84 Effect of incorporating forage pea (c.v. Pisium sativum L.) into cereal hay on ruminal fermentation and apparent digestibility when fed to beef heifers

Abstract

Abstract The objective was to evaluate the effect of inclusion rate of pea hay in barley and oat hay when fed to beef cattle. Six ruminally-cannulated heifers (407 ± 38 kg) were used in a 6 × 6 Latin square with a 2 × 3 factorial design and 25-d periods. Treatments included barley or oat hay blended with pea hay to achieve inclusion rates of 0, 15, or 30% (DM basis). Pea inclusion increased DMI (P = 0.03) by 0.75 kg/d, and generally reduced sorting (P ≤ 0.006) against NDF and ADF compared to the cereal-only treatments. Pea inclusion decreased CP digestibility by 2.87% relative to cereal-only treatments, but did not affect the predicted microbial protein supply or nitrogen retention (P ≥ 0.77). Pea inclusion did not affect total ruminal SCFA concentration, but increased the molar proportions of acetate and butyrate and decreased the molar proportion of propionate (P ≤ 0.01). While cereal type did not affect DMI (P = 0.36) or total SCFA concentration (P = 0.61), use of oat hay improved DM digestibility (67.73 vs. 63.22% for oat and barley, respectively; P < 0.001) and increased nitrogen retention (P = 0.03) when compared to barley. Overall, incorporating pea into cereal hay increased DMI, reduced CP digestibility, and altered ruminal fermentation.