This document summarizes work to improve the representation of livestock in the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT) model. Key improvements include disaggregating livestock production across systems, capturing differences in feed requirements, and linking available feeds to landscape and market sources. The modeling framework accounts for demand and supply-side factors, models livestock feed mixes and stocking rates. It also examines interactions between livestock, aquaculture, and use of co-products as animal feed under different scenarios. Remaining challenges include better representing rangelands and incorporating direct impacts of heat and water stress.