Добірка наукової літератури з теми "Heifer calves"
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Статті в журналах з теми "Heifer calves"
Furniss, S. J., A. Stroud, H. Barrington, S. P. J. Kirby, J. P. Wray, and P. Dakin. "The effect of dam’s parity on the first lactation performance of dairy heifers." Proceedings of the British Society of Animal Production (1972) 1986 (March 1986): 102. http://dx.doi.org/10.1017/s0308229600016093.
Повний текст джерелаCônsolo, Nara, Jasper Munro, Stéphanie Bourgon, Niel Karrow, Alan Fredeen, Janel Martell, and Yuri Montanholi. "Associations of Blood Analysis with Feed Efficiency and Developmental Stage in Grass-Fed Beef Heifers." Animals 8, no. 8 (August 2, 2018): 133. http://dx.doi.org/10.3390/ani8080133.
Повний текст джерелаElliott, Lisa M., Joe L. Parcell, and David J. Patterson. "Determination of the Value of Minimum Sire Accuracy Traits." Journal of Agricultural and Applied Economics 45, no. 2 (May 2013): 259–75. http://dx.doi.org/10.1017/s1074070800004739.
Повний текст джерелаColeman, Lucy, Natalia Martín, Penny Back, Hugh Blair, Nicolás López-Villalobos, and Rebecca Hickson. "Low Birthweight Beef Bulls Compared with Jersey Bulls Do Not Impact First Lactation and Rebreeding of First-Calving Dairy Heifers—A Case Study in New Zealand." Dairy 3, no. 1 (January 27, 2022): 87–97. http://dx.doi.org/10.3390/dairy3010007.
Повний текст джерелаKeane, M. G., and M. J. Drennan. "Growth and Carcass Composition of Implanted and Non-Implanted Heifers and Steers Reared Together." Proceedings of the British Society of Animal Production (1972) 1986 (March 1986): 23. http://dx.doi.org/10.1017/s0308229600015348.
Повний текст джерелаNewman, J. A., S. D. M. Jones, M. A. Price, and B. C. Vincent. "Feed efficiency in once-calved and conventional systems of heifer beef production." Canadian Journal of Animal Science 73, no. 4 (December 1, 1993): 915–30. http://dx.doi.org/10.4141/cjas93-093.
Повний текст джерелаRigby, I. "Once-bred heifer systems." Proceedings of the British Society of Animal Production (1972) 1989 (March 1989): 8. http://dx.doi.org/10.1017/s0308229600010096.
Повний текст джерелаGordon, I. "Modern techniques for enhancing reproduction in suckler cattle systems." Proceedings of the British Society of Animal Production (1972) 1989 (March 1989): 6. http://dx.doi.org/10.1017/s0308229600010072.
Повний текст джерелаLOSINGER, WILLARD C., and A. JUD HEINRICHS. "Management practices associated with high mortality among preweaned dairy heifers." Journal of Dairy Research 64, no. 1 (February 1997): 1–11. http://dx.doi.org/10.1017/s0022029996001999.
Повний текст джерелаKerby, Mike, Tom Clarke, Tom Angel, and Kythé Mackenzie. "The use of fixed time artificial insemination programmes for the use of sexed semen in block calving dairy heifers." Livestock 26, no. 3 (May 2, 2021): 124–30. http://dx.doi.org/10.12968/live.2021.26.3.124.
Повний текст джерелаДисертації з теми "Heifer calves"
Daniels, Kristy M. "Effects of Milk Replacer Composition on Measures of Mammary Development in Holstein Heifer Calves." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/27174.
Повний текст джерелаPh. D.
Wright, Ashley Diane. "Evaluating Residual Feed Intake in Replacement Heifer Calves for Correlation with Breed and Sire." Thesis, The University of Arizona, 2014. http://hdl.handle.net/10150/323227.
Повний текст джерелаPempek, Jessica Ann. "Effects of Alternative Housing and Feeding Systems on the Behavior and Performance of Dairy Heifer Calves." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313550358.
Повний текст джерелаGeiger, Adam John. "The Effect of Increased Nutrient Intake and Exogenous Estrogen on Mammary Gland Growth, Morphology, Histology, and Gene Expression of Holstein Heifer calves." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/73324.
Повний текст джерелаPh. D.
Weston, Emily Iris. "Evaluation of Cortisol in Saliva Relative to Serum in Lactating Cows, Heifer Calves and Piglets in Response to Applied Stress." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-05122009-103900/.
