Four structures of data with different degree of genetic connectness and heterogeneity of parameters among herds: 1) heterogeneity of all parameters; 2) genetic means homogeneous and other parameters heterogeneous; 3) heterogeneity of phenotypic parameters and 4) no heterogeneity for herds, were simulated. After prediction of breeding values, the percentage of top animals common to group 1 (animals ranked by the true breeding values) and group 2 (animals ranked by the predicted breeding values) was calculated. For data with heterogeneity of […]

Data consisting of 3,531 test day records of 620 first parity Jersey cows were used to estimate genetic parameters for milk yield. Covariance components were estimated by repeatability and random regression animal models. The Wilmink function was used in the random regression model to fit the fixed effect of season of calving and the additive genetic, permanent environment and residual random effects. The repeatability model included the fixed effects of herd-year-month of test, season of calving and age at calving […]

Data from the Caracu herd of Sertãozinho Experimental Station, selected for post weaning weight between 1979 and 2002, was analyzed to describe effective size, generation coefficient, generation interval, selection differentials and genetic gain in this population. Genetic gain was estimated by the product of the average weighted standardized differential (kg) and heritability divided by the average generation interval. Averages of sire and dam weighted selection differentials for post weaning weights were 1.10 and 0.28 standard deviations units (s.d.u). Sire and […]

Data comprising 5,007 records of first lactation of Holstein cows, daughters of 930 sires, from 33 herds in the state of Rio Grande do Sul, from 1984 to 1998, were used to estimate heritability coefficients and genetic trends for milk (MY) and fat (FY) yields and for fat percentage (%F). An animal model considered the genetic additive direct and residual as random effects and milking/day number, herd and year/season of parturition, and cow age at parturition as fixed effects, linear […]

Data comprising 8,183 test day records of 1,273 first lactations of Gyr cows from herds supervised by ABCZ were used to estimate variance components and genetic parameters for milk yield using repeatability and random regression animal models by REML. Genetic modelling of logarithmic (FAS), exponential (FW) curves was compared to orthogonal Legendre polynomials (LP) of order 3 to 5. Residual variance was assumed to be constant in all (ME=1) or some periods of lactation (ME=4). Lactation milk yield in 305-d […]

Covariance components for test day records and lactation milk yield using 263.390 records of 32.448 first lactation Holstein cows, were estimated using animal models by REML. Besides the lactation model, two alternative repeatability models (RM) were analyzed. Lactation model included fixed effects of herd-year-season and age of cow with linear and quadratic terms, and random effects of animal and error. The first model for test-day yield (RMF) included the same effects, but fixed effect of contemporary group, defined as herd-year-month […]

With the purpose of re-evaluating seventeen pigeon-pea lines originated from accessions previously selected for favorable agronomic characteristics, experiments were installed in five locations of the State of São Paulo. The confirmation of those characteristics was necessary because the original accessions presented various degrees of mechanical mixtures and segregation and were submitted to purification process in pollination controlled conditions. In those trials, the lines were cut in several occasions to evaluate forage yield. Each time, it was determined the number of […]

Objective was to evaluate the behavior average inbreeding coefficient associated to the selection limit considering selected population as base population. GENESYS program was used for simulation of the genome (one trait of h2 = 0.40), base population, initial population and populations under selection. Three different generations were considered as base generations, zero (G0PB), three (G3PB) and seven (G7PB). Populations were selected based on best linear unbiased predictor (BLUP) and on individual phenotype in which were considered: a) two effective population […]

First lactation milk and fat yields of 5086 purebred and crossbred Gir cows were used to estimate genetic components of (co)variance using multivariate and bivariate animal models solved by a REML derivative-free algorithm. Both models were used to predict breeding values (EBV) for milk (MY) and fat (FY) yields of purebred and crossbred Gir cows. In the multivariate model it was assumed yields from each genetic group as different traits to account for heterogeneous phenotypic variance for milk yield. This […]

The traits of the haircoat (haircoat thickness, average hair lenght with respect skin surface, number of hair per unit area, hair mass density, hair angle and average hair diameter) were estimated in 973 Holstein cattle in the period between November 2000 and April of 2001. These traits were measured in an area 20cm below the dorsal line in the center of the thorax, for the black as for the white haircoat. Hair samplings were performed with adapted pliers. The method […]