Leptin, from Greek "leptos" meaning "thin", is the product of the ob gene. It is a 16 kDa protein hormone secreted mainly by white adipose tissue, and which acts to regulate food intake, energy expenditure, homeostasic body weight, and consequently influences fat deposition in both animals and humans. The aim of the study was to determine if cattle breeds differing in their carcass characteristics also differ in their blood and tissue leptin profile.

Three breeds, Belgian Blue (BB) (n = 12), Limousin (L) (n = 12) and Aberdeen Angus (AA) (n = 12) differing in their ability to deposit fat and protein were compared. Subcutaneous adipose tissue percentage was determined as well as plasma leptin concentration, leptin gene expression and leptin receptor gene expression in subcutaneous adipose tissue.

The BB bulls showed lowest values in leptin gene expression (BB: 0.37 ± 0.18, L: 0.89 ± 0.29, AA: 1.16 ± 0.6) and values of plasma leptin concentration (BB: 2.66 ± 0.74, L: 3.00 ± 1.16, AA: 3.35 ± 0.87 ng/mL) and of leptin receptor gene expression (BB: 1.18 ± 0.76, L: 1.40 ± 0.62, AA: 2.07 ± 1.13) tended to be lower in BB than in the other breeds. For a similar amount of subcutaneous adipose tissue, BB bulls showed higher values of plasma leptin concentration (BB: 0.258 ± 0.064, L: 0.156 ± 0.06, AA: 0.141 ± 0.036) whereas normalised leptin gene expression (BB: 0.036 ± 0.017, L: 0.047 ± 0.015, AA: 0.049 ± 0.023) and leptin receptor gene expression (BB: 0.115 ± 0.069, L: 0.075 ± 0.039, AA: 0.082 ± 0.040) did not significantly differ between breeds.

Supported by Ministry of Agriculture and Rurality of the Région Wallonne (project 2612/1).