Inseminação artificial em cabras leiteiras com estro induzido e sincronizado por bioestimulação (efeito macho)

Abstract

New market requirements are established and with them, new production models it should be adopted to meet the consumers demands, without resulting in damage to system productivity, with less environmental impact. The aim this study was to evaluate the effectiveness of Male Effect by fertility rate of goats inseminated artificially. Thus, we evaluated the fertility and calving rates of 73 goats belonging to genetic group Saanen and its crossbred. This does had their estrus induced and synchronized by the male effect and it were artificially inseminated with fresh semen. The experiment took place during the rainy (March-April) and dry (August-September) seasons of 2012. We collected data on climatic variables (RT: room temperature; and RH: relative humidity) for calculating the THI (temperature and humidity index). Data were analyzed statistically at 5% probability. The THI was higher (P<0.05) in the rainy season, and it assumed values above ideal for goats, with an emergency situation to the rainy season, and dangerous situation to the dry season. The male effect was effective regardless of season, it resulting in 94.5% of estrus. The duration of the first estrus was same between the rainy and dry season, it had a mean duration of 23.4 hours. The interval between the onset of the male effect and estrus was 11 days, and there was a greater manifestation of estrus (first heat) in the first week for both seasons. Overall, 65 % of goats returned in estrus, it been the interval between the onset of the male effect and second estrus manifestation was greater (P<0.05) during the rainy season (27.8 days). This is related to the estrous cycle length, where there was a greater (P <0.05) number of normal estrus cycles (20) during rainy season, and high (P <0.05) number of short estrus cycles (15) during dry season. The fertility during the dry season (57.6 %) was proportionally greater than rainy season (44.4 %). However, the calving rate showed a trend (P = 0.57) to be higher the dry season. This lower rate during rainy season may be related to high climate variability observed during this experimental period. The second estrus was more like to result in fertility, during rainy or dry season. This indicates that the artificial insemination of goats with induced and synchronized estrus by male effect is a management can be utilized in goat production systems resulting in satisfactory reproductive rates.