Estratégias de manejo reprodutivo associado ao efeito macho em cabras Anglo-Nubiana criadas no semi-árido do Estado de Pernambuco

Abstract

This work aimed to evaluate reproductive handling strategies male effect associated in the goats pluriparous Anglo-Nubian goats (n = 184), aged 24 to 60 months old, raised in semi-extensive regime in the semi-arid region of the State of Pernambuco. The goats were kept 300 m away from the males (n = 3) which were maintained behind fences made of bush-type native vegetation. Before the start of the experiments, the males underwent fertility testing and the females were selected according to body condition score by both vaginoscopy and ultra-sound. Concentration of progesterone was measure to determine cyclicity conditions. Pregnancy was diagnosed by ultra-sound 60 days after the last mating. During the first experiment, the influence of duration of the mating season in the dry period (DP) and wet period (WP) was evaluated. The evenly distributed goats (n = 120), were submitted to mating seasons of 25 (MS-25D), 35 (MS-35D) and 45 (MS-45D) days. Estrous percentages during DP and WP were 100% at MS-25D, MS-35D e MS-45D, except for 95% obtained at MS-45D during DP. These data did not reveal any influence (P > 0.05) of the mating season during exhibition of estrous during DP and WP. During the DP, the presence of double estrous was observed in 30% of the females at the MS-25D, 35% at the MS-35D and 35% at the MS-45D, as well as 25% at the MS-25D, 30% at the MS-35 and 25% at the MS-45D during the WP. The presence of a triple estrous was only recorded in 5% of the females at the MS-35D and MS-45D during the WT. There was no influence (P > 0.05) of duration of the mating season on repetition of estrous during the DP or the WP. It was found that the intervals between estrous during the WS varied from 1 to 21 days in the first, and from 7 to 21 days during the second estrous at MS-25D. At MS-35D, it varied from 1 to 23 days, and from 6 to 27 days during the second. The third estrous occurred on the 24th day. At MS-45D, it varied from 1 to 23 days during the first and from 9 to 20 days during the second. The third estrous occurred on the 30th day. During the DS, it varied from 1 to 17 days during the first, and from 6 to 23 days during the second estrous at MS-25D. At MS-35D, it varied from 1 to 20 days in the first, and from 6 to 21 days during the second estrous. There was no third estrous during the DS. Pregnancy percentages during the WP were 90.0% at MS-25D, 95% at MS-35D and 95% an MS-45D. During the DP, these percentages were 75% at MS-25D, 80% at MS-35D and 75% at MS-45D, with no influence (P > 0.05) of duration of mating season both during the DP or WP. In the second experiment, the effect of temporary interrupted of suckling was evaluated. The goats (n = 64) were randomly distributed in three treatments (TS0, TS24, TS48). At TS0 (n = 20), there was no suckling interruption, while at TS24 (n = 22), suckling was interrupted for 24 hours and at TS48, (n = 22), interruption was for 48 hours. Estrous distribution was scattered up to the 16th day at TS0, 13th day at TS24 and 11th at TS48. Estrous synchronization at to the 5th day of the mating season was 70% (TS0), 80% (TS24) and 72% (TS48), with no difference between treatments. Estrous percentages in the normal cycle were 85% (TS0), 95.45% (TS24) and 100% (TS48), with no different (P > 0.05) among treatments. Short cycle estrous percentages were 58.00% (TS0), 57.14% (TS24) and 36.36% (TS48), with no difference among treatments. Pregnancy percentages were 52.94% (TS0), 80.95% (TS24) and 36.36% (TS48), and it was found that the percentage at TS24 was higher (P < 0.05) than those of TS0 and TS48, while there was no difference between P > 0.05) between TS0 and TS48 percentages. Prolificacy was 1.44 (TS0), 1.35 (TS24) and 1.37 (TS48), with no difference (P > 0.05) among treatments. The results allow us to conclude that duration of the mating season during the DP and WP have no influence on the percentages of exhibit of estrous and pregnancy. Therefore, it is possible to recommend the use of MS-25D because, besides reducing mating time, it standardized the lot of offspring and costs such as supplementary feeding and skilled personnel to observe estrous and supervise deliveries. Moreover, it is also possible to conclude that the 24-hour suckling time can be recommended as a strategy for reproductive handling due to reducing the delivery/conception period in the Anglo-Nubian goats not intervening with the prolificness.