Abstract
Aiming to determine the relationship between the frequency of testicular shape and the andrological aspects in young Nellore bulls, 18,676 animals were assessed. All andrological examinations were performed between the years 2000 and 2008. Animals were classified as able for breeding, able for breeding in natural mating system, unable for breeding and discarded. The testicular shape was classified as long, fairly long, oval-long, spherical-oval, and spherical. The analysis of Pearson correlations was performed for testicular shape with scrotal circumference, testicular volume, progressive motility, sperm vigor, major defects, minor defects and total defects. Testicles with oval shape prevailed (99.61%). It was obseved that 76.34; 66.34; 64.34; 58.33 and 50.00% of the animals were classified as sound for breeding for shapes long, fairly long, oval-long, spherical-oval, and spherical, respectively. Correlations between testicular shape with scrotal circumference, testicular volume, progressive motility, sperm vigor, major, minor and total defects were 0.26; 0.08; 0.00; 0.11; -0.02; 0.02 and -0.01, respectively. Testicular shape had no influence upon the andrological examination results. Testicles of long shape were prevalent within the population.
Highlights
The rate of approximately 70% of Zebu animals and their crosses in the Brazilian cattle population corresponds to over 173 million (ANUALPEC, 2010)
The performance of the breeding depends on the improvement of management techniques and nutrition, but the physiology of testicular development and weight are crucial, in addition to the factors that potentially interfere with these processes, such as sexual precocity and the ability of sperm production (Moura et al, 2002)
Measurements for length and width of testis were obtained with the aid of caliper rule, and the length measured in the longer sense the gonad, including the head, excluding the tail of the epididymis, and the breadth in the wider region of the gonad the lateral-medial direction were achieved using the body of the animal as reference
Summary
The rate of approximately 70% of Zebu animals and their crosses in the Brazilian cattle population corresponds to over 173 million (ANUALPEC, 2010). In Brazil, among the Zebu breeds, Nellore is the one that has been studied with the aim of identifying good selection criteria (Lira et al, 2008). The prevalence of long testicular shape in Zebu males, Nellore, according to scrotal circumference usually small, has gotten farmers preoccupied about selecting their breeders. This fact is due largely to the selection criteria adopted by the scrotal circumference, so that males with long testicles can be eliminated because they had less girth than their contemporaries of oval testicles (Unanian et al, 2000)
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