Dietary formulation with rendered spent hen meals on a total amino acid versus a digestible amino acid basis.

Previous results indicated that performance of chicks fed a high level (15%) of rendered spent hen meal (SHM) was lower than performance of chicks fed a corn-soybean meal (SBM) diet. The latter difference was hypothesized to be due to variation in digestible amino acid (AA) levels among the diets. This study evaluated diets containing SHM formulated on an equivalent total AA basis vs an equivalent digestible AA basis compared to a corn-SBM diet. Three SHM (A, B, and C), produced in commercial rendering plants, were evaluated. Mean true digestibility coefficients (percentages) for 17 AA in SHM A, B, and C were 73.1, 63.4, and 75.5, respectively. In two chick trials, 1-wk-old New Hampshire x Columbian male chicks were fed from 8 to 20 d of age a corn-SBM diet or diets containing 15% SHM formulated to be equal in total or digestible AA to the corn-SBM diet. All diets contained 21.5% CP and 3,200 kcal TME(n)/kg. Chicks fed 15% SHM (A, B, or C) diets formulated on a total AA basis had significantly lower (P < 0.05) weight gain and feed efficiency than chicks consuming the corn-SBM diet. Formulating diets containing SHM B or SHM C on a digestible AA basis yielded growth performance equivalent to chicks fed the corn-SBM diet. Growth performance of chicks fed the SHM A diet formulated on a digestible AA basis was greater (P < 0.05) than that obtained from the SHM A diet formulated on a total AA basis but was still lower than performance of chicks consuming the corn-SBM diet. Additional AA and energy supplementation of the SHM A diet formulated on a digestible AA basis only partially alleviated the latter performance difference. The results of this study indicated that formulation of diets containing SHM on a digestible AA basis is superior to formulation on a total AA basis and that 15% inclusion of two of the three SHM in chick diets had no detrimental effects on performance if the diets were formulated to contain adequate levels of digestible AA.