ABSTRACT This study investigates whether pre-pubertal scrotal circumference (SC) and anti-Müllerian hormone (AMH) concentrations indicate sexual precocity in Brahman and Simmental bulls. Fifty-three bulls (Brahman, n = 27; Simmental, n = 26) were used. Scrotal circumference was measured at three periods: pre-puberty (Brahman = 19.99±0.20 months; Simmental = 9.13±0.17 months), puberty (Brahman = 21.42±0.20 months; Simmental = 18.26±0.17 months), and post-puberty (Brahman = 33.34±0.55 months; Simmental = 24.07±0.17 months). A single sample taken at the pre-pubertal period was used for […]

The objective of the present study was to determine the possible use of heifer pregnancy at 16 months (HP16) as a selection criterion and its possible genetic associations with weaning weight (WW) and average daily gain from weaning to yearling (ADGWY). Covariance components were estimated by uni and bivariate animal models assuming a linear model for weaning weight and average daily gain from weaning to yearling and a nonlinear for HP16. Variance components and breeding values were estimated using Bayesian […]

Scrotal circumference (SC) is a trait of economic importance because it is related to reproduction and sexual precocity of males and females. This research aimed to evaluate the effects of yearling age (YA) and weight at 15 months of age (W15) on measures of SC using 1.892 records of Caracu young males. Two different models were compared. Both models included the contemporary group (CG) effect, but differed by using YA as a covariate (linear and quadratic components) in model 1 […]

Genetic parameters and environmental effects were estimated for 9,355 Nelore cattle scrotal circumference measurements (PE). The univariate analysis considered animal effect (random effect) and fixed effects of contemporary group (GC) and linear and quadratic effects of age at yearling (IDS) and yearling weight adjusted to 550 days (PSAJ). Contemporary group was defined by: year, season at birth and management group at birth, weaning and yearling. Heritability estimates were: 0.42 ± 0.04 (after IDS and PSAJ); 0.41 ± 0.04 (after PSAJ) […]

This work studied the effects of age and weight on scrotal circumference (SC) of Nellore young breed bulls, and also estimated the SC correction factors (CF) for those effects. The information came from the Production Registry of the Paraguayan Nellore Breeders Association, obtained from 1986 to 1997 from 110 herds, totalling 7,458 observations. The regression coefficients that allowed the calculation of CF for SC were estimated by the least square methods. The model considered the contemporary group (animals born in […]