Effects of Low Protein Amino Acid Balanced Diets on Growth Performance,Serum Parameters and Apparent Protein Digestibility of Finishing Pigs in High Ambient Temperature

The experiment was conducted to investigate the effects of low protein amino acid balanced diets on growth performance, serum parameters and apparent protein digestibility of finishing pigs in high ambient temperature.Ninety Landrace x Large White x Duroc pigs with average initial body weight about (65.90±3.37) kg were randomly allocated into 3groups with 3replicates in each group and 10 pigs in each replicate.Pigs in three groups were fed with diets differently in protein level for 16.02% (trial group 1as control) , 14.08% (trial group2) and 12.05 (trial group 3) respectively.The experiment lasted for 40 days.The results showed that, at average temperature between 29.53℃to 31.16℃, average daily gain (ADG) in group 2and 3was increased respectively by2.49% and 1.81% (P>0.05) comparing to control group.There were no significant differences among the groups (P>0.05) in average daily feed intake (ADFI) and F/G (feed/gain) , in the concentration of serum cortisol (F) and endocrine hormone T3, T4.Comparing to control group, the concentration of serum urea nitrogen (BUN) in group 2and 3was decreased respectively by 10.45% and 19.13% (P<0.05) while no significant differences were found in the apparent digestibility of crude protein among the groups (P>0.05) .The N excretion in group 2and group 3 was decreased by 10.48% and 25.64%, respectively, comparing with it in group 1 (P <0.05) .In conclusion, Low-protein diet did not alleviate the effects of high temperature stressing on growth performance, serum parameters and apparent protein digestibility of finishing pigs.