Environmental and behavioral effects on pregnancy rate of Nellore cows synchronized to fixed-time artificial insemination protocol: multivariate analysis

Abstract

The aim of the study was to evaluate the influence of behavioral reactivity, body condition score (BCS), corral temperature (CT), difficulty and time of insemination on pregnancy rate of Nellore females raised in the Pantanal area and submitted to a fixed-time artificial insemination (FTAI) protocol. Thus, 167 females, kept in an extensive grazing system were evaluated. The variables recorded were BCS, escape velocity (EV), CT, insemination difficulty (ID), chute behavior (CB), insemination time (IT) and pregnancy rate. Initially, Fisher's Exact Test was performed to verify differences between expected and observed for BCS, CB, EV, ID, IT and CT, in which the influence of each variable on pregnancy rate was individually analyzed and it was not significant influence of these variables was observed (P<0.05). Subsequently, the result of the pregnancy diagnosis (success = 1 and failure = 0) was used to study the probability of pregnancy. Multivariate analysis was used to assess the influence of several characteristics together on the conception rate, creating different evaluation scenarios. In none of the scenarios extracted from the cluster analysis was there a statistically relevant influence on the number of pregnancies. Under the conditions in which the study was conducted, there was no influence of corral temperature, reactivity, time and difficulty of insemination, body condition score and animal category on pregnancy rate of bovine females submitted to a FTAI protocol.