Aníbal Eugênio Vercesi Filho

Objetivos de seleção e valores econômicos de características de importância econômica para um sistema de produção de leite a pasto na Região Sudeste

As part of a preliminary study on the design of a breeding program involving Holstein Friesian and crossbred cattle (Holstein x Zebu) in the Southeast region of Brazil, economic values for milk volume (V), fat (F) and protein (P) production, age at first calving (AFC), mature body weight (MBW) and herd life (HL) were derived for a pasture based milk production system of crossbred cattle (Holstein x Zebu). The feeding regime was based on rotational grazing of elephantgrass during the rainy season and grazing plus maize silage during the dry season. Concentrates were fed when daily individual productions exceed 6-kg milk (1 kg concentrate: 2.5 kg milk). Sensitivity analyses were carried out to evaluate the effect of the change of payment system and milk price variation on economic values of the traits. Economic values were also derived for an alternative source of roughage supplementation based on the mixture of sugar cane plus urea. The economic values (US

Parâmetros Populacionais do Rebanho Gir Mocho Registrado no Brasil

) derived for the current payment system for V, F, P, AFC, MBW and HL were, respectively: 0.15; -0.48; -0.31; -0.11; 0.08 and 0.04. Results of sensitivity analyses are presented and discussed.

Parâmetros Populacionais do Rebanho Sindi Registrado no Brasil

The aim of this study was to describe the population structure of the registered Polled Gir cattle in Brazil. Descriptive statistics of the distribution of the number of progeny, the generation interval and the effective population size were estimated using pedigree records of animals registered from 1976 to 1998. The observed generation interval in each of four periods (1979-1983, 1984- 1988, 1989-1993 and 1994-1998) was, respectively, 4.5, 6.05, 7.17 and 9.14 yr. The effective population size for the periods were, respectively, 3, 22, 63 and 70.

Estrutura genética da raça Sindi no Brasil

The aim of this study was to describe the population structure of the registered Red Sindhi cattle in Brazil. Descriptive statistics of the distribution of the number of progeny are presented, and the generation interval and effective population size were estimated, using pedigree records of animals registered from 1955 to 1998. The observed generation interval for the whole time period was 7.65 yr, and for the period 1994-1998 it was 7.96 yr. The effective population size for the following periods (1979-83, 1984-88, 1989-93 and 1994-98) were, respectively, 501, 26, 20 and 19.

Association between electrical conductivity and milk production traits in Dairy Gyr cows

The aim of this research was to describe the genetic structure of the Brazilian Red Sindhi breed using pedigree records from registered animals born from 1955 to 1998. The data file was separated in the following periods: 1979-1983, 1984-1988, 1989- 1993 and 1994-1998. The total inbreeding increased from 0.38 to 10.13%, the expected inbreeding under random mating increased from 0.07 to 5.65%, and the inbreeding due to population subdivision increased from 0.30 to 4.74%, from the first to the final period, indicating that genetic subdivision in the Red Sindhi breed is relevant. The effective population size was estimated from the total inbreeding and decreased vertiginously from 161 to 9. Based on probabilities of gene origin the effective numbers of founders, ancestors and remaining genomes were calculated and decreased over the total period, reaching values of 16, 9 and 7, respectively.

A new way to measure milk yield persistency: a genetic point of view with application to Gyr (Bos indicus) cattle.

ABSTRACT This study investigated the association of electrical conductivity (EC) of milk with milk production and composition traits in Dairy Gyr cows. Monthly milk samples were collected on the official milk recording day for laboratory analysis of somatic cell count, EC and milk composition. A total of 680 samples from 268 cows belonging to eight herds in the southeastern region of Brazil were collected between January and July 2012. Traits were analysed by the restricted maximum likelihood method using mixed models in order to associate EC and somatic cell score (SCS) with the other traits. Mean EC and SCS were 4.90 mS/cm and 4.66, respectively, and the correlation between these traits was 0.41. Linear regression of EC on SCS indicated an increase in EC of 0.094 mS/cm per SCS. Despite the relationship between EC and SCS, the former analysed only on the official recording day may not be a reliable method for the diagnosis of mastitis. However, EC could be used as an auxiliary trait in the analysis of mastitis resistance simultaneously with somatic cell count since, in addition to the association between these two traits, the measurement of EC is an inexpensive, simple and rapid method.

Incorporation of lactations with non-conventional drying-off causes in genetic evaluation of Gyr dairy cattle

The objective of this work was to estimate genetic parameters for a measure of persistency of milk yield and to evaluate its association with 305-d cumulative milk yield and lactation length. 12 346 records from 8202 dairy Gyr cows including lactations up to fifth calving were used. The measure of persistency was obtained from one of the parameters of a quadratic model that describes the cumulative yield across lactation as a function of days in milk. A three-trait multivariate analysis was done. Heritability and repeatability for persistency were 0.08 and 0.21, respectively. Deviance Information Criterion provided evidence that the additive genetic covariance between the measure of persistency studied and 305-d cumulative yield is zero. Genetic correlations between persistency and lactation length were 0.50 and 0.27 for first or all lactations, respectively. Milk yield persistency as measured in this study has low heritability. Selection for persistency can increase lactation length. The measure of milk yield persistency studied here is genetically independent of total milk yield and can be included in routine genetic evaluations of dairy cattle.

Pesos econômicos para seleção de gado de leite

Test-day records of milk yields from the first three lactations were used to verify consequences of incorporation of lactation with non-conventional drying-off causes in genetic evaluation of Gyr dairy cattle. The first file (File1) was composed of test-day records of lactations with conventional drying-off causes. In the second file (File2), the test-day records of lactations with non-conventional drying-off causes were included, such as drying-off by death or separation of the calf, disease, death or sale of cow, and removal of cow from milking control. Data were analyzed by mixed models, using an autoregressive process to adjust the random effects of long-term and short-term environment. The inclusion of test-day records from lactations with non-conventional drying-off causes increased the number of controls by 12% and the number of cows by 18%, and it generated an increase in the estimates of variance components. These results impacted estimates of heritability, calculated at 0.32, 0.28 and 0.26 for the first, second and third lactations in File1, respectively, while in File2 they were 0.34, 0.30 and 0.28 to the same lactation order. The estimated accuracy of predicted breeding values in File2 were higher in relation to File1, but the Pearson and Spearman correlations between predicted breeding values of animals in the two files were high. Lactations with non-conventional drying-off causes can be incorporated to the routines of genetic evaluation of Gyr dairy cattle, because they provide higher estimates of heritability and accuracy of breeding values, which could raise expectations of genetic gains with selection.