BREEDING SOUDNESS EXAMINATION IN NELORE ZEBU BULLS AND SPERM VIABILITY, ACROSSOME AND CHROMATIN INTEGRITY ASSAY FOR THREE BREEDING SEASONS

Abstract

This work aimed to verify the evolution of seminal quality in zebu Nellore bulls in three years by the breeding soundness examination and integrity of plasmatic membrane, acrosome and chromatin and establish relationships among those characteristics and the pregnancy with different females groups. Forty six bulls with age between 30 and 120 months were used to evaluation of the seminal quality and the reproductive aptitude. The animals had been kept in extensive conditions, with feeding the grass, receiving mineral supplementation and serving a herd with 3,782 females of some categories (heifers and cows). Data enclosed measured of scrotal circumference and evaluation of the semen collected by eletroejaculation and evaluated the physical characteristics (volume, mass activity, motility, strong), morphologic (major, minor and total defects) and spermatic structure integrity (integrity of plasmatic membrane, acrosome and chromatin) in this period had been carried through that preceded three consecutive mating season (2003, 2004 and 2005). The data had been submitted analyze of variance, the averages compared for test SNK and the coefficient of correlation of Pearson was calculated using the SAS. The bulls presented scrotal circumference of 33.8 ± 2.8cm, 15.6 ± 8.5% of total spermatic defects, 40.1 ± 23.1% of gametes with normal membrane and acrosome and 8.8 ± 3.8% of fragmented chromatin. The relations between scrotal circumference, physical and morphologic characteristics, spermatic integrity and the reproductive performance of the herd had been low and not significant (P< 0.05). The bulls reproductive characteristics showed acceptable standards in three years. The sperm defects, plasmatic membrane and acrosome integrity, fragmented chromatin had not high frequency to compromise the seminal quality. There are not relationships among sperm defects with acrosome integrity and fragmented chromatin. No relationships was observed between pregnancy and bull reproductive characteristics.
KEY WORD: Acrosome, bulls, cattle, chromatin, nelore, reproduction, sperm defects.