Effect of dried distillers’ grains plus solubles on enteric methane emissions and nitrogen excretion from growing beef cattle.

Hünerberg, M., McGinn, S.M., Beauchemin, K.A., Okine, E.K., Harstad, O.M., and McAllister, T.A. (2013). "Effect of dried distillers’ grains plus solubles on enteric methane emissions and nitrogen excretion from growing beef cattle.", Journal of Animal Science, 91(6), pp. 2846-2857. doi : 10.2527/jas.2012-5564  Access to full text

Abstract

The objectives of this study were to examine the impact of corn- or wheat-based dried distillers’ grains with solubles (CDDGS, WDDGS) on enteric methane (CH4) emissions from growing beef cattle, and determine if the oil in CDDGS was responsible for any response observed. Effects of CDDGS or WDDGS on total N excretion and partitioning between urine and fecal N were also examined in this replicated 4 × 4 Latin square using 16 ruminally cannulated crossbreed heifers (388.5 ± 34.9 kg of initial BW). The control diet contained (DM basis) 55% whole crop barley silage, 35% barley grain, 5% canola meal, and 5% vitamin and mineral supplement. Three DDGS diets were formulated by replacing barley grain and canola meal (40% of the dietary DM) with CDDGS, WDDGS, or WDDGS plus corn oil (WDDGS+oil). For WDDGS+oil, corn oil was added to WDDGS (4.11% fat DM basis) to achieve the same fat level as in CDDGS (9.95% fat DM basis). All total mixed diets were fed once daily ad libitum. Total collection of urine and feces was conducted between d 11 and 14. Enteric CH4 was measured between d 18 and 21 using 4 environmental chambers (2 animals fed the same diet per chamber). Methane emissions per kg of DM intake (DMI) and as % of GE intake (GEI) among heifers fed WDDGS (23.9 g/kg DMI and 7.3% of GEI) and the control (25.3 g/kg DMI and 7.8% of GEI) were similar (P = 0.21 and P = 0.19), while heifers fed CDDGS (21.5 g/kg DMI and 6.6% of GEI) and WDDGS+oil (21.1 g/kg DMI and 6.3% of GEI) produced less (P <0.05) CH4 Total N excretion (g/d) differed (P < 0.001) among treatments with WDDGS resulting in the highest total N excretion (303 g/d) followed by WDDGS+oil (259 g/d), CDDGS (206 g/d) and the control diet (170 g/d), respectively. Compared to the control diet, heifers offered WDDGS, CDDGS and WDDGS+oil excreted less fecal N (P < 0.001), but more (P < 0.001) urinary N. Results suggest that high-fat CDDGS or WDDGS+oil can mitigate enteric CH4 emissions in growing beef cattle. However, to completely assess the impact of dried distillers’ grains with solubles on greenhouse gas emissions of growing feedlot cattle the potential contribution of increased N excretion to heightened NH3 and nitrous oxide emissions requires consideration.

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