Effect of hormonal synchronisation and/or short-term supplementation with maize on follicular dynamics and hormone profiles in goats during the non-breeding season

• Nine days nutritional supplementation increased concentration of insulin, leptin and IGF-1.
• Supplementation with maize in hormonally treated goats increased the ovulation rate by 43%.
• Supplementation with maize could be reducing rate of atresia to influence ovulation rate.
• Follicular development was not mediated by gonadotrophins secretion.

This study aimed to evaluate the reproductive response of anoestrous goats that were either hormonally treated and/or supplemented with maize for 9 days to determine which treatment combination was the most effective in enhancing follicular development and ovulation rate, and whether these responses were associated with increases in metabolic hormones. The experiment was carried out using 28 does, using a 2 × 2 factorial design with seven does in each group to test the effect of synchronisation of oestrus, supplementation with maize and their interactions. Synchronisation of oestrous cycles (P < 0.001) but not supplementation with maize or the interaction between the two (P > 0.05) increased the number of codominant follicles, the diameter of the largest follicle on Day 9 and growth rate of follicles during the period of supplementation. Compared with non-supplemented animals, supplementation with maize increased the total number of follicles observed between Days 7 and 9 (P = 0.039). In addition, nutritional supplementation with maize in combination with synchronisation of oestrus increased the ovulation rate by 43% (P = 0.074). Interactions between time and supplementation with maize showed that plasma concentrations of insulin, leptin and IGF-1 were greater in does supplemented with maize compared with non-supplemented does (P < 0.001). The findings show that hormonal synchronisation had the most influence on modifying follicular development and ovulation in anoestrous goats. Supplementation with maize increased the concentrations of insulin, leptin and IGF-1, which could potentially modify the sensitivity of follicles to gonadotrophins and reduce rates of atresia.