Effect of processing method and severity for hybrid fall rye on dry matter intake, ruminal fermentation, and apparent total tract nutrient digestibility in ruminally cannulated beef heifers

Abstract

This study compared dry-rolled and tempered hybrid rye when processed to a coarse or fine severity on dry matter intake (DMI), ruminal fermentation, and apparent total tract nutrient digestibility for beef cattle. Eight ruminally cannulated Sim-mental heifers (327 ± 33.1 kg, mean ± SD) were used in a replicated 4 × 4 Latin square (21-day periods with 16 days for adaptation and 5 d collection) balanced for carry-over effects with a 2 × 2 factorial arrangement of treatments. Feeding tempered rye increased (P = 0.01) DMI when compared to dry-rolled rye, but there was no effect of processing severity. Cattle fed dry-rolled rye had a greater (P = 0.04) area that pH was <5.5 when compared to those fed tempered rye. Feeding dry-rolled rye increased dry matter digestibility (P = 0.02) and crude protein digestibility (P = 0.01) when compared to tempered rye, and there was a greater effect to increase total tract starch digestibility with increasing severity of processing for tempering than for dry rolling (interaction, P = 0.03). In conclusion, tempered hybrid rye processed to a fine severity may result in similar total tract starch digestibility to dry-rolled hybrid rye without the marked reductions in DMI and ruminal pH.