The Study Of The Effection Of Thermal Acclimation On Hatching Stage On The Thermotolerance Of Broiler In Later Growing Stage

Heat stress damage is still one of the important reason that reduce the economic benefit of broiler breeding since many years ago.In order to fall the harm of heat stress, enhancing broiler,s thermotolerance is an important method except to improve raising evironmental condition and adjust broiler,s diet and so on. Based on this goal, this research has disscused the effection of thermal acclimation on hatching stage on broiler,s thermotolerance. In this experiment we has carried three different temperature thermal acclimation on broiler on later period of hatching stage and has determined the hatching rate,the production performance,and the blood biochemical indexes,immunity fuction, HSP70 mRNA level on the 35th and the 42th day.The experiment selects 800 high quality AA breeding eggs, and divides into four groups(F0,F1, F2, F3). Three of these groups (F1, F2, F3) separately carries on three kind of different temperatures(38.2℃, 38.6℃, 39℃) thermal acclimation on 16～18th day in hatching process; the other group as the compared group (F0), carries on normal temperature (37.8℃) hatching. The thermal acclimation was conducted for 3 hours every day, and arranged 9:00-12:00 in the morning. As hatching is over, calculate each group's hatching rate and average hatch-weight. Each group select 72 healthy male broilers; there are 6 replicates in each group and 12 chickens in each replication. These broilers was supplied complete feed and watering freely ,feed in suitable environment and carried on the routine immunity according to the handbook of AA broiler raising. After the normal temperature raising for 5 weeks, on the 36th day 7:00 broilers was moved into environment-controled cabin and exposed to heat, and on the 43th day 7:00 moved out. In the raising process weigh and calculate average daily feed intake, average daily weight gain and feed conversion ratio of broiler in different four time sections (1st week, 2nd week, 3～5th week, 6th week). On the 42th day calculate survive ratio of each group. Separately on the 35th age and the 42th day, dissect...