity, hence profit (PIN). Selection on PIN was expected to give a 5% higher annual rate of genetic progress in economic merit compared with selection on YIN, and PIN was robust to most assumptions made in the calculation. Genotype by environment interaction was investigated for a range of traits. Selection (S) and Control line (C) cows, housed and managed at the Langhill Dairy Cattle Research Centre, have been offered ad libitum complete mixed diets, with proportions (in total DM) of concentrates, silage, brewers' gains of either 20:5:75 (LC; 1.0 ton concentrate per annum) or 45:5:50 (HC; 2.5 ton concentrate), over a full lactation. No diet x genetic line interactions were observed for a number of traits, describing milk production, feed intake, efficiency and body tissue mobilisation. However, regression coefficients of milk yield and condition score on pedigree index for fat plus protein yield were significantly different between LC and HC. Phenotypic and genetic variances were generally larger on HC than on LC, but difficulties in separating the permanent environmental variance from the additive genetic variance might have obscured some of the comparisons.
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Obike, Onyemauchechi Mercy. "Genetics of health and lameness in dairy cattle." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4113.
Full textAbstract:
For the modern dairy cow, advances in genetics and breeding for productivity has resulted in an increasing incidence of health disorders and reduced longevity. One of the most important health problems is lameness, which has led to significant economic, production and welfare consequences. A reduction in lameness will improve the economic future of the dairy industry through increased profitability and decreased welfare-related problems. Although positive attempts have been made by researchers and the industry towards improving lameness, it has remained a persistent ailment for dairy farmers. Further analysis of the genetic and environmental factors influencing lameness is warranted so that selection indices and management practices can be modified leading to improved health and welfare of the dairy cow. Several factors that cause dairy cow lameness have been implicated. I reviewed previous studies on these causative factors as well as the association between lameness, longevity and fertility. It has also been suggested that lameness affects milk production of dairy cows, but reports on the association between lameness and daily milk yield of cows have varied among researchers. Using locomotion score data on 248 cows from the Langhill herd, I investigated the relationship between locomotion score which has a high genetic correlation with lameness and various explanatory variables and also the association between daily milk yield and lameness. The study revealed that the most significant factors affecting locomotion are management regime (high concentrate feed and all year indoor housing; low concentrate feed and outdoors in summer) and time of year when cows are locomotion scored. It also showed that lameness adversely affects the milk yield of later lactation cows, and that high yielding cows are more susceptible to lameness. Housing environment plays a significant role in the health and welfare of dairy cows. With national type evaluation records, I estimated the association between housing systems and lameness-related type traits as well as genetic parameters for the locomotion traits. The analysis indicated that cows kept at pasture had favourable linear and composite type trait scores compared with cows in cubicles, straw yards and slatted floors or loafing yards. Locomotion score had strong genetic and phenotypic correlations with the leg and feet composite. Bone quality, which is a new trait in the UK type classification scheme, was moderately heritable (0.23) and had a moderate and positive genetic association with locomotion and leg and feet composite. This suggests that breeding for flatter, more refined bones could reduce locomotion disorders and help improve the longevity of the dairy cow. Analysis of national data again showed reduced incidence of digital dermatitis (DD) for cows at pasture and those with flatter, more refined bones, higher locomotion score and better leg and feet composite. Estimates of genetic parameters indicated heritable variation of DD among cows and moderate genetic associations between DD and production traits and longevity. Incorporating DD in future selection indices will be useful for increased productive life. Using random regression, I analysed changes in type traits associated with lameness (locomotion, rear legs, side view, foot angle and leg and feet composite) in relation to time (months) that cows had spent in cubicles before being classified. The general trend supported the fact that cubicle housing is unfavourable to these traits. There was significant evidence of a genotype x environment interaction, suggesting variation between bulls in the sensitivity of their daughters to cubicle housing with time.
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Carlén, Emma. "Genetic evaluation of clinical mastitis in dairy cattle /." Uppsala : Dept. of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, 2008. http://epsilon.slu.se/200863.pdf.
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Pillars, Roxanne Bee. "Control strategies for Johne's disease in dairy cattle." Diss., Connect to online resource - MSU authorized users, 2008.
Find full textAbstract:
Thesis (PH.D.)--Michigan State University. Large Animal Clinical Sciences, 2008.Title from PDF t.p. (viewed on Aug. 28, 2009) Includes bibliographical references (p. 260-281). Also issued in print.
