Dolores López-Magaña

In subtropical latitudes, goats are managed under semi-extensive systems grazing natural vegetation without supplementation. During the dry season, reduced forage availability leads to undernutrition and reduced breeding activity in bucks. This study evaluated whether pre-breeding nutritional supplementation enhances testosterone and reproductive performance in bucks joined with anestrous females. On 15 March, bucks were assigned to two groups (n = 6 each) and placed with separate flocks of 90–100 females grazing 9 h/day. Control bucks received no supplementation; supplemented bucks received 600 g/day of concentrate from 15 March to 30 May. Males were fitted with aprons until 1 June to prevent mating. Testosterone was low and similar between groups in March and April (P > 0.05). In supplemented bucks, testosterone increased from mid-May to mid-June, reaching higher than controls (P < 0.05). Females joined with supplemented bucks had higher fertility (71% vs. 53%; P < 0.01), earlier parturition, and a shorter kidding period (P < 0.0001). In conclusion, pre-breeding supplementation increases testosterone, improves fertility, and advances and synchronizes kidding under semi-extensive conditions.