Different amino acid supplementation patterns in low-protein diets on growth performance and nitrogen metabolism of goslings from 1 to 28 days of age.

The investigation aimed to explore the suitable amino acid (AA) supplementation pattern for goslings under low-protein diets. A total of 364 1-day-old male goslings were randomly divided into 4 experimental groups, with 7 pens containing 13 goslings each. The 4 groups were control (CP, 18.55%), LPM (CP, 15.55% + major AA), LPA (CP, 15.55% + all AA), and LPR (CP, 15.55% + AA content reduced proportionally to the control's CP). The corn-soybean meal diets are formulated according to the ideal AA model of goose and its nutritional requirements. The results indicated that the ADG and BW were the lowest, and the F: G was the highest in LPR (P < 0.05); the other three groups were not significantly different (P > 0.05). The ADFI and mortality were not different among all the groups (P > 0.05). Among the AA content in serum and breast muscle, lysine in serum significantly decreased compared with the control (P < 0.05). The UREA content was approximately 2-fold higher in the LPR group than in the LPM and LPA groups (P < 0.05). No difference in IgA, IgG, IgM, and IgE levels was observed among the groups (P > 0.05). The nitrogen excretion was decreased in LPM and LPA compared to the control and LPR (P < 0.05). Nitrogen deposition did not differ among groups (P > 0.05). Nitrogen utilization was highest in the LPA and LPM groups, followed by the control group and LPR (P < 0.05). In conclusion, the patterns of supplementation of major AA and all AA in low-protein diets (CP, 15.55%) had no adverse effect on the growth performance compared with the control (CP, 18.55%) of the goslings. Besides, the two patterns could decrease nitrogen excretion and increase nitrogen utilization. Furthermore, from the perspective of dietary cost and environmental protection, the pattern of supplementing major AA in a corn-soybean meal low-protein diet is suggested.