Variation in the onset of the breeding year in the goat

A series of upwards of 6000 matings of goats has been arranged according t o the month of service and correlated with temperature and rainfall. The maximum of reproduction is found to be in October, and the minimum in May. A cool summer produces early oestrus while a hot one has the opposite effect. The August temperature is of paramount importance in this respect. Rainfall had no effect, on the onset of oestrus in the series examined. The hypothesis is advanced that most mammals breed only in the spring and autumn because their body temperature may be too high in summer for follicular development.