Abstract
This experiment was carried out to examine the preference of feed supplemented butyric acid and lactic acid by an applied method of a two-choice preference test and paired preference test, as a model of low and high quality in silage. Castrated sheep were fed with Italian ryegrass (at the length of 2 cm) supplemented acids of concentrations at the nine steps from 0.0375% to 9.6% (experiment 1) and at the seven steps from 0.6% to 38.4% (experiment 2). The test rations fed stepwise the concentrations from low to high with nonsupplemented ration. The percentage intake of the test rations in regard to total ration in each concentration was defined as a preference index. Preference indexes were defined under 40% as a rejection zone, from 40% to under 60% as a nondiscrimination zone, from 60% to under 80% as a weak preference zone and above 80% as a strong preference zone, respectively. In case of the test supplemented butyric acid, the preference indexes changed around at discrimination zone by supplements from 0.0375% to 2.4% of butyric acid, but ones increased by supplements of above 4.8%. The maximum preference indexes were obtained 97% at supplement of 9.6% in experiment 1 and 86% at supplement of 19.2% in experiment 2, respectively. In case of the test supplemented lactic acid, on the other hand, the preference indexes were shown weak preference at supplements of 4.8% in experiment 1 and 2, but ones changed around at discrimination zone under supplements of 19.2%. In the supplement of 38.4%, however, preference index decreased to 25% in weak rejection zone. Increase of butyric acid concentration in silage suggested not to cause the decline of preference in feed.