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Jansson, Mörk Marie. "Validation of disease recordings in Swedish dairy cattle." Uppsala : Dept. of Clinical Sciences, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200966.pdf.
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Golder, Helen Marie. "Increased understandings of ruminal acidosis in dairy cattle." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/12176.
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ABSTRACT Ruminal acidosis remains an important and prevalent disorder of economic and welfare concern to the dairy industry worldwide. There are inconsistencies in the diagnostic techniques and definitions of ruminal acidosis and a requirement for further information on the pathogenesis of ruminal acidosis, in particular in regard to the role of feed substrates, such as starch, sugar, and protein (Chapter 1). A greater understanding of changes to the microbiome during ruminal acidosis, feed management, and the possible synergistic effects of feed additive control agents is also required (Chapter 1). Consequently, the overall hypothesis of this thesis, which was supported, is that starch-, sugar-, and protein- or amino acid-based feed substrates would produce different ruminal and blood measures and distinct rumen bacterial community composition associated with different risks of ruminal acidosis. Secondly, that partial mixed ration feeding strategies and feed additive control agents would promote favorable ruminal conditions and reduce the risk of ruminal acidosis, which was also supported; however, whether feed additive control agents reduced the risk of ruminal acidosis was equivocal. Heifers exposed to a single feeding of grain and fructose had an increased risk of ruminal acidosis and accumulated ruminal lactate, compared to those fed grain only (Chapter 2). This highlights that diets with high sugar content should be fed with caution and increase the risk of ruminal acidosis when physically effective fiber is inadequate. Different oxidative stress responses were not observed among treatment groups of heifers fed single exposures of different substrates (Chapter 3) or different feed additives over a 20 d period (Chapter 7), but were evident in a heifer with acute clinical ruminal acidosis (Chapter 8). This suggests oxidative stress responses may only occur during acute clinical ruminal acidosis. Distinct ruminal bacterial community composition occurred among heifers fed a single exposure to different substrates (Chapter 4) and also among lactating cows fed different feeding strategies at different supplementary feeding amounts (Chapter 5) and these communities were associated with rumen fermentation characteristics. Cattle appeared to have host specific rumen bacteria and a core microbiome (Chapters 4 and 5). This suggests that host specificity in rumen ecosystems may be associated with the individual susceptibilities of cattle to ruminal acidosis and a need to tailor feed management and control for ruminal acidosis for individual cattle. Supplementary feeding amount and ruminal concentrations of propionate and valerate appeared to have the largest association with ruminal bacterial communities in Chapter 5 and may be good predictors of ruminal acidosis. A partial mixed ration feeding system, compared with component feeding, decreased ruminal acidosis (Chapter 5), suggesting benefits of this feeding system; however, milk production and milk component benefits were not observed for this feeding system. Feed additive control agents perturbed the rumen by different mechanisms but had minimal synergistic effects when combinations of feed additives were fed and ruminal acidosis control was equivocal (Chapters 6 and 7). Feed additives may not be capable of controlling ruminal acidosis in all cattle when large amounts of readily fermentable carbohydrates are fed (Chapter 7). Concentrations of the volatile fatty acids (VFA): butyrate, propionate, valerate, isobutyrate, isovalerate, and caproate were below detectable limits in a heifer with acute clinical ruminal acidosis 24 h after she consumed a ration with 19.1% sugar and 54.1% starch on a DM basis and her acetate concentration was <20 mM. However, concentrations of these VFA were higher 55 h after she consumed the ration. These findings demonstrate that the rumen is extremely dynamic and can rapidly recover from severe perturbation. Throughout this thesis it has been evident that classic models of ruminal acidosis may not be sufficient to describe the pathogenesis of ruminal acidosis when diets with a high sugar content are fed and uncharacterized rumen bacteria may be involved in the pathogenesis of ruminal acidosis. Definitions of ruminal acidosis to describe acidosis when cattle are fed different substrates, in particular diets with a high sugar content are required. The rumen appears to be better adapted to respond to changes in starch intakes, compared with sugar intakes and cattle have individual rumen responses and susceptibilities to ruminal acidosis during shifts in feed substrates. In summary, this thesis has increased our understandings of the pathogenesis of ruminal acidosis and control strategies for ruminal acidosis in cattle.
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Tjondronegoro, Soedjiharti. "A study of reproductive failure in dairy cattle." Thesis, Tjondronegoro, Soedjiharti (1987) A study of reproductive failure in dairy cattle. Masters by Research thesis, Murdoch University, 1987. https://researchrepository.murdoch.edu.au/id/eprint/53179/.
