Fetal programming in sheep: effects on pre- and postnatal development in lambs.

This systematic review and meta-analysis aim to summarize the effects of maternal undernutrition or overnutrition during pregnancy on fetal weight and morphometric measurements during pregnancy, at birth, and postnatal period in sheep. After completing the search, selection, and data extraction steps, the measure of effect was generated by the individual comparison of each indicator with the average of the control and treated group (undernutrition or overnutrition) using the DerSimonian and Laird method for random effects. Subgroup analyses were also performed for lambing order, litter size, sex, as well as level, timing, and duration of the intervention. Fetal weight during the first third of pregnancy was not affected by maternal undernutrition or overnutrition. On the other hand, undernutrition in the second and last third of gestation reduces the weight of the lamb both during pregnancy, at birth, and during the postnatal period, requiring at least 120 postnatal days to achieve the same weight as its contemporaries in the control treatment. However, this reduction in weight is not accompanied by reductions in morphometric measurements, demonstrating that the animals were lighter, but of equal size. In overnutrition, there is an increase in fetal weight in the second third of gestation. However, in the last third of the gestational period, there are no differences in fetal weight for the multiparous subgroup, but it was reduced in primiparous ewes. There are no effects of overnutrition on birth weight; however, this result is highly heterogeneous. Thus, maternal nutrition of ewe during pregnancy has effects on fetal and postnatal weight, but not on size. Furthermore, the effects of undernutrition are more homogeneous while overnutrition showed heterogeneous responses.

Evaluation and prediction of scrotal circumference in beef bulls.

Scrotal circumference (SC) is considered a useful tool for predicting age at puberty and is performed to improve the reproductive performance in beef cattle industry. We aimed to fit several nonlinear mixed models for SC measurements of five different breeds to better predict testicular growth. Data of SC (cm), body weight (BW; kg), and age (A; days), farm location, sire and dam, and birth dates of 169,094 beef bulls were collected from five breeds: Nelore (N) (n = 110,814); Angus (AA) (n = 6541); Brangus (BA) (n = 42,910); Polled Hereford and Hereford (HH) (n = 4640); and Braford (BH) (n = 7480). Data comprise a total of 8640 sires and 115,172 dams and grouped in 2908 contemporary groups (CG). The full model development for SC was defined as: SC = CG + A + A*A + BW + BW*BW + Æ. Bulls from HH (34.1 ± 3.2) and AA (33.5 ± 3.0) had the highest value of SC, followed by BH (32.2 ± 3.7), BA (30.6 ± 4.1), and N (26.9 ± 3.6). There was a curvilinear effect of BW on the SC measurements of HH and AA bulls, reaching the maximum point around 600 kg, whether both breeds presented a similar testicular growth pattern. In British breeds, inflection points of average daily SC growth of 0.039 and 0.042 cm/kg were obtained from 700 kg HH and 600 kg AA bulls, respectively. Scrotal circumference values of 0.042 and 0.046 cm/kg reaching the maximum growth point at 450 kg BW were obtained for BH and BA bulls, respectively. We also observed SC values of 0.044 and 0.048 cm/d reaching the maximum growth point at 550 d of age for BH and BA bulls, respectively. Thus, estimate testicular size at maturity should be measured between 500 and 600 kg BW in British genotypes and between 550 and 600 d in Bos indicus and crossbreeds animals. Therefore, SC adjustment can be used by breed-specific criteria associated with BW and/or age to determine testis growth as a selection criterion in beef cattle breeding programs.