Повний текст джерелаAlmeida, Daniel Mageste de. "Effects of supplementation levels on performance and metabolic and nutritional characteristics of cows, suckling female calves and heifers on grazing." Universidade Federal de Viçosa, 2017. http://www.locus.ufv.br/handle/123456789/10524.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico
A reprodução é o principal fator limitante na eficiência da produção de carne, e a baixa taxa de concepção observada no rebanho brasileiro reflete a baixa taxa de fertilidade das vacas e a idade tardia à puberdade das novilhas de substituição. A fim de fornecer mais informações sobre as estratégias nutricionais para o melhor desenvolvimento das novilhas Nelore e melhorar o desempenho das vacas, foram realizados três estudos e os resultados são apresentados em quatro artigos. No primeiro trabalho, foram utilizadas 80 vacas Nelore grávidas (6 meses de gestação) com idade inicial de seis anos e peso inicial médio e escore de condição corporal inicial de 515,5 ± 1,34 kg e 4,68 ± 0,15, respectivamente. O delineamento experimental foi inteiramente casualizado, com quatro tratamentos e vinte repetições. As estratégias avaliadas foram suplementação com 1 kg/vaca/dia de suplementação somente no pré-parto, somente no pós-parto, no pré e pós-parto, e somente mistura mineral ad libitum durante o pré e pós-parto. Observou-se o efeito da suplementação sobre o peso corporal (PC) das vacas no parto e sobre o peso dos bezerros ao nascimento (P <0,05). Houve também efeito da suplementação no pré e pós-parto (P <0,05) no PC final, ganho médio diário e escore de condição corporal final dos animais. Houve uma tendência, com a suplementação no pós-parto, de maior produção de leite das vacas (P = 0,065) e, para os seus componentes, houve efeito de suplementação no pós-parto apenas para proteína do leite (PL) (P = 0,003). Houve um efeito da suplementação no pós-parto sobre nitrogênio ureico sérico, glicose, ácidos graxos não esterificados, β-hidroxibutirato e progesterona (P <0,05). Todos os metabólitos foram influenciados (P <0,05) no dia pós-parto. As vacas suplementadas no pós-parto apresentaram maior taxa de concepção do que a observada em animais não suplementados (P = 0,005). A suplementação com 1 kg/dia de suplementação com 28,6% de PC no pré-parto melhorou algumas das características produtivas, no entanto, a suplementação no pós-parto permite efeitos mais expressivos sobre a eficiência produtiva, metabólica e reprodutiva das vacas. Portanto, a suplementação no pós-parto é recomendada quando os animais têm escore de condição corporal vi (ECC) adequada ao parto. As bezerras das vacas do primeiro experimento foram utilizadas no segundo trabalho para avaliar estratégias de suplementação no sistema creep-feeding. Utilizaram-se quarenta e quatro bezerras Nelore, com idade e peso médio inicial, de quatro meses e 147,6 ± 1,34 kg, respectivamente. Um único suplemento com aproximadamente 20% de proteína foi fornecido em quantidades diferentes dependendo do peso corporal (PC). Os tratamentos consistiram no suprimento de 0,0%, 0,2%, 0,4% ou 0,6% do PC deste suplemento. Observou-se aumento do efeito linear (P <0,05) do peso corporal final e ganho médio diário de novilhas com aumento da suplementação. A suplementação múltipla aumentou o consumo, em kg/dia, de matéria seca (MS), matéria orgânica (MO), proteína bruta (PB), matéria seca digerida (MSD) e nutrientes digestíveis totais (NDT). Não houve efeito da suplementação (P> 0,05) nas concentrações de AGNE. Houve um efeito linear crescente (P <0,05) de suplementação sobre as concentrações de insulina. Conclui-se que a suplementação melhora o desempenho, as características nutricionais e metabólicas dos animais, sendo o suprimento de 0,6% do PC de suplemento com 20% de PB o tratamento mais efetivo. As mesmas novilhas foram utilizadas no terceiro experimento após o desmame para avaliar os efeitos da suplementação estratégica de novilhas Nelore após o desmame à concepção. As estratégias avaliadas foram: BAAL - suplementação com 0,2% de PC/animal/dia de suplementação nos primeiros 90 dias e suplementação com 0,6% de PC/animal/dia nos 90 dias subseqüentes; MEME - suplementação com 0,4% de PC/animal/dia durante 180 dias; ALBA - suplementação com 0,6% de PC/animal/dia de suplementação nos primeiros 90 dias e suplementação com 0,2% de PC/animal/dia nos 90 dias seguintes; e MM - apenas mistura mineral ad libitum durante os 180 dias. Observou-se que a suplementação melhorou o desempenho dos animais durante os primeiros 90 dias de experimento, o que pode ser verificado pelo ganho médio diário (GMD) das fêmeas (P = 0,001). O mesmo fato foi observado na fase de transição seca/água, onde a suplementação melhorou o peso corporal final (PCf) (P = 0,002) e GMD (P = 0,001). Verificou-se também que a suplementação múltipla aumentou o consumo de matéria seca (MS), matéria orgânica (MO), proteína bruta (PB), matéria seca digestível (MSD) e nutrientes digestíveis totais (NDT) durante todo o experimento e fibra em detergente neutro digestível(FDNd) e fibra em detergente neutro corrigida para cinzas e proteínas (FDNcp) apenas na transição seca/água. A suplementação aumentou o coeficiente de digestibilidade aparente de MS, MO, PB, vii FDNcp e NDT (P <0,05), ou seja, de todos os parâmetros analisados. Os níveis de nitrogênio ureico sérico (NUS), glicose (GLIC), insulina (INS) e progesterona (PROG) foram maiores em novilhas suplementadas do que em novilhas não suplementadas (P < 0,05). Por outro lado, a suplementação reduziu as concentrações de ácidos graxos não-esterificados (AGNE) (P = 0,001). Finalmente, foi obsevado que a taxa de concepção foi maior em novilhas suplementadas (P = 0,002). Concluiu- se que os melhores níveis de NUS, INS, GLIC, AGNE e PROG das novilhas suplementadas associadas ao maior PCf, digestibilidade e consumo dos componentes da dieta proporcionaram melhor desempenho reprodutivo para as novilhas suplementadas, independentemente da suplementação.
