Research On Amino Acids Requirements Of 10～20kg Landrance×Rongchang Crossbred Piglets

This study was conducted to examine the growth model of NRC (1998) and then establish the model of amino acids requirements of LandracexRongchang crossbred pigs for our country and determine the amino acids requirements of them. 30 LandracexRongchang crossbred piglets were involved to determine the growth performance, carcass indexes and free-fat lean index at the stage of 10~20kg by feeding and slaughter trial. The piglets were alloted to six pens with five piglets per pen, of which three pens were barrows and the other three pens were gilts. The piglets were given pelleted diets based on NRC (1998) and adjusted according to practice in China. One piglet from each pen was slaughtered at liveweights of 10 and 20kg approximately. With the determined indexes of this study and Yan Feiyun et al (2002), the regression equations were established to predict average daily gain (ADG), free-fat lean index (FFLI) and protein accretion index (PAI) by liveweight. With the prediction equation for FFL1, and with the coefficient of free-fat lean index to protein accretion and the lysine requirement of protein accretion, the mathematical model of lysine requirement was established, and then the amino acids requirements of 10~20kg LandracexRongchang crossbred piglets were predicted by the mathematical model and were examined by the method of whole carcass. The .results showed that:1. ADG at the whole stage was 709g/d. The regression equation for ADG was Y=0.0006X3 - 0.2224X2-21.974X+172.67, R2=0.9978.2. FFLI at the whole stage was 222.5g/d. The free-fat lean index of barrows was 7.4% highter than that of gilts. The regression equation for FFLI was Y= - 0.001 IX3 + 0.1177X2-0.3548X+110.24, R2=0.9840.3. PAI at the whole stage was 87.2g/d. The regression equation for PAI was Y=- 0.0004X3+0.0462X:-0.1409X+43.246, R2=0.9839.4. The mathematical model of lysine requirement according to NRC (1998) growth model was: the true digestible lysine requirement (TDLR) (mg/d)=?.0515BW3+ 5.5412BW2-16.904BW+5189.6+36BW?5. Based on the model, TDLR was 6.28g/d at the liveweight of 10~20kg, while the total lysine requirement (TLR) was 7.26g/d. TDLR'and TLR were 0.69%, 0.80% respectively, based on air-dry diet when the daily feed intake was 910g/d. The requirements of the other amino acids could be predicted on the basis of the ratio of the other amino acids to lysine in the ideal protein.5. The lysine accretion index (LAI) at the stage of 10i~20kg was 5.32g/d determined by the method of whole carcass, and with the coefficient of the true digestible lysine in diet to the lysine in protein accretion, TDLR was 6.46g/d while the total lysine requirement was 7.47g/d. Based on air-dry diet when the daily feed intake was 910g/d, the TDLR was 0.71% while the total lysine requirement was 0.82%.The results suggested that:The difference of the lysine requirement of 10 ?20kg LandracexRongchang crossbred piglets was insignificant between the prediction of NRC(1998) growth model and the method of whole carcass. So we can draw a conclusion that NRC(1998) growth model was applicable to LandracexRongchang crossbred piglets in our country, too.