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Interpretive Summary: Effects of roughage type on particle separation, rumination, fiber mat characteristics, in situ degradation, and ruminal fermentation parameters in beef steers

By: Dr. Emily Taylor

Physically effective neutral detergent fiber (peNDF) is essential for maintaining the rumen epithelial lining and can be estimated based on the diet's particle size and NDF concentration. Roughages have unique physical characteristics that contribute to the density of the ruminal mat and influence ingredient digestibility, retention times, and particle degradation. In addition, roughage diversity varies based on geographical location, availability, and costs. Little is known about the peNDF of various roughages and their effect on chewing behaviors, fibrous mat, and fermentation characteristics in beef cattle. Therefore, the objective of the current study was to evaluate the rumination, ruminal mat fiber concentration, and ruminal fermentation of beef steers fed steam flaked corn-based diets with 7% corn stalks (CS), wheat silage (WS), or cotton burrs (CB). 

Dry matter intake (DMI) was significantly greater for steers consuming the CS diet; however, not different for the CB and WS diets. Rumen fiber mat (RF), RF dry matter, RF weight, and RF:DMI ratio was not influenced by roughage type. While daily rumination was not different among roughages, the min/kg of peNDF was significantly more significant for the CS diet when compared to the WS and CB diets. Wheat silage was found to have the greatest percentage of soluble and degradable DM.  An in situ study was also performed and determined that CB-R and CS-R had the greatest percentage of ruminal undegraded DM. 

To optimize the performance of finishing cattle, understanding the impacts of a roughage source to better estimate inclusion rates in finishing diets is critical. The present study indicated that cotton burrs have a cotton-like physical characteristic that may contribute to larger particle size and homogenous mixing within the rumen. In contrast, steers consuming wheat and corn silage had smaller particle sizes that may have increased the passage rate. The study provides evidence that these unique physical characteristics contribute and alter ruminal fiber mat development, rumination time, and fermentation characteristics and may be beneficial to the health of the rumen.

This article is available in the Journal of Animal Science.