Physiological,Production And Expression Of Hsp70 Protein In High-yielding Dairy Cow Under Heat Stress

Heat stress of dairy cow caused by Greenhouse effects global warming has led to significant losses in the global milk industry as a serious concern of global attention.In order to solve the problem of milk loss caused by heat stress in summer.The study used the first parity(n=5,weight 559.6±3.6 kg,body condition 2.8,calving days 189 days),second parity(n=5,weight 646.2±4.4 kg,body condition 2.7,calving days 164 days)and third parity(n=5,weight 664.4±5 kg,body condition 2.95,calving days 129.8 days)highyielding dairy cows for the test animals.Four trials: environmental test,physiological test,production test(milk production,milk composition)and Hsp70 protein expression test,the test time in July and August 2015,to compare the physiological changes,milk production changes and Hsp70 protein expression in different parities of high-yielding dairy cows under Chongqing's heat stress weather.The results are as follows:1,Environmental weather dataEnvironmental temperature,dry bulb temperature,wet bulb temperature,relative humidity and temperature and humidity index(THI)were significantly different at different times(P < 0.01).During the test,the average temperature of the barn was 27.4 ?,the average relative humidity was 47.9%,the average THI index was 78.73,and the daily average THI index exceeded 72.The maximum daily temperature at 14:00h,the average temperature reached 34.1 ?,THI index reached 83.5.2,Physiological testThe respiratory rate,skin temperature and rectal temperature increased significantly with the increase of THI,the difference was significant(P < 0.01),the highest value appeared at 14:00h(THI = 84).There was no significant difference in breast temperature between different THI(P > 0.36).Different physiological records of high-yielding dairy cows were as follows: The difference of respiration rate was significant(P < 0.01),changes in the range of 50 bpm ~ 90 bpm,the third birth cow> first birth cow> second birth cow;Difference of rectal temperature was not significant(P > 0.1),and the range was between 38.5 ? and 39.5 ?.Skin temperature third birth cows > first and second births,the first birth rate of cows and second births of dairy cows is not significant difference;Difference of breast temperature was not significant(P > 0.1),and increased with the increase of THI.With the increase of THI,the physiological response of dairy cows increased,the third highest rate of dairy cows but with the highest THI fluctuation stable,the second birth rate of dairy cows slowed down and with the THI increased volatility,the first fetal cows physiological reaction And with the THI increased volatility.In summary,the physiological response to the degree of intensity of the first births of the cow> third birth cow> second birth cow.3,Milk production testThe milk yield in different parities of high-yielding cows was significantly different(P <0.01),The average daily milk production of the first,second and third parity of cows were 8.1kg / head,9.3kg / head and 9.7kg / head respectively.There were significant differences in milk production at different times(P < 0.03),milk production was the same at 04:00h and 12:00h,but higher than that at 20:00h.Milk protein,lactose,milk acidity and milk casein were significant difference(P < 0.01).However,there was no significant difference in the total fat and milk urea of different parities(P > 0.1).The daily average contents of milk production in high-yielding dairy cows were: milk fat 3.49 g / 100 g,milk protein 2.63 g / 100 g,lactose 5.01 g / 100 g,non-fat solids 12.2 g / 100 g,milk acidity 11.7 ° T.Under heat stress,high-yielding dairy cows milk production third parity> second parity> first parity;milk protein and milk acidity first parity = second parity> third parity;Lactose First parity> Second parity = Third parity;Milk casein First parity> Second parity> Third parity.4,Hsp70 protein testThe expression of Hsp70 protein in blood of different parities in high-yielding dairy cows under heat stress: First parity> third parity> second parity,the difference was significant(P < 0.01).To sum up,with the THI different,compared with physiological response,production performance and Hsp70 protein expression in different parities of highyielding dairy cows,proved that heat resistance were the second parity cow> the third parity cow > the first parity cows.