Evaluating the Response of Cobb MV × Cobb 500 Broilers to Varying Amino Acid Density Regimens for a Small Bird Program

Abstract

SUMMARY: Primary breeder companies are continuously striving to improve existing commercial broiler crosses to increase performance and reduce cost. The objective of this study was to evaluate the response of a new commercial broiler cross (Cobb MV × Cobb 500) under 4 different amino acid density (AAD) regimens on live performance and carcass yield during a 36 d grow-out period with 2 processings to collect data at 32 and 35 d. Two basal diets were formulated to low AAD (LAAD, digestible lysine, dLys 1.08, 0.95, and 0.87% for starter, grower, and finisher) and very high AAD (VHAAD, dLys 1.39, 1.26, and 1.12%). Medium and high AAD (MAAD and HAAD) diets were created by mixing the LAAD and VHAAD diets at ratios of 66.6:33.3 and 33.3:66.6, respectively. This was a randomized complete block design with 12 replications/treatment (16 birds/pen, 0.07 m2/bird). Feed intake/bird was reduced (P < 0.05) when birds were fed the VHAAD diet at 0–32 and 0–35 d. As AAD increased, FCR decreased significantly in a stepwise manner by approximately 4 points at each AAD level (P < 0.05). Feeding higher levels of AAD improved broiler live performance and carcass yields. At 33 d, birds fed the HAAD diet had the highest potential gross profit/bird, and at 36 d, birds fed the VHAAD diet had the highest potential gross profit/bird. Further research should evaluate the effects of feeding increased AAD diets to male and female Cobb MV × Cobb 500 separately, as well as in different feeding phases and longer grow-out periods.

Keywords

• amino acid density
• lysine
• live performance
• processing yield