LAUSR

BACKGROUND With the easy availability and competitive prices of crystalline amino acids (AA), a further reduction of dietary crude protein (CP) would be possible. Two experiments were conducted to assess the growth efficiency of early and late finishing pigs fed with protein-restricted diets supplemented with Lys, Met, Thr, Trp, Val, Ile and His under practical conditions. In Exp. 1, a total of 840 early finishing pigs were allocated to 4 dietary treatments with CP levels designed at 150, 142, 134, and 126 g kg-1 diet. In Exp. 2, a total of 768 late finishing pigs were allotted to 4 dietary treatments providing CP levels at 140, 130, 120, and 110 g kg-1 diet. RESULTS In Exp. 1, data showed that CP levels could be decreased from 150 to 126 g kg-1 without adversely affecting performance of early finishing pigs as no significant difference was observed for final bodyweight, average daily gain (ADG), feed to gain ratio (F:G), or average daily feed intake (ADFI). In Exp. 2, late finishing pigs consuming 120 g kg-1 CP tended to have the highest ADG and lowest F:G while those fed the 110 g kg-1 CP diet showed the opposite trend. Based on quadratic analysis, the optimum CP levels to maximize ADG and minimize F:G were 126 and 127 g kg-1 , respectively. CONCLUSION These findings showed that dietary CP levels can be decreased to 126 g kg-1 for early finishing pigs while improved performance was noted in late finishing pigs consuming 120 g kg-1 CP. This article is protected by copyright. All rights reserved.