The effect of drying method temperature, collection method, and marker type on apparent ileal amino acid...

For accurate estimation of nutrient digestibility, an ideal drying and sampling method is required to preserve the quality of the digesta. A standard corn-soybean meal (corn-SBM) broiler starter diet was fed from d 0 to 10 before birds were placed on the experimental diets until d 21. One hundred and sixty-eight male Cobb 500 broiler chicks were used to evaluate the effect of two drying methods (freeze-dryer vs. forced air-oven) and two drying temperatures (40 vs. 55°C) (Exp 1), while ninety-six chicks were used to evaluate the effect of flushing and squeezing as well as marker types (titanium vs. chromium) on apparent ileal DM, N, Ca, P, and AA digestibility (Exp 2). There were seven (Exp 1) or eight (Exp 2) replicate cages per treatment with 6 birds/cage. Digesta from the distal two thirds of the ileum was obtained from birds following euthanasia on d 21 by squeezing (Exp 1) and squeezing or flushing (Exp 2). Samples collected were stored in the freezer at -20°C until they were either freeze-dried (FD) or oven-dried (OD) at 40 or 55°C. There were no interactions between the drying methods and drying temperatures (Exp 1) on apparent ileal DM, N, and AA digestibility. Met had the highest (92.3%) while Cys had the lowest (73.8%) digestibility value. In Exp 2, no interaction between sampling methods and marker types was observed. The effect of sampling methods was not significant except for Arg and Met where squeezing resulted in higher (P < 0.05) digestibility values. Furthermore, apparent ileal His, Ile, Cys, Ser, and Tyr digestibility tended to be higher (P < 0.1) in squeezed digesta compared to the flushed digesta. Results from these studies showed that OD ileal digesta at 40 or 55°C had no negative effect on apparent ileal AA digestibility. Likewise, marker type did not influence apparent ileal AA digestibility values.