Anestro em vacas de corte

Abstract

The objective of this study was to evaluate possible factors that may influence the occurrence of anestros in bovine females. The data used came from a farm producing registered Nelore cattle, which refer to 733 females of reproductive age, distributed in all age categories: 165 nulliparous, 118 primiparous, 122 secondary and 328 pluriparous. All females that had no corpus luteum 35 days after the two protocols of artificial insemination at fixed time (IATF), as well as in the diagnosis of final gestation performed at the end of the mating season, were considered in anestrous. The anestrus assessments were performed by a veterinarian using an ultrasound. The variables evaluated were: age, body condition score (CBC), birth weight (PN) and weaning age (PD) of calves, puerperium and ultrasound data of mothers, with the genetic quality index (IQG) being the loin eye area / 100kg (AOL / 100kg), ratio, marbling, subcutaneous fat thickness / 100kg (EGS / 100kg) and the measure of the picanha. Regarding age, it was observed that approximately 20% of the females after the first IATF were in anestrus. Of these, 14.4% continued in anoestrus at the end of the second IATF protocol. The primiparous and the pluriparous presented the highest percentages of anestrous, with values of 21.2% and 33.3% for the primiparous and 45.2% and 33.3% for the pluriparous ones, in the first and second IATF, respectively. The CBC, PN, PD and data of the variables collected on ultrasonography did not have an effect on the occurrence of anestrus, since the values of these variables for females in anestrous are practically the same as those that they did.The puerperium was the variable considered to have the greatest effect on the occurrence of anestrus, since the females in thiscondition had lower puerperium values than the one recommended in the literature.