A Study of Solar Radiation as Related to Physiological and Production Responses of Lactating Holstein and Jersey Cows

Abstract

The influence of summer weather conditions in central Texas upon lactating" Holstein and Jersey dairy cattle was studied. Analysis of variance and multiple regression methods were used to study the effects of weather factors upon milk production and body temperature~ respiration rate, and pulse rate responses of these animals. Weather factors studied were ambient temperature, solar radiation, and vapor pressure. Breed comparisons and comparisons between animals exposed to direct solar radiation and those shaded from direct solar radiation were nmde. Parts of this study were further subdivided into high and low ambient temperature groups.