Using whole oats grain as a source of fiber in calves’ rations
Two experiments were carried out aiming to study the value of whole oats (WO) as a potential source of physically effective fiber (peNDF) in rations for calves. In experiment 1, 24 Hereford calves (177 ± 18 kg) were randomly assigned to eight groups and these into one of four experimental rations (79% concentrate), varying in the replacement level of grass hay (GH) for WO: 0:21, 7:14, 14:7, 21:0% dry matter (DM) basis WO:GH, respectively. Increasing WO level resulted in a quadratic response for peNDF (P= 0.04) with values above 15% of dm. Intake increased quadratically (P= 0.03) and dm digestibility increased linearly (P= 0.03). As a result, feed conversion efficiency tended to improve (P= 0.08). In Experiment 2, four rumen cannulated steers were assigned in a crossover design to one of two experimental rations (65% concentrate) varying in peNDF fiber source: 35% gh or 35% WO, aiming to study the fermentative pattern. Replacing GH for WO reduced mean daily rumen pH (5.9 vs. 6.3, P < 0.01), varying between 6.1 and 5.8, and always below pH values in gh. No differences were observed for the potentially degradable dm fraction, but fermentation rate was higher for WO (35.0 vs. 9.0 %/ h; P= 0.02), hence increasing effective degradability (58.3 vs. 65.4%; P= 0.048). Results from both experiments suggest it is viable to use WO as a peNDF source for concentrated rations.
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