LAUSR

This study evaluated the effects different seasons (rainy, rainy-dry transition, dry, dry-rainy transition) throughout the year on the reproduction and endocrine profile of Saanen bucks reared in a tropical climate. During these seasons environmental data were recorded (ambient temperature and relative air humidity) to calculate the temperature and humidity index. Reproductive parameters were also evaluated in the same periods to check seasonal variations, wherey semen was collected twice a month from nine Saanen bucks using an artificial vagina. Furthermore, scrotal circumference, scrotal surface temperature and serum levels of testosterone, triiodothyronine (T3), thyroxine (T4) and cortisol were measured. The climate parameters influenced the reproductive parameters, mainly during the dry period, when higher values of ambient temperature reduced sperm quality, however, scrotal circumference and surface temperature, as well as serum levels of testosterone increased. In conclusion, Saanen bucks reared in a tropical climate are subject to heat stress, evinced by transient seasonal variations in reproductive parameters, where the first season is the most favorable to reproduction.