Automated head chamber systems (AHCS) implemented into beef cattle research allow estimation of gas flux, heat production (HP), and calculated gas-adjusted dietary net energy for maintenance (gaNE_m) and gain (gaNE_g) values when paired with recovered energy. However, a comparison between AHCS-derived values and performance-adjusted NE_m (paNE_m) and NE_g (paNE_g) from either live performance (live paNE_m and paNE_g) or carcass data (carcass paNE_m and paNE_g) has not been conducted. Accordingly, the objectives of this experiment were to evaluate the agreement between gaNE_m and gaNE_g, estimated using different approaches for calculating HP, with live paNE_m and paNE_g or carcass paNE_m and paNE_g. Accounting for urinary nitrogen or methane when calculating HP does not appreciably influence HP estimates or subsequent calculations to estimate dietary NE_m and NE_g. There was excellent agreement between live paNE_m and gaNE_m, and between paNE_g and gaNE_g. Measures of precision, accuracy, and agreement were lower for carcass than for live-derived values when compared to gaNE_m and gaNE_g but were still acceptable. These results suggest that researchers can implement the AHCS to provide estimates of HP, gas flux, and estimates of dietary energy values in unrestrained finishing beef cattle-fed diets ranging in crude protein content (10.8% to 12.5%). Additional research is warranted on the use of the AHCS to conduct energetic studies across varying diets and production systems, particularly grazing systems.

Read the full article in the Journal of Animal Science.