ESTIMATES OF TRUE AMINO-ACID DIGESTIBILITIES IN FEED INGREDIENTS USING PRECISION-FED, CECECTOMIZED ROOSTERS

Twenty seven cecectomized mature Single Comb White Leghorn cockerels w ere used to estimate true amino acid digestibilities (TAAD) coefficien ts for eight feedstuffs for cecectomized roosters. The objective of th is paper was to evaluate alternative feed ingredients TAAD coefficient s using a standard precision fed (crop-intubation) methodology. The in gredients tested were corn, wheat bran (WB), two sources of soybean me al (SBM 1 and SBM 2), cottonseed meal (CSM), poultry by-product (PBP), and two samples of meat and bone meal (MBM 1 and MBM 2). A group of t hree roosters was fasted 24 hours prior to each assay to allow measure ment of endogenous amino acid production. True lysine digestibility (T LD) in CSM (71.8%) was significantly lower (P<.01) than in all the oth er feed sources. No differences (P>.01) were found for TLD among the o ther ingredients. Means and standard error of means for TAAD were: cor n 103.03+/-4.30, WE 90.35+/-2.26, SBM 1 93.13+/-1.55, SBM 2 92.99+/-2. 39, CSM 81.16+/-4.67, PBP 86.23+/-2.14, MBM 1 86.2+/-2.49, MBM 2 85.98 +/-2.26. In general the averages of the coefficients for TAAD of the i ngredients used are in the range of the values reported in the literat ure and can be used to formulate diets based on amino acid digestibili ty.