Effect of Non-Genetic Factors on Test-Day Milk Yields and First Lactation Milk Yields in Holstein Friesian × Sahiwal Cattle

The present study was carried out using first lactation monthly test-day milk yield records of 466 crossbred (HF × Sahiwal) cattle calved from 2000 to 2018 sired by 89 bulls maintained at Directorate of Livestock Farms, GADVASU, Ludhiana. Mixed model analysis was carried out by least-squares maximum likelihood programme to study the effects of non-genetic factors on first full lactation milk yield (FFLMY), first lactation 305-day milk yield (FL305MY) and monthly test-day (TD) milk yield records of crossbred cattle. The least squares means of different monthly TD milk yields (1st to 11th) were 12.05 ± 0.42, 15.65 ± 0.42, 15.38 ± 0.44, 14.44 ± 0.43, 13.79 ± 0.41, 12.88 ± 0.40, 12.27 ± 0.42, 11.83 ± 0.37, 10.85 ± 0.42, 10.64 ± 0.45 and 10.28 ± 0.50 kg, respectively. For FFLMY and FL305MY the means were 4979.60±184.45 and 3818.17±103.26 kg. The effects of different AFC groups were non-significant on TDs and FL305MYs, whereas it was significant (p≤0.01) for FFLMY. The season was significant (p≤0.01) for all the monthly TDs whereas it was non-significant for FFLMY and FL305MY. The sire was significant (p≤0.01) for most of the TDs and FL305MYs except the later TDs (9th, 10th and 11th TD) and FFLMYs. The present investigation revealed the importance of non-genetic factors in performance evaluation of crossbred cattle based on monthly test-day milk yield, FL305MY and FFLMY records

Genetic parameters for milk, fat and protein yields in Murrah buffaloes (Bubalus bubalis Artiodactyla, Bovidae)

The objective of the present study was to estimate genetic parameters for test-day milk, fat and protein yields and 305-day-yields in Murrah buffaloes. 4,757 complete lactations of Murrah buffaloes were analyzed. Co-variance components were estimated by the restricted maximum likelihood method. The models included additive direct genetic and permanent environmental effects as random effects, and the fixed effects of contemporary group, milking number and age of the cow at calving as linear and quadratic covariables. Contemporary groups were defined by herd-year-month of test for test-day yields and by herd-year-season of calving for 305-day yields. The heritability estimates obtained by two-trait analysis ranged from 0.15 to 0.24 for milk, 0.16 to 0.23 for protein and 0.13 to 0.22 for fat, yields. Genetic and phenotypic correlations were all positive. The observed population additive genetic variation indicated that selection might be an effective tool in changing population means in milk, fat and protein yields.

Persistência na lactação para vacas da raça Holandesa criadas no Estado do Rio Grande do Sul via modelos de regressão aleatória / Lactation persistency for Holstein cows raised in the State of Rio Grande do Sul using a random regression model

Foram utilizados 21.702 registros de produção de leite no dia do controle de 2.429 vacas primíparas da raça Holandesa, filhas de 233 touros, coletados em 33 rebanhos do Estado do Rio Grande do Sul, entre 1992 e 2003, para estimar parâmetros genéticos, para três medidas de persistência (PS1, PS2 e PS3) e para a produção de leite até 305 dias (P305) de lactação. Os modelos de regressão aleatória ajustados aos controles leiteiros entre o sexto e o 300o dia de lactação incluíram o efeito de rebanho-ano-mês do controle, a idade da vaca ao parto e os parâmetros do polinômio de Legendre de ordem quatro, para modelar a curva média da produção de leite da população e os parâmetros do mesmo polinômio, para modelar os efeitos aleatórios genético-aditivo direto e de ambiente permanente. As estimativas de herdabilidade obtidas foram 0,05, 0,08 e 0,19, respectivamente, para PS1, PS2 e PS3 e 0,25, para P305 sugerindo a possibilidade de ganho genético por meio da seleção para PS3 e para P305. As correlações genéticas entre as três medidas de persistência e P305, variaram de -0,05 a 0,07, indicando serem persistência e produção, características determinadas por grupos de genes diferentes. Assim, consequentemente, a seleção para P305, geralmente praticada, não promove progresso genético para a persistência.

There were used 21,702 test day milk yields from 2,429 first parity Holstein breed cows, daughters of 2,031 dams and 233 sires, distributed over 33 herds in the state of Rio Grande do Sul, from 1992 to 2003. Genetic parameters for three measures of lactation persistency (PS1, PS2 e PS3) and for milk production to 305 days (P305) were evaluated. A random regression model adjusted by fourth order Legendre polynomial was used. The random regression model adjusted to test day between the sixth and the 305th lactation day included the herd-year-season of the test day, the age of the cow at the parturition effects and the order fourth Legendre polinomial parameters, for modeling the milk production average curve of the population, and parameters of the same polinomial for modeling the random additive genetic and permanent environmental effects. The estimated heritabilities were 0.05, 0.08 and 0.19, respectively to PS1, PS2 and PS3, and 0.25 to P305, suggesting the possibility of a genetic gain by selection for PS3 and P305. The genetic correlations between persistency measurements and P305 ranged from -0.05 to 0.07, suggesting being, persistency and milk yield, characteristics determined by different gene groups, and that the selection for P305, usually done, do not promote genetic progress for persistency.

Milk and fat production of crossbred Holstein-Gir cows (Bos taurus taurus-Bos taurus indicus) in the agreste region of the Brazilian state of Pernambuco

The productive performance of four Holstein-Gir genetic groups (1/2H, 1/4H, 5/8H, 5/8Hinter se) and the effects of non-genetic factors on production traits was evaluated using a data set of 7,951 test-day samples collected between January 1980 and December 1999 from the Arcoverde Experimental Station in the Brazilian state of Pernambuco (Empresa Pernambucana de Pesquisa Agropecuária). The statistical model included the fixed effects of calving year (1980 to 1999) and month (January to December), genetic group of the cow, age at months of calving (33 to 190) and days in milk at each test-day. Random effects were sire, cow and residual with test-days treated as repeated records within each cow within each lactation. For the four genetic groups the milk yield (MY) means were 1/2H = 8.61 kg ± 1.16 kg, 1/4H = 5.34 kg ± 0.46 kg, 5/8H = 7.42 kg ± 0.39 kg and 5/8Hinter se = 5.76 kg ± 0.46 kg; the fat yield (FY) means were 1/2H = 0.375 kg ± 0.052 kg, 1/4H = 0.231 kg ± 0.026 kg, 5/8H = 0.299 kg ± 0.025 kg and 5/8Hinter se = 0.231 kg ± 0.026 kg; and the fat percentage (FP) means were 1/2H = 4.45 kg ± 0.29 percent, 1/4H = 4.08 kg ± 0.12 percent, 5/8H = 3.87 kg ± 0.10 percent and 5/8Hinter se = 3.89 kg ± 0.12 percent. Phenotypic correlations between tests were MY = 0.97, FY = 0.94 and FP = 0.98. The best productive performance was for the 1/2H group, followed by the 5/8H group. The performance of the synthetic group was substantially below the performance of the 5/8H group.