Estimation of genetic parameters for fat deposition and carcass traits in broilers.

Abdominal and subcutaneous fat are regarded as the main sources of waste in the slaughterhouse. Fat stored intramuscularly is regarded a favorite trait related to meat quality. The objective of current study was to estimate genetic parameters for fat deposition in the 3 different parts of body and their relationships with other carcass traits. Traits were recorded for 1,752 females and 1,526 males from a meat-type chicken line. Heritability estimates for abdominal fat percentage, skin percentage as a measure of subcutaneous fat, and intramuscular fat percentage were 0.71, 0.24, and 0.08, respectively. Heritabilities of the other carcass traits were moderate to high (0.28 to 0.73). There was a high genetic correlation between abdominal fat weight and skin weight (0.54), whereas the genetic correlation between abdominal fat weight and intramuscular fat percentage was almost zero (0.02). The BW at 7 wk showed a positive genetic correlation with fat production traits, which were high for intramuscular fat percentage (0.87) and moderate for skin percentage (0.17) and abdominal fat percentage (0.13). Therefore carcass traits could be improved by selection for increased breast muscle and reduced abdominal fat without decreased intramuscular fat.