Reproduction is the main limiting factor in meat production efficiency and the low offtake rate observed in the Brazilian herd reflects the low fertility rate of cows and the late age at puberty of replacement heifers. In order to provide more information about nutritional strategies to better develop Nellore heifers and to improve dams’ performance, three studies were conducted and the results are here presented in four papers. In the first paper, were used 80 pregnant Nellore cows (6 months gestation) with initial age of six years and mean initial weight and initial body condition score of 515.5 ± 1.34 kg and 4.68 ± 0.15, respectively.The experimental design was completely randomized, with four treatments and twenty repetitions. The strategies evaluated were supplementation with 1 kg/cow/day of supplementation only in the pre-partum, only in the postpartum, in the pre and postpartum, and only ad libitum mineral mixture during the pre and postpartum.The effect of supplementation on the body weight (BW) of cows at calving and calf weight at birth (P <0.05) was observed. There was also effect of pre and postpartum supplementation (P <0.05) on the final BW, mean daily gain and final body condition score of the animals. There was a trend of postpartum supplementation on milk production from the matrices (P = 0.065) and, for its components, there was post-partum supplementation effect only on milk protein (MP) (P = 0.003). There was an effect of postpartum supplementation on serum urea nitrogen, glucose, non-esterified fatty acids, β- hydroxybutyrate and progesterone (P < 0.05). All metabolites were influenced (P < 0.05) by the postpartum day. Cows supplemented postpartum had a higher conception rate than that observed in non-supplemented animals (P = 0,005). Supplementation with 1 kg/day supplementation with 28.6% of CP in pre-partum improved some of the productive characteristics, however, postpartum supplementation allows more expressive effects on the productive, metabolic and reproductive efficiency of cows. Therefore, postpartum supplementation is recommended when the animals have adequate body condition score (BCS) at calving. The heifer calves of cows used in the first experiment were used in the iii second paper to evaluate supplementary strategies in the creep feeding system. Were used fourty-four Nellore heifer calves, with age and initial mean weight, of four months and 147.6 ± 1.34 kg, respectively.A single supplement with approximately 20% of protein was provided in different amounts depending on body weight (BW). Treatments consisted in the supply of 0.0%, 0.2%, 0.4% or 0.6% of BW from this supplement.Increasing linear effect (P < 0.05) of final body weight and average daily gain of heifer calves were observed with increased supplementation. Multiple supplementation increased consumption, in kg/day, of dry matter (DM), organic matter (OM), crude protein (CP), digested dry matter (dDM) and total digestible nutrients (TDN).There was no effect of supplementation (P > 0.05) on NEFA concentrations. There was an increasing linear effect (P < 0.05) of supplementation on insulin concentrations. It is concluded that supplementation improves the performance, nutritional and metabolic characteristics of the animals, being the supply of 0.6% of BW of supplement with 20% of CP the most effective treatment.The same heifers were used in the third experiment after weaning to evaluate the effects of strategic supplementation for Nellore heifers after weaning to conception. The evaluated strategies were: BAAL- supplementation with 0.2% of BW/animal/day of supplement in the first 90 days and supplementation with 0.6% of BW/animal/day in the subsequent 90 days; MEME - supplementation with 0.4% of BW/animal/day for 180 days; ALBA - supplementation with 0.6% of BW/animal/day of supplement in the first 90 days and supplementation with 0.2% of BW/animal/day in the subsequent 90 days; and MM - only mineral mix ad libitum during the 180 days.It was observed that supplementation improved the performance of the animals during the first 90 days of experiment, and this fact can be verified by the heifers' average daily gain (ADG) (P = 0.001).The same fact was observed in the dry/water transition phase, where supplementation improved final body weight (fBW) (P = 0.002) and ADG (P = 0.001).It was also verified that multiple supplementation increased dry matter (DM), organic matter (OM), crude protein (CP), digestible dry matter (dDM) and total digestible nutrients (TDN) during the whole experiment, and digested neutral detergent fiber (dNDF), and neutral detergent fiber corrected for ash and protein (apNDF) only in the dry/water transition.Supplementation increased the total apparent digestibility coefficient of DM, OM, CP, apNDF and TDN (P <0.05), that is, of all analyzed parameters. Serum urea nitrogen (SUN), glucose (GLUC), insulin (INS) and progesterone (PROG) iv levels were higher in supplemented heifers than in non-supplemented heifers (P <0.05). On the other hand, supplementation reduced the concentrations of non- esterified fatty acids (NEFA) (P = 0.001). Finally, it was found that the conception rate was higher for supplemented heifers (P = 0.020). It was concluded that the best levels of SUN, INS, GLUC, NEFA and PROG of the supplemented heifers associated to the higher fBW, digestibility and consumption of the diet components provided better reproductive performance independently of the supplementation.
Silva, Alex Lopes da. "Prediction of starter feed intake of preweaned dairy calves and effects of rumen undegradable protein on performance and digestive characteristics of dairy holstein heifers." Universidade Federal de Viçosa, 2017. http://www.locus.ufv.br/handle/123456789/9977.
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Conselho Nacional de Desenvolvimento Científico e Tecnológic