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The overall objectives of this project were: (1) to study the epidemiology of reproductive failure in a number of dairy herds operating under commercial conditions, (2) to investigate whether the reproductive performance of dairy cows was affected by factors such as herd size, lactation number (age), season, month of calving or herd management and (3) to investigate a means of inducing synchronized oestrus and advancing the time of insemination in cows not observed to be in oestrus by 49 days postpartum.
The reproductive performance of dairy cows in 4 dairy herds in Western Australia and the epidemiology of infertility in these herds was described by measuring the:
a. Inter-calving interval
b. Interval from calving to first observed oestrus
c. Interval from calving to first service
d. Number of cows observed in oestrus by 60 days postpartum
e. Number of services per conception f. First service conception rates
g. Prevalence of reproductive disorders
Retrospective analysis of data from each farm based on lactation listing, and monthly and annual dairy herd health reports from 1977 to 1985, revealed that reproductive efficiency and the performance of the dairy herds studied is unsatisfactory when compared with recognized targets of performance for dairy herds in Australia (Blood et al., 1978; Radostits and Blood, 1985). The mean inter-calving interval of the 4 herds was approximately 400 days, which was 35 days above the target of 365 days. The mean interval from calving to first service was prolonged by 15 days above the target of 65 days. The mean conception rates to first 1 service also fell short of the target (40% vs a target of 70%).
Failure of cows to exhibit behavioural oestrus (’no visible oestrus’) in the postpartum period, inadequate oestrus detection, inaccurate time of insemination, failure to rebreed cows in the early postpartum period, delayed interval from calving to first service after calving, increased number of services per conception and poor conception rates to first insemination were the major contributing factors in prolonging intervals from calving to conception, hence inter-calving intervals. Poor first service conception rates can be attributed to a number of causes such as insemination at the wrong time during oestrous periods, poor oestrus detection, failure to conceive and early embryonic mortality.
The size of the herd, month of calving lactation number or body condition scores at calving did not affect inter-calving intervals. Seasons of the year did not influence the conception rates to first service or the number of cows observed in oestrus by 60 days postpartum. The month of calving and lactation number had a significant effect on the incidence of reproductive disorders.
In the second part of this study, behavioural oestrus was synchronized in postpartum dairy cows using two types of intravaginal devices which released progesterone. Groups of lactating dairy cows were treated with intravaginal devices containing either progesterone only or progesterone plus an initial dose of oestradiol benzoate for 9 or 12 days. Milk samples were taken at frequent intervals before and after the removal of the devices to obtain profiles of progesterone.
The proportion of cows showing oestrus within 5 days after removal of the devices was greater for groups of cows treated with progesterone plus oestradiol benzoate. Within 5 days after removal of the intravaginal device, the mean milk 5 progesterone level of all cows which did not show oestrus (NVO) was significantly greater than that of cows which showed oestrus. However, about 61 % of NVO cows had a decrease in milk progesterone concentrations after removal of the devices followed by a typical post-ovulatory rise, which indicated that these cows were cyclic, though behavioural oestrus was absent.
Poor reproductive performance of the dairy herds in the present study, which reflects a general lack of concern by the farmer of problems that limit their cow’s reproductive performance, causes major economic losses to the dairy farmers by reducing the farm's milk production and decreasing the number of calves born per year. The procedures adopted in the second part of the present study represent a programme which can be applied to enhance control over reproduction in the dairy herd so that the efficiency of reproduction and production in dairy herds can be improved.
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Rioja-Lang, Fiona C. "The effects of feed area design on the social behaviour of dairy cattle." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3516.
