Comportamento e desempenho reprodutivo de cabras nulíparas criadas no semi-árido do estado de Pernambuco - Brasil

Abstract

Two experiments were carried out to evaluate the reproductive behavior and performance of nulliparous goats during the breeding season in the rainy and dry seasons. Nulliparous goats averaging 8 to 12 months old, 25.65 ± 0.67 and 26.76 ± 2.36 kg, body condition score of 3.0 and serum progesterone concentration of 1.36 ± 1.51 ηg/mL and 0.45 ± 0.44 ηg/mL were used. In the first experiment, the effect of male effect on reproductive performance of goats (n=40) equally assigned according to the season (rainy and dry) was evaluated. The first estrus manifestation occurred from the 7th and 8th day after the male introduction in the dry and rainy seasons, with higher concentration from the 11th to 15th day, of 75 and 65%, respectively. No effect treatment (P>0.05) in the in the dry and rainy seasons was observed, when 95 and 80% of goats presented one or more estrus until the 15th day, and the last estrus occurred in the 28th and 34th day after the male introduction, respectively. The estrus interval ranged from 20 to 22 days and from 7 to 18 days, in the dry and rainy seasons, respectively. No estrus of short cycle was recorded in the rainy season, but only of 5% in the dry season. The results showed that 75% of conceptions occurred until the 15th day after the male introduction. No treatment effect (P>0.05) on fertility rate (85 and 75%) the dry and rainy seasons, respectively. In the second experiment, nulliparous goats (n = 120) were assigned into three groups: EM-25 (breeding season of 25 days), EM-35 (35 days) and EM-45 (45 days), according to seasons (rainy and dry). In the rainy season fertility indexes of 80, 85 and 85% and e pregnancy indexes of 84.20, 89.47 and 89.47% were observed for EM-25, EM-35 and EM-45, respectively, with no effect (P>0.05) the dry season, when it was observed fertility rates of 45, 65 and 65% and pregnancy rates of 60, 76.47 and 76.47%. %. It was observed prolificacy of 1.18 and 1.27 kids, for the rainy and dry seasons, respectively, with no effect (P>0.05) of year season. The weight gain observed during the mating period in the rainy and dry seasons was 1.60 kg (EM-25), 2.7 kg (EM-35) and 4,55 kg (EM-45) and of 1.05 kg (EM-25), 2.00 kg (EM-35) and 3.29 kg (EM-45). No effect (P>.05) of birth season and delivery type on the kid birth weight in both seasons, that was of 2.94 ± 0.32 and 3.03 ± 0.2 (singleton), 2.90 ± 0.09 and 3.03 ± 0.14 (twin birth), was observed. No dystocia was detected but 94.11 and 84.61% of eutocic calving in the rainy and dry seasons, respectively was detected. Abortion rate of 5.8 and 15.3% was detected in the rainy and dry seasons,was detected, with pregnancy rate of 89.47 and 75% in respectively, with no difference (P>0.05). The results showed that a the answer to stimulus of male effect starts from 7th and 8th day after male introduction and that no breeding season effect on reproductive efficiency was observed, but females bred at 35 days can express until three estrus, due to the adequate feeding and nutritional support.