Estudo da interação genótipo ambiente em búfalos leiteiros do Brasil e da Colômbia

Pós-graduação em Zootecnia - FCAV

Parâmetros ruminais e produtivos de cabras alimentadas com raspa de mandioca em substituição ao milho

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

Avaliação das características do líquido ruminal associada à termografia digital e atividade pedométria em vacas holandesas

Pós-graduação em Medicina Veterinária - FMVZ

Desempenho de vacas leiteiras em pastejo de alfafa

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

Effects of rumen-protected choline supplementation on metabolic and performance responses of transition dairy cows

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

Aplicação de modelos de regressão aleatória utilizando diferentes estruturas de dados

A total of 3.035 lactations of Holstein cows from four farms in the Southeast, to check the influence of data structure of milk yield on the genetic parameters. Four dataset with different structures were tested, weekly controls (CW) with 122.842 controls, monthly controls (CM) 30.883, bimonthly controls (CB) with 15,837 and quarterly controls (CQ) with 12,702. The random regression model was used and was considered as random additive genetic and permanent environment effects, fixed effects of the contemporary groups (herd-year-month of test-day) and age of cow (linear and quadratic effects). Heritability estimates showed similar trends among the data files analyzed, with the greatest similarity between dataset CS, CM and CB. The dataset submitted all the CB estimates of genetic parameters analyzed with the same trend and similar magnitude to the CS and CM dataset, allowing the claim that there was no influence of the data structure on estimates of covariance components for the dataset CS, CM and CB. Thus, milk recording could be accomplished in a CB structure.

Reaction norm model to describe environmental sensitivity across first lactation in dairy cattle under tropical conditions

Reaction norm models have been widely used to study genotype by environment interaction (G × E) in animal breeding. The objective of this study was to describe environmental sensitivity across first lactation in Brazilian Holstein cows using a reaction norm approach. A total of 50,168 individual monthly test day (TD) milk yields (10 test days) from 7476 complete first lactations of Holstein cattle were analyzed. The statistical models for all traits (10 TDs and for 305-day milk yield) included the fixed effects of contemporary group, age of cow (linear and quadratic effects), and days in milk (linear effect), except for 305-day milk yield. A hierarchical reaction norm model (HRNM) based on the unknown covariate was used. The present study showed the presence of G × E in milk yield across first lactation of Holstein cows. The variation in the heritability estimates implies differences in the response to selection depending on the environment where the animals of this population are evaluated. In the average environment, the heritabilities for all traits were rather similar, in range from 0.02 to 0.63. The scaling effect of G × E predominated throughout most of lactation. Particularly during the first 2 months of lactation, G × E caused reranking of breeding values. It is therefore important to include the environmental sensitivity of animals according to the phase of lactation in the genetic evaluations of Holstein cattle in tropical environments.

Allonursing in river buffalo, Bubalus bubalis: Nepotism, incompetence, or thievery?

Allonursing was investigated in a dairy herd of 30 river buffalo cows and their calves. The primary behavioural variables were solicitations of allonursing by calves and acceptances of calves by cows. The sample of cows included a group of nine half-sisters, two additional pairs of half-sisters, and a pair of full-sisters. All of the calves were half-siblings owing to putative common paternity. Ancillary variables were age, milk-yield and docility of cows, as well as age, sex, weight and growth rate of calves. Three hundred and fifty-one instances of allonursing and 341 of filial nursing were recorded. There were large individual differences in the cows' tendencies to accept their own offspring and non-filial calves, and for the calves to successfully solicit milk from their mothers and other cows. Thirteen of the 30 cows accounted for 97% of the allonursing. Frequent allonursing was correlated with decreased growth rate in the donors' calves. Allonursing was unrelated to kinship or reciprocal relationships among the cows, and was associated with a lack of maternal experience in young cows and apparent milk theft by hungry calves whose mothers were not providing them with sufficient milk. © 1995 The Association for the Study of Animal Behaviour.

The manipulation of progesterone profiles during progesterone + estradiol timed ai protocols in dairy cattle: effects on fertility

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

Óleo funcional na dieta de vacas leiteiras

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo genômico da produção de leite e seus constituintes em bovinos da raça Guzerá

Pós-graduação em Genética e Melhoramento Animal - FCAV

Fontes proteicas para vacas leiteiras

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Seleção genômica para características longitudinais de bovinos da raça Holandesa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise multivariada de características reprodutivas e produtivas de vacas da raça Holandesa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise multivariada de características reprodutivas e produtivas de vacas da raça Holandesa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)