Feeding Management Strategies to Mitigate Methane and Improve Production Efficiency in Feedlot Cattle

SIMPLE SUMMARY: Decreasing enteric CH(4) emissions and nutrient excretion in feces and urine by growing and finishing beef cattle is an important climate-related goal for the beef industry. Feeding management systems such as programming cattle to achieve a specific rate of gain or restricting feed intake relative to predicted or observed ad libitum intake could be important tools to decrease overall feed intake and thereby decrease CH(4) emissions and nutrient excretion. These management systems can increase the efficiency of gain relative to ad libitum feeding, but they can also increase time on feed, which offsets the effects of decreased feed intake. Using programmed feeding instead of traditional growing programs based on high-forage diets should decrease enteric CH(4) emissions and nutrient excretion. For feedlot finishing, incorporating programmed or restricted feeding for a portion of the finishing period will have limited effects on CH(4) emissions unless gain efficiency is increased during programming or in a subsequent ad libitum feeding period. Defining optimal feeding management systems that will reproducibly decrease enteric CH(4) emissions and nutrient excretion should be the focus of future research. ABSTRACT: Mitigation of greenhouse gases and decreasing nutrient excretion have become increasingly important goals for the beef cattle industry. Because feed intake is a major driver of enteric CH(4) production and nutrient excretion, feeding management systems could be important mitigation tools. Programmed feeding uses net energy equations to determine the feed required to yield a specific rate of gain, whereas restricted feeding typically involves decreasing intake relative to the expected or observed ad libitum intake. In the context of growing/finishing systems typical of those in the United States and Western Canada, experimental results with programmed and restricted feeding have often shown decreased overall feed intake and increased gain efficiency relative to ad libitum feeding, but too much restriction can negatively affect harvest weight and associated carcass quality. Slick feed bunk management is a time-based restriction that limits day-to-day variation in feed deliveries, but the effects on intake and performance are not well defined. Simulations to estimate enteric CH(4) emission and nitrogen excretion indicated that programmed feeding of a high-grain diet could appreciably decrease CH(4) emissions and nitrogen excretion compared with traditional growing programs based on high-forage diets. For feedlot finishing, programming gain for a portion of the feeding period will decrease CH(4) emission and N excretion only if cattle perform better than expected during the programmed phase or if compensatory growth occurs when cattle are transitioned to ad libitum feeding. Optimal approaches to implement programmed or restricted feeding that will yield increased efficiency should be the subject of future research in this area.