Effects Of Energy Level,Carbohydrate Type And Rumen Bypass Amino Acid On Heat Stress Of Dairy Cows

This study consisted with two trials,and studied the effect of different energy levels,adding different doses of rumen product lysine and methionine;supplementing different carbohydrate type feed on cows physiological function,milk yield,blood index and Heat stress related genes relative quantity expression in cows peripheral blood lymphocyte.Trial: We adopted L9(34)orthogonal experimental design and feed energy level in the diet,supplementary feeding types of carbohydrates and rumen protective amino acids(RPAA)as test factors.The suitable addition amount of rumen bypass methionine and lysine has three levels: RPMet 5g/d·head+RPLys 15g/d,RPMet 10g/d·head +RPLys 30g/d,RPMet 20g/d·head+RPLys60 g/d·head;energy level: 0.8times the energy needs,1times the energy needs,1.2times the energy needs.The result shows that supplemente suitable amount of molasses can alleviate the heat stress of dairy cows,but supplementary feeding quantity still need to study.When the energy level of the ration is 0.8 times the energy required,cows’ milk production is low and has an adverse effect on cows heat stress.When each cow was supplemented 0.6 kg of molasses,the cows dry matter intake does not decreased and the cow milk production has increased accordingly.When increased the molasses feeding amount decreased the cows dry matter intake.When adding high doses of rumen bypass methionine and lysine the cows’ milk yield and dry matter intake were higher.In the heat stress period appropriate increasing of cows diet energy level,adding a certain amount of rumen bypass methionine lysine combination and supplementing suitable amount of molasses can alleviate the heat stress of dairy cows in summer.Trial 2: At the end of the trial 1 blood sample were taken from caudal vein and extract peripheral blood lymphoeytes.Using fluorescence quantitative PCR technology measure the genes quantity expression of HSP70,ATP1A1,GXP3,SOD3 in cows peripheral blood lymphocyte.And to study the effect of different energy levels,adding different doses of rumen product lysine and methionine;supplementing different carbohydrate type feed on heat stress related genes mRNA relative quantity expression in cows peripheral blood lymphocyte.In the trial the diet energy levels had the greatest influence on the heat stress related genes.When the energy level is 1.2 times energy need ATP1A1 and GXP3 gene expression quantity were significantly higher than the energy level of 0.8 times and 1 times.Because of during the heat stress period the enzyme activity regulated by those genes were decreased and this lead to body metabolic disorders.The increased amount of heat stress related gene expression can help the body to resist damage resulting from heat stress.According to heat stress related genes expression can be speculated that 1.2 times the energy need level is helpful to relieve the cow heat stress.And Supplementing steam-flaked corn is better for dairy cows healthy than supplementing molasses and supplementing wheat bran during heat stress.When supplemente rumen bypass lysine 60 g and rumen bypass methionine 20 g per cattle per day the effect is better.