The spermiogram of 10 mature bulls, ranging in age between three and 10 years and comprising five indigenous (Bos indicus) and five exotic (Bos taurus) bulls, was studied for 12 months. There were no significant seasonal variations in sperm cell concentration, percentage live sperm cells and sperm cell abnormalities in the indigenous bulls but the exotic breed showed significant seasonal fluctuations with higher sperm cell abnormalities, lower percentage live-sperm cells and lower sperm cell concentration during the hot periods. In both groups the sperm cell concentration was significantly higher in the relatively younger, mature bulls (three to seven years) than in the older bulls (seven-and-a-half to 10 years) Histological study of the testes of 240 indigenous bulls over the same period showed that percentage spermatogenesis was lower in the older than in the younger bulls. This lower sperm output was associated with degenerative changes in the seminiferous tubules. It is suggested that thermal stress in the tropics has significant adverse effects on spermatogenesis only in bulls of non-indigenous breeds. Senile testicular degeneration could be a significant factor in the low reproductive performance of the local bulls.

No abstract

________________________________________________________________________________ AbstractThe objective of this study was to evaluate the effect of a progestagen treatment (fluorogestone acetate sponge) alone or in combination with equine chorionic gonadotrophin (eCG) on oestrus response in Red Sokoto (RS) goats. One hundred RS does were treated with 30 mg fluorogestone acetate (FGA) sponges for 14 days. At the end of the progestagen treatment, does that retained the sponges were allocated to two groups; FGAeCG and FGA. The FGAeCG group (n = 28) received 200 IU eCG i.m. concurrently with the sponge removal, while the FGA group (n = 28) did not receive eCG at sponge removal. Oestrus was detected twice daily (at 07:00 -10:00 and 15:00 -18:00) using sexually active bucks for five days following progestagen withdrawal. There was no significant difference in oestrus response between groups FGAeCG (82.1%) and FGA (78.6%). There was a significant difference in the time to the onset (29.3 ± 4.6 and 44.2 ± 6.3 h for the FGAeCG and FGA, respectively) and duration of the induced oestrus period (38.9 ± 5.1 and 22.7 ± 4.6 h for the FGAeCG and FGA groups, respectively). It is concluded that although both groups showed good oestrus synchronization rates, administration of eCG shortened the time to onset of oestrus and increased the duration of oestrus in Red Sokoto does. ________________________________________________________________________________

The objective of the present study was to evaluate the effect of a progestagen treatment alone or in combination with equine chorionic gonadotrophin (eCG) on estrus response in Sahel (SH) goats. One hundred (n=100) SH does were treated with 30 mg fluorogestone acetate (FGA) sponge for 14 days. At the end progestagen treatment, does that retained the intravaginal pessary were allocated into two groups; A: FGA & eCG (n=42) and B: FGA (n=41). Does in group A received additional 200 IU eCG i.m. concurrent with sponge removal. Estrus was detected twice daily (at 07.00 -10.00 and 15.00 -18.00 h) using sexually active bucks for 5 days after pessary removal. Estrus response was different (p<0.05) between A (73.8 %) and B (58.5 %). Estrus onset for group A and B (Mean ± S.E.M.) was 27.9 ± 8.3 and 38.4 ± 9.6 h while estrus duration (Mean ± S.E.M.) for group A and B was 35.8 ± 3.2 and 23.1 ± 5.2 h, respectively. Estrus onset and duration of estrus were different (p<0.05) between group A ( FGA & eCG) and B (FGA). It is concluded that additional eCG treatment following a 14-day progestagen (Fluorogestone acetate) treatment increased estrus response, hastened onset of estrus, lengthened duration of estrus and improved tightness of synchrony in Sahel does.

The present work evaluated the effects of feeding graded levels of whole cottonseed on reproductive parameters of Red Sokoto bucks. Twenty Red Sokoto bucks were used for the experiment. After a 14-day pre-treatment period, bucks were assigned for 90 days to one of four isonitrogeneous treatments: control (diet A); 0 mg kg-1 of total gossypol, (diet B); 15% mg kg-1 of total gossypol, (diet C); 30% mg kg-1 of total gossypol and (diet D); 45% mg kg-1 of total gossypol. The mean percentage sperm gross motility was significantly (p < 0.05) lower in group D (45% WCS) compared to groups C (30% WCS) and A (control) at days 60, 75 and 90. The mean semen pH and reaction time were not significantly (p > 0.05) different among treatment groups. Semen colour of the bucks in the control group was majorly creamy, in group C (30% WCS) and B (15% WCS) creamy to milky and group D (45% WCS) colourless. The mean semen volume was significantly (p < 0.05) higher in groups C and A compared to group D (45% WCS) at days 60, 75 and 90. The mean semen concentration was significantly (p < 0.05) lower in group D (45% WCS) when compared to group A (control) at days 30, 45, 60, 75 and 90. Group A (control) bucks had significantly (p < 0.05) higher percentage live sperm compared to those in group D (45% WCS) at days 45, 60, 75 and 90. Mean Sperm morphological abnormalities including detached head, free tail curved tail and midpiece droplets were significantly (p < 0.05) higher in group D (45%) than in group A (Control) at day 15 (for free tails) and day 90 (for all). Testicular and epididymal sperm reserves were higher in animals supplemented with up to 30% whole cottonseed. In conclusion, feeding bucks above 30% WCS resulted in more deleterious effects on the semen characteristics and testicular profile.