Validation of net energy system of feed formulation in growing-finishing pigs fed barley based diets with alternative feed ingredients
The aim of this study was to determine the growth performance and carcass characteristics of growing-finishing pigs fed diets formulated on net energy (NE) basis thereby validating the NE system of feed formulation. Twenty four pigs (12 barrows and 12 gilts) with an initial BW of 25 kg were blocked by sex and allotted 1 of the 3 treatments, resulting in 8 replicates, 4 barrows and 4 gilts per treatment. Dietary treatments were; a barley-based control diet with alternative feed ingredients (distillers dried grains with soluble, canola meal and peas) formulated on digestible energy (DE) basis (Diet A), control diet formulated on a NE basis (Diet B) and Diet B + Multi-carbohydrase enzyme (Diet C). Pigs were offered their respective diets in a 3-phase feeding program for 25 to 50 kg (phase 1), 50 to 75 kg (phase 2), and 75 to 110 kg (phase 3) BW. Diet A was formulated to contain 3,402 kcal/kg of DE and Diet B and diet C to contain 2,475 kcal/kg of NE with 0.98, 0.85, and 0.73% SID Lys for phases 1, 2, and 3, respectively. Individual pig BW and feed disappearance were monitored biweekly during each phase to determine average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F) ratio. Pigs were slaughtered once they reached 100 kg BW to determine carcass characteristics. During phase 1, an improvement in ADFI (P = 0.02) was observed for diets formulated on NE basis with enzyme supplementation (1.78 kg/d) when compared to Diet B without enzymes (1.57 kg/d). In phase 3, a significant difference was observed for ADG (P = 0.01), wherein Diet B showed a BW gain of 0.89 kg/d compared to 0.79 kg/d for the control diet. Also a trend for an increase in G:F ratio (P = 0.072) was observed between diets formulated on DE and NE basis. For overall performance, when compared to the control diet, pigs fed Diet B showed significant improvement in ADG (0.90 vs. 0.96 kg/d; P = 0.02) and G:F (0.43 vs. 0.47; P = 0.05). No significant differences (P > 0.10) were observed among dietary treatments for any of the carcass characteristics. In conclusion, the results indicate a better growth performance when diets were formulated on a NE basis when compared to the DE system. Though not significant, enzyme supplementation numerically enhanced the overall performance.
Keywords: Enzyme, net energy, pig.