Adipose cellularity in nonselected and selected broiler stocks: measurements at equal weights and ages

A population of nonselected broilers (AC) and a stock of commercial broilers (C) differ in growth characteristics. The two stocks of broilers were examined for differences in adipose tissue at equal ages at 28 and 54 days of age and at equal body weights. Body composition and abdominal adipose tissue were measured. Total adipocyte number, adipocyte size distributions, and DNA content of the abdominal fat pad were determined. Partial correlations of abdominal fat, expressed as a percentage of body weight, with mean adipocyte volume and abdominal adipocyte number were calculated. Body weights of C birds were greater than body weights of AC birds at 28 days of age (903 +/- 21 and 355 +/- 12 g; X +/- SE) and at 54 days of age (2,410 +/- 45 and 892 +/- 31 g). Abdominal fat pads were heavier in C birds than in AC birds on an absolute basis (P less than .01) and as a proportion of body weight (P less than .01). The C birds had more and larger adipocytes than AC birds at equal weights (P less than .05) and equal ages (P less than .01). Age did not significantly affect adipocyte size in AC birds, but adipocytes were larger in C birds at 28 days of age (117.3 vs. 78.8 pL, P less than .01) and further increased in size at 54 days (177.3 vs. 79.1 pL, P less than .01) when compared with those in AC birds at the same age.(ABSTRACT TRUNCATED AT 250 WORDS)