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The objective with this trial was to evaluate the potential of ionophore (33 mg of monensin/kg DM) and condensed tannins (offered at 3% of DMI) to mitigate enteric methane production by beef steers fed corn dried distiller's grain (DDG) in finishing diets. Eight British-cross steers, 12 ± 2 mo old weighing 212 ± 11.7 kg, were assigned to two replicated Latin rectangle design (LRD, n = 32) to evaluate four treatments: control (no DDG or feed additive), DDG (40% DDG inclusion), DDGI (40% DDG inclusion + ionophore), and DDGCT (40% DDG inclusion + condensed tannins). Animals were randomly assigned to the diets fed at an intake of 2.5% of BW (DM basis). Animals were adapted to the diets for 14 d prior to collection periods. Enteric methane measurements were collected in two open circuit respiration, pull mode chambers in which animals were fed twice daily 0800 and 1600 h. The data acquisition consisted of a 48-h period of measurements (runs). The statistical analysis was performed using random coefficients model methodology in SAS 9.4 (SAS Inst., Cary, NC) assuming fixed effects of treatment (diet) and random effects of animals and runs. An effect of diet was observed (P< 0.001) for CH4 (L/d) production at 12h, 24h and 36h, but not at 48h. The addition of DDG significantly decreased CH4(L/d; P< 0.001) at 12h, 24h, 36h, and 48h when compared to the control diet. Additionally, the inclusion of ionophore and condensed tannins decreased CH4 production (L/d; P< 0.001) at 12h, 24h and 36h, but only DDGCT decreased CH4 production (L/d; P< 0.001) at 48h when compared to the control diet, suggesting a more prolonged effect of condensed tannins over enteric CH4 mitigation. At 24h DDG, DDGI, and DDGCT diets were not different for CH4 production (L/d; P< 0.001), but at 36h DDGI and DDGCT had a significant effect on CH4 mitigation when compared to the control or DDG. Our results indicated that DDGCT was a prominent CH4 reducer over 48h followed by the DDGI treatment. The inclusion of ionophore and condensed tannins to DDG-based diets significantly affected enteric CH4 production (L/d; P< 0.001). |
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