Nutritional management during fetal and postnatal life, and the influence on testicular stereology and Sertoli cell numbers in Corriedale ram lambs.

The aim of the experiment was to determine whether supplementation of the lamb-ewe unit during intra-uterine and postnatal life affects testicular stereology, particularly Sertoli cell numbers, in 120 pregnant Corriedale ewes grazed either native pastures (control group) or improved pastures+grain supplement (treated group). Ewes bearing single ram lambs were maintained under the same feeding regime until lambs were castrated (99 days of age). Body weight, testosterone and FSH blood serum levels were recorded at 45, 75 and 99 days of age.

Influence of pre- and post-pubertal grazing regimes on adult testicular morphology in extensively reared corriedale rams.

The aim of the present study was to determine whether pre- and post-pubertal young rams on different grazing regimes, resulting in differences in live weight (LW), would show corresponding differences in testicular growth or testicular morphometry that could influence the reproductive traits of these rams upon reaching adulthood. Forty-one spring-born Corriedale rams were reared on either native pasture (low feeding level, Group L, n=22) or improved pasture (higher feeding level, Group H, n=19) from 1 to 7 months of age. Thereafter, half the animals in the native-pasture group were placed on improved pasture and vice versa, thus creating an additional four differential-grazing treatment groups (Groups LL, n=11; LH, n=11; HL, n=10; and HH, n=9).

Influence of grazing management on the seasonal change in testicular morphology in Corriedale rams.

The present study was conducted: (a) to determine the degree of seasonal variation in testis stereology in Corriedale rams between autumn and winter; (b) to test the hypothesis that testis stereology of Corriedale rams grazing native pastures during autumn and winter would differ from those of Corriedale rams grazing sown pastures and supplemented with grain during the same period; and (c) to determine whether Sertoli cell numbers differ in adult rams between the breeding season (autumn) and the following non-breeding season (winter). Twenty experimental animals were studied. Six rams (autumn control group, C-A) that had been grazing on native pasture (stocking rate = 2-3 animals ha(-1)) were castrated at the beginning of the experiment (March, early autumn).

Reproductive seasonality of corriedale rams under extensive rearing conditions.

The objective of the present study was to describe seasonal changes in scrotal circumference (SC), live weight (LW), sperm morphology and plasma levels of testosterone (T) and thyroxine (T4) in young Corriedale rams reared under extensive conditions typical for the southern Latin American region. A total of 31 Corriedale rams, 11 months of age and with a LW of 36 +/- 1.1 kg and (SC) of 23.

Development of the genital peritoneal folds in sheep.

Development of the genital peritoneum in the sheep was studied in embryos/fetuses that were 27-69 days old. The plica mesonephrica was the first visible fold of the urogenital organs of the embryos and was the origin of the proximal mesorchium or mesovarium. The plica suspensoria gonadalis fixed the gonad to the mesonephros and held the cranial genital ligament and the cranial part of the gubernaculum.