Este trabalho foi desenvolvido a partir de três estudos. Assim, o objetivo do primeiro estudo foi identificar variáveis que afetam o consumo de concentrado (CC), e desenvolver equações para predizer o CC de bezerros leiteiros até os 64 dias de vida. O banco de dados foi composto pelos dados individuais de 189 bezerros de 8 experimentos, totalizando 6.426 observações diárias de consumo. A informação coletada dos estudos foram: peso corporal ao nascimento (PCi; kg), CC (kg/dia), consumo de leite ou sucedâneo (CL; L/dia), sexo (macho ou fêmea), raça (Holandês ou mestiço Holandês×Gir) e idade (dias). A correlação entre o CC e as variáveis quantitativas CL, PCi, PCi metabólico (PCi0,75) e idade foi estabelecida. Posteriormente, foi realizada uma avaliação gráfica do comportamento padrão dos dados; e um modelo exponencial foi escolhido. Os dados foram avaliados usando a técnica de meta-análise para estimar os efeitos fixos e os efeitos aleatórios associados aos experimentos através de modelos mistos não-lineares. A técnica de validação cruzada foi utilizada para estimar a acurácia e precisão das equações desenvolvidas, com base no quadrado médio do erro de predição (QMEP), coeficiente de correlação de concordância, que foi decomposto em acurácia (Cb) e precisão (ρ). De forma adicional, uma análise tipo “bootstrap” foi utilizada para estimar o viés associado a cada parâmetro das equações desenvolvidas. Uma correlação negativa entre CC e CL foi observada (r= -0,388), no entanto, idade apresentou uma correlação positiva com CC (r= 0.66). Não foi observado efeito do tipo de alimento líquido utilizado (leite ou sucedâneo) no desenvolvimento da equação. No entanto, foram ajustadas 2 equações, significantemente diferente para todos os parâmetros, para predizer o CC para bezerros consumindo menos que 5 (CC<5) ou mais que 5 (CC>5) litros/dia de leite ou sucedâneo: CC<5 = 0,1839±0,0581 × CL × exp((-0,0040±0,0011 × CL + 0,0333 ±0,0021 ) × (I- (6,0332 ±0,3583 × CL + 0,8302± (0,12 × CL); CC>5 = 0,1225±0,0005 × CL × exp((-0,0015±0,0001 × CL + 0,0217±0,0006) ×))) 0,5092 - (I- (1,9508 × CL + 3,5382± )))1,3140 ±0,1710 - (0,12 × CL); onde CC<5 e CC>5 = consumo predito de concentrado para bezerros que consomen menos de 5 ou mais de 5 litros/dia de leite ou sucedâneo, respectivamente (kg/dia); CL = consumo de leite ou sucedâneo (L/dia) e I = idade (dias). Estas equações apresentaram alta acurácia (Cb de 0,97 e 0,95 para CC<5 e CC>5, respectivamente) e o erro aleatório do QMEP foi de 99,8 e 99,9% para CC<5 e CC>5, respectivamente. A análise “bootstrap” indicou um baixo viés para todos os parâmetros estimados em ambas as equações. A precisão das equações foi moderada, com valores de r2 de 0,61 e 0,52 e valores de ρ de 0,78 e 0,72 para CC<5 e CC>5, respectivamente. Conclui-se que a utilização de leite ou sucedâneo como alimento líquido não afeta o CC, ou o desenvolvimento do CC ao longo do tempo, o qual aumenta exponencialmente de acordo com a idade do bezerro. O CC foi negativamente afetado pelo CL e, por esta razão, diferentes equações são necessárias para estimar o CC de acordo com o CL. O segundo estudo objetivou avaliar a influência de diferentes níveis de proteína não-degradável no rúmen (PNDR) sobre o consumo, desempenho, características de carcaça, balaço de N, desenvolvimento da glândula mamária e o status hormonal de novilhas Holandesas em diferentes estágios fisiológicos (EF). Foram utilizadas 16 novilhas pré-puberes (PRE), com peso corporal inicial de 106±7,6 kg e 4±0,46 meses de idade, bem como 16 novilhas púberes (PUB), com peso corporal inicial de 224±7,9 kg e 12±0,45 meses de idade. O experimento teve uma duração de 84 dias e foi conduzido segundo um delineamento inteiramente casualizado, segundo um esquema fatorial 4×2, com 4 níveis de PNDR na proteína total da dieta ((38, 44, 51 e 57%) e animais em duas idades diferentes (pré-puberes e púberes). Entre os dias 36 e 40 e os dias 78 e 82 os animais foram submetidos à ensaios de digestibilidade com coleta de alimentos, sobras e coletas “spot” de fezes e urina. No dia 0 (imediatamente antes do início do experimento) e dia 83 foram tomadas imagens de ultrassom na área lombar dos animais. Nos dias 0, 21, 42, 63 e 84 foram tomadas imagens de ultrassom da glândula mamaria. E, por fim, nos dias 0 e 84 foram tomadas amostras de sangue para estimar as concentrações séricas de progesterona, estrógeno, IGF-I e insulina. O EF afetou a digestibilidade aparente da MS, e novilhas PRE apresentaram menores valores. Novilhas PRE também apresentaram consumo preferencial por fibra em detergente neutro corrigida para cinzas e proteína (FDNcp) e atividade de seleção contra a proteína bruta (PB) maior que novilhas PUB. O ganho médio diário (GMD) e a retenção de N foram afetados pelo EF, e novilhas PRE apresentaram um GMD de 505 g/dia, enquanto novilhas PUB apresentaram um valor médio de 905 g/dia. Adicionalmente, estas variáveis foram afetadas pelo nível de PNDR, e maiores valores foram obtidos para o tratamento com 51% de PNDR. A análise de pixels na glândula mamária apontou efeito do EF, e novilhas PRE apresentaram maiores valores de pixel. As mensurações iniciais de progesterona sérica demonstraram que as novilhas PRE e PUB mantiveram seu EF durante o experimento. A concentração de IGF-I foi afetada somente pelo EF, e novilhas PUB apresentaram maiores valores. A concentração de insulina não foi afetada pelo EF, mas apresentou uma tendência de ser maior para os tratamentos com 51% de PNDR. Conclui-se que o nível dietético de 51% de PNDR é responsável por aumentar o desempenho de novilhas PRE e PUB. Adicionalmente, novilhas PRE tem menor habilidade de seleção, o que afeta, negativamente, a sua digestibilidade e desempenho. Finalmente, estes animais são mais propensos a ter uma maior proporção de gordura na glândula mamaria, mesmo sob moderadas taxas de crescimento. O terceiro estudo foi conduzido com o objetivo de avaliar de níveis crescentes de PNDR sobre o consumo, as digestibilidade parciais e total, a cinética e as características ruminais, bem como a utilização do N de novilhas leiteiras holandesas. Foram utilizadas 8 novilhas holandesas fistuladas no rúmen, com peso corporal inicial de 276±8,3, em delineamento em quadrado latino 4×4 duplo, com quatro níveis de PNDR na proteína dietética, como segue: 38% de PNDR (38PNDR); 44% de PNDR (44PNDR); 51% de PNDR (51PNDR) e 57% de PNDR (57PNDR). O experimento teve duração de 84 dias, subdivididos em 4 períodos experimentais de 21 dias (14 dias de adaptação + 7 dias de coletas). Foram realizadas 8 coletas “spot” de fezes, urina, conteúdo ruminal e digesta omasal, com intervalo de 8 horas entre cada coleta, como segue: no 15o dia as amostras foram coletadas as 0600h e 1500h; no 16o dia as amostras foram coletadas as 0000h, 0900h e 1800h; e no 17o dia as amostras foram coletadas as 0300h, 1200h e 2100h. No 19o dia foi realizado esvaziamento completo do rúmen 4 horas após a alimentação matutina e no 21o dia o esvaziamento foi realizado imediatamente antes da alimentação matutina. O consumo diário de MS, matéria orgânica (MO), PB, FDNcp e FDNcp potencialmente digestível (pdFDNcp) não foi afetado pelos níveis de PNDR. Adicionalmente, o consumo relativo (g/kg de peso corporal) de MS, PB e FDNcp, assim como o fluxo ruminal de MS, MO, PB, FDNcp pdFDNcp não foram afetados pelos níveis de PNDR. A digestibilidade