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The overall objective of this thesis was to assess the effect of feed area design including feeding space availability, barrier type and stocking density, on the feeding behaviour of dairy cows. Feed intake in dairy cows is directly related to milk production, thus a good food supply is extremely important to the modern, high producing dairy cow. Intake is critical for improving milk production, health, body condition and the welfare of the animals. Feeding designs can have a major effect on behaviour and feed intake, therefore it is an important consideration when housing cattle and other livestock. The effect of altering the amount of space allowance available at the feed-face highlighted a significant effect on feeding patterns. As the space allowance increased the number of feeding bouts also increased (P<0.001) and length of bouts decreased (P<0.05). However, when provided with extra space at the feed-face, cows did not increase their feed intake as hypothesised, possibly as a result of the differences between individual animals being masked by an overall group effect. The number of aggressive interactions decreased as the space allowance increased (P<0.001) and furthermore, the number of times individuals were displaced from the feeding area also decreased as the space allowance increased (P<0.05). Subsequently, preference tests were used as a behavioural tool to determine how individual cows perceive their feeding environment with specific emphasis on understanding what difficulties low ranking animals face at the feed-face. Subordinate cows showed a significant preference for feeding alone rather than next to a dominant when they were offered high quality feed on both sides of a Y-maze test (P<0.001). When “asked” to trade-off between feed quality and proximity to a dominant cow, subordinate cows chose to feed alone on low quality food. A follow-on experiment using the same methodology was undertaken and aimed to identify the space allowances at which cows would not trade-off food quality. Four different space allowances were tested. At the two smaller space allowances, cows preferred to feed alone and for the two larger space allowances, cows had no significant preferences. The feed barrier has been shown to have a major effect on feeding and social behaviour of group housed dairy cows. A barrier design that provides some sort of separation between cows has also been shown to reduce competition. The aim of the final study was to determine if a feed barrier which obscured the cows’ visual field whilst feeding would increase vigilance behaviour and alter normal feeding behaviour, particularly for subordinates. Two different types of feed barrier were tested at four different stocking densities. The average daily feeding time was higher when cows were fed using a conventional headlock system compared to an electronic feeding system (P<0.05). All groups of cows displayed vigilance scans, however, neither type of barrier, feed space allowance, or dominance rank had an effect on the frequency of scans. These results indicate that neither feeder design nor stocking rate affect vigilance in dairy cows, at least over the treatment conditions assessed in the current study. The results of this research illustrate that to achieve the maximum levels of feeding behaviour and a reduction of aggressive behaviour, the cows’ environment must be such that it provides sufficient space and feed barrier design which will allow normal social behaviour. Over-stocking at the feed-face should be avoided to reduce competition. Future research should consider the long term effects of over stocking and competition on dry matter intake (DMI), milk production and health.
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Almeida, Rodrigo de. "Study of abnormal test-days in Quebec Holstein cows." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23995.
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The influences of some environmental and genetic factors on the incidence of abnormal test-days in milk-recorded cows enrolled in the Quebec Dairy Herd Analysis Service (QDHAS) was determined in this study. Conditions Affecting Records (CAR) codes, collected monthly by QDHAS's supervisors, are possible explanation for a reduced production in the day of test. For the purpose of this study, CAR codes were used to analyze the incidence of health problems under generalized linear models methodology. Poisson and logistic regression model analyses were able to model the number of cases of abnormal test-days and health problems per lactation. Herd, testing program, parity number, and stage of lactation were important systematic effects included in the analysis. However, calving year, season of calving, and herd production level were not statistically significant in most analysis. Sires significantly differed in the incidence of some health problems of their daughters. Low heritability values, between 0.02 and 0.05, were found showing that most variability was explained by non-genetic factors. Regardless of the low heritability, the genetic variability has been shown to be considerable, suggesting that a significant genetic improvement of the disease resistance is achievable if proper procedures are adopted.
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Tejomurtula, Jyothsna. "Identification of a novel importin [alpha] predominantly expressed in bovine oocytes and early embryos." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5488.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains vi, 45 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 40-45).
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Starbuck, Gareth Robert. "Progesterone and fertility in the dairy cow." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324102.
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Lindström, Tina. "Feeding behaviour in dairy cows : motivational aspects /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-5761-0.pdf.
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Nennich, Tamilee Dawn. "Characterization of manure excretion and environmental impacts of nutrient management in dairy production systems." Online access for everyone, 2004. http://www.dissertations.wsu.edu/Dissertations/Fall2004/T%5FNennich%5F112204.pdf.
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Tutusaus, Batlle Joan. "Clinical aspects of C. burnetii infection in dairy cattle." Doctoral thesis, Universitat de Lleida, 2014. http://hdl.handle.net/10803/146131.
