Variance heterogeneity for milk yield in Brazilian and Colombian Holstein herds

Heterogeneity of variances for milk yield (MY) was determined for Brazilian and Colombian herds. The herds were grouped as high or low variability within each country, using as criterion the phenotypic standard deviation (PSD) of MY in the contemporary groups of cows, from the first to the sixth calving. Brazilian and Colombian herds with PSD greater than 1,168 kg or 1,012 kg, respectively, were classified as high variability while the herd groups with values lower than those were classified as low variability. The genetic parameters for MY within each herd group were estimated using bivariate analysis in an animal model and the restricted maximum likelihood method with a derivative free algorithm, using 72,280 first lactations of cows, daughters of 1,880 sires. Heterogeneous variances were found, and Brazilian herds with high PSD had the greatest additive and residual genetic variances and heritability coefficients for MY. MY genetic correlation coefficients between herds of high and low variability within each country were 0.96 and 0.93 while between countries they varied from 0.72 to 0.81, suggesting that there was a reclassification of animals in the two countries and also heterogeneity of variances. This phenomenon leads to the questioning of the strategy of imported semen usage and the need to do genetic evaluations to identify sires with greater genetic potential for (sub) tropical environmental conditions.

Evaluación genética de búfalos de la raza Murrah para la producción de leche en el día de control y a los 305 días de lactancia

There were analyzed 4757 complete lactations of the Murrah breed, daughters of 187 bulls, with the goal of verifying the viability upon employing the test-day (PDLC), on substitution of the milk yield at 305th day of lactation (PL305), in the genetic evaluations. The components of variance for the PDLC1 to PDLC9 and for the PL305 were estimated in uni-traits analysis according to maximum restricted likelihood method. The used model included the genetic direct additive random effects, of residual and permanent environment. There were considered as fixed effects, the contemporary group and the number of milkings and the age of the cow at the moment of parity co-variable (quadratic and linear effect). The contemporary groups were constituted by the herd-year-month of control for the PDLC and by herd-year-epoch of parity for PL305. The estimates of heritability for the PDLC and PL305 were 0.12 to 0.23 and 0.22, respectively. The correlations of order of the predicted genetic values for the 187 bulls, obtained between the PDLC and the PL305, were from moderate to high, varying from 67.74 to 83.12. From the minimum selection of the 10% of the best bulls relating to the predicted genetic value for the PL305, the coincidence among the classification of these animals was over 68%, when evaluated by the PDLC3,PDLC4,PDLC5 and PDLC6. Upon selecting the 5% of the best animals that coincidence presented a lower value.

Genetic parameters for milk yield, age at first calving and interval between first and second calving in milk Murrah buffaloes

In the present study, data of 1,578 first lactation females, calving from 1985 to 2006 were analysed with the purpose of estimating genetic parameters for milk yield (MY), age at first calving (AFC) and interval between first and second calving (IBFSC) in dairy buffaloes of the Murrah breed in Brazil, Heritability estimates for MY, AFC and IBFSC traits were 0.20, 0.07 and 0.14, respectively. Genetic correlations between MY and AFC and IBFSC were -0.12 and 0.07, respectively, while the corresponding phenotypic correlations were -0.15 and 0.30, respectively. Genetic and phenotypic correlations between AFC and IBFSC were 0.35 and 0.37, respectively. Genetic correlation between MY and AFC showed desirable negative association, suggesting that daughters of the bulls with high breeding values for MY could reach physiological mature at a precocious age. Genetic correlation between MY and IBFSC, showed that the selection for milk production could result in the increase of calving intervals.

Índice de seleção bioeconômico para fêmeas de corte da raça nelore

The reproductive efficiency of Nellore females was described on the basis of sexual precocity, staying productive in the herd (NP), maternal productivity (PM) and estimated cost for maintenance (CM). The combination of these traits resulted in the bioeconomic maternal revenue index (RMat) ensures reproductive efficiency. The index estimates the return in kilograms of live weight produced per cow per year. In addition, the composition of calf weight produced was considered, adding to the PM the information on the scores of conformation, muscling and early finishing at weaning, in order to input the calf biotype. The females considered precocious had their age at first calving before 30 months. The NP was expressed by the number of calving till 53 months of age. The CM was calculated according to the estimated feed intake of dry matter. The estimated average RMat was 62.02±24.12 kg/ cow/year. Estimates of additive genetic and residual variances for RMat, using restricted maximum likelihood under a single trait animal model was equal to 195.35 and 242.96, respectively. The heritability estimated was 0.45±0.02, indicating that RMat is inheritable and can be applied in the breeding program to improve reproductive efficiency. The NP was the main component of variation for RMat. Sires selected based on RMat tended to have more efficient daughters.

The Latin American social agenda in the year 2000

Includes bibliography

Multiple-trait random regression models for the estimation of genetic parameters for milk, fat, and protein yield in buffaloes

In this study, genetic parameters for test-day milk, fat, and protein yield were estimated for the first lactation. The data analyzed consisted of 1,433 first lactations of Murrah buffaloes, daughters of 113 sires from 12 herds in the state of São Paulo, Brazil, with calvings from 1985 to 2007. Ten-month classes of lactation days were considered for the test-day yields. The (co)variance components for the 3 traits were estimated using the regression analyses by Bayesian inference applying an animal model by Gibbs sampling. The contemporary groups were defined as herd-year-month of the test day. In the model, the random effects were additive genetic, permanent environment, and residual. The fixed effects were contemporary group and number of milkings (1 or 2), the linear and quadratic effects of the covariable age of the buffalo at calving, as well as the mean lactation curve of the population, which was modeled by orthogonal Legendre polynomials of fourth order. The random effects for the traits studied were modeled by Legendre polynomials of third and fourth order for additive genetic and permanent environment, respectively, the residual variances were modeled considering 4 residual classes. The heritability estimates for the traits were moderate (from 0.21-0.38), with higher estimates in the intermediate lactation phase. The genetic correlation estimates within and among the traits varied from 0.05 to 0.99. The results indicate that the selection for any trait test day will result in an indirect genetic gain for milk, fat, and protein yield in all periods of the lactation curve. The accuracy associated with estimated breeding values obtained using multi-trait random regression was slightly higher (around 8%) compared with single-trait random regression. This difference may be because to the greater amount of information available per animal. © 2013 American Dairy Science Association.

Estimación de parámetros genéticos para producción de leche en el día de control en búfalas de primer parto

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Perfil sanguíneo de fêmeas bovinas em gestação e no periparto e avaliação da transferência de imunidade passiva aos descendentes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dinâmica da infecção por Neospora caninum em rebanhos leiteiros do município de Avaré/SP

Pós-graduação em Medicina Veterinária - FMVZ

Percepções de mães e crianças das relações familiares permeadas por violência sexual do pai contra a filha: análise de variáveis

Pós-graduação em Psicologia do Desenvolvimento e Aprendizagem - FC

Genetic relationship between reproductive traits in Nellore cattle

Pós-graduação em Genética e Melhoramento Animal - FCAV

Estimativas de parâmetros genéticos para produção de leite em búfalas por modelos de repetibilidade, multi-característica e de regressão aleatória

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Interação genótipo-ambiente para a produção de leite em bubalinos no Brasil e na Colômbia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Interação genótipo ambiente sobre características reprodutivas de fêmeas da raça Nelore

Pós-graduação em Genética e Melhoramento Animal - FCAV

Uso do Rad7 para a caracterização do torônio em águas de estâncias hidrominerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)