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., McAllister, T.A. (2013). Effect of dried distillers grains plus solubles on enteric methane emissions and nitrogen excretion from growing beef cattle, 91(6), 2846-2857. http://dx.doi.org/10.2527/jas.2012-5564
The objectives of this study were to examine the impact of corn-or wheat-based dried dis-tillers grains with solubles (CDDGS or WDDGS) on enteric methane (CH4) emissions from growing beef cattle and determine if the oil in CDDGS was respon-sible 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 replicat-ed 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 bar-ley silage, 35% barley grain, 5% canola meal, and 5% vitamin and mineral supplement. Three dried distillers grains with solubles (DDGS) diets were formulated by replacing barley grain and canola meal (40% of 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 col-lection 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 kilo-gram of DM intake (DMI) and as percent 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) whereas 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 greatest total N excretion (303 g/d) fol-lowed by WDDGS+oil (259 g/d), CDDGS (206 g/d), and the control diet (170 g/d), respectively. Compared with 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 com-pletely assess the impact of DDGS on greenhouse gas emissions of growing feedlot cattle, the potential contri-bution of increased N excretion to heightened NH3 and nitrous oxide emissions requires consideration. © 2013 American Society of Animal Science. All rights reserved.
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