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La febre Q és una zoonosis re-emergent endèmica mundialment, causada per Coxiella burnetii, un bacil Gram negatiu intracel.lular. Els remugants domèstics són el reservori principal per als humans. La infecció és principalment asimtomàtica en boví, però se l’ha relacionat amb desordres reproductius. L’objectiu d’aquesta tesis ha estat proporcionar informació per millorar el seu control a les explotacions bovines. S’han estudiat la serologia, els patrons d’excreció de C. burnetii i la seua relació amb el rendiment reproductiu de les vaques lleteres. A més, s’ha evaluat la bioseguretat d’una vacuna inactivada contra C. burnetii fase I aplicada en vaques gestants i la seua capacitat per millorar el rendiment reproductiu. Les conclusions són que no s’han detectat anticossos precalostrals en vedells de mares infectades, l’excreció i la seropositivitat no es relacionen negativament amb el rendiment reproductiu i que la vacunació de vaques en gestació avançada no redueix l’excreció però millora el rendiment reproductiu.La fiebre Q es una zoonosis re-emergente endémica mundialmente, causada por Coxiella burnetii, un bacilo Gram negativo intracelular. Los rumiantes domésticos son el reservorio principal para los humanos. La infección es principalmente asintomática en bovino, pero se la ha relacionado con desórdenes reproductivos. El objetivo de esta tesis fue proporcionar información para mejorar su control en las explotaciones bovinas. Se estudiaron la serología, los patrones de excreción de C. burnetii y su relación con el rendimiento reproductivo de las vacas lecheras. Además, se evaluó la bioseguridad de una vacuna inactivada contra C. burnetii fase I aplicada en vacas gestantes y su capacidad para mejorar el rendimiento reproductivo. Las conclusiones son que no se detectaron anticuerpos precalostrales en terneros de madres infectadas, excreción y seropositividad no se relacionaron negativamente con el rendimiento reproductivo y que la vacunación de vacas en gestación avanzada no reduce la excreción pero mejora el rendimiento reproductivo.
Q fever is a worldwide re-emerging zoonosis caused by an intracellular Gram negative bacillus, Coxiella burnetti. Domestic ruminants are the main reservoir to humans. Despite the infection is mainly asymptomatic in cattle, is has been linked with reproductive disorders. Therefore, the aim of this thesis was to provide information about C. burnetii infection to improve its control in dairy herds. A study of serological profiles, shedding patterns and its relationship with reproductive performance has been performed. In addition, a C. burnetii inactivated phase I vaccine has been tested evaluating the biosafety for use in pregnant cows and in assessing its ability to improve reproductive performance in dairy herds. The results indicate no detectable precolostral antibody response in calves born from infected dams, seropositivity and shedding are not related to reproductive disorders and vaccination of advanced pregnant cows was not able to reduce bacterial shedding but improves reproductive performance.
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Ventura, Beth Ann. "Understanding industry and lay perspectives on dairy cattle welfare." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54881.
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The welfare of dairy cattle is of rising concern in North America. This thesis explores how stakeholders relevant to dairy production—including those working within but also those external to the industry—interpret issues around dairy cattle welfare, with the aim to unearth the root of disagreements and identify common values between diverse groups. Chapter 1 begins by exploring the relevant literature and identifies important gaps. Chapters 2 and 3 describe multi-cohort focus groups of farmers, veterinarians, and other industry stakeholders. Chapter 2 investigates their interpretations of the priority welfare issues facing the dairy industry and demonstrates that these stakeholders hold a broad conception of animal welfare with the potential to link to values in broader society. Chapter 3 explores how these stakeholders perceive challenges to welfare and their desired solutions for change; it shows consensus for education, particularly in the form of peer-led extension strategies, to address low welfare knowledge among farmers and veterinarians. Chapter 4 describes a survey of non-farming citizens before and after touring a dairy farm and demonstrates that, as with industry stakeholders, citizens’ animal welfare values are diverse. Chapter 4 also shows that citizens respond differently to learning more about dairy farming, with some becoming more concerned and others less so. Chapter 5 then describes the use of an online engagement tool to explore in greater depth what appears to be one of the most contentious practices in dairy production—that of early separation of the dairy calf from the cow. It illustrates that support of this practice varies markedly among stakeholder groups, but that people are often concerned with the same issues regardless of their stance, providing paths for compromise on practice and policy. Chapter 6 concludes with a summary of findings and recommendations, including: 1) farmers should engage with veterinarians and researchers to help them adopt practices in better alignment with societal values (such as pain mitigation), 2) industry decision makers should commit to transparency but also be prepared to listen and adapt to informed critiques, and 3) researchers should explore engagement strategies to aid in conflict resolution between industry and lay citizens.Land and Food Systems, Faculty of
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Fatehi, Jalal. "Genetic aspects of advanced reproductive biotechnologies in dairy cattle." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0022/MQ51061.pdf.
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