Effect of fasting versus feeding oasis after hatching on nutrient utilization in chicks.

Two experiments were conducted to determine the effects of fasting, feeding Oasis, or feeding a corn-soybean meal (SBM) or dextrose-casein diet immediately after hatching on growth performance, MEn and apparent amino acid (AA) digestibility. In each experiment, five or six pens of eight chicks were assigned to one of five treatments: feeding a corn-SBM or dextrose-casein diet immediately after hatching, fasting for 48 h (no feed or water) after hatching, or feeding Oasis for 24 or 48 h (no water) after hatching. The fasting and feeding Oasis treatments were followed by feeding the corn-SBM diet for 21 d. Excreta were collected at 0 to 2, 3 to 4, 7, 14, and 21 d on feed for determination of MEn and AA digestibility. Fasting chicks for 48 h posthatching significantly depressed weight gains compared to all other treatments at 21 d of age. Although weight losses were not significantly different at 48 h posthatching, chicks fed Oasis for 48 h had significantly (P < 0. 05) higher weight gains at 1 and 3 wk of age than did chicks fasted for 48 h. Chicks fed the dextrose-casein diet had significantly (P < 0.05) higher weight gains at 48 h and 7 d posthatching than chicks fed the corn-SBM diet immediately after hatch in Experiment 2. As time on feed increased from 3 to 21 d, MEn increased substantially (25%) for all the treatments in which chicks were fed the corn-SBM diet. In addition, the MEn of the corn-SBM diet for chicks fed Oasis was significantly (P < 0.05) higher for than chicks fasted for 48 h. The MEn of the dextrose-casein diet was high immediately after hatching and increased only slightly (2%) with increasing age. Digestibility of most AA increased with increasing age for all the corn-SBM treatments, and the digestibility values were similar among treatments. However, AA digestibility values for the dextrose-casein diet were consistently high at all ages and much higher (P < 0.05) than the other dietary treatments. Our results indicated that feeding Oasis (compared to fasting) had a beneficial effect on growth performance and subsequent energy utilization of a corn-SBM diet and that Oasis may stimulate early gut development even though very early growth (0 to 48 h) is not affected.