Measuring feed intake in cows.

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. Considerable evidence indicates the existence of a genetic by environment interaction for feed efficiency. 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, and the cost, labor and technology required to measure economically relevant traits in mature cows, little is known about forage utilization efficiency in beef cows. The beef cow/calf segment of the industry represents, by far, the greatest opportunity to reduce beef production input costs and reduce the industry's carbon footprint. We reason that selection tools for feed intake and feed efficiency developed over the last 20 years are effective for the post-weaning growing and finishing phases, although only marginally effective for beef cows consuming unprocessed, moderate to low-quality forage. In this session, we will discuss challenges, opportunities, and experiences associated with measuring forage intake and recovered energy in beef cows. [ABSTRACT FROM AUTHOR]