Efeito do cordeiro ao pé na expressão de cio de ovelhas sincronizadas

Abstract

The sheep herd has been growing, as has the increase in the quest for good animal protein. With this in mind, we need to produce more and more lambs, reduce the interval between deliveries and reduce anestrous postpartum of the sheep. Therefore, we must go to the search for the reduction of the seasonality of ovine production, being the estral cycle manipulated through the application of reproductive hormones. Thus, the objective of this work was to evaluate the expression and return rates of oestrus Crioulas, with and without lamb at the foot, submitted to the application of prostaglandin. The experiment was carried out at the Agricultural School of the Federal University of Pampa - UNIPAMPA / Campus of Dom Pedrito, RS, from February 1 to 24, 2019. Fifty-eight adult sheep were divided into two treatments: single sheep and lactating sheep, submitted to estrus synchronization through the application of two doses of 0.5 ml prostaglandin hormone, with an interval of ten days. The males stayed from 8:00 a.m. to 7:00 p.m. along the females, after that time the males were removed from the females to stay overnight. Both treatments remained in the native field, with shade and water ad libitum during the evaluation days and received 1.5% of the live weight of the ration with 14% PB at the end of the day. Of the 70 evaluations (n = 70) made during the twenty four day experiment at the return frequency of estrus was 29% (n = 9) for the single group and 22% (n = 4) to the foot (P = 0.6116). On the other hand, values related to gestation, 76% (n = 23) and 80% (n = 8) presented gestation, respectively, in the single group and the foot group, respectively (P = 0.8332). Regarding the frequencies of evaluation, 61.4% (n = 43) coverage occurrences were observed in the single group, compared to 38.5% (n = 27), in the group with foot breeding (P = 0.8231). There were three significant factors: return to estrus and age of lamb, occurrence of gestation and body condition score (27.88%, 25.84%, 18.45%), respectively. In the evaluation of the Logistic Regression procedure, a negative correlation between the return to estrus (x = independent variable) and gestation (y = dependent variable) was observed (P = -0.3629), showing that those in the single group showed more return to the estrus and presented lower index gestation, in relation to those with foot. Thus, it was concluded that lactating ewes have dispersed cords, that is, the synchronization did not act efficiently, in contraception with single ewes that presented cynoses synchronously, predicting that the protocol in these sheep was efficient.