The combined effects of supplementing monensin and 3-nitrooxypropanol on methane emissions, growth rate, and feed conversion efficiency in beef cattle fed high-forage and high-grain diets1

Abstract

The study objective was to evaluate the combined effects of supplementing monensin (MON) and the methane (CH4) inhibitor 3-nitrooxypropanol (NOP) on enteric CH4 emissions, growth rate, and feed conversion efficiency of backgrounding and finishing beef cattle. Two hundred and forty crossbred steers were used in a 238-d feeding study and fed a backgrounding diet for the first 105 d (backgrounding phase), transition diets for 28 d, followed by a finishing diet for 105 d (finishing phase). Treatments were as follows: 1) control (no additive); 2) MON (monensin supplemented at 33 mg/kg DM; 3) NOP (3-nitrooxypropanol supplemented at 200 mg/kg DM for backgrounding or 125 mg/kg DM for finishing phase); and 4) MONOP (33 mg/kg DM MON supplemented with either 200 mg/kg DM or 125 mg/kg DM NOP). The experiment was a randomized complete block (weight: heavy and light) design with 2 (NOP) × 2 (MON) factorial arrangement of treatments using 24 pens (8 cattle/pen; 6 pens/treatment) at the main feedlot and 8 pens (6 cattle/pen; 2 pens/treatment) at the controlled environment building (CEB) feedlot. Five animals per treatment were moved to chambers for CH4 measurements during both phases. Data were analyzed using a Mixed procedure of SAS with pen as experimental unit (except CH4). Location (Main vs. CEB) had no significant effect and was thus omitted from the final model. Overall, there were few interactions between MON and NOP indicating that the effects of the 2 compounds were independent. When cattle were fed the backgrounding diet, pen DMI was decreased by 7%, whereas gain-to-feed ratio (G:F) was improved by 5% with NOP supplementation (P < 0.01). Similarly, MON improved G:F ratio by 4% (P < 0.01), but without affecting DMI. During the finishing phase, DMI tended (P = 0.06) to decrease by 5% with both MON (5%) and NOP (5%), whereas ADG tended (P = 0.08) to decrease by 3% with MON. Gain-to-feed ratio for finishing cattle was improved with NOP by 3% (P < 0.01); however, no effects were observed with MON. 3-Nitrooxypropanol decreased CH4 yield (g/kg DMI) by 42% and 37% with backgrounding and finishing diets (P ≤ 0.01), respectively, whereas MON did not lower CH4 yield. Overall, these results demonstrate efficacy of NOP in reducing enteric CH4 emissions and subsequently improving feed conversion efficiency in cattle fed high-forage and high-grain diets. Furthermore, effects of NOP did not depend on whether MON was included in the diet.

Micrometeorological Methods for Measuring Methane Emission Reduction at Beef Cattle Feedlots: Evaluation of 3‐Nitrooxypropanol Feed Additive

“…The 70% reduction in CH 4 emissions due to 3‐NOP (125 mg kg −1 DM daily) was greater than the 12% (100 mg kg −1 DM daily; Vyas et al, 2018) and 41% (125 mg kg −1 DM daily; Vyas et al, 2018) reduction reported previously with beef cattle fed high grain diets containing 3‐NOP. Those studies measured CH 4 emissions using whole‐animal chambers.…”

The effects of dietary supplementation with 3-nitrooxypropanol on enteric methane emissions, rumen fermentation, and production performance in ruminants: a meta-analysis

“…2019R1F1A1056904). ments methods of CH 4 emissions among all used studies [12][13][14][15][16][17][18][19][20][21][22][23][24][25] (Table 1). In short, the administration methods of NOP were direct administration via cannula, top dressed, and mixed with diet.…”

“…The most important factor in investigating an effective CH 4 mitigation strategy in rumen is persistent efficacy. With our knowledge, total 5 in vivo studies were conducted to investigate the effects of NOP supplementation on sustained mitigation of CH 4 emission [15,16,19,22,25]. Romero-Perez et al [19], conducted a long-term study where eight ruminally cannulated heifers were fed a TMR, with a 60% forage ratio, supplemented with NOP (2 g/d of NOP) for about 146 d. Methane emissions were reduced up to 59% for both the g/d and g/kg of DMI in the NOP supplemented groups.…”

“…In the present meta-analysis, therefore, we hypothesized that NOP supplementation might be affected differently on rumen fermentation characteristics depending upon animal type adding recent in vivo studies which was not included in previous meta-analysis studies [13][14][15]25]. The aim of this study was to investigate the effects of NOP on enteric gas production, rumen fermentation, and animal performances depending on animal type using a meta-analysis approach.…”

“…The NOP is a structural analogue of methyl coenzyme-M, which inhibits the activity of methyl coenzyme-M reductase related to the final step of methanogenesis [11]. Until now, total 14 in vivo studies using NOP supplementation were performed on various domestic ruminants, including sheep [12], beef cattle [13][14][15][16][17][18][19], and dairy cattle [20][21][22][23][24][25]. According to the results of previous studies using NOP in vivo, the CH 4 emissions and proportion of acetate (% total volatile fatty acids, VFA) clearly decreased, whilst the proportion of propionate (% total VFA) significantly increased, but any adverse effects were not detected.…”