The Reproducibility of Roughage Preference Evaluation Result by Sheep

Abstract

An experiment was conducted to investigate the influence of repetition of preference trial on preference evaluation for roughage. Four sheep were used to conduct paired comparison trials of (1) two grass species: timothy (Phleum pretense L.) hay (TH) and oats (Avena sativa L.) hay (OH), (2) two different rice (Oriza sativa L.) genotypes whole-crop silage (RWCS): Bekogonomi and NERICA, and (3) the aforementioned 2 genotypes of RWCS mixed with apple-pomace (AP) at 50% on fresh-matter basis (50%AP-RWCS). Each sheep was simultaneously offered 2 test feeds and the intake was recorded for an hour. A 5-day comparison session on alternate days for each pair was conducted in order of hays, RWCSs, hays, 50%AP-RWCSs and hays. Dry-matter intake (DMI) of OH was significantly lower than TH for the first 5-day comparisons and most of the second 5-day session. However, DMI of hays was not different at the third 5-day comparisons. Similarly, DMI of Bekogonomi-RWCS was significantly lower than that of NERICA-RWCS at the initial 2 days, but it increased gradually and DMI of RWCS was not different in the later of trial. DMI of 50%AP-RWCS was not different throughout 5 days. These results suggest that receptiveness of unpalatable feeds can be improved by recurrent exposure.