INFLUENCE OF PROCESSING ON THE FEEDING VALUE OF OATS FOR FEEDLOT CATTLE

Ninety-six crossbred steers (312 kg) were used in a 118-d feedlot grow th performance trial to determine the relative effects of degree of st eam processing on the feeding value of oats in a 90% concentrate finis hing diet. Treatments were 1) steam-flaked corn (SFC, density = .28 kg /L); 2) dry-rolled oats (DRO, density = .36 kg/L); 3) steam-rolled oat s, coarse flake (SRO-C, density = .33 kg/L); and 4) steam-rolled oats, thin flake (SRO-T density = .17 kg/L). Feed intake was similar (P > . 10) across oats treatments. However, ADG was lower (13.2%, P < .01) an d feed/gain was higher (11.1%, P < .05) for SRO-T than for SRO-C diets . Diet NE(m) was 7.2% lower (P < . 10) for SRO-T than for SRO-C diets. Daily weight gain was greater (9.3%, P < .01) and feed intake and fee d/gain were lower (13.1 and 20.8%, respectively; P < .01) for SFC than for oats treatments. Diet NE(m) and NE(g) were higher (20.0 and 26.5% , respectively; P < .01) for SFC than for oats treatments. Dressing pe rcentage was 2.5% lower (P < .01) in steers fed the oats diets than in those fed the SFC diet. Four Holstein steers (232 kg) with cannulas i n the rumen and proximal duodenum were used in a 4 x 4 Latin square ex periment to evaluate treatment effects on characteristics of digestion . Ruminal digestibility of OM, starch, and ADF were similar (P > .10) for oats treatments, averaging 58.2, 93.5, and 9.6%, respectively. Rum inal digestibility of OM was greater (19.2%; P < .01) for SFC than for oats diets. Passage of nonammonia N to the small intestine was greate r (17.1%, P < .05) for oats than for SFC diets. Total tract digestion of OM, ADF, and starch were greater (14.0, 62.1, and 1%, respectively; P < .01) for SFC than for oats diets. The DE and ME values were great er (11.4 and 11.9%, respectively; P < .01) for SFC than for oats diets . The DE and ME values were greater (P < .05) for SRO than for DRO die ts. It is concluded that current feed standards are accurate for DRO ( 1.88 Mcal/kg, DM basis). However, steam processing and rolling to prod uce a course flake will further increase its energy value 7.6%. Thin r olling may decrease the feeding value of steam-processed oats. The com parative NE(m) of DRO, SRO-C, and SRO-T averaged 1.85, 1.99, and 1.72 Mcal/kg, respectively.