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Abstract The study aimed to assess the impact of three different non-forage fiber sources (NFFS); soy hulls (SH), cottonseed hulls (CSH), and beet pulp (BP) on methane (CH4) production and rumen fermentation using a 24-h batch culture system. These NFFS were incorporated partially into a conventional total mixed ration (TMR) diet consisting of alfalfa (40%), cracked corn (30%), soybean meal (10%), and an individual NFFS (20%; DM basis). Methane production, total gas production, volatile fatty acids (VFA) concentration, and dry matter (DM) digestibility were measured at the end of the incubation period. One way ANOVA test was used to analyze the means and significance was declared at P 0.05. The results of the study indicated a significant 5% reduction (P 0.05) in CH4 production with the BP diet compared with the other treatments. However, DM digestibility was found to be significantly less (P 0.05) with the BP diet compared with the other diets. Total gas and VFA production were greater (P 0.05) with the BP diet compared with the other diets. Additionally, the molar proportions of acetate and propionate were greater (P 0.05) with the BP diet and least with the SH diet. No significant differences were recorded for the ratio of acetate to propionate (C2:C3) between treatment diets. Results from this study suggest that BP is a more effective non-forage fiber source in the TMR due to its favorable effects on rumen CH4 production and rumen fermentation. However, it is important to consider the trade-off with decreased DM digestibility when selecting BP as an NFFS in TMR diets.
Grey et al. (Sun,) studied this question.