Nutritional evaluation of low phytate and high protein corns

Three chick experiments and two cecectomized rooster experiments were condu cted to determine P bioavailability and amino acid (AA) digestibility in tw o low phytate corns (LP), a high protein corn (HP), and a corn containing b oth low phytate and high protein content (HP/LP) compared with conventional corn (CONV). From 8 to 20 or 21 d of age, 1-wk-old New Hampshire x Columbi an chicks were fed a cornstarch-dextrose-soybean meal (SBM) basal diet cont aining 0.10% available P or the basal diet supplemented with two concentrat ions of P (0.05 or 0.06% and 0.10 or 0.12%) from KH2PO4 or two concentratio ns of the corns (20 or 21% and 40 or 42%). Bioavailability of P based on ti bia bone ash was much higher for LP than for CONV; values ran,oed from 21 t o 40% for CONV and from 59 to 95% for LP. Digestibility of AA in cecectomiz ed roosters indicated no significant differences (P > 0.05) between CONV an d HP in the first rooster experiment. Digestibilities of eight AA, includin g lysine, methionine, and arginine, in LP and HP/LP were higher (P < 0.05) than these in CONV in the second rooster experiment. The results of this st udy indicated that the P in LP was two to three times more bioavailable tha n the P in CONV and that the digestibilities of AA in HP/LP were equal to o r higher than those in CONV.