Dietary amino acid concentration should closely meet maintenance and tissue accretion needs of commercial broilers, especially at the higher feed intake rates at the end of the grow–out period, to avoid costly excesses, according to L. Mejia of Mississippi State University and co-authors there and with Ajinomoto Heartland LLC, Chicago.

In a paper in Journal of Applied Poultry Research, they explain that the purpose of their study, using 1,248 Ross ×, Ross 708 male broilers, was to evaluate simultaneously the dietary needs of lysine and threonine from 35 to 49 days of age.

Production of dose–response diets was accomplished via the diet–dilution technique, and diets were formulated to provide a range from 0.70 to 1.15 per cent and 0.40 to 0.85 per cent true digestible lysine and threonine, respectively.

The only parameter that allowed for an estimation of lysine and threonine requirements using quadratic regression was bodyweight gain, with recommended estimates of 1.09 and 0.72 per cent true digestible lysine and threonine, respectively.

The researchers, therefore, estimated a true digestible threonine–to–lysine ratio of 66 for maximising bodyweight gain. Additionally, Mejia and co–authors calculated requirement estimates for true digestible threonine of 0.67, 0.72, and 0.74 per cent for feed consumption, feed conversion and breast meat weight, respectively.

Reference

Mejia L., P.B. Tillman, C.D. Zumwalt and A. Corzo. 2012. Assessment of the threonine-to-lysine ratio of male broilers from 35 to 49 days of age. J. Appl. Poult. Res. 21(2):235-242. doi: 10.3382/japr.2011-00344

Further Reading You can view the full report (fee payable) by clicking here.