The effects of dietary amino acid (AA) density and apparent metabolisable energy (AME) on the growth and meat yield of summer-reared Cobb × Cobb 700 (CCB-700) broilers were evaluated by W. Zhai and colleagues at Mississippi State University and their paper is published in the current issue of Journal of Applied Poultry Research.

They also compared the responses of CCB-700 and Cobb × Cobb 500 (CCB-500) broilers to dietary AME levels (with low AA) were compared.

All chicks were fed through a starter, grower, finisher and withdrawal phase programme.

Grow-out performance, carcass traits, meat yield and feed cost efficiency were evaluated using two separate two-way ANOVA based on two separate 2×2 factorial arrangements of treatments.

Each group includes 14 replicate pens with 14 chicks per replicate.

Mortality was not affected by treatment. However, compared with birds fed other diets, feeding CCB-700 broilers a low-AME and high-AA density diet decreased feed intake and bodyweight on days 35, 42 and 54, and decreased carcass, breast, wing, front half and back half weights on day 55.

CCB-500 broilers consumed more feed and gained more weight than CCB-700 broilers at 14, 28 and 35 days of age. However, at 55 days of age, breast weight and wing yield were observed to be higher in the CCB-700 than in the CCB-500 broilers. However, the back half (drumstick and thigh) weights were lower in the CCB-700 than in the CCB-500 broilers.

Zhai and colleagues concluded that, without affecting feed costs, broiler performance and carcass yield were affected by diet in both strains.

More specifically, a higher AME diet and lower AA density increased the yield of all cut-up parts, except for legs, in summer-reared CCB-700 chicks.

Reference

Zhai W., E.D. Peebles, L. Mejia, C.D. Zumwalt and A. Corzo. 2014. Effects of dietary amino acid density and metabolizable energy level on the growth and meat yield of summer-reared broilers. J. Appl. Poult. Res. 23:501-515. doi: 10.3382/japr.2014-00961

October 2014