Study On The Effect Of Traditional Low Protein Diet On Protein Utilization And Growth Performance Of Fattening Pig

In 2017,the annual production volume of pigs in China was 690 million,and the number of pigs at the end of the year was 430 million.The live pig production accounts for about 47% of the total output value of China's animal husbandry.In the past 40 years of reform and opening up,the pig industry has made tremendous achievements and has made significant contributions to agricultural and rural development and farmers' income.However,it also faces many problems and challenges.In 2017,the total amount of animal manure produced in China was about 4 billion tons,and the nitrogen emission was 30 million tons,of which the nitrogen emission from pig manure accounted for 60% of the total.Soybean imports amounted to more than 95.5 million tons in the year,and the import dependency was as high as 80%.In pig production,how to ensure healthy and sustainable development of live pig production while achieving environmental friendliness and resource conservation is an important technical issue that needs to be urgently resolved.In this study,the Duroc × Landrace × Large White three-way hybrid castrated boars are used as subjects to study the effect of arginine supplementation in traditional low-protein diets on the protein utilization and growth performance of growing-finishing pigs,so that we can get an effective method to reduce the proportion of protein in pig diets and to reduce nitrogen emissions from swine manure.The main results obtained in this study are as follows:Experiment I: Effects of arginine supplementation in low-protein diets on protein utilization and nitrogen release of growing pigs.27 Duroc × Landrace × Large White three-way hybrid castrated boars were selected,and were randomly assigned to three groups: 18.0% crude protein(control group),15.0% crude protein + 0.5% arginine(test group),and 12.0% crude protein + 1.0% arginine(test group).Each group of 9 pigs was tested for 21 days.The results are as follows:1.The total nitrogen emissions of the three group(18.0% crude protein,15.0% crude protein + 0.5% arginine and 12.0% crude protein + 1.0% arginine)are 45.6 g/d,38.3 g/d,and 30.4 g/d respectively.The urinary nitrogen emissions are 30.3 g/d,26.1 g/d,and 20.5 g/d respectively,and the fecal nitrogen emissions are 15.3 g/d,12.2 g/d,and 9.93 g/d,respectively.The nitrogen deposition amount is about 28.0 g/d,the urinary energy is 0.53 MJ/d,0.35 MJ/d,0.34 MJ/d,and the feces energy is 7.53 MJ/d,6.36 MJ/d,and 6.26 MJ/d,respectively.These results show that,compared with the high-protein diet group,fecal nitrogen,urinary nitrogen,total nitrogen,fecal energy,and urinary energy are significantly reduced in the low-protein diet supplemented with the arginine group.However,there is no significant change in nitrogen deposition and nitrogen digestibility.2.The cholesterol concentration distribution in the blood of pigs in three groups(18.0% crude protein,15.0% crude protein + 0.5% arginine,and 12.0% crude protein + 1.0% arginine)are 3.45mmol/L,2.49mmol/L,2.01mmol/L respectively,and triglycerides are 0.68mmol/L,0.46mmol/L,0.23mmol/L respectively.The urea nitrogen is 5.34mmol/L,3.64mmol/L,2.14mmol/L respectively,and the aspartate aminotransferases are 58.9 U/L,45.1 U/L,31.9 U/L respectively.The alanine aminotransferases are 8.69 U/L,6.69U/L,4.36 U/L,respectively.Glucose in the liver is 3.01 mmol/g prot,4.48 mmol/g prot,5.29 mmol/g prot respectively.The ?-Ketoglutarate is 10.9 pg/mgprot,17.1 pg/mgprot,26.3 pg/mgprot respectively.The pyruvate is 9.21 umol/g prot,7.83 umol/g prot,4.71 umol/g prot respectively.The aspartate aminotransferase is 19.9 U/gprot,14.1 U/gprot,11.9 U/gprot,respectively.The alanine aminotransferase is 3.59 U/gprot,2.69 U/gprot,1.86 U/gprot respectively.These results show that,Compared with the high-protein diet group,the concentration of urea nitrogen,total cholesterol,and triglyceride in the blood of the low-protein diet supplemented with the arginine group are significantly reduced.The activity of alanine aminotransferase and aspartate aminotransferase in the liver are also significantly reduced.Experiment II: Effects of Arginine Supplementation in Low Protein Diets on Growth Performance of Growing Finishing Pigs.60 Duroc × Landrace × Large White three-way hybrid castrated boars are selected,and are randomly assigned to three groups: 18.0% crude protein(control group),15.0% crude protein + 0.5% arginine(test group),and 12.0% crude protein + 1.0% arginine(test group).Each group of 20 pigs is tested for 35 days.The results show that the feed-to-meat ratio of the three protein groups(18.0% CP,15.0% CP,12.0% CP)is 0.293,0.269,and 0.248 respectively.The thymus index is 0.36.g/kg,0.51 g/kg,0.75 g/kg respectively.The spleen indexes are 1.16 g/kg,1.69 g/kg,1.99 g/kg respectively.The lymph node indexes are 2.13 g/kg,2.69 g/kg,2.08 g/kg respectively.Kg,the IgG in blood is 383 ?g/mL,409 ?g/mL and 423 ?g/mL respectively.The total antioxidant capacity is 308 U/ml,368 U/ml,381 U/ml respectively.The superoxide dismutase is 383 U/ml,409 U/ml,423 U/ml respectively.The malondialdehyde is 10.9 nmol/L,7.2 nmol/L,and 3.61 nmol/L respectively.The average daily weight gain is ± 0.910 kg/d.These results show that,compared with the high protein diet group,the feed conversion rate,immune ability,and antioxidant capacity of the low-protein diet supplemented arginine group are increased significantly,and the average daily gain is not reduced significantly(P<0.05).In summary,providing diets containing 15.0% crude protein + 0.5% arginine,or 12.0% crude protein + 1.0% arginine can significantly reduce pig manure N-nitrogen emissions,improve feed conversion,immunity and antioxidant capacity of pigs.Adding arginine and reducing the amount of protein feed appropriately is a possible way to achieve environmentally friendly and resource-saving pig production.