total da MS, MO, PB, FDNcp e pdFDNcp, bem como as digestibilidade ruminal e intestinal da MS, MO, FDNcp e pdFDNcp não foram afetados pelos níveis de PNDR. No entanto, as digestibilidade ruminal e intestinal da PB apresentaram uma tendência de decréscimo de acordo com o aumento nos níveis de PNDR. Não foram observados efeitos dos níveis de PNDR sobre as taxas de ingestão, passagem e digestão, assim como sobre a concentração de ácidos graxos voláteis. O tratamento 38PNDR apresentou maior concentração de nitrogênio amoniacal ruminal em relação aos outros tratamentos. A excreção de nitrogênio urinário apresentou tendência de queda de acordo com o aumento nos níveis de PNDR. Adicionalmente, o nitrogênio retido apresentou tendência de aumento de acordo com o aumento nos níveis de PNDR e foi maior para os tratamentos 51PNDR e 57PNDR. A síntese de proteína bruta microbiana, a eficiência de síntese de proteína microbiana (PBmic) e a eficiência de uso do nitrogênio para síntese de proteína microbiana diminuíram de acordo com o aumento nos níveis de PNDR na dieta. O fluxo de PNDR aumentou, enquanto a quantidade de proteína degradável no rúmen decresceu de acordo com o aumento nos níveis de PNDR. Adicionalmente, o fluxo de proteína metabolizável apresentou tendência de aumento de acordo com o aumento nos níveis de PNDR e maiores valores foram observados para os tratamentos 51PNDR e 57PNDR. Conclui-se que a digestibilidade intestinal da PB é negativamente afetada pelos níveis de PNDR, o que é proporcionado pela redução no fluxo de PBmic, sendo que esta, provavelmente, digestibilidade intestinal da proteína maior que os alimentos. A excreção urinária de N diminui à medida que a PNDR dietética aumenta, o que é proporcionado pela queda nas perdas ruminais de nitrogênio na forma de amônia e pelo aumento na reciclagem de nitrogênio para o rúmen. A redução na excreção urinaria de nitrogênio, aliada ao aumento no fluxo de proteína metabolizável, o qual foi promovida pelo aumento no fluxo de PNDR ao intestino delgado, são determinantes para promover aumentos na retenção de nitrogênio, o que ocorreu nos tratamentos 51PNDR e 57PNDR.
This work was developed from three studies. Therefore, the objective of the first study was to identify variables that influence starter feed intake (SFI), and to develop equations to predict SFI in milk-fed dairy calves up to 64 days of age. The database was composed of individual data of 189 calves from 8 experiments, totaling 6,426 daily observations of intake. The information collected from the studies were: birth body weight (birth BW; kg), SFI (kg/day), fluid milk or milk replacer intake (MI; L/day), sex (male or female), breed (Holstein or Holstein×Gyr crossbred), and age (days). A correlation between SFI and the quantitative variables MI, birth BW, metabolic birth BW (birth BW 0.75), and age was established. Subsequently, data were graphed and based on a visual appraisal of the pattern of the data; an exponential function was chosen. The data were evaluated using a meta-analysis approach to estimate fixed and random effects of the experiments using nonlinear mixed coefficients statistical models. Cross-validation was used to estimate the accuracy and precision of the developed equations using the mean square error of prediction (MSEP), concordance correlation coefficient, which was decomposed into accuracy (Cb) and precision (ρ) parameters, and the coefficient of determination (r 2) as a proxy for precision. In addition, a bootstrap analysis was used to estimate the bias associated with each parameter of the developed equation structure. A negative correlation between SFI and MI was observed (r = –0.388), but age had a positive correlation with SFI (r =0.66). No effect of liquid feed source (milk or milk replacer) was observed in developing the equation. However, 2 equations, significantly different for all parameters, were fit to predict SFI for calves that consume less than 5 (SFI<5) or more than 5 (SFI>5) L/day of milk or milk replacer: SFI<5 = 0.1839±0.0581 ×MI×exp((-0.0040±0.0011× MI + 0.0333 ±0.0021) × (A- (6.0332 × MI + 0.8302±)))±0.35830.5092 - (0.12 × MI); CC>5 = 0.1225±0.0005 × MI × exp((-0.0015±0.0001 × MI + 0.0217±0.0006) × (A- (1.9508±0.1710 × MI + 3.5382±1.3140))) - (0.12 × MI); whereSFI<5 and SFI>5 = starter feed intake prediction for calves that consume less than 5 and more than 5 L/day of milk or milk replacer, respectively (kg/d); MI = milk or milk replacer intake (L/d) and A = age (days). These equations had high accuracy (Cb of 0.97 and 0.95, respectively) and the random errors of MSEP were 99.8 and 99.9% for SFI<5 and SFI>5 equations, respectively. Small biases were observed with the bootstrap analyses for all estimated parameters. The equations’ precision was moderate, with r 2 values of 0.61 and 0.52 and ρ values of 0.78 and 0.72 for SFI<5 and SFI>5, respectively. In conclusion, the use of milk or milk replacer as liquid feed did not affect SFI, or development of SFI over time, which increased exponentially with calf age. Starter feed intake was negatively affected by MI and, and for this reason, different equations are necessary to predict calf SFI according to MI. The second study aimed to evaluate the influence of different levels of rumen undegradable protein (RUP) on intake, performance, carcass characteristics, N balance, mammary gland development and hormonal status of Holstein heifers at different physiological stage (PS). Sixteen prepubertal (PRE) heifers with 106±7.6 kg of initial body weight and aged 4±0.46 months old, as well as, 16 pubertal (PUB) heifers with 224±7.9 kg of initial body weight and aged 12±0.45 months old were used. The experiment was carried out during 84 days following a complete randomized design, in a 4×2 factorial arrangement, with four levels of RUP in dietary protein (38, 44, 51, and 57%), and animals at two PS (prepubertal or pubertal). Between days 36 and 40 and between days 78 and 82 the animals were subjected to digestibility trials with collections of feeds, orts and spot collections of feces and urine. At days 0 (immediately before the beginning of the experiment) and 83 body ultrasound images were taken at the rib area. At days 0, 21, 42, 63 and 84 images of the mammary gland were taken via ultrasound. Finally, at days 0 and 84 blood samples were taken to estimate serum concentration of progesterone, estrogen, IGF-I and insulin. The PS affected the apparent digestibility of DM, and PRE heifers presented lower values. The PRE heifers also presented a preferential consumption for neutral detergent fiber corrected for ash and protein (NDFap) and sorting