Assessing the potential of a novel feed additive and an unsaturated fat alone and in combination to lower methane emission from cattle and reduce their contribution to climate change

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University of Delaware
Methane (CH4) emissions from enteric fermentation of ruminant animals, such as beef and dairy cattle, makes up approximately 2.5% of the total greenhouse gas emissions in the United States and can account from anywhere between 2 and 12% of gross energy intake (GEI) (Johnson and Johnson, 1995; IPCC, 2013; EPA, 2015). Therefore, there is an immediate need to decrease CH4 emission for both environmental as well as economic reasons (Beauchemin et al., 2008). The objective of this study was to assess the potential of 3-nitrooxypropanol, a novel CH4 inhibitor; and canola oil, a known methane mitigant; alone and in combination on CH4 emissions, rumen fermentation, and diet digestibility. Eight ruminally cannulated beef heifers (Angus cross, 732 ± 43 kg) were used in a double 4 × 4 Latin square design with four 28-d periods and assigned to one of four dietary treatments. The dietary treatments were: 1) control (CON) (no supplementation of 3-nitrooxypropanol or canola oil), 2) canola oil alone (OIL) (5% of diet DM), 3) 3-nitrooxypropanol alone (NOP) (200 mg/kg of diet dry matter (DM); DSM Nutritional Products Ltd., Kaiseraugst, Switzerland), and 4) 3-nitrooxypropanol and canola oil combined (NOP+OIL). After a 14-d diet adaption, dry matter intake (DMI) was recorded daily. Rumen contents were collected on d 14 and 17 for volatile fatty acid (VFA) analysis and protozoal populations. Enteric CH4 emissions were measured on d 18 to 21 using open circuit chambers. Diet digestibility was measured on d 24 to 27. Methane production was lowered from 26.2 (CON) to 19.6, 17.9, and 12.7 g/kg of DMI, for OIL, NOP, and NOP+OIL, respectively (P < 0.01). Total VFA concentrations (mM) were greatest for CON (101.3), similar between OIL (94.8) and NOP (94.8), and lowest for NOP+OIL (88.3) (P < 0.01). A decrease in acetate and increase in propionate proportions, and therefore a decrease in the acetate: propionate ratio was also observed with the OIL, NOP, and NOP+OIL treatments compared with CON (P < 0.01). The OIL and NOP+OIL treatments had a reduction in protozoa counts and a reduction in DM, organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibilities when compared to CON and NOP (4.43 × 104 vs. 4.24 × 105/ mL rumen fluid; 60.7 vs. 66.8%; 62.0 vs. 68.7%; 47.6 vs. 61.0%; and 46.5 vs. 60.0%, respectively; P < 0.01). The results indicated that OIL and NOP are effective means of decreasing CH4 production, and the combination of both caused the greatest reduction of CH4 emissions in cattle.
Biological sciences, Health and environmental sciences, 3-nitrooxypropanol, Canola oil, Cattle, Methane