Logan Thompson, sustainable grazing systems & Carlee Salisbury, graduate student
Sustainability is a topic that has been commonly discussed, sometimes at a frustrating frequency, as something the beef industry needs to make progress on, on several fronts. Today, the aspect of sustainability that is brought up by consumers, policymakers and industry members is greenhouse gas emissions. Really, what the conversation is about is carbon. Either carbon in the soil as a result of sequestrated carbon dioxide (CO2) or methane (CH4) produced as a byproduct of rumen fermentation. This is a potent greenhouse gas (GHG) with a global warming potential of 28 times that of CO2 over a 100-year time horizon and is responsible for 30% of the methane budget in the U.S.
When it comes to CH4 emissions, there is considerable interest and research funding being invested in developing new tools to reduce emissions from cattle, particularly those in confinement. For example, 2 feed additives have reached the market in recent years with air quality or greenhouse gas claims – 1) Bovaer – approved for use in dairy cattle to reduce enteric CH4 emissions, and 2) Experior – approved for use in feedlot cattle to reduce ammonia emissions. While these compounds will have utility for the industry, a one size fits all approach, or “silver bullet”, to reduce emissions will not work for all 
producers or production sectors. Further, as carbon markets mature it is expected that there will be numerous pathways for producers to receive compensation for management changes that reduce emissions beyond technological interventions. Management strategies that could fall under a “Best Management Practices” umbrella, such as improved grazing management, proper supplementation, and feed management could all potentially be utilized by carbon markets considering their low adoption rates across the industry
Many growing cattle in the Great Plains are fed on family-owned farms and feedlots, and a frequent management strategy is limit-feeding because of observed increases in animal efficiency with a moderate reduction in intake below ad libitum. We decided to explore this from a carbon credit prospective with a series of finishing trials conducted at Kansas State University and South Dakota State University. Finishing steers were either fed ad libitum, 96 percent of ad libitum or 92 percent of ad libitum. We observed no differences in average daily gain or feed efficiency between the restricted and ad libitum cattle, but carcass quality was reduced for the 92 percent ad libitum steers. However, steers fed 96% ad libitum emitted 17% less enteric CH4 emissions than ad libitum fed steers. Therefore, if carbon prices reach a level to compensate for any potential reduction in carcass quality that may occur when limit feeding finishing cattle, it may be a viable and easy to adopt strategy for some producers to enter carbon markets.
Measuring enteric CH4 emissions and common supplementation strategies have not been extensively conducted and little work has been done in collaboration with beef cattle producers. This is a key knowledge gap as grazing management is one of the most practical ways to reduce the environmental footprint of grazing beef production. In my job as the “Sustainability Guy” at K- State Animal Science and Industry, I often refer to the reality that the last robust measurements of best management practices that impact GHG emissions were published 20 years ago, and the work was conducted 25 years ago in Louisiana. The Louisiana results will have limited relevance for beef producers in Kansas, with the primary forages utilized in that study being fertilized bermudagrass, bahiagrass, and ryegrass pastures. In an effort to examine Kansas management strategies, we looked at the impact of different supplementation strategies on beef heifers grazing low (<3.5 percent crude protein) quality dormant pasture containing big bluestem, indiangrass, and switchgrass. Heifers were sorted into treatment groups to receive: 1) 2 lbs per head per day of a 30% CP hand-fed supplement, fed 3 days per week or, 2) a self-fed protein block that contained 20% crude protein. Heifers were supplemented approximately 50 days from April through late May prior to moving to summer pastures. No differences were observed in heifer performance over the supplementation period. A difference was found in enteric CH4 emissions, with the hand-fed heifers emitting 9% less enteric CH4 than their self-fed counterparts. While more replication is needed to confirm this, it does follow the rationale that supplementation that corrects nutritional imbalances (i.e. protein and energy in these pastures) improves ruminal fermentation efficiency, while also having the benefit of reducing GHG emissions.
If you are interested in reading why we are focused on sustainability, I would encourage you to read the read more here: https://www.ncba.org/producers/sustainability
