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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 exp. 1, a total of 138 Nellore bulls (iBW, 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 days, containing 1) no addition of 3-NOP (control), 2) inclusion of 3-NOP at 100 mg/kg DM, and 3) inclusion of 3-NOP at 150 mg/kg DM. No adverse effects of 3-NOP were observed on DM intake, 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 exp. 2, 24 bulls (iBW, 366 ± 39.6 kg) housed in 12 pens (two bulls/pen) from Exp.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; ~ 49.3%), CH4 yield (CH4/DM intake; ~40.7%) and CH4 intensity (CH4/ADG; ~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.

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