Feeding 3-nitrooxypropanol reduces methane emissions by feedlot cattle on tropical conditions

Our objective was to evaluate the effects of feeding 3-nitrooxypropanol (3-NOP; Bovaer, DSM Nutritional Products) at two levels on methane emissions, nitrogen balance, and performance by feedlot cattle. In experiment 1, a total of 138 Nellore bulls (initial body weight, 360 +/- 37.3 kg) were housed in pens (27 pens with either 4 or 5 bulls per pen) and fed a high-concentrate diet for 96 d, containing 1) no addition of 3-NOP (control), 2) inclusion of 3-NOP at 100 mg/kg dry matter (DM), and 3) inclusion of 3-NOP at 150 mg/kg DM. No adverse effects of 3-NOP were observed on DM intake (DMI), animal performance, and gain:feed (P > 0.05). In addition, there was no effect (P > 0.05) of 3-NOP on carcass characteristics (subcutaneous fat thickness and rib eye area). In experiment 2, 24 bulls (initial BW, 366 +/- 39.6 kg) housed in 12 pens (2 bulls/pen) from experiment 1 were used for CH4 measurements and nitrogen balance. Irrespective of the level, 3-NOP consistently decreased (P < 0.001) animals' CH4 emissions (g/d; similar to 49.3%), CH4 yield (CH4/DMI; similar to 40.7%) and CH4 intensity (CH4/average daily gain; similar to 38.6%). Moreover, 3-NOP significantly reduced the gross energy intake lost as CH4 by 42.5% (P < 0.001). The N retention: N intake ratio was not affected by 3-NOP (P = 0.19). We conclude that feeding 3-NOP is an effective strategy to reduce methane emissions, with no impairment on feedlot cattle performance. The potential of 3-NOP in reducing daily CH4 emissions per animal daily, per kilogram dry matter intake, and average daily gain has been effective. 3-NOP consistently reduced CH4 emissions similar to 49.3%, methane yield similar to 40.7, and CH4 intensity similar to 38.6%. Lay Summary During fiber digestion in the rumen, enteric methane is produced. Methane is a potent greenhouse gas. Recently several studies have focused on developing synthetic compounds and their utilization as specific inhibitors of methanogenesis. 3-Nitrooxypropanol is a structural compound that can help to mitigate CH4 emissions. The objective of this study was to evaluate the effects of feeding 3-nitrooxypropanol (3-NOP; Bovaer, DSM Nutritional Products) at two levels on methane emissions, nitrogen balance, and performance by feedlot cattle. No effect of 3-NOP on animal performance and N balance was found. However, regarding CH4 production 3-NOP consistently decreased (P < 0.001) animals' CH4 emissions (g/d; similar to 49.3%), methane yield (CH4/dry matter intake; similar to 40.7%), and CH4 intensity (CH4/average daily gain; similar to 38.6%). This study provides information on the potential role of 3-NOP on reducing CH4 emissions from feedlot cattle without reducing animal performance.