PSXIV-41 Warm-season annual or perennial hay fed to growing beef steers with or without dried distillers grains supplementation: ruminal fermentation characteristics, digestion, and feeding behavior

Abstract

Abstract The effects of hay type and protein supplementation on intake, feeding behavior, nutrient digestion, and ruminal digestion characteristics were evaluated. Ruminally cannulated Angus beef steers (n = 6; BW = 304 kg ± 11 kg) were randomly assigned within a sequence of treatments using a 4 × 6 unbalanced Latin square design (6 steers; and 4 diets; fed once-daily). A 2 x 2 factorial treatment arrangement was used as follows: 1) ‘WW-B. Dahl’ Old World bluestem [Bothriochloa bladhii (Retz) S.T. Blake; WWBD or Eragrostis tef (Zucc.) Trotter; TEFF); and 2) dried distillers grain (DDGS) at 0 or 0.5% BW. Each period consisted of a 14-d of adaptation and 7-d collection. Steers were observed (5-min intervals, 24 h) for behavioral assessment; while ruminal pH was continuously measured (wireless pH probe), and ruminal fluid collected at 0, 2, 4, 8, and 16 h after-feeding. Steers fed TEFF hay and those fed DDGS (both, P = 0.04) had greater DMI compared to WWBD and not supplemented. Chewing activity did not differ (P ≥ 0.54). Non-supplemented steers spent more time eating hay (P < 0.01) than supplemented steers. Average ruminal pH of TEFF (6.32) was lower (P > 0.01) than WWBD (6.56). Non-supplemented steers produced less in vitro total gas and methane (both, P = 0.02) per g rumen fluid DM. The VFA profile was not affected (P ≥ 0.45) by treatments. Apparent total-tract digestibility and ruminal degradation (P ≤ 0.01) were greater with TEFF fed steers than WWBD. Hemicellulose digestion was reduced by 6.95% (P = 0.03) with DDGS supplementation. An annual hay in place of a conventional perennial hay improved intake, ruminal digestion of nutrients, without affecting feeding behavior, while supplementation with DDGS reduced forage intake time and quantity, without negatively affecting ruminal fiber digestion.