Identifying Forage Efficient Cows

Abstract In recent years, substantial progress has been made in understanding the sources of biological variation and genetic components of feed efficiency in growing animals consuming energy-dense mixed diets during the post-weaning phase. Much less is known about within-animal variation of feed efficiency for beef cows consuming moderate to low-quality forage diets common to most cow/calf production systems and where > 74% of the total feed energy required to produce beef is consumed. Considerable evidence indicates the existence of a genetic by environment interaction for feed efficiency. Therefore, more rapid progress in forage utilization efficiency and reduction in greenhouse gas emissions in the cow herd could be made by studying feed efficiency when cattle consume moderate quality, unprocessed forage diets. Phenotype for feed intake and feed efficiency are most practically and cost effectively determined during the post-weaning growing stage. However, due to the additional nutrient sinks associated with gestation and lactation, little is known about the repeatability of forage utilization efficiency between growing heifers and beef cows. An update of recent advancements to identify forage-efficient cows will be provided during the presentation.