230 Effects of encapsulated calcium-ammonium nitrate on performance and methane production of beef steers grazing mixed winter forage

Abstract

Abstract The effects of encapsulated calcium-ammonium nitrate (eCAN) on in vivo methane production and performance were evaluated. A generalized randomized block design was used with beef steers grazing a mixed winter forage (Triticum aestivum, Triticosecale rimpaui, and Secale cereale) for 49 d. Thirty-six Angus-crossbred steers (332 ± 53 kg) were blocked by BW and randomly assigned to 1 of 3 treatments: 1) winter pasture + corn (WC), 2) WC + 328 mg/kg of BW eCAN (WCN) and 3) WC + 124 mg/kg of BW UREA (WCU), all supplemented with corn (0.3% BW treatments). Treatments WCN and WCU were isonitrogenous. A 14d adaptation period was used to adapt cattle to treatments. Methane emissions were measured using the sulfur hexafluoride tracer technique. Blood samples and BW were taken at d 0, 24, 35, and 49. Supplemental corn and NPN orts were collected daily. Data were analyzed using the MIXED procedure of SAS with the fixed effect of treatment and random effect of pasture (block); BUN, supplement intake and CP intake were analyzed with repeated measures. Steer was considered the experimental unit. Methane production was not different (P > 0.05) considering g/d, g/kg of BW, g/kg of MBW, or g/kg of ADG. Treatments did not affect ADG (P = 0.941). Supplement intake was affected by treatment (P < 0.001), with WC (0.979 kg) being greater compared to WCU (0.887 kg) and WCN (0.706 kg). Total CP intake increased (P < 0.001) with WCU (0.155 kg) and WCN (0.116 kg), compared to WC (0.074 kg), which did not have a non-protein source. Blood urea nitrogen was affected by day, with d 24 (18.598 mg/dL) being greater compared to d 0 (8.215 mg/dL), 35 (10.549 mg/dL) and 49 (14.5744 mg/dL). The eCAN did not effectively replace urea as a NPN source to mitigate enteric methane.