The Effect Of Heating On Digestibility Of Cottonseed Meal Amino Acids In Pig Ileal

The cotton seeds of the same kind vary in colors and physico-chemical properties such as the PS due to different technological skills during the actual production process in each refinery, such as different heating temperature and time in the hot working. To study the effects of heat treatment on the DE, protein and ileal digestibility value of amino acids in cotton seeds, this research collects the cotton seeds of the same kind but with different PS in Hubei province. The effects of different process time on the PS and chemical ingredients can be observed by simulating the heat treatment in the production process with the temperature set at 116℃while changing the heat-up time; the relationship between DE and PS can be determined by testing the digestibility of 6 chosen pigs by means of square design; another 6 pigs are chosen so that the relationship between ileal digestibility value of amino acids and the heating time can be determined by testing the proteins of cotton seeds, digestibility value of amino acids and protein digestibility value in feces by means of T-fistula method and square design so as to simplify the testing methods and offer guidance to the actual application of cotton seeds and the making of the diet.Test One:The effects of heating on PS and chemical composition of cottonseed meal.The effects of the heating time on the PS can be observed through the heat treatment of cold-pressed cotton seeds in the autoclaves with the temperature set at 116℃while changing the heating time to Omin, 10min,15min,20min,30min,40min,45min, 55min,60min,65min and 75min. Then 5 kinds of cotton seeds with strikingly different PS are chosen to further test all the chemical ingredients and study the effect of heating time on them.The test shows:i. The colors of cotton seeds change and the PS declines markedly as the heating time prolongs. The PS is strikingly reverent to the heating time and their relation accords with unary quadratic curves:PS=88.17-0.94T+0.0046T2 (R2=0.9861, P<0.001; T is short for time).ii. The NDF and ADF content increase strikingly while FG content declines markedly.The relation between time and NDF accords with equation of a degree:Y(NDF)= 15.53+0.37T (R2=0.9732; P<0.001); the relation between time and FG accords with equation of two degree:Y(FG)=1295.74-31.95T+0.29T2(R2=0.9560;P<0.009).Test Two:The effects of heating on cottonseed meal digestible energy values and the ileal amino acid digestibility of pig researchthe relationship between DE and PS can be determined by testing the digestibility of 6 chosen pigs by means of square design; another 6 pigs are chosen so that the relationship between ileal digestibility value of amino acids and the heating time can be determined by testing the proteins of cotton seeds.The teat shows:i Five PS were:69%,61%,55%,49%,42%of the cottonseed meal digestible energy values were:11.9MJ/Kg,13.1MJ/Kg,12.5MJ/Kg,12.3MJ/Kg,11.1 MJ /Kg.The DE value is markedly related to the heating time and PS. The cotton seeds have the highest DE values when the heating time is 30min and the PS is 61%.ii The relation between PS and DE value accords with quadratic equation. The prediction model established by their relation:DE(MJ/Kg)=13.079+0.911PS-0.079PS2(R2=0.9328, P<0.05). The DE value is strikingly related to NDF content and their relation accords with quadratic equation. The prediction model: DE(MJ/Kg)=-0.3143NDF2+1.6457NDF+10.7(R2=0.8872, P<0.05).iii The PS gradually reduces and terminal ileum protein digestibility value and protein digestibility value in feces rise first and then drop.The terminal ileum protein digestibility value is lower than the protein digestibility value in the body of animals.The cotton seeds whose PS values are 55% have the highest digestibility values in the terminal ileums and the feces.iv. The digestibility values of aspartic, threonine, serine and lysine rise first and then drop as the heating time prolongs and the PS values decrease. The lysine has the highest digestibility value when the PS value is 61% and the heating time is 30min. Arginine, phenylalanine and tyrosine markedly decrease and has the highest digestibility value when the PS value is 69% and the heating time is 20min.Test Four:The protein digestibility value of cotton seeds in vitro methodThe test shows that the protein digestibility value strikingly drops as the heating time prolongs and the PS decreases. The vitro digestibility value is the highest when the heating time is 20min and the PS is 69%.