Effects of Heat Stress on Holstein, Jersey and Jersey×Holstein Dairy Cows

To study the heat resistance performance of cows in heat str ess and provide a theoretical basis for the screening of the dairy cow bearing the hot and humid climate, 45 cows were divided into three groups and each was 15 in the principle of pilot varieties packet: Holstein cows group, Jersey cows group, the hybrid of Jersey ×Holstein dairy group. The test period was carried on by non-heat stress and heat stress period according to the THI situation. The results showed that Jersey cattle milk production was significantly lower than holstein and the hybrid of jersey ×holstein cattle(P0.05) under the heat stress; The milk yield was reduced by 26.3%,14.08% and 23.49% in Holstein, Jersey and the hybrid of Jersey ×Holstein cattle, respectively. The dry matter intake of Holstein cows in the period of heat stress raised by 36. 47% in relation to non-heat stress; Jersey cow raised by 30.45%; the hybrid of Jersey × Holstein cattle raised 31.86%. The content of Jersey cattle milk fat, milk protein was significantly higher than that of the Jerseys and the hybrid of Jersey×Holstein cattle(P0.05). Although other indicators were not significantly different(P0.05), the consolidated status of Jerseys was better than Jersey ×Holstein and Holstein cattle was the worst. Among the comprehensive three cattle groups, Jersey ×Holstein cattle can be regarded as better heat resistance varieties for amplification and research.