Adknowtedgments: PIRINNOVHFA103/ 1S project Is co-flnanced by FEOER wlthln the POCTEFA framewotk.

The aim was to study the variation in the amount of adipose tissue, size and number of adipocytes and lipogenic enzyme activities in does with different body condition scores (BCS). These parameters were studied in the omental (OM), mesenteric (MES), perirenal (PR), subcutaneous (SC) and intermuscular (IM) fat depots of 22 adult, non-pregnant and non-lactating Blanca celtibérica does, with a BCS ranging from 1.5 to 4.5 (scale 0–5). SC adipose tissue showed the highest deposition-mobilization phase (highest fat relative to the variation per BCS unit of 74%), followed by OM (65%), PR (63%), MES (48%) and IM (46%) adipose depots. Adipocyte size varied with the amount of fat (P<0.001), while the SC depot was the only depot that showed a positive correlation between adipocyte number and BCS (r2=0.20; P<0.05). The activities of glycerol 3-phosphate dehydrogenase (G3PDH) and fatty acid synthetase (FAS) enzymes were not generally affected by BCS, due to the fact that animals were on a maintenance diet prior to slaughter. The findings obtained in this work indicate that the processes of storage and mobilization of fat reserves in adult goats are principally due to variation in the size of the adipocyte cells. Therefore, the use of BCS could be a good method for predicting nutritional status in goats.

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±1.2kg BW, 45±4days 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 (289.1kcal/kg versus 252.8kcal/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 C18:1 composition did not change.

The aim of the study was to assess the effect of body condition score on tissue and metabolic characteristics of the adipose depots in sheep of Rasa Aragonesa breed. Ewes were uniformly assigned according to their body condition score (BCS) (scale 0 to 5), to four groups: 0.75–1.75, 2–2.75, 3–3.75, and 4–4.5. The amount of fat and the adipocyte size in the different adipose depots increased as BCS did (P < 0.001) while the number of adipocytes did not change. The greatest ability to accumulate or mobilize fat was the subcutaneous depot (slope of the regression between amount of fat and BCS, b = 1.92; P < 0.001). Fatty acid synthase (FAS) lipogenic enzyme activity was affected by BCS, while G3-PDH and G6-PDH activities were not. Key words: Adipose tissue, body condition score, adipocyte size, lipogenic enzyme activity, ewes

Four pre-slaughter measurements, liveweight (LW), body condition score (BCS) and fat thickness, measured by ultrasound, in the lumbar (FTL) and sternal regions (FTS), and four post-slaughter measurements, empty liveweight (ELW), hot carcass weight (HCW) and diameter of adipocytes in subcutaneous (DSC) and omental (DOM) fat depots¸ were used to predict the weight of fat in the omental (OM), mesenteric (MES), perirenal (PR), subcutaneous (SC) and intermuscular (IM) depots of ewes. Linear and multiple regressions were fitted to data from 42 adult, non-pregnant and non-lactating Rasa Aragonesa ewes, with liveweights between 29.8 and 79.2 kg and body condition scores between 0.75 and 4.5. Using a single parameter, ELW and HCW gave the most accurate predictions of the total depot fat (R2 = 0.88 and 0.90, RSD = 1.571 and 1.484 kg, respectively). Multiple regressions predicted total weight of fat depots from the pre-slaughter variables LW, BCS and FTS with an R2 value of 0.92 (RSD=1.317 kg). This result confirms the utility of using in vivo measures as fat reserve predictors in Rasa Aragonesa ewes. Key words: Fat tissue, liveweight, body condition score, adipocytes, ultrasound, ewes

The effects of sex, genotype, and adipose depot on lipogenic enzyme activity have been investigated in Holstein and Pirenaican bulls and heifers, taking into account differences in adipocyte size. Fifteen Pirenaican bulls and 15 heifers and 15 Holstein bulls and 13 heifers were fattened until slaughter (12 to 13 mo old and 450 to 500 kg of body weight). During the fattening period, animals had ad libitum access to commercial concentrates and straw. The 10th rib was dissected to determine the fat content. Adipocyte size and activities of the following lipogenic enzymes were determined: glycerol 3-phosphate dehydrogenase, fatty acid synthase, nicotinamide adenine dinucleotide phosphate (NADP)-malate dehydrogenase, glucose 6-phosphate dehydrogenase, and NADP-isocitrate dehydrogenase, in the omental, perirenal, subcutaneous, and intermuscular adipose depots, respectively. Because adipocyte mean cell volume varied with sex, breed, and depot, regression analyses of log(e) activity per cell and log(e) cell volume were used to compare activities per unit volume. Sex, breed and depot had no effect (P > 0.05) on the gradients of regressions, which did not differ significantly from 1. Thus, activity per unit volume did not vary with cell size. Consequently, sex, breed, and depot effects on the regression analyses were equivalent to effects on activity per unit volume. Females had greater amounts of fat in the 10th rib (P < 0.001), larger adipocytes (P < 0.001) and, in general, greater (P < 0.05) lipogenic activity per cell, even when adjusted for cell size, than males. These findings suggest that differences in adiposity between sexes are mainly due to females having a greater capacity for lipid synthesis, and hence, hypertrophy, than males. When adjusted for differences in carcass weight, Holsteins had larger adipocytes than Pirenaicans. The abdominal depots, omental and perirenal, had a greater adipocyte size (P < 0.001) and, in general, greater lipogenic enzyme activities per cell (P < 0.05) than the subcutaneous and intermuscular carcass depots. However, when activity per cell was adjusted for cell size, subcutaneous depots had greater fatty acid synthae, glucose 6-phosphate dehydrogenase, and NADP-malate dehydrogenase activities than omental and perirenal, indicating that other factors such as nutrient supply may restrict hypertrophy of carcass adipocytes.

Factors responsible for breed- and depot-specific differences in the development of lipogenic enzymes, and hence lipogenic capacity of adipocytes, in sheep adipose tissue have been investigated using a serum-free cell culture system. Effects of insulin, tri-iodothyronine and exogenous lipid on the development in vitro of the lipogenic enzymes glycerol 3-phosphate dehydrogenase (G3PDH), fatty acid synthetase (FAS), NADP-malate dehydrogenase (ME), glucose 6-phosphate dehydrogenase (G6PDH), and isocitrate dehydrogenase (ICDH) in omental and subcutaneous pre-adipocytes from Lacha and Rasa Aragonesa lambs were investigated. Addition of insulin plus tri-iodothyronine caused pre-adipocyte differentiation, which was enhanced by addition of a lipid supplement. G3PDH activities achieved by differentiation of pre-adipocytes in vitro were similar to those found in vivo; furthermore after differentiation in vitro adipocytes from Rasa Aragonesa lambs had a greater G3PDH activity than adipocytes from Lacha lambs, as found in vivo. In contrast activities of FAS, G6PDH and ME achieved by differentiation in vitro were much greater than those found previously in vivo. While breed- and depot-specific changes in G6PDH observed after differentiation in vitro were similar to those observed in vivo, changes in FAS induced in vitro differed from those found during development in vivo. The study shows that pre-adipocytes from Rasa Aragonesa and Lacha lambs have intrinsic depot- and breed-specific differences in their ability to differentiate and express lipogenic enzymes. The combination of insulin, tri-iodothyronine and a lipid supplement appears to be sufficient to account for in vivo G3PDH activities but other factors are required to explain activities of FAS, G6PDH and ME found in vivo.