Production performance of sheep and goat breeds at a farm in a semi-arid region of Namibia

This study retrospectively investigated the effect of breed and season on the lambing/kidding dynamics, growth performance, neonatal viability, and weaning dynamics of sheep (Damara, Dorper, and Swakara) and goats (Boer goat and Kalahari Red) at a farm in the Khomas Region of Namibia between 2004 and 2015. Litter size was dependent on breed (X²(12, N = 3388) = 796, p < 0.001), with twinning more frequent in Dorper sheep and Kalahari Red and Boer goats than in the Damara and Swakara sheep (p < 0.05), while triplets were more prevalent in the Dorper sheep and Kalahari Red goats (2.8% and 1.0%, respectively; p < 0.05). Distribution of birth weight categories was dependent on breed. There was a significant difference in the proportions of birth weight categories between breeds (X²(12, N = 3388) = 467, p < 0.001) whereby Dorper lambs were mostly born weighing below 3 kg (2.6%, p < 0.05); Boer goat kids, Kalahari Red kids, and Damara lambs were mostly born weighing 3 to < 4 kg (4.3%, 6.3% and 19.9%, respectively; p < 0.05); Swakara lambs were mostly born weighing 4 to < 5 kg (12.2%, p < 0.05), and Swakara lambs were mostly born weighing ≥ 5 kg (3.3% and 2.3%, respectively, p < 0.05). Weaning age categories were dependent on breed (X²(12, N = 3388) = 241, p < 0.001) whereby Dorper lambs were mostly weaned at below 3 months of age (2.8%, p < 0.05); Damara lambs were mostly weaned at 3 to < 5 months of age (12%, p < 0.05), and Boer goat kids were mostly weaned at ≥ 5 months of age (0.9%, p < 0.05). Neonatal viability was dependent on breed (X²(8, N = 3388) = 49.2, p < 0.001) whereby Dorper lambs were more susceptible to abortions and neonatal deaths (0.6% and 1.5%, respectively; p < 0.05) than the rest of the breeds. Breed and lambing season interacted to produce effects on the birth weight of offspring although lambing season alone did not have a significant effect on Boer goat and Kalahari Red kids' birth weights.

Progesterone doses of 5, 3 or 1 mg do not prevent short ovulatory cycles in goats exposed to photo-stimulated bucks

The aim of this study was to determine whether lower doses than 25 mg of progesterone reduce the frequency of short ovulatory cycles in seasonal anestrous goats exposed to sexually active bucks. Females from the control group were given an im dose of 2 mL olive oil (n = 9). Females from the experimental groups were given an im dose of 1 mg (n = 15), 3 mg (n = 16), 5 mg (n = 15) or 25 mg (n = 16) of progesterone diluted in 2 mL olive oil, 48 h prior exposition to bucks (n = 1 per group). Males were daily switched among groups, and they remained with goats during 21 days. The proportion of goats that ovulated was high (≥87%), and was not different among groups (P > 0.05). In contrast, the proportion of goats that displayed short ovulatory cycles differed among groups (P < 0.05). Indeed, the proportion of goats displaying short ovulatory cycles was lower in those treated with 25 mg (12%) than in those from the control (78%), 1 mg (85%), 3 mg (50%), or 5 mg (71%) groups (P < 0.05), but there were no differences among these last four groups (P > 0.05). Finally, the percentage of kidding females (≥40%) and the number of kids born per female (≥1.4) did not differ among groups (P > 0.05). In conclusion, an im dose of 25 mg of progesterone was more effective than 5, 3 or 1 mg to avoid the short ovulatory cycles in seasonal anestrous goats exposed to the male effect.