Nitrogen balance in barrows fed low-protein diets supplemented with essential amino acids

• Published in: Livestock science 2007-05, Vol.109 (1), p.220-223
• Main Authors: Deng, D., Huang, R.L., Li, T.J., Wu, G.Y., Xie, M.Y., Tang, Z.R., Kang, P., Zhang, Y.M., Fan, M.Z., Kong, X.F., Ruan, Z., Xiong, H., Deng, Z.Y., Yin, Y.-L.
• Format: Article
• Language: English
• Subjects: Dietary protein; Nitrogen balance; Pigs
• ISSN: 1871-1413; 1878-0490
• DOI: 10.1016/j.livsci.2007.01.122

This study was conducted to determine the effect of addition of essential amino acids (EAA) to low-protein diets on N balance in barrows. Thirty barrows (Duroc × Yorkshire) with an initial BW of 36 kg were fed 5 corn- and soybean meal-based diets containing 13.6 to 18.2% crude protein (CP) for 10 d in a randomized complete block design. The 18.2% CP diet was formulated without addition of EAA (Lys, Met or Thr). The other diets contained 13.6 to 16.5% CP and were supplemented with EAA to provide 0.83% true digestible lysine equal to that in the 18.2% CP diet. Fecal, urinary, and total N excretion as well as N retention (g/d) decreased with decreasing dietary CP level ( P < 0.01). The apparent digestibility of N was almost the same for the 18.2 and 16.5 CP diets, but the value was 2% higher ( P = 0.07) than that for the 13.6% CP diet. These findings indicate that, compared with the 18.2% CP diets, supplementation with three EAA to the lowest-protein diets (13.6 CP) is inadequate for maximum intestinal protein digestion, amino acid absorption, or tissue protein deposition in growing barrows.