The Dietary Supplemental Effect of Nitroethanol in Comparison with Monensin on Methane Emission, Growth Performance and Carcass Characteristics in Female Lambs

SIMPLE SUMMARY: The objective of present study was to determine the effects of 2-nitroethanol (NEOH) in comparison with monensin on methane (CH(4)) emission, growth performance and carcass characteristics in female lambs. Both monensin and NEOH are potent CH(4) inhibitors that can reduce dietary energy loss. The average daily gain (ADG) and feed conversion rate were improved with monensin and NEOH addition, suggesting that NEOH in comparison with monensin presented a similarly lasting beneficial effect on feed efficiency for female lambs. In addition, monensin and NEOH increased the net muscle percentage to carcass weight (p = 0.03), and they caused a reduction in feed consumption and feed costs resulting in a higher net revenue and economic efficiency. In summary, NEOH in comparison with monensin presented a greater promoting effect on energy utilization in the female feedlotting lambs by inhibiting rumen methanogenesis more efficiently. ABSTRACT: This study was conducted to evaluate the dietary supplemental effects of 2-nitroethanol (NEOH) in comparison with monensin on methane (CH(4)) emission, growth performance and carcass characteristics in female lambs. Sixty female, small-tailed Chinese Han lambs (3.5 ± 0.3 month) were randomly allotted into three dietary treatment groups: (1) Control group, a basal control diet, (2) monensin group, the basal diet added with 40 mg/kg monensin, (3) NEOH group, the basal diet added with 277 mg/kg nitroethanol, and the feedlotting trial lasted for 70 days. Although dietary addition of monensin and NEOH did not affect nutrient digestibility of lambs, both monensin and NEOH decreased the calculated CH(4) production (12.7% vs. 17.4% decrease; p < 0.01). In addition, the CH(4) production represents less dietary energy loss in the monensin and NEOH group than in the control, indicating that monensin and NEOH are potent CH(4) inhibitors that can reduce dietary energy loss. Dietary addition of monensin and NEOH decreased dry matter intake (p < 0.01); however, they increased the ADG of female lambs (p < 0.01). As a result, both monensin and NEOH increased feed conversion efficiency of the feedlotting lambs (p < 0.01), suggesting that feed energy saved from CH(4) production promoted the feed efficiency and ADG in the present study. Except for the fact that NEOH addition increased the net muscle percentage to carcass weight (p = 0.03), neither monensin nor NEOH had a significant influence on carcass characteristics of female lambs (p > 0.05). From an economic point of view, NEOH and monensin caused a reduction in feed consumption costs, therefore resulting in a higher net revenue and economic efficiency than the control. In summary, dietary supplementation of NEOH in comparison with monensin presented a more promoting effect on energy utilization in female lambs by inhibiting rumen methanogenesis more efficiently, and NEOH improved the net revenue and economic efficiency more significantly than monensin.