ABSTRACT The present study aimed to correlate the age and weight of Girolando heifers with uterine and ovarian development. Sixty heifers between 12 and 36 months old were weighed and subjected to ultrasound assessment to measure the diameters of each uterine horn and ovaries, monthly. These measures continued until their first ovulation. The animals were divided, for data analysis, according to their age into five groups: GI (12 to 14 months), GII (15 to 18 months), GIII (19 to 24 […]

ABSTRACT The objective of this study was to evaluate the effect of high or low energy intake on carcass composition and expression of hypothalamic genes related to the onset of puberty. Twenty-four prepubertal Nellore heifers, 18-20- months-old, with 275.3±18.0 kg body weight (BW), and 4.9±0.2 (1-9 scale) body condition score (BCS) were randomly assigned to two treatments: high-energy diet (HE) and low-energy diet (LE). Heifers were housed in two collective pens and fed diets formulated to promote average daily gain […]

In order to determine the profile of leptin and insulin values in seminal plasma and their correlations with sperm patterns during the peripuberty, a total of 16 crossbred Gyr dairy bulls were monitored from 60 days before to 60 days after puberty, separated into two groups, early and regular, according to the onset of puberty. Hormone values were determined by radioimmunoassay after gel filtration in fast performance liquid chromatography and semen patterns, according to the Brazilian College of Animal Reproduction. […]

The objective of this study was to determine the age at puberty and sexual maturity and its relationship with body weight and testicular measurements in Simmental young bulls raised under pasture conditions in a tropical climate. Forty-four young bulls at 1 to 30 months of age were used. Body and testicular measurements were made monthly and ejaculates collected fortnightly, from six months of age by using the method of electroejaculation. Age at puberty was 13.42 ± 3.02 months and sexual […]

The aim of this experiment was to evaluate the effect of the duration of progestagen (P4) exposure and sexual maturity of prepubertal and pubertal heifers submitted to timed artificial insemination (TAI). A hundred and fourteen 16- month old Bradford heifers were classified, according treatment and sexual maturity, in 4 groups: PPLPG (prepubertal long exposure to P4, n=21), PPSPG (prepubertal short exposure to P4, n=19), PLPG (pubertal long exposure to P4, n=34) and PSPG (pubertal short exposure to P4, n=40). On […]

This work was carried outo to evaluate the effect of levels of energetic supplementation in productive and reproductive performance of sixty-four Charolais heifers and their crosses with Nellore, mantained in cultivated pasture of black oat (Avena strigosa Schreb) plus Italian ryegrass (Lulium mulktiflorum Lam.). The treatments considered supplementation of 0; 0.7 and 1.4% of the live weight (LW)/day of rice bran associated with citric pulp, in the proportion of 1:1. A continuous grazing system with variable stocking rate was used, […]

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 […]