activity against CP greater than PUB heifers. The average daily gain (ADG) and N retention were affected by PS, and PRE heifers presented an ADG of 505 g/d, while PUB heifers presented an average value of 905 g/d. In addition, these variables were affected by RUP levels, where greater values were obtained for treatments with 51% of RUP. The analysis of pixels in mammary gland images pointed effects of PS, and PRE heifers presented greater pixels values. The initial and final measurements of serum progesterone demonstrated that PRE and PUB heifers kept their PS during the experiment. The IGF-I concentration was only affected by PS, and PUB heifers presented greater values. In addition, insulin was not affected by PS, but presented a tendency to be greater at treatments with 51% of RUP. In conclusion, the dietary level of 51% of RUP is responsible to increase the performance of PRE and PUB Holstein heifers. In addition, PRE heifers have lower sorting ability, what affected, negatively, their digestibility and performance. Finally, these animals are more likely to have greater fat proportion in the mammary gland, even under moderate rates of growth. The third study aimed to evaluate the influence of increasing levels of RUP on intake, total and partial digestibilities, rumen kinetics and characteristics, as well the N use of dairy Holstein heifers. Eight rumen-cannulated Holstein heifers, with an average initial body weight of 276±8.3 were used in a double 4×4 Latin Square design with four levels of RUP in the total dietary protein, as follows: 38% of RUP (38RUP); 44% of RUP (44RUP); 51% of RUP (51RUP) and 57% of RUP (57RUP). The experiment was carried out during 84 days subdivided into 4 experimental periods of 21 d (14 d for adaptation + 7 d for collections). Eight spot collections of feces, urine, ruminal content and omasal digesta were performed with 9 hours interval between each collection, as follows: on 15th d samples were collected at 0600 h and 1500 h; on 16th day samples were collected at 0000 h, 0900 h and 1800 h; on 17th d samples were collected at 0300 h, 1200 h and 2100 h. On 19th d a complete rumen evacuation was performed, 4 hours after the morning feeding and on 21st d immediately before morning feeding. Daily intake of DM, organic matter (OM), CP, NDFap and potential digestible NDFap (pdNDFap) were not affected by RUP levels. In addition, the relative intake (g/kg of body weight) of DM, CP and NDFap, as well as the ruminal outflow of DM, OM, CP, NDFap and pdNDFap were not affected by RUP levels. Total digestibility of DM, OM, CP, NDFap and pdNDFap, as well as ruminal and intestinal digestibilities of DM, OM, NDFap and pdNDFap were not affected by RUP levels. However, ruminal and intestinal digestibilities of CP presented a tendency to decrease according to RUP supply increase. Effects of RUP levels were not observed on the ingestion, passage and digestion rates, as well on the total volatile fatty acid concentration. Treatment 38RUP presented greater concentration of rumen ammonia nitrogen in relation to the other treatments. The urinary N excretion presented a tendency to decrease according to RUP supply increase. In addition, retained N presented a tendency to increase according to RUP levels and greater values were observed for treatments 51RUP and 57RUP. Microbial crude protein (CPmic) synthesis, microbial efficiency and the efficiency of use of N for microbial synthesis, decrease as the supplied RUP increases. Flow of RUP increased, while the amounts of rumen degradable protein decrease according to RUP supply increase. In addition, the flow of metabolizable protein presented a tendency to increase and greater values were observed for treatments 51RUP and 57RUP. In conclusion, the intestinal digestibility of CP is negatively affected by RUPvlevels, what is due to the reduction in the CPmic flow, which, probably, has greater intestinal digestibility than protein of feedstuffs. The urinary N excretion decrease according to RUP supply increase, what is due to the decrease in ruminal N losses as ammonia and the increase in N recycling. The reduction in the urinary N excretion allied to increases in the flow of metabolizable protein, which are promoted by increases in the flow of RUP to the small intestine, are determinant to promote increases in the retained N, which occurred for treatments 51RUP and 57RUP.
Grobler, Susanna Maria. "Growth performance of Holstein calves fed milk or milk replacer with or without calf starter." Diss., 2008. http://upetd.up.ac.za/thesis/available/etd-06032008-122140.
Повний текст джерела(13991741), Lisa J. Maclellan. "Morphology and function of ovarian follicles and oocytes following superstimulation treatments in heifer calves." Thesis, 2001. https://figshare.com/articles/thesis/Morphology_and_function_of_ovarian_follicles_and_oocytes_following_superstimulation_treatments_in_heifer_calves/21377328.
Повний текст джерелаGenetic improvement in cattle has focused in recent years on the large reproductive potential that resides in the ovaries of females at an early age. It is estimated that approximately 150,000 oocytes are present in primordial follicles in foetal ovaries at birth, and recruitment of follicles from the primordial pool has been initiated by the time of birth. Further, follicular growth can be superstimulated in heifer calves from around 4 weeks of age by treatment with gonadotrophins, and oocytes recovered and placed through in vitro maturation and fertilisation procedures to produce viable embryos.
The capacity to use embryos derived from heifer calves has the potential to reduce generation intervals and increase the rates of genetic gain in cattle. Studies on embryo production from heifer calves have reported inconsistent and unpredictable responses to superstimulation of follicle growth with FSH, similar to that observed in sexually mature heifers. Heifer calves that had a relatively large (>10mm) follicle on the ovary at the end of superstimulation, had a smaller number of total follicles compared with heifer calves that did not have a large follicle on the surface of the ovary. This observation led to the suggestion that follicular interrelationships may occur from an early age in heifers, and that a large follicle may suppress the development of other follicles. Nutrition appears to influence ovarian follicle status in peri-pubertal and pubertal heifers and possibly the response to superstimulation of follicular growth in older animals. There may be a role, therefore, for nutrition in ovarian follicle growth and responses to superstimulation in heifer calves.
