BIOMETRIC, TESTICULAR, SEMINAL CHARACTERISTICS AND GENETIC PARAMETERS OF PERTAINING BULLS TO THE PROGRAM OF GENETIC IMPROVEMENT OF THE NELLORE RACE.

Abstract

An andrological exam was carried out in 1058 animals of Nellore breed with the objective to evaluate the andrological parameters of bulls that took part in a genetic enhancing program, Genetic Enhancing Program of Nellore Breed (GEPNB) and its genetic correlations, as well as the influence of the consanguinity in genetic parameters of fertility. Descriptive statistics were applied to evaluate the existing variability among the evaluated characteristics and also correlations were made to establish the association level between different characteristics. We can observe that the existent variability among the characteristics analyzed in the andrological exam is important. Animals that have scrotal perimeter measurement (EP) and superior testicle volume (TV) presented positive numbers for motility and spermatic strengh. In relation to major defects, minor defects and the total of abnormalities there could not be found significant correlations (p<0,05) with the EP and TV. Most of the correlations between the andrological exam and the genetic values, expected difference in the progeny (EDP) and total genetic merit (TGM), were not significant, a relevant fact is that animals that have Edp’s for the perimeters 365, 450, and 550 longer and superior shows a slight tendence to present minor total defects, that, being a good indicator that the selection for the EP reduces the number of total defects found in the andrological exam. The EP and the TV measured aproximately on the 700^th day of life presented a minor correlation with the weights and EP measured in all ages. The motility and the spermatic strengh observed in the andrological exam does not correspond with any taken measurement until the 550^th day of life, but correlates positively with the measurements of the EP on the 700^th day of life, therefore we can say that the motility and the strengh vary according to the age of the reproducer. Different from what was observed on the 700^th day of life, the animals that presented major standard weight and scrotal perimeters until the 450^th day of life had less quantity of minor, major and total defects in the andrological, therefore, the sexual precocity of growth can tell us forwardly which animals with good phenotypic measurements present less amount of defects in the spermatic morphology. No significant consanguinity effect (p<0,05) was found in the analysed characteristics.

KEYWORDS:  Bulls. Nellore. Andrological