Effect of feeding lambs oleic acid calcium soaps on growth, adipose tissue development andcomposition

A study was performed to determine the influence of calcium soaps of olive fatty acids in the diet of lambs on animal and adipose tissue growth and fatty acid composition during the fattening period. After weaning (15 +/- 1.2 ka BW, 45 +/- 4 days of age), 18 male Rasa Aragonesa breed lambs were fed, for 35 days, in two groups (nine animals per group) on one of two diets. Control group animals were fed a concentrate diet mainly barley and soya, whereas olive group lambs were fed a similar isoproteic diet that included 5% calcium soaps of olive fatty acids and barley straw, both offered ad libitum. The ME intake of olive concentrate feeding was higher than of the control (289.1 kcal/kg versus 252.8 kcal/kg; P < 0.05), but daily gain, DMi and feed conversion of both groups were similar. The higher energy intake of Olive group lambs resulted in more omental (OM) and perirenal (PR) adipose tissue than in Control animals (446 versus 334 and 374g versus 242g, respectively; P < 0.05). Significant differences between groups were not observed with respect to back fat thickness (BFT), percentage subcutaneous (SC) and intermuscular (IN) shoulder adipose tissue, or Longissimus dorsi (L.D.) muscle lipid content. The greater OM and PR adipocyte size of the Olive group lambs and the lack of differences in adipocyte number, indicated that adipocyte hypertrophy was mainly responsible for the differences in accumulated fat observed between the groups of lambs. No changes in PR, SC and IM percentages of saturated and monounsaturated fatty acids or C18:1 content were observed between groups, indicating that compensatory mechanism exists to maintain the fatty acid composition of the depots or that fatty acid protection of calcium soaps was not absolute. The fact that PR polyunsaturated fatty acid percentage was greater in Control animals: than in the Olive group (6.92 versus 4.19; P < 0.05) was related to a lower adipose tissue content and a smaller adipocyte size in the Controls. Finally, the inclusion of 5% calcium soaps of oleic acids in the diet, for a period exceeding 35 days, increased adipose tissue in internal depots by adipocyte hypertrophy, whereas adipose and meat C 18:1 composition did not change. (c) 2005 Elsevier B.V. All rights reserved.