Direct and maternal genetic effects for ascites-related traits in broilers.

The objective of the present study was to estimate heritabilities for ascites-related traits in broilers and to assess the importance of maternal genetic effects for these traits. Several traits related to ascites were measured on more than 4,000 broilers kept under cold conditions. Heritabilities were estimated using an animal model with a direct genetic effect and a model with direct and maternal genetic effects. Estimated heritabilities from the direct genetic effects model were 0.46 for hematocrit value, 0.42 for BW, 0.47 for right ventricular weight, 0.46 for total ventricular weight, 0.45 for ratio of right ventricular weight to the total ventricular weight, 0.32 for total mortality, and 0.18 for fluid accumulation in the heart sac. Maternal effects significantly influenced the traits BW, total ventricular weight, and total mortality. Direct and maternal heritabilities, respectively, for BW were 0.21 and 0.04, for total ventricular weights were 0.29 and 0.03, and for total mortality were 0.16 and 0.05. The heritability estimates for ascites-related traits and the significance of maternal genetic effects for most of these traits indicate that direct and maternal genetic effects play an important role in the development of the ascites syndrome.