The impact of starch, protein and fat digestive dynamics on growth performance in broiler chickens from 7-28 days

Amino acids and glucose should be available in appropriately balanced quantities at the sites of protein synthesis for efficient protein deposition and growth performance; previous studies have suggested that feed conversion efficiency may be enhanced by rapidly digestible protein or to a lesser extent, slowly digestible starch. A 3-factor- 3-level Box-Behnken response surface study was conducted to determine the influence of rapidly digestible starch (wheat, 0, 300, 600 g/kg), rapidly digestible protein (whey protein, 0, 50, 100 g/kg) and tallow (0, 25, 50 g/kg) inclusions on growth performance from 7-28 days post-hatch in male Ross 308 broiler chickens offered sorghumsoybean meal based diets. All diets were formulated to be iso-energetic and contain the same digestible lysine and essential amino acids. Each of the 13 diets was offered to 30 birds in 5 replicated cages (6 birds per cage). High tallow and wheat inclusions led to increased relative fat pad weight. There were quadratic relationships between weight gain and wheat, whey protein and tallow inclusions which suggested a balance between the extent and rate of starch, protein and fat digestion is important.