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Optimizing low-protein diets in swine nutrition is critical for reducing nitrogen excretion and resource waste. However, these diets may reduce meat quality, disrupt amino acid (AA) balance, affecting growth and health. Supplementing with non-protein nitrogen sources such as diammonium phosphate (DP) can enhance nitrogen utilization and support protein synthesis efficiently.
Objective: This study aimed to investigate the effects of adding DP to low-protein diets on growth performance, carcass traits, meat quality, and AA composition in growing pigs.
Methods: Seventy-five barrows (Duroc × Landrace × Yorkshire) were randomly assigned to five dietary treatments: Pos Ctrl (CP: 13.50%), DP1 (CP: 12.00% + DP), DP2 (CP: 10.50% + DP), DP3 (CP: 9.00% + DP), and Neg Ctrl (CP: 9.00%). Each DP-supplemented diet aimed to maintain an essential AA nitrogen to total nitrogen ratio of 0.48. Pigs had ad libitum access to food and water for 41 days, with monthly recordings of body weight and feed intake. After an overnight fast, they were euthanized, and carcass traits, meat quality, and organ indices were evaluated. Blood, liver, and muscle samples were collected for plasma biochemistry and amino acid profile analysis.
Results: The study found that feeding the DP2 diet resulted in the best growth performance, while the DP3 diet significantly improved ADG and G:F compared to the Neg Ctrl diet. The DP3 diet also significantly increases relative liver weight compared to the Neg Ctrl diet. Although no significant differences were observed in carcass traits or meat quality among the dietary treatments, the DP3 diet tended to reduce plasma total protein levels relative to the Neg Ctrl diet. Feeding the DP3 diet did not alter the free AA profile in plasma and liver of growing pigs compared with the Neg Ctrl diet, and there was no effect between the different diets on the hydrolyzed AA profile in muscle. Furthermore, the DP3 diet significantly increased Tau concentrations in the longissimus dorsi muscle while significantly reducing Car levels compared to the Neg Ctrl diet.
Conclusion: These results suggest that adding DP to the low-protein diet can enhance growth performance and improve meat flavor-related AA content without compromising carcass traits or meat quality.
Zeng X, Xiao G, Liu W, Yin L, Zhang Y, Geng C, Wang Q, Yang H. Diammonium phosphate supplementation in low-protein diets enhances growth performance in growing pigs without compromising carcass traits and meat quality. Journal of Animal Science. 2025skaf088. https://doi.org/10.1093/jas/skaf088
