Study On The Relationship Between HSP70 And Heat Tolerance Of Dairy Cow

Dairy cows are able to bear cold and unable to endure hot livestock,The change of Temperature and Humidity Index(THI)often cause the cows' stress and affect its production performance.The normal body temperature of Holstein cows is 38.5℃,the adaptive breeding environmental temperature is 10℃-20℃.At present,heat stress has become one of the bottlenecks to constrain the development of dairy industry.This experiment was designed to study the relationship between HSPT0 and heat tolerance of Holstein cows and the different expression of the HSP70 in breeds,for providing theoretical basis to choose heat tolerant Biochemical index in serum of dairy cow.In Exp.1:16 Holstein cows were selected randomly to study the relationship among respiratory rate,pulse and rectal temperature.The result indicated that:(1)comparing mild heat stress period(THI 74.6)with negative heat stress period(THI 64.4),the respiratory rate,pulse and rectal temperature were differ significantly(P＞0.05), comparing moderate heat stress period(THI 84.3)with negative heat stress period(THI 64.4),the respiratory rate,pulse and rectal temperature were significantly(P＜0.05), comparing moderate heat stress period(THI 84.3)with mild heat stress period(THI 76.4), the respiratory rate and rectal temperature were significantly(P＜0.05),the rate of pulse was rise,but the difference were differ not significantly(P＞0.05).From mild heat stress period to moderate heat stress period,THI rise 1,the respiratory rate of dairy cows increase 3.4n/min,rectal temperature increase 0.04℃;(2)during mild heat stress period and moderate heat stress period,the milk yield of dairy cow decrease by13.8%and by 26.9%respectively(P＜0.01),the relationship between milk yield and THI were negative (P＜0.01)(R=-0.82),THI rise 1,the milk yield of dairy cow decrease by 1.9%.In Exp.2:9 Holstein cows were selected randomly to study the relationship among respiratory rate,pulse and rectal temperature.Using western bolt method tests the expression of HSP70 in blood lymphocytes,for exploring the relationship between HSP70 and THI.The result indicated that:during heat and negative stress period,the Holstein cows can express HSP70.With the rising of temperature,the expression of HSP70 increased.Comparing serious heat stress period(THI 93.5)with negative heat stress period(THI 57.0)and moderate heat stress period(THI 76.6),the expression of HSP70 is 6.9 times(P＜0.01)than that of negative period and 1.9 times(P＜0.01)than that of moderate period.The expression of HSP70 in moderate heat stress period is 3.6 times(P＜0.05)than that of negative heat stress period,the relationship between HSP70 and THI were positive(P＜0.01)(R=0.91),THI rise 1,the expression of HSP70 increase 2172.In Exp.3:Random selecting 9 Holstein cows and 9 Jersey×Holstein F1 dairy cows, Using western bolt method tests the different breeds expression of HSP70 in serious heat stress in blood lymphocytes.The result indicated that:Under the same THI conditions The expression of HSP70 in Jersey×Holstein F₁ dairy cows are higher than that of Holstein cows(P＜0.01),it infered that the heat tolerance of Jersey×Holstein F₁ cows is better than Holstein cows.