Simple SummaryBroilers were fed increasing levels of supplemental choline chloride in diets where methionine was minimally reduced (0.15%), reared under summer conditions for 41 days, and then processed. Supplemental choline improved broiler feed efficiency by reducing feed intake without altering body weight gain. Increasing dietary choline concentrations also increased carcass yield, breast yield, and the incidence and severity of wooden breast. It can be concluded that when broilers are reared under high environmental temperature and fed diets with reduced methionine, supplemental choline chloride can positively impact growth performance and carcass yields.AbstractCholine has been demonstrated to partially substitute methionine in broiler chicken diets due to their interconnected biosynthesis pathways. Yet, research on the impacts of dietary choline supplementation on modern strains of high-yielding broilers is limited. The objective was to evaluate the effect of increasing additions of choline chloride on the performance and carcass characteristics of broilers fed reduced methionine diets and reared under summer environmental conditions. Ross 708 x Yield Plus male broilers were reared for 41 days on used litter in floor pens (n = 2232; 31 birds per pen). Birds were fed one of six corn and soybean meal-based, reduced methionine diets containing 0, 400, 800, 1200, 1600, or 2000 mg of added choline chloride per kg of feed. Diets were provided in three phases. On day 43, 10 birds per pen were processed. Increasing dietary choline resulted in similar body weight gain, reduced feed intake, and improved feed efficiency. Choline chloride supplementation linearly increased both breast and carcass yields while concomitantly increasing the incidence and severity of wooden-breast-affected fillets. These results indicate that supplementing reduced-methionine broiler diets with choline chloride during high environmental temperatures may improve feed efficiency and increase carcass and breast yields but may also increase wooden breast.