赖氨酸与粗蛋白质比例对猪生产性能及氮利用率的影响-动物营养与饲料科学专业论文.docx

AbstractThree Abstract Three feeding trials and two metabolic trials were conducted to investigate the effects of lysine to protein ratio in practical swine diets on performance and the efficiency of nitrogen utilization in sow,piglet and growing-finishing pig． In trial l and 2．30 later pregnant SOWS and 60 lactating SOWS were selected and allotted to five treatments，respectively,based on the parities and body weight．In pregnant sow trial，five lysine to protein rations w站3．5，4．0，4．5，5．0 and 5．5 g，100 g，respectively．Each treatment had six replicates．The results showed that the body weight and the back-fat thickness of SOWS were increasing linearly with lysine to protein ratios increased from 3．5 to 4．5(尸0．05)；with the ratios of lysine to protein increased from 3．5 to 5．5．the serum urea nitrogen significantly decreased linearly or quadratiely(，0．05)，but serum free amino acid increased linearly or quadratic(P o．00；the optimum lysine to protein ration was 4．0—4．5 g，100 g for later pregnant SOWS．In lactating sow trial，five treatments oflysine to protein rations was 4．S，5．3，5．8，6．3 and 6．8 g／100 g，respectively．Each treatment had twelve replicates(each sow as a replicate)．The results showed that the body weight loss and back-fat thickness loss of lactating SOWS decreased quadraticly with the increasing of lysine to protein ratio fP0．05)．The body weight loss occurred earlier than that of back-fat loss．The 20th day’s milk yield and litter body weigh gain increased linearly fP0．01) or quadraticly但0．05)with the increased of lysine to protein ratios，but the 21th day milk compositions had no significant change∽0．05)；with the ratios of lysine to protein increased， the serum urea nitrogen on 14th and 21th day decreased linearly or quadraticly fPo．00 while as the serum free amino acid has a linearly and quadratiely(P0．05)，which showed to improve the efficiency ofnitrogen utilization and decrease the nitrogen excretion． In trial 3．90 piglets with 7．8±】．0 kg initial body weight were