Avaliação andrológica por pontos e comportamento sexual em touros da raça Nelore

Abstract

The objective of this work was to study the relation between two reproductive potential evaluation methods - Andrologic Evaluation by Points - CAP and sexual behavior of Nelore bulls, and to verify the accuracy of these tests in predicting the reproductive potential of bulls through the gestation rate at the end of the breeding season, with average duration of ninety days. Fourteen bulls were used, all classified as able for reproduction, evaluated through andrologic examination, being submitted to CAP and observation of the sexual behavior at field (libido test) during 12 hours. Eleven bulls were evaluated in individual handling, with an average bull:cow ratio of 1:46 and the rest of the animals (three), evaluated in a multiple handling, with an average bull:cow ratio of 1:23. The average score obtained by CAP was 78.92 ± 8.92 (very good) and the score of 9.85 ± 0.36 (excellent) for the libido test. The longer the test was, the higher libido scores were obtained. At the first time of observation, the bulls were classified as with questionable libido and at the end of the test as with excellent libido. The correlations between libido, scrotal circumference (SC), physical and morphological characteristics of the semen and the gestation rate were low. The scores obtained through CAP was positively correlated with SC and physical characteristics of the semen; however, no correlation was observed for the morphologic characteristics. No correlation was observed between CAP and gestation rate or between libido and CAP. The overall gestation rate after the breeding period was 74.69%. The results suggest that both CAP and the libido test were not efficient to predict the reproductive potential of Nelore bulls and should be used as a complement to the andrologic evaluation. © 2009 Sociedade Brasileira de Zootecnia.