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Effects of Seasonal Climatic Changes on Certain Physiological Reactions, Semen Production and Fertility of Dairy Bulls

Dairy Department, Louisiana State University, Baton Rouge

ABSTRACT

During recent years the practice of artificial insemination of dairy cattle has spread rapidly into the Gulf Coast area of the United States and also into other subtropical and tropical areas of the world having a similar warm, humid climate. Since most of the bulls used in these programs have been of the European breeds developed in temperate areas there is a need for knowledge of the effects of such a climate on the thermoregulatory mechanisms, semen characteristics, and fertility of such bulls. The opinion that certain breeds are better adapted to southern conditions than are others has been expressed frequently, but few careful studies of breed reactions and seasonal fertility have been carried out.

Gaalaas (6), Seath (12), and Seath and Miller (13, 14) have reported studies which indicated that air temperatures of 90° F. or above cause marked increases in body temperatures and respiration rates of lactating cows, whereas relative humidity did not show such a relationship.