低蛋白饲粮添加限制性氨基酸对生长阉公猪生产性能、 血清生化指标、营养物质表观消化率及氮排放的影响.

This experiment was conducted to explore the effects of adding limiting amino acids in low protein diets on growth performance, serum biochemical indexes, nutrient apparent digestibility and nitrogen emissions of growing barrows. Thirty-two Duroc × Landrace × Yorkshire boars with initial body weight [(24.16±2.23) kg] were randomly divided into 4 groups. The control group A was the normal protein level diet group, namely 18% crude protein (CP), the experimental group B, C and D were low protein level diets, which were 15% CP, 14% CP and 13% CP, and supplemented with lysine, methionine, threonine, tryptophan and isoleucine, respectively. The experiment lasted for 35 days. The results showed that: ① reducing dietary protein level to 14% had no significant effect on the growth performance of growing barrows (P>0.05) and decreased to 13% could significantly reduce the final weight, average daily gain and average daily feed intake (P<0.05). ② The nitrogen intake, fecal nitrogen emission, urinary nitrogen emission and total nitrogen emission of growing barrows were decreased with the decrease of dietary protein level. The urinary nitrogen and total nitrogen emissions of each experimental group were significantly lower than those of the control group (P<0.01), the urinary nitrogen emissions in group B, C and D were reduced by 37.86%, 46. 11% and 52. 21%, respectively, and the total nitrogen emissions in group B, C and D were reduced by 22.57%, 28.80% and 32. 48%, respectively. There was no significant difference in nitrogen deposition and nitrogen deposition rate among all groups (P> 0.05). There was no significant difference in nitrogen deposition and nitrogen deposition rate among all group (P>0.05); The apparent biological value of nitrogen in each experimental group was higher than that in the control group, but the difference was not significant (P>0.05). ③ Serum urea nitrogen was mainly affected by dietary CP level. Compared with the control group, the serum urea nitrogen content of each experimental group was significantly decreased (P<0.05). There was no significant difference in serum total protein, albumin, blood glucose, cholesterol and triglyceride levels among all the groups (P> 0.05). ④ Compared with the control group, the weight gain cost of group B was decreased by 1.99% (P> 0.05), and the weight gain cost of group C was decreased by 1.94% (P>0.05). It can be seen that when the CP level was reduced to 14% after the addition of restrictive amino acids to the low-protein diet, it not only had no significant effect on the production performance of growing pigs, but also significantly reduced urinary nitrogen and total nitrogen emissions, and the cost of weight gain was also lower. [ABSTRACT FROM AUTHOR]