Meta-analysis of poultry organ weights and their relationship with meat yield

Late-stage mortality is a significant challenge for the poultry industry, leading to substantial economic losses, concerns about animal welfare, and operational sustainability. Heart-related conditions, including ascites syndrome, pulmonary hypertension syndrome, hypertrophic cardiomyopathy, and sudden death syndrome, contribute significantly to this issue. The increasing prevalence of these conditions is potentially linked to intense selection pressure aimed at maximizing meat yield, particularly breast meat. However, the precise relationship between meat yield, heart size and cardiovascular health remains unclear. To address this, a systematic literature review and meta-analysis were conducted to explore the relationship between breast meat yield and organ size (heart, lungs, liver), in which 91 publications meeting specific inclusion criteria were identified. Data extracted included variables such as live weight, portion yields (breast, leg, wing), organ weights (heart, lungs, liver), and the prevalence of heart-related conditions (pulmonary hypertension syndrome, ascites syndrome). A backward selection modeling approach was used to develop linear mixed models, treating the study as a random effect, to examine the relationship between organ weights as a percentage of body weight (% BW), meat yield and other animal attributes. The best heart weight model (% BW) included the effects of sex, species (chicken or turkey), bird purpose (meat or egg), breast meat yield (%), and live weight (g). The best liver weight model (% BW) included species, bird purpose, breast meat yield (%), and live weight (g). The best lung weight (% BW) model included heart weight (g). Model performance was evaluated using residuals analysis, root mean squared prediction error, and the concordance correlation coefficient. Findings suggest that laying hens have larger hearts relative to body weight compared to broiler chickens and turkeys. The liver and lung models revealed that broiler chickens had larger livers (% BW) compared to laying hens, and that lung weight (% BW) was negatively correlated to heart weight (g). These results highlight the potential need to consider organ health in breeding programs focused on meat yield.