Testicular and epididymal function during the peripuberal period in Brahman bulls receiving various amounts of protein degradable in the rumen

Alleviation of reproductive toxicity of gossypol using selenium supplementation in rams

The objective of this study was to evaluate the reproductive toxicity of gossypol and the possible counteracting effect of selenium supplementation in rams. Twenty-five mature crossbred (Barki × Rahamni) rams were randomly divided into 5 equal groups. The first group served as a control (no gossypol in diet). The second and third groups received diets containing free gossypol of 9 and 14 mg·kg(-1) BW·d(-1)(low level and high level of gossypol), respectively. The fourth and fifth groups received the same diets given to the second and third groups, respectively, with an oral administration of 1 mg selenium (as sodium selenite) daily for each animal. Results showed reductions in ejaculate volume (P = 0.028), percentage of dead sperm (P = 0.003), total functional sperm fraction (P < 0.001), and blood serum concentration of testosterone (P < 0.001) in the presence of both levels of gossypol inclusion. Furthermore, high level of gossypol reduced forward motility (P < 0.001) and semen initial fructose concentration (P = 0.002) and increased abnormal-head sperm (P = 0.003) and blood serum concentration of triiodothyronine (P = 0.006). Regardless of selenium supplementation, increasing level of free gossypol in diet resulted in a significant decrease in the percentage of forward motility (P = 0.037) and significant increases in the mean values of sperm concentration (P < 0.001), total sperm output (P = 0.002), percentage of total abnormal sperm (P = 0.058), and abnormal-head sperm (P = 0.016). On the other hand, regardless of levels of gossypol inclusion, selenium supplementation resulted in significant increases in libido (P < 0.001), mean values of ejaculate volume (P < 0.001), percentage of forward motility (P = 0.019), total sperm output (P < 0.001), total functional sperm fraction (P < 0.001), semen initial fructose concentration (P = 0.031), and blood serum concentrations of both testosterone and triiodothyronine (P < 0.001). In conclusion, free gossypol in diet induced adverse effects on semen quality in rams, but selenium supplementation successfully counteracts most of the hazardous effects of gossypol on semen characteristics.

Peripubertal traits of Brahman bulls in Yucatan

In order to investigate elements of puberty in Brahman (Bos indicus) bulls, 12 animals were studied from 10 mo of age until puberty, which was defined as the moment of production of the first ejaculate with at least 50 x 10(6) sperm with 10% progressive motility. Body weight and scrotal circumference were recorded every 2 weeks. From 14 mo of age onwards, the bulls were electroejaculated at the same intervals and ejaculates were evaluated. Blood samples were taken from 6 of the bulls every 30 min for 6 h at 12, 14, 17 and 20 mo of age to study serum concentrations of testosterone, which were determined by RIA. Mean age (+/- SEM) at puberty was 17 +/- 0.4 mo, body weight was 374.6 +/- 22.5 kg and scrotal circumference was 28.6 +/- 0.6 cm. Serum testosterone increased from 12 to 17 mo and then decreased slightly, mean (+/- SEM) concentration being 0.4 +/- 0.1, 1.4 +/- 0.4, 2.9 +/- 0.5 and 2.7 +/- 0.3 at 12, 14, 17 and 20 mo of age, respectively. It was concluded that Brahman bulls, under the conditions studied, attain puberty between 16 and 17 mo of age, with considerable variation, and that serum concentrations of testosterone prior to puberty seem to form a pattern similar to that shown by Bos taurus bulls, however the pattern occurs at a later age.