The effect of age and gender on the fat distribution in Merino lambs

Abstract

The goal of this study was to determine the effect of gender on visceral and subcutaneous fat distribution of Merino lambs finished off under feedlot conditions. The diet (16% protein, 10MJ ME/kg feed) was fed ad libitum and animals had free access to water. A total of 108 lambs (58 wethers, 50 ewes) were divided into six groups. Groups of lambs were slaughtered every three weeks at respectively 90, 111, 132, 153, 174 and 195 days of age. The visceral fat was removed, weighed and expressed as a percentage of carcass mass, while the subcutaneous fat thickness was measured at the 13^th rib. A growth curve was calculated for each gender, and the effect of age on the different fat parameters determined. The growth rates of male and female lambs did not differ and were respectively 45.2 g and 43.2 g per day. Age had a positive effect on % visceral fat with an increase of 0.029% for wethers and 0.032% for ewes per day. Similarly, fat thickness increased at a rate of 0.070 mm for wethers and 0.053 mm for ewes per day, indicating that gender had an influence on the rate of fat deposition. However, the inverse rate of deposition between the genders
(visceral fat versus subcutaneous fat) warrants further discussion.

Keywords: Growth, fat thickness, sheep, age, feedlot