A preliminary experiment to establish a method for maintaining the protein content of milk high in summer was carried out by examining the influence of heat stress on the nitrogen content in true protein, casein, whey proteins, and urea in cow's milk. Four dairy cows were kept in a temperature controlled room (18°C and then 28°C) and were fed on a corn-based concentrate supplemented with soybean meal or soybean meal and fish meal as protein sources. Heat (28°C), compared to thermoneutral condition (18°C), decreased the content of casein-N as well as true protein-N but had no effect on whey-N and significantly (P<0.05) increased the urea-N content in milk. At 28°C, high humidity (80%RH) reduced the contents of true protein-N and casein-N compared to 40% RH. Results of this experiment suggest that heat stress and high humidity conditions have negative effect on the production of milk true proteins and increases urea-N content in milk.
No takes yet. Share an insight, caveat, or question.
Muroya et al. (1997) studied this question.