Utilizing gas flux from automated head chamber systems to estimate dietary energy values for beef cattle fed a finishing diet

Authors: PROCTOR, JARRET - Texas A&M University; SMITH, JASON - Texas A&M Agrilife; LONG, NATHAN - Texas A&M University; Gunter, Stacey; GOUVÊA, VINÍCIUS - Texas A&M Agrilife; Beck, Matthew

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2024
Publication Date: 6/12/2024
Citation: Proctor, J.A., Smith, J.K., Long, N.S., Gunter, S.A., Gouvêa, V.N., Beck, M.R. 2024. Utilizing gas flux from automated head chamber systems to estimate dietary energy values for beef cattle fed a finishing diet. Journal of Animal Science. 102. Article skae167. https://doi.org/10.1093/jas/skae167.
DOI: https://doi.org/10.1093/jas/skae167

Interpretive Summary: Traditionally, energetic studies with beef cattle require restraining animals in respiration chambers, which limits normal behavior and can reduce voluntary feed intake. As such, using respiration chambers to assess energetic efficiency of feeds and animals may not be wholly representative of what occurs in production settings. As such, conducting experiments with unrestrained cattle may be important. The GreenFeed system (C-Lock Inc., Rapid City, South Dakota) may provide an alternative method to respiration chambers to assess energetic efficiency of unrestrained cattle. Another means to estimate energetic efficiency of cattle can be achieved through calculations based on observed animal performance. To date there has been no investigation into using the GreenFeed system to assess energetic efficiency and to assess its agreement with values derived from observed animal performance. Accordingly, scientists from ARS in Bushland, TX and Woodward, OK, as well as from Texas A&M University; Texas A&M AgriLife Research and Extension aimed to determine the agreement between these two systems to estimate dietary energy values. Doing so may provide a means to independently validate the GreenFeed system’s use in energetic experiments. There was excellent agreement between energy values estimated from observed performance and the GreenFeed system. This indicates that the GreenFeed system is adequate in conducting energetic experiments in feedlot cattle.

Technical Abstract: Dietary net energy for maintenance (NEm) and gain (NEg) can be estimated using calculations based on live performance or adjusted-final body weight, which is calculated based on carcass characteristics and these values are commonly referred to as performance adjusted (pa) NEm (paNEm) and NEg (paNEg). The NEm and NEg of a diet can also be estimated by adding recovered energy (RE) with heat production (HP) derived from an automated head chamber system (AHCS), which we will term gas-adjusted (ga) NEm (gaNEm) and NEg (gaNEg). Furthermore, HP from the Brouwer’s equation requires an estimate of urine nitrogen (UN) excretion, which can be calculated based on N intake, blood urea N, and UN concentration and urine creatinine, or it could be simply ignored. Alternatively, HP can be calculated using an alternative equation based on respiratory quotient. Demonstrating agreement between pa and ga derived dietary energy values provides an opportunity to independently validate using the AHCS for energetic experiments and this comparison has not been conducted previously. Accordingly, the objective of this experiment was to assess the agreement between live and carcass paNEm and paNEg with gaNEm and gaNEg, where HP was calculated using 4 different approaches. Estimation of HP was not different (P = 0.99) between the 4 approaches employed, indicating that all options investigated are appropriate. Live paNEm and paNEg [Lin’s concordance correlation coefficient (CCC) = 0.91] had higher agreement with gaNEm and gaNEg than carcass values (CCC = 0.84). These results suggest that researchers can implement the AHCS to provide estimates of dietary energy values in cattle that are unrestrained.