ABSTRACT The objective of this study was to evaluate the effect of timed artificial insemination (TAI) on pregnancy rates, reproductive efficiency, and mean weaning weight of calves at the end of breeding season in Nellore females. In this work, 744 Nellore females were divided into two groups: in group I (n = 396), the females were subjected to natural service during the breeding season, which lasts for 180 days. In group II (n = 348), a hormonal protocol was performed […]

This work aimed at estimating the genetic effects that affect the pre-weaning performance of animals from multibreed crosses. In order to do so, it was used information of the weight at weaning of 79,521 animals, sired by 1,020 bulls and 61,898 cows from Aberdeen Angus and Nellore breeds and from many genetic groups resulted from their crosses. Five genetic models were tested: model 1, containing the fixed breed genetic effects (additive direct and maternal effects, heterozygote direct and maternal effects, […]

A model fitted to grazing females Nellore during the rearing periods of the Cerrado Region of Central Brazil was simulated and validated in this study. Body weight gain (BWG) was determined during three years as follows: 1) first dry season after weaning on Brachiaria brizantha (Hochst) Stapf., 2) rainfall season and 3) second dry season both on Panicum maximum Jacq. cv. Tanzânia and averaged 0.020, 0.550, and 0.172 kg, respectively. In the second rainfall season during the rearing period heifers […]

Body weight gain of 103 Nelore calves until 20/21 months old when weaned on cultivated pasture and supplemented during the dry period was evaluated during three years to obtain steers with body weight to be finished immediately at fedlot. At the beginning and end of supplementation period, the animals averaged body weight and age of 189.51± 21.08 kg and 254 ± 29.22 days and 242.38 ± 29.22 kg and 400 ± 31.08 days, respectively. The mean daily feed intake was […]

The productivity of Nelore cows on Brachiaria decumbens Stapf pasture was measured during four years, in a soil initially improved with limestone and fertilizer and with free access to a mineral mixture. Pregnancy rate (PR), calving rate (CR), weaning rate (WR), calves weaning body weight (BWC), productivity (P = kg of calf/cow) and efficiency (E= P/100 kg of cow) per cow, productivity per area (AP = calves kg/ha), as well as cow body weight and body condition before the calving […]

The aims of this research were to estimate the influence of age of dam at calving (AC), and julian date of birth (JDB) on weaning weight (WW) and preweaning average daily gain (ADG) of gyr calves and adjustment factors for them. It was analyzed 10,685 and 18,339 records, on WW and ADG of Gyr calves, from the Associação Brasileira dos Criadores de Zebu data set belonging to 1229 and 1979 contemporary groups (CG), respectively. AC, for males, was fitted as […]

The data utilized in this work were originated from 53.938 pure and crossbred (Angus x Nelore), collected in different regions of Brazil and Argentina born from 1987 to 1998 were analyzed. The objectives of this work were to verity the heritabilities and correlation among the growing and scrotal circumference traits. The variables analyzed were the average daily gain from birth to weaning (ADGBW), days to reach 160 kg from birth to weaning (D160), weaning weight (WW) and scrotal circumference at […]

This research was carried out to evaluate the inbreeding effects and its possible influence on the beef cattle growth. Data with 27,406 observations of weaning weight, standardized to 205 (WW), and 14,317 observations of yearling weight, standardized to 365 days (YW), from Gyr breed animals, from 1970 to 1995, were used. The analysis were made using the least square method that included the random effect of contemporary group and the fixed effects of generation (class), age of cow at calving, […]

The objective of this study was to evaluate the indirect effects of selection for post-weaning weight on body measures and scrotal perimeter of 809 Nellore males from selected herds (NeS and NeT) and control herd (NeC), of the Estação Experimental de Zootecnia de Sertãozinho. The statistical analyses were performed by using a sire mixed model where the random source of variation, sires, was nested within herds. The fixed effects were herds, year of performance test (PGP), age of cow and […]