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Maximizing the number of offspring born per female is a key functionality trait in commercial- and/or subsistence-oriented livestock enterprises. Although the number of offspring born is closely associated with female fertility and reproductive success, the genetic control of these traits remains poorly understood in sub-Saharan Africa livestock. Using selection signature analysis performed on Ovine HD BeadChip data from the prolific Bonga sheep in Ethiopia, 41 candidate regions under selection were identified. The analysis revealed one strong selection signature on a candidate region on chromosome X spanningBMP15, suggesting this to be the primary candidate prolificacy gene in the breed. The analysis also identified several candidate regions spanning genes not reported before in prolific sheep but underlying fertility and reproduction in other species. The genes associated with female reproduction traits includedSPOCK1(age at first oestrus),GPR173(mediator of ovarian cyclicity),HB-EGF(signalling early pregnancy success) andSMARCAL1andHMGN3a(regulate gene expression during embryogenesis). The genes involved in male reproduction wereFOXJ1(sperm function and successful fertilization) andNME5(spermatogenesis). We also observed genes such asPKD2L2,MAGED1andKDM3B, which have been associated with diverse fertility traits in both sexes of other species. The results confirm the complexity of the genetic mechanisms underlying reproduction while suggesting that prolificacy in the Bonga sheep, and possibly African indigenous sheep is partly under the control ofBMP15while other genes that enhance male and female fertility are essential for reproductive fitness.

To understand the ovarian basis for prolificacy of Bonga sheep, a total of 31 ewes were selected based on litter size (LS) records and divided into two groups: High Prolificacy (HP) (n = 20) with LS ≥ 2 and Low Prolificacy (LP) (n = 11) with LS = 1. At a synchronized estrus, follicular dynamics were determined using transrectal ultrasonography. Plasma estradiol concentrations were also monitored. In total 27 ewes were observed in estrus being 9/11 LP (82%) and 18/20 HP (90%). On the day of estrus (day 0), the mean number of large follicles was higher (p < .05) in HP (1.78 ± 0.19) than in LP (1.0 ± 0.28) ewes. Prior to estrus, more (p < .05) medium follicles were visible for HP compared to LP ewes. Plasma estradiol concentrations were higher in HP compared to LP ewes (18.91 ± 0.41 vs. 14.51 ± 0.65 pg/ml; p < .05) and similarly was ovulation number (2.3 ± 0.15 vs. 1.28 ± 0. 14; p < .05). Higher ovulation rates and litter size in Bonga sheep are evidenced by the previous presence of more large follicles and the existence of co-dominance effects as most likely medium follicles are selected to ovulate.

Effects of dietary concentrate level and grass hay source were determined to evaluate a method (www2.luresext.edu/goats/research/suppconc.html) of predicting negative associative effects between feedstuffs in Boer goat wethers. Forage DM intake (g/kg BW0.75) was similar (P = .157) between growing and yearling wethers (34.9 and 30.8) and ranked 0 and 15 > 30 > 45 g/kg BW0.75 of concentrate dry matter (48.5, 41.8, 25.9, and 15.2, respectively). Age and concentrate level interacted in neutral detergent fibre digestibility (57.3%, 60.6%, 61.4%, and 58.4% for growing and 56.6, 62.9, 56.8, and 30.0% for yearling wethers with 0, 15, 30, and 45 g/kg BW0.75, respectively). There was a tendency (P = .074) for an interaction in metabolizable energy (ME) intake between age and concentrate level (361, 530, 634, and 709 for growing and 363, 547, 541, and 555 kJ/kg BW0.75 for yearling wethers with 0, 15, 30, and 45 g/kg BW0.75); values predicted for treatments with concentrate were 563, 631, and 619 for growing ...