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. T his 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 eval uated. 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, l -wk-old New Hampshire x Columbian male chicks were fed from 8 to 20 d of ag e a corn-SBM diet or diets containing 15% SHM formulated to be equal in tot al or digestible AA to the corn-SBM diet. All diets contained 21.5% CP and 3,200 kcal TMEn/kg. Chicks fed 15% SHM (A, B, or C) diets formulated on a t otal AA basis had significantly lower (P < 0.05) weight gain and feed effic iency than chicks consuming the corn-SBM diet. Formulating diets containing SHM B or SHM C on a digestible AA basis yielded growth performance equival ent to chicks fed the corn-SBM diet. Growth performance of chicks fed the S HM A diet formulated on a digestible AA basis was greater (P < 0.05) than t hat obtained from the SHM A diet formulated on a total BA basis but was sti ll 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 t hat 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 le vels of digestible AA.