In a number of studies oocytes obtained from heifer calves were reported to have a reduced developmental competency in vitro compared with oocytes obtained from ovaries of post-pubertal heifers.
In cattle, treatment with agonists of gonadotrophin hormone releasing hormone (GnRH) desensitises the anterior pituitary gland to GnRH which blocks pulsatile secretion of LH but allows continued basal LH secretion. Antagonists of GnRH prevent both pulsatile and basal secretion of LH. It is possible that treatment with GnRH agonists and antagonists might be used to regulate gonadotrophin secretion in heifer calves and prevent the development of large (functionally dominant) follicles. Subsequent initiation of superstimulation when a pool of small gonadotrophinresponsive follicles are present on the ovaries, and maturing these follicles in synchrony in vivo, may allow a pool of oocytes at similar stages of maturation to be collected for in vitro procedures.
The first two experiments in this thesis examined the requirement of LH for oocyte maturation by treating calves with gonadotrophin hormone releasing hormone (GnRH) agonist and antagonist before and during superstimulation with FSH. Simultaneous treatment with a GnRH agonist during superstimulation of ovarian follicle growth with FSH tended to increase the number of follicles stimulated to grow and significantly increased the number of Grade A and Grade B oocytes collected. In a second experiment, treatment with a GnRH antagonist tended to increase blastocyst development rate after in vitro fertilisation. It was concluded from these findings that exposure of oocytes to pulsatile secretion of LH, and/or a 'pre-ovulatory like' surge release of LH, is not an obligatory requirement for oocyte growth and development in heifer calves.
A third experiment examined the effects of nutrition and growth rate on maturation of the reproductive endocrine axis and the response of calves to superstimulation of ovarian follicle growth with FSH. Heifer calves were raised on two planes of nutrition (relatively low and high) and subsequently superstimulated with FSH. The nutritional treatments resulted in a significant difference in growth rate between the two groups of heifers. However, there were no apparent differences in ovarian follicular responses to stimulation with FSH, oocytes recovered, or in vitro developmental competency of oocytes, between the two groups of heifers.
In the fourth experiment, in vitro developmental competency was compared between oocytes obtained from heifer calves superstimulated with FSH, heifer calves that had not undergone superstimulation and post-pubertal heifers and cows that had not been stimulated with FSH. There were no differences in developmental competency between Grade A and Grade B oocytes derived from the three groups of animals. This finding demonstrated that oocytes obtained from pre -pubertal heifers do not have an intrinsic reduced capacity for in vitro development compared with oocytes obtained from post -pubertal heifers.
The ultimate test of viability of embryos derived from heifer calves is the transfer to recipients and the birth of calves. The aim of the fifth experiment therefore was to test the viability of embryos derived from 10 week-old heifer calves in which ovarian follicular growth was superstimulated with FSH. Transfer of blastocysts produced from oocytes obtained from heifer calves to recipient sexually mature heifers resulted in the birth of normal calves.
In summary, the competency of oocytes collected from heifer calves from an early age has been well established in the series of experiments undertaken in this thesis. The use of superstimulation protocols with heifer calves pre-treated with a GnRH agonist or antagonists increased the number of Grade A and Grade B oocytes, and tended to increase the development to blastocyst post-fertilisation. Grade A and Grade B oocytes collected from heifer calves form blastocysts at rates comparable to oocytes collected from mature cows, and establish pregnancies which result in the birth of calves.
Dikotope, Lenkie Magapu. "The effects of Megasphaera elsdenii on dairy heifer performance." Diss., 2018. http://hdl.handle.net/10500/25797.
Повний текст джерелаAgriculture and Animal Health
M. Sc. (Agriculture)
Книги з теми "Heifer calves"
National Animal Health Monitoring System (U.S.). Housing the dairy calf: National Dairy Heifer Evaluaiton Project. Fort Collins, Colo: U.S. Dept. of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, 1992.
Знайти повний текст джерелаNational Animal Health Monitoring System (U.S.), ed. Milk replacer management practices: National Dairy Heifer Evaluation Project. Fort Collins, Colo: U.S. Dept. of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, 1993.
Знайти повний текст джерелаNational Animal Health Monitoring System (U.S.). Dairy herd management practices focusing on preweaned heifers, April 1991 - July 1992: National Dairy Heifer Evaluation Project. Fort Collins, CO: USDA:APHIS, National Animal Health Monitoring System, 1993.
Знайти повний текст джерелаNational Animal Health Monitoring System. and United States. Animal and Plant Health Inspection Service. Veterinary Services., eds. Cryptosporidium is common in dairy calves: National Dairy Heifer Evaluation Project. Fort Collins, Colo: U.S. Dept. of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, 1993.
Знайти повний текст джерелаNational Animal Health Monitoring System (U.S.) and United States. Animal and Plant Health Inspection Service. Veterinary Services., eds. Transfer of maternal immunity to calves: National Dairy Heifer Evaluation Project. Fort Collins, Colo: U.S. Dept. of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, 1993.
Знайти повний текст джерелаUnited States. Animal and Plant Health Inspection Service. Veterinary Services. Centers for Epidemiology and Animal Health. Passive transfer status of heifer calves on U.S. dairies, 1991-2007. Fort Collins, CO: U.S. Dept. of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, Centers for Epidemiology and Animal Health, 2010.
Знайти повний текст джерелаNational Animal Health Monitoring System (U.S.) and United States. Animal and Plant Health Inspection Service. Veterinary Services., eds. Dairy calf management: Feeds & weaning practices : National Dairy Heifer Evaluation Project. Fort Collins, Colo: U.S. Dept. of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, 1993.
Знайти повний текст джерелаC, Garnsworthy Philip, ed. Calf and heifer rearing: Principles of rearing the modern dairy heifer : proceedings of the 60th University of Nottingham Easter School in Agricultural Science. Nottingham: Nottingham University Press, 2005.
