71 Effect of dry rolled, temper rolled, or steam flaked barley on dry matter intake, feeding behavior, and ruminal fermentation of finishing beef heifers.

Abstract Barley grain is typically dry rolled (DR), temper rolled (TR), or steam flaked (SF) prior to feeding; however, few studies are comparing these processing methods for barley. This study compared the effects of including DR, TR, or SF barley into a finishing diet on dry matter intake, feeding behavior, and ruminal fermentation. Nine ruminally cannulated heifers (355 ± 23 kg) were used in a replicated 3×3 Latin square design with 28-d periods. Periods included 21 d for dietary adaptation and 7 d for data and sample collection. The DR, TR, and SF barley originated from the same source and were processed to achieve a density that was 70 ± 2% of the original barley grain bulk density. Diets included (% inclusion, DM basis) oat/pea silage (10%), mineral and vitamin supplement (3%), wheat dry distillers’ grain (3%), and the treatment barley (84%). Heifers were fed once daily for ad libitum intake. Dry matter intake (DMI) was not affected by the processing method averaging 9.2 kg/d. While meal frequency, meal duration, and eating time were not different, rumination time was less (P = 0.03) for heifers fed DR compared to SF and TR barley. Heifers fed DR barley sorted more for particles retained on the 8-mm (P = 0.04) sieve, and reduced sorting against particles retained on the 1.18-mm (P < 0.01) sieve of the Penn State Particle Size Separator when compared to SF and TR. Total ruminal digesta weight (kg as is basis) was at least 2.6 kg less (P = 0.02) for DR compared to SF and TR. However, the ruminal digesta DM weight was only greater for heifers fed SF than those fed DR or TR barley. Mean ruminal pH (average = 6.07, SEM = 0.07), the duration that ruminal pH was < 5.5 (average = 261 min/d, SEM = 71.5 min/d), and the area that ruminal pH was < 5.5 (average = 75 pH × min/d, SEM = 29.8 pH ×min/d) did not differ among treatments. Likewise, the concentration of total short-chain fatty acids and the molar proportion for most of the individual acids were not affected by treatment. However, the molar proportion of propionate was less (P = 0.003) for SF compared to DR and TR. In conclusion, despite some differences in feed sorting behavior and rumination time, the use of DR, TR, or SF barley in a finishing diet, when processed to the same severity, did not affect dry matter intake or ruminal pH.