-
Views
-
Cite
Cite
C. J. Boardman, T. A. Wickersham, L. A. Trubenbach, J. E. Sawyer, 086 Effects of monensin and dietary energy intake on diet utilization, VFA profile and ruminal fill in beef steers, Journal of Animal Science, Volume 94, Issue suppl_1, February 2016, Page 43, https://doi.org/10.2527/ssasas2015-086
Close - Share Icon Share
Abstract
Digestibility is known to be increased in limit-fed cattle, while ionophores are known to alter ruminal fermentation. However, there is limited literature on combining these feeding techniques. Sixteen ruminally cannulated Angus×Hereford steers (BW 288 ± 20 kg) were used in an experiment designed to examine the effects of ionophore inclusion and intake on digestibility, ruminal pH, VFA concentrations and ruminal fill. A total mixed ration (TMR; 1.54 Mcal NE/kg) was used to apply treatments in a 2´2 factorial arrangement. Two levels of NE intake (80%, L; and 120%, H predicted NRC requirements) were fed either without (0) or with (200) monensin (mg·hd-1·d-1). Steers were adapted to diets for 14-d, followed by 4-d for measurement of intake and digestion, 1-d for collecting ruminal fermentation parameters, and 1-d to determine ruminal fill. Steers fed L had greater (P < 0.01) digestion of DM, OM, ADF and GE than those fed H, while monensin did not affect digestion (P > 0.15). Observed values of DE (Mcal/kg DM) were greater (P < 0.01) for L (2.90) than H (2.68, but were not affected (P = 0.74) by monensin inclusion. Passage rate was slower (P < 0.01) for L (1.70% / hr) than H (2.37% / hr) and for 200 (1.90%/hr) compared to 0 (2.16% / hr; P = 0.03). Ruminal DM (total kg and %BW) was greater in H (P < 0.01) compared to L and for 200 compared to 0 (P < 0.05). Mean rumen pH over a 16-h period was greater (P = 0.01) for L than H (6.49 vs. 6.33 respectively) and for 200 compared to 0 (6.49 vs. 6.34 respectively; P = 0.02). Acetate:propionate was unaffected (P < 0.01) by intake level, but was lower (P < 0.01) for 200 (2.39) compared to 0 (3.1). Total VFA concentration was lower (P = 0.03) for L than H and lower (P <0.01) for 200 than 0. Results suggest that digestibility increases with intake restriction, potentially providing a pathway for increasing dietary energy extrapolation. Data also supports historical literature, indicating that monensin alters ruminal fermentation, such that NE efficiency is increased through end product utilization.
