Changes in cell number and size and in lipogenic enzyme activity in adipose tissues during growth and fattening of Lacha (Manech) lambs

— Variations during growth and fattening in the number and size of adipocytes and in the activity of the lipogenic enzymes, G3PDH, FAS, EM and G6PDH, were studied in the omental, mesenteric, kidney knob and channel fat, subcutaneous and intermuscular adipose tissues of 57 male Lacha (Manech) lambs. The animals were slaughtered at live weights (LW) of 11.4 (n = 15), 18.1 I (n = 15), 24.6 (n = 15) and 35.3 (n = 12) kg. A significant increase in the quantity of fat was observed as the LW of the lambs increased (P < 0.001 Fattening was more rapid between 24 and 36 kg LW than between 12 and 24 kg LW. Hyperplasia of adipocytes occurred predominantly between 12 and 24 kg, when changes in size and lipogenic activity were small. Between 24 and 36 kg LW, a marked increase in fat deposition was accompanied by an increase in the size of adipocytes and in lipogenic enzyme activity. adipocytes / lipogenic enzyme activity / lambs / growth Rsum — Variation de la cellularit et des activits enzymatiques lipogniques des tissus adi- peux chez l'agneau de race!Lacha (Manech) pendant la croissance et l'engraissement. L'volution du nombre et de la taille des adipocytes ainsi que les activits enzymatiques lipogniques de diffrents tissus adipeux ont t tudis chez 57 agneaux mles de race Lacha (Manech), pendant les priodes de croissance et d'engraissement. Les agneaux ont t abattus au poids vif (PV) de 11,4 (n = 15) (G12), 18,1 (n = 15) (G18), 24,6 (n = 15) (G24) et 35,3 (n = 12) kg (G36) l'ge respectif de 25, 69, 87 et 131 j. Les agneaux du groupe G 12 ont t abattus le jour du sevrage ; ceux des groupes G 18, G24 et G36 ont t sevrs respectivement 13,3, 14,2 et 14,5 kg de PV soit 36, 36 et 37 j d'ge. Ils ont eu leur disposition de l'aliment concentr et de la paille d'orge ad libitum jusqu' l'abattage. Les paramtres tudis sont la quantit de gras et le nombre des adipocytes dans les dpts omental (OM), msentrique (MES) et plvique-rnal (KKCF), et dans les dpts OM, MES, KKCF, sous- cutan (SC) et intermusculaire (IM), le diamtre des adipocytes et l'activit des enzymes glycerol 3-