Effects of Low-Protein Amino Acid-Supplemented Diets on Growth Performance,Serum Biochemical Indices and Fecal Nitrogen Content of Beijing Ducks

This experiment was conducted to investigate the effects of low-protein amino acid-supplemented diets on growth performance,serum biochemical indices and fecal nitrogen content of Beijing ducks.Four hundred and fifty one-day-old Beijing ducks were randomly allocated to 3 groups with 5 replicates per group and 30 ducks per replicate.Diets were prepared with 2-phase feeding program.Three diets were formulated for each phase.The control group was fed diets with crude protein level of 20% during 1 to 14 days of age and 18% during 15 to 42 days of age.The experimental groups Ⅰ and Ⅱ were fed diets with the crude protein levels of 1 and 2 percentages less than the control diet,respectively,but supplemented amino acids.The results showed as follows: 1) there were no significant differences in average daily feed intake,average daily gain and feed/gain among 3 groups during 1 to 14,15 to 42 and 1 to 42 days of age(P0.05).2) At 14 and 42 days of age,no significant differences in serum total protein,uric acid and urea nitrogen contents,and alanine aminotransferase and glutamic-oxaloacetic transaminase activities were found among 3 groups(P0.05).3) Compared with the control group,the fecal nitrogen content in experimental groups Ⅰ and Ⅱ was reduced by 4.60% and 15.71% at 1 to 14 days of age and by 10.77% and 15.82% at 15 to 42 days of age(P0.05),respectively.It is concluded that reducing dietary crude protein level by 1 to 2 percentages has no significant effects on growth performance and serum biochemical indices,while significantly decreases fecal nitrogen content of Beijing ducks under the premise of meeting the amino acid requirements