Synchronization of ovulation in cattle using equine chorionic gonadotropin with and without restricted nursing

Abstract

<em>Introduction</em>: To make the most of the productive and genetic potential in cattle, it is necessary to achieve the conception of cows as soon as possible. Postpartum anestrus can affect fertility for a long time, which is associated with many factors, including the presence of calf and maternal behavior. <em>Objective</em>: To compare ovulation synchronization protocols using equine chorionic gonadotropin (eCG), with and without restricted nursing, in anestrous Brahman cows with calves at foot. <em>Methodology</em>: Of a total of 240 cows, 184 study animals were selected by non-probabilistic sampling, based on the inclusion criteria, and were randomly assigned to one of the treatments. Two treatments and two controls were carried out. Ovulation synchronization protocols using progestogens and estrogens varied according to whether they used eCG or not, and whether nursing was restricted or not. <em>Results:</em> Using Pearson’s proportion comparison test for independent samples, it was possible to determine, with 95% confidence (p=0.8308), that there were no significant differences in the percentage of pregnancies between “restricted” or “not restricted” nursing when eCG was used in the synchronization protocols. <em>Conclusion:</em> The use of protocols for ovulation synchronization for fixed-time artificial insemination (FTAI) with the administration of eCG in anestrus and without restricted nursing is an alternative reproductive management that increases the percentage of pregnancies and favors the breeding of calves.