Effect of season on scrotal circumference, semen characteristics and testosterone serum concentration in Mexican Corriente and other beef breed bulls

Abstract

To evaluate the effects of season on semen, scrotal circumference and testosterone concentration in Corriente and European-breed bulls, 758 samples were analyzed in four years. Comparisons were made between bulls of the same breed in different seasons and between bulls of different breeds in the same season. Scrotal circumference of both breeds was higher in the summer and autumn (P < 0.01). Sperm concentration, individual motility and live cells were lower in summer and autumn in European-breed bulls (P < 0.01). All percentages of sperm defects were higher, and testosterone was lower in European-breed bulls during summer and autumn (P < 0.01). Gross motility tended to be lower (P = 0.09) in European-based bulls during winter. Scrotal circumference was higher in Europeanbreed bulls than Corriente bulls in all seasons (P < 0.01). Ejaculate volume and sperm concentration were similar in Corriente and European-breed bulls in all seasons (P > 0.1). Individual motility was lower in Europeanbreed than in Corriente bulls in summer and autumn (P < 0.01 and <0.01). Live cells count was lower in European-breed than in Corriente bulls during the summer and autumn (P < 0.01 and <0.01). Major sperm defects were higher for Corriente than European-breed bulls during winter (P < 0.01). Minor cell defects were higher in summer and autumn (P < 0.01) in Europeanbreed than in Corriente bulls. Total defects were lower in Corriente than in European-breed bulls during summer and autumn (P < 0.01), and higher during winter (P < 0.01). Testosterone was higher in Corriente bulls during summer (P < 0.01) and autumn (P < 0.01) than in European-breed bulls. Gross motility was lower (P < 0.05) in European-breed than in Corriente bulls in winter. Season had no effect on most semen characteristics in Corriente bulls, while European-breed bulls had lower semen quality during the hotter seasons. This indicates a better adaptation of Corriente cattle, suggesting that these bulls can be used for mating all year in hot environments.

Influence of Testosterone on Body and Testicular Development in Zebu Cattle in the Tropical Climate

“…Testicular development occurs slowly before the significant increase of the testosterone; gonad growth peaks during puberty, followed once more by slow growth, indicative of sexual maturity. In the present study, the high positive correlation between the concentration of testosterone and scrotal circumference renders measurement of the latter a good indicator of puberty, confirming reports by [1,2,8].…”

“…The rapid physical development and acceleration of weight gain during the puberty of male specimens of beef cattle breeds stems from the increase in testosterone [1]. Zebu beef cattle breeds exhibit greater adaptability to tropical climates, as their relative testosterone decrease is smaller than that of European breeds during the summer [2]. The study of puberty in young zebus is of great importance, due to selection of sexually precocious (i.e.…”

Individual variation in fresh and frozen semen of Bali bulls (Bos sondaicus)

“…The reproductive performance of bulls can be assessed from their semen quality. The quality of semen is influenced by various factors, including environmental factors such as the season [7][8][9], relative humidity [10], temperature [7], feed [11], and genetic factors [12]. The variation of individual bulls is one aspect of genetic factors.…”

Genetic evaluation of the scrotal circumference of beef bulls in the Czech Republic

“…The circumference is larger in the summer and in the autumn when there is a decrease in the testosterone level, sperm concentration, and individual sperm motility at the same time. The influence on the semen volume was not confirmed (Quezada-Casasola et al 2016). Compared to breeds originating from tropical and subtropical areas, European breeds of beef cattle are more sensitive to these changes (Quezada-Casasola et al 2016;Morrell 2020) and, therefore, any changes in the semen quality may limit the use of bulls in hot summer months.…”

“…The influence on the semen volume was not confirmed (Quezada-Casasola et al 2016). Compared to breeds originating from tropical and subtropical areas, European breeds of beef cattle are more sensitive to these changes (Quezada-Casasola et al 2016;Morrell 2020) and, therefore, any changes in the semen quality may limit the use of bulls in hot summer months.…”