Increased Amino Acid Digestibility, Apparent Metabolizable Energy, and Growth Rate in Broiler Chicks Fed an Energy-Restricted Corn-DDGS Diet Supplemented with a Carbohydrase Mixture

Introduction

The non-starch polysaccharide content of corn-derived distiller dried gains with soluble (DDGS) is 3-4 times higher compared to corn. The high-fiber content of DDGS is partially responsible for its low ME in poultry, which may be increased with dietary inclusion of a mixture of carbohydrases. Our objective was to measure in growing broilers increases in amino acid (AA) digestibility, energy utilization, and growth performance in an energy-restricted diet with 20% inclusion of corn-DDGS and supplemented with a carbohydrase mixture.

Cobb 500 broilers (7-d-old, 8 chicks/pen, 6-7 pens/diet) were randomly allotted to 4 dietary Treatments with ad libitum access to feed and water. Corn and DDGS diets were supplemented or not with carbohydrases. DDGS diets contain 90% of the metabolizable energy (ME) of corn diets. At 2 and 3 wk of age, excreta and ileal digesta samples were collected to determine apparent ME (aME), and standardized ileal digestibility (SID) of AA (Ravindran et al. 2001; Lemme et al. 2004; Stein et al., 2007). Data were analyzed using proc mixed (SAS® Institute, Gary, NC)

Overall growth performance of chicks receiving corn diets were higher (P < 0.001) than DDGS diets regardless of carbohydrase supplementation. In wk 2, carbohydrase inclusion increased (P < 0.05) aME by 9.4% but had no effect on average weight gain (AWG). In wk 3, inclusion of carbohydrase improved (P < 0.05) AWG in both corn and DDGS diets. Supplementation of carbohydrase increased (P < 0.01) aME by 11.7%, which made it comparable in ME to both corn diets. However, AWG of chicks fed DDGS+ carbohydrase was lower than corn groups with or without enzyme supplementation (P < 0.01). Overall AA SID was not affected by inclusion of DDGS except for Leu, Met, and Phe at wk 3. Carbohydrase supplementation increased (P < 0.05) SID of all AA except for Asp+Asn at wk 2 and Met at wk 3. Regardless of diet, SID increased with age (P < 0.05) except for Ser, His, Thr, Val, Met, and Ala.

Results indicate the ability of carbohydrases to increase aME and AA SID of a ME-deficient diet containing 20% DDGS. A lag in growth response at equal aME suggests a metabolic adaptation to the use dietary carbohydrase supplementation.

Carbohydrase supplementation may be used to increase AA digestion and energy utilization in broiler diets containing DDGS or other high-fiber containing feedstuffs.

Ravindran et al. 2001; Lemme et al. 2004; Stein et al., 2007; Stein H et al., 2007. J. Anim. Sci. 85:172-180; Wubben J et al., 2001. Contemp. Top. Lab. Anim. Sci. 40:27-31.