Cycle of the seminiferous epithelium and its duration in the zebu, Bos indicus

Testicular Histomorphometric Evaluation of Zebu Bull Breeds

“…In the present study a higher tubular volumetric proportion (p<0.05) was observed in the Nelore breed compared to the Gir, Guzerat and Tabapuã breeds. The values observed in Nelore (85.2%) and Polled Nelore (84.0%) bulls were higher than those observed by Cardoso and Godinho (1983) in Nelore bulls (81.4%), suggesting that the genetic selection applied to these breeds could have resulted in an increase in the volumetric proportion of the seminiferous tubules in the testicles. Much lower values were observed by Goiozo et al (2005), who reported 76.4% in pure-origin Nelore breeds, and by Santos et al (1999), who found 72.0% in zebu bulls without breed information.…”

“…The body weight allocated to the testicles did not differ significantly between the studied zebu breeds. The mean value was 0.13%, which was a rate higher than that observed by Cardoso and Godinho (1983) in Nelore cattle (0.08%) and also that of young animals (17-18 months) of the Shorthorn breed (0.08%, Swierstra 1966). The volumetric proportion of the components of the testicular parenchyma varies considerably among species, directly reflecting the efficiency of sperm production for each breed (França and Russell 1998).…”

“…The results obtained in several studies have demonstrated a variation of 10 to 15 meters in domestic mammals (França and Russell 1998). Comparing the results, there has been some progress on various parameters obtained in Nelore cattle in the present study compared to those of Cardoso and Godinho (1983), such as the gonadosomatic index, volumetric proportion and diameter of the seminiferous tubules and tubular length per gram of testicular parenchyma. In addition to the differences in methodology between the studies, the origin of the animals used by Cardoso and Godinho (1983), common Nelore, might have negatively influenced the results compared to the purebreds of this study.…”

“…Comparing the results, there has been some progress on various parameters obtained in Nelore cattle in the present study compared to those of Cardoso and Godinho (1983), such as the gonadosomatic index, volumetric proportion and diameter of the seminiferous tubules and tubular length per gram of testicular parenchyma. In addition to the differences in methodology between the studies, the origin of the animals used by Cardoso and Godinho (1983), common Nelore, might have negatively influenced the results compared to the purebreds of this study. Moreover, during the elapsed three decades, the genetic improvement applied to the zebu breeds in Brazil might have contributed to the increase of the parameters related to spermatogenic capacity, mainly in the Nelore breed.…”

“…Despite the great importance of zebu cattle in tropical regions, there are few published studies on the process of spermatogenesis in these animals. The study of Cardoso and Godinho (1983), who described in detail the kinetics and quantification of spermatogenesis in Nelore bulls, can be highlighted.After many years of genetic improvements applied to the Nelore breed, it is possible that some of the results obtained by Cardoso and Godinho (1983) have already been superseded. Furthermore, publications describing the process of spermatogenesis in other breeds of zebu bulls are rare.…”