Periódicos Brasileiros em Medicina Veterinária e Zootecnia

p. 01-05

Seasonal effects on semen and testosterone in zebu and taurine bulls

George Mungai Chacur, MarceloToshiuki Mizusaki, KristofferRoberto Almeida Gabriel Filho, LuisOba, EuniceAmorim Ramos, Alcides

Background: In Brazil, a higher percentage of abnormal sperm after high temperature and relative humidity observed a higher semen volume in the rainy. The semen quality may be significantly affected by environment, by fluctuations in temperature, humidity and photoperiod. The objective of this study was to evaluate the seasons influence (spring, summer, autumn and winter) on semen characteristics and testosterone levels in Nellore and Simmental bulls raised on field. Materials, Methods & Results: The city of Presidente Prudente-SP-Brazil, where the experiment was realize, presents latitude 2129`50``S, longitude 49º14`2``W and altitude of 475 meters. In 2008/2009, the climatic factors measured for Spring - SP; Summer - SU; Autumn A and the Winter - W were: average temperature (SP - 25.9; SU - 26.6; A - 21.9 and W - 21.1C), stroke (SP - 400.9; SU - 464.0; A - 721.3 and W - 142.6 hours), cumulative rainfall (SP - 291.8; SU - 925,0; A - 273.0; and W - 191.8 mm) and average relative humidity (SP - 65.9; SU - 71.7; A - 70.1 and W - 66.7%). Five Nellore and five Simmental bulls with 48-72 months old, extensively managed were evaluated for sexual soundness using physical and morphological characteristics of semen and testosterone serum levels. Sixteen semen samples by automatic electroejaculation were carried out in each of 10 bulls, totaling 160 samples. The experiment was con

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