This study was conducted to determine optimum test duration for measuring performance, feed intake and feed efficiency. Sixty young Nellore bulls were submitted to feeding performance test and fed in individual pens to determine feed intake and performance over 112 days. Body weight was determined every 28 days, after fasting of water and feed for 16 hours. Changes in variance, relative variance and Pearson and Spearman correlations among data from shortened test periods (28, 56 and 84 days) and full […]

The effects of calving year and season, property, sex of the calf, feeding regime, age of calf and age of dam at calving, maternal and direct additive effects of Charolais breed, and maternal heterosis effects among Charolais and zebu breeds were evaluated by the method of least squares on economical importance traits such as weight, scrotal circumference and visual scores for slaughter conformation, navel score and hair coat at weaning of the Canchim breed. Data from 12,334 Canchim calves born […]

It was evaluated the bioeconomic impact of the breeding soundness evaluation on beef cattle production in southern Brazil. Two similar production systems, with and without the use of breeding soundness evaluation, were compared during 4 years in the municipality of Júlio e Castilhos. The rate of unsound bulls in the first examination was 22.8%. By performing the examination, calf production increased by 31%, 13.8 calves/bull/year and 24 kg of calves/cow/year. The benefit/cost ratio on the investment with the breeding soundness […]

Data from 79,884 Nellore breed animals were used to estimate genetic parameters and to evaluate the relationships among scores of conformation, precocity and musculature obtained at weaning and after yearling ages and weight of mature females. It was used the restricted maximum likelihood method in a multi-trait analysis with the model that included direct additive genetic and residual effects, as random effects, and the fixed effects of contemporary group and, as covariables, animal age at weighing and age of dam […]

This work was carried out with the goal of demonstrating and performing internal evaluation of the mathematical model developed to describe the reproductive performance in production systems and to simulate reproductive performance of beef cows from the body condition score at calving (BCSAC). This model is based on the relationship between BCSAC and the interval between calving and conception (ICC) for lactating cows; for heifers and empty cows at conception, it was based on the probability of occurrence. For internal […]

This research aimed at evaluating ponderal performance of the calves from birth to 189 days of age. Ninety-five calves were used (55 Aberdeen Angus and 40 Hereford), grazing natural pasture. Milk production of cows was estimated by the weight-suckled-weight method, and ponderal performance of the calves was evaluated in 21-day intervals from birth. Calving season was divided at time 1 (September) and time 2 (October). For analyses, it was included in the statistical model as fixed effects, breed of the […]

The objectives of this work were to evaluate different models, regarded to considered maternal effects, for growth traits and to estimate genetic parameters for these traits in Canchim breed bovine, by one, two and multitrait analyses. The weight traits at birth, at weaning, standardized weight for 12, 18, 24 and 30 months of age in males and females, and mature female weight were analyzed using four models with random effects added in sequence. Maternal effects influenced birth weight at 2 […]

Genetic parameters and genetic and phenotypic trends were estimated for weight at weaning (WW) and visual scores (VS) of conformation (C), precocity (P), musculature (M) and navel (N) for Angus × Nellore crossbred calves. It was used 39,676 records from pre-weaning phase of animals born from 1992 to 2002 in mid-western, southeastern and southern Brazil. The components of covariance were estimated using REML, in animal model, considering as random the maternal and direct additive genetic effects, and as fixed, the […]

Two Nellore herds were compared, one selected for greater postweaning weight and the other, control, selected for average postweaning weight, to evaluate the effects of 29 years of selection on feed efficiency. Sixty Nellore males (41 selected and 19 control) averaging 205 kg and 267 days of age were evaluated in individual pens during performance test. Performance and dry matter intake were used to determine the following feed efficiency traits: feed conversion; residual feed intake; residual gain; partial growth efficiency; […]

The study was carried out to develop and to evaluate new equations to predict dry matter intake (DMI) of Nellore and Zebu-crosses cattle using meta-analysis procedure. The data used to estimate the parameters were collected from independent performance experiments using growing and fattening Nellore and Zebu-crosses cattle, and they were compiled from 561 experimental units. Before proposing an equation to predict DMI, it was observed that the genetic group was a source of statisticaly significant variation. Therefore, equations to predict […]