Weight and Fat Content of Adipose and Nonadipose Tissues in Broilers Selected For or Against Abdominal Adipose Tissue

Abstract After two generations of divergent sib selection for or against abdominal adipose tissue (AT) in broilers, combined with within-family selection of males for body weight, a difference of approximately 100% in the weight of the abdominal AT was found between the high-fat (HF) and low-fat (LF) lines at 9 weeks of age. The weight and fat concentration of five AT (abdominal, gizzard, sartorial, neck, and mesenterial) were determined in 4- and 9-week-old chicks from the two lines. The relative weight (g/100 g body weight) of all the AT, except mesenterial AT, was significantly higher in the HF than in the LF line at the two ages. The line differences in adiposity increased further in the S3 generation. In the HF line, AT relative weight either increased with age or remained unchanged. In the LF line, a decrease in the relative weight of some of the AT was observed. Low and nonsignificant correlations were found between body weight and the weight of the various AT within each line-sex group. Abdominal AT was highly correlated with the other AT studied. The concentration of fat in all the AT was 5 to 10% larger in the HF than in the LF chicks. Similar differences were found between ages and sexes; they could be related to the degree of development of the AT. Liver and blood plasma of the HF chicks had higher fat concentration than those of the LF chicks. The fat concentration of the breast muscle and the empty carcass was not affected by the selection. Breast weight, as percentage of body weight, was significantly higher in the LF chicks.