Знайти повний текст джерелаNational Animal Health Monitoring System (U.S.) and United States. Animal and Plant Health Inspection Service. Veterinary Services., eds. Colostrum management on U.S. dairy farms: National Dairy Heifer Evaluation Project. Fort Collins, Colo: U.S. Dept. of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, 1993.
Знайти повний текст джерелаMcGuirk, Sheila, and Sandra Godden. Dairy Heifer Management: Food Animal Practice. Elsevier - Health Sciences Division, 2008.
Знайти повний текст джерелаЧастини книг з теми "Heifer calves"
Halachmi, I., A. Schlageter Tello, A. Peña Fernández, T. van Hertem, V. Sibony, S. Weyl-Feinstein, A. Verbrugge, M. Bonneau, and R. Neilson. "4.6. Discussion: PLF in genetics & health of beef, calves and heifers." In Precision livestock farming applications, 169–70. The Netherlands: Wageningen Academic Publishers, 2015. http://dx.doi.org/10.3920/978-90-8686-815-5_4.6.
Повний текст джерелаRegler, F., K. Ziegler, H. Bernhardt, T. Förster, K. Hemmert, C. Koch, and H. Sauerwein. "Closing data-gaps between calves and cows – Conceptualization of a specified sensor system for data acquisition in calf and heifer husbandry." In AgEng LAND.TECHNIK 2022, 387–96. VDI Verlag, 2022. http://dx.doi.org/10.51202/9783181024065-387.
Повний текст джерелаAkers, R. M. "Mammary development in calves and heifers." In Large Dairy Herd Management, 815–28. American Dairy Science Association, 2017. http://dx.doi.org/10.3168/ldhm.0959.
Повний текст джерелаMiller-Cushon, Emily, Ken Leslie, and Trevor DeVries. "Ensuring the health and welfare of dairy calves and heifers." In Burleigh Dodds Series in Agricultural Science, 123–54. Burleigh Dodds Science Publishing, 2017. http://dx.doi.org/10.19103/as.2016.0006.07.
Повний текст джерелаMiller-Cushon, Emily, and Jennifer Van Os. "Advances in understanding behavioral needs and improving the welfare of calves and heifers." In Understanding the behaviour and improving the welfare of dairy cattle, 163–98. Burleigh Dodds Science Publishing, 2021. http://dx.doi.org/10.19103/as.2020.0084.10.
Повний текст джерелаZuseva-Özkan, Veronika B. "Heinrich Heine and Timur Kibirov: the Formula of Similarity." In Russia – Germany: Literary Encounters (after 1945), 483–512. A.M. Gorky Institute of World Literature of the Russian Academy of Sciences, 2022. http://dx.doi.org/10.22455/978-5-9208-0683-3-483-512.
Повний текст джерелаMagliocca, Gerard N. "Master of Mount Vernon." In Washington's Heir, 66–77. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780190947040.003.0008.
Повний текст джерелаStillwell, John. "Classical Analysis." In Reverse Mathematics, 51–69. Princeton University Press, 2019. http://dx.doi.org/10.23943/princeton/9780691196411.003.0003.
Повний текст джерелаRodden, John G. "Leipzig, 1991 Of Laughter and Forgetting: A Faculty-Student Conflict of Generations." In Repainting the Little Red Schoolhouse. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195112443.003.0016.
Повний текст джерелаGreen, Matthew N., and Douglas B. Harris. "Challenges to the Heir Apparent." In Choosing the Leader, 116–57. Yale University Press, 2019. http://dx.doi.org/10.12987/yale/9780300222579.003.0005.
Повний текст джерелаТези доповідей конференцій з теми "Heifer calves"
Dubovskova, M. P., and N. P. Gerasimov. "Genetic constants of CAPN1, TG5, GH and LEP genes in Hereford bull-calves and heifers of different generations." In PROCEEDINGS OF THE II INTERNATIONAL CONFERENCE ON ADVANCES IN MATERIALS, SYSTEMS AND TECHNOLOGIES: (CAMSTech-II 2021). AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0093938.
Повний текст джерелаSUHANOVA, Elena, Larisa SYChEVA, and Nikolay Morozkov. "Application of an experimental phytonutrients to young cattle." In Multifunctional adaptive fodder production 29 (77). ru: Federal Williams Research Center of Forage Production and Agroecology, 2022. http://dx.doi.org/10.33814/mak-2022-29-77-183-187.
Повний текст джерелаDavidovic, Vesna, Bojan Stojanovic, Predrag Perisic, Slavica Aleksic, Ivana Bozickovic, and Renata Relic. "ISPITIVANJE VREDNOSTI POKAZATELJA ENERGETSKOG I PROTEINSKOG STATUSA MLEČNIH KRAVA." In XXVI savetovanje o biotehnologiji sa međunarodnim učešćem. University of Kragujevac, Faculty of Agronomy, 2021. http://dx.doi.org/10.46793/sbt26.259d.
Повний текст джерелаCole, Kevin D., Filippo de Monte, Robert L. McMasters, Keith A. Woodbury, Junghoon Yeom, and James V. Beck. "Applications in Education for a Heat Conduction Database." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52179.
Повний текст джерелаReunanen, Tero, and Vesa Taatila. "Shared Work Load and Team Spirit - Correlations between University Students and University Personnel." In 13th International Conference on Applied Human Factors and Ergonomics (AHFE 2022). AHFE International, 2022. http://dx.doi.org/10.54941/ahfe1002293.
Повний текст джерелаЗвіти організацій з теми "Heifer calves"
Brosh, Arieh, Gordon Carstens, Kristen Johnson, Ariel Shabtay, Joshuah Miron, Yoav Aharoni, Luis Tedeschi, and Ilan Halachmi. Enhancing Sustainability of Cattle Production Systems through Discovery of Biomarkers for Feed Efficiency. United States Department of Agriculture, July 2011. http://dx.doi.org/10.32747/2011.7592644.bard.
Повний текст джерела