Effects of Substituting Barley Grain and Silage with High-moisture Corn Products in Western Canadian Beef Finishing Diets on Ruminal Fermentation Patterns and Site and Extent of Starch Digestibility

With the introduction of short-season hybrids, corn production in western Canada is increasing with the majority being used for corn silage or standing corn grazing. High-moisture corn products (high-moisture corn and snaplage) could be harvested to replace traditional barley-based components in feedlot diets, but there are no studies evaluating the use of these products from short-season corn hybrids. The objective of this study was to investigate the impact of partially replacing barley grain and barley silage with high-moisture corn products on ruminal fermentation and the site and extent of starch digestion for heifers fed finishing cattle diets. Six heifers (420 ± 21 kg body weight) equipped with ruminal and duodenal cannulas were used in a replicated 3×3 Latin square with 25-d periods. The control diet (BG; DM basis) contained dry-rolled barley grain (85%) and barley silage (9.7%). For the high-moisture corn treatment (HC), high-moisture corn replaced 50% of the barley grain, and for the snaplage treatment (SN), the silage and 12.5% of the barley grain were replaced by snaplage relative to BG. Ruminal digesta samples were collected over 24 h and analyzed for short-chain fatty acids (SCFA) and ammonia. Indwelling ruminal pH meters recorded pH every 5 minutes. Duodenal and fecal samples were collected to determine the site and extent of digestibility. Dry matter intake (6.9 ± 0.4 kg) and starch intake (3.9 ± 0.2 kg) did not differ among treatments, but NDF intake was greater for SN than HC (P = 0.02), although neither differed from BG. Ruminal starch digestibility was greater (P = 0.05) for SN than BG, while these treatments did not differ from HC. Intestinal and total tract starch digestibility were not affected. Mean ruminal pH averaged 6.19 ± 0.13 and did not differ among treatments. Likewise, concentrations of total SCFA and the molar proportion of individual SCFA did not differ. This research indicates that high-moisture corn can be used as a partial replacement for barley grain and that although snaplage increases the digestion of starch in the rumen, it can be used to partially replace barley grain and silage in finishing cattle diets without impacting total tract starch digestibility.

Key words: starch, snaplage, high-moisture corn, feedlot.

Presented at the 2022 Animal Nutrition Conference of Canada. For information on the next edition, click here.