Effect of Encapsulated Nitrate and Microencapsulated Blend of Essential Oils on Growth Performance and Methane Emissions from Beef Steers Fed Backgrounding Diets

SIMPLE SUMMARY: The use of supplemental dietary nitrate (NO(3)(−)) to minimize enteric methane (CH(4)) emissions from ruminants is hindered by potential toxicity effects. In the current study, the potential effects of feeding encapsulated NO(3)(−) (EN), microencapsulated blend of essential oils (MBEO), and their combination on growth performance and enteric CH(4) emissions of beef cattle were evaluated. There was no interaction effect between feeding EN and MBEO on CH(4) emissions and the presence of MBEO did not affect the potential of EN to reduce CH(4). Feeding MBEO increased CH(4) emissions without affecting animal performance. Inclusion of EN as a replacement for urea reduced CH(4) emissions without incurring any adverse effects on cattle health and performance. ABSTRACT: A long-term study (112 days) was conducted to examine the effect of feeding encapsulated nitrate (NO(3)(−)), microencapsulated blend of essential oils (EO), and their combination on growth performance, feeding behavior, and enteric methane (CH(4)) emissions of beef cattle. A total of 88 crossbred steers were purchased and assigned to one of four treatments: (i) control, backgrounding high-forage diet supplemented with urea (1.17% in dietary DM); (ii) encapsulated NO(3)(−) (EN), control diet supplemented with 2.5% encapsulated NO(3)(−) as a replacement for urea (1.785% NO(3)(−) in the dietary DM); (iii) microencapsulated blend of EO (MBEO), control diet supplemented with 150 mg/kg DM of microencapsulated blend of EO and pepper extract; and (iv) EN + MBEO, control diet supplemented with EN and MBEO. There was no interaction (p ≥ 0.080) between EN and MBEO on average dry matter intake (DMI), average daily gain (ADG), gain to feed ratio (G:F), feeding behavior, and CH(4) emission (using GreenFeed system), implying independent effects of feeding EN and MBEO. Feeding MBEO increased CH(4) production (165.0 versus 183.2 g/day; p = 0.005) and yield (18.9 versus 21.4 g/kg DMI; p = 0.0002) but had no effect (p ≥ 0.479) on average DMI, ADG, G:F, and feeding behavior. However, feeding EN had no effect on ADG and G:F (p ≥ 0.119) but reduced DMI (8.9 versus 8.4 kg/day; p = 0.003) and CH(4) yield (21.5 versus 18.7 g/kg DMI; p < 0.001). Feeding EN slowed (p = 0.001) the feeding rate (g of DM/min) and increased (p = 0.002) meal frequency (events/day). Our results demonstrate that supplementing diets with a blend of EO did not lower CH(4) emissions and there were no advantages of feeding MBEO with EN. Inclusion of EN as a replacement for urea reduced CH(4) emissions but had no positive impact on animal performance.