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At weaning (33 days of age), 246 hybrid rabbits (782 ± 53 g live weight) were divided into six experimental groups and fed ad libitum six iso-ADF diets formulated according to a bifactorial arrangement with two protein levels (152 and 162 g/kg) and three soluble fibre-to-starch ratios (0.2, 0.6 and 1.5), the latter obtained by replacing starch (from 209 to 91 g/kg) with soluble fibre (from 48 to 136 g/kg). The trial lasted for 42 days until slaughter. The rabbits that were fed the diet with the highest protein level and the lowest soluble fibre-to-starch ratio showed the highest mortality rate (17.1% v. 1.7% on average; P < 0.001) and sanitary risk (mortality + morbidity: 20.0% v. 8.1%; P = 0.04) compared with the rabbits fed the other diets. With increasing dietary crude protein level, the digestibility of dry matter (DM; 0.615 to 0.626) and gross energy (0.620 to 0.630) as well as aNDF (without sodium sulphite; 0.298 to 0.323) and hemicelluloses (0.417 to 0.461) significantly (0.001 < P < 0.10) improved. Moreover, total volatile fatty acids (VFAs) in the caecal content increased (59.0 to 68.4 mmol/l; P = 0.01) and ileum crypt depth tended to reduce (P = 0.07). Neither growth performance nor slaughter results were affected by the protein level. When increasing soluble fibre-to-starch ratio, the digestibility of DM and gross energy did not change, whereas the digestibility of aNDF (0.264 to 0.352), ADF (0.167 to 0.267) and hemicelluloses (0.400 to 0.470) linearly increased (P < 0.001). At caecum, N-ammonia tended to decrease linearly (P = 0.08), total VFA concentration (56.0 to 67.3 mmol/l) and acetate proportion (80.4 to 83.3 mmol/100 mmol VFA) linearly increased (P < 0.01), whereas butyrate and valerate proportions decreased (0.01 < P < 0.05). Growth performance was similar among groups, whereas at slaughter the proportion of the gastrointestinal tract linearly increased (177 to 184 g/kg; P < 0.01) without effect on dressing percentage, however. As soluble fibre-to-starch ratio increased, meat pH linearly decreased and lightness (L*), redness (a*) and yellowness (b*) colour indexes increased (0.01 < P < 0.05).

The chemical composition and the level of twelve PCB congeners (IUPAC Nos. 18, 28, 31, 44, 52, 101, 118, 138, 149, 153, 180 and 194) were determined in 133 specimens of European sea bass (Dicentrarchus labrax), collected from four Italian aquaculture facilities: extensive valley, semi-intensive ponds, intensive concrete tanks and sea-cages. Fish muscle composition varied based on the rearing system (P<0.001): moisture was higher and fat concentration was lower in fish from the extensive system in comparison to fish from intensive tanks; intermediate values were found in fish from semi-intensive ponds and sea-cages. Concentrations of the 12 measured PCBs (PCB(tot)) and of the seven indicator congeners (PCB(7)) (Nos. 28, 52, 101, 118, 138, 153 and 180), when expressed on fat weight, were lower in extensively-reared sea bass (112.0 and 74.6 ng g(-1) fat, respectively) with respect to sea bass from the other systems (average values: 179.7 and 123.2 ng g(-1) fat) (P<0.001). When the values were expressed on fresh muscle weight, PCB(tot) and PCB(7) were lower in extensively-reared sea bass (3.412 and 2.266 ng g(-1)fw), intermediate in fish from semi-intensive ponds (15.398 and 10.632) and sea cages (13.123 and 8.882), and higher in specimens from the intensive tanks (18.176 and 12.440) (P<0.001). PCB 153 was the most abundant in all of the rearing systems. Within farm, muscular fat content and slaughter weight were positively correlated (r=0.79). PCB(7) concentration expressed in ng g(-1) fat and in ng g(-1) fw was positively correlated with both fish slaughter weight (r=0.71 and 0.73) and muscular fat concentration (r=0.86 and 0.96).

In the present work we investigated by immunohistochemistry the cellular localization of constitutive as well as inducible heat shock protein 70 in several tissues of common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss) exposed to transport stress.In carp, the constitutive form (HSC70) was detected only in red skeletal muscle of both control and stressed animals. In the same species, the inducible form (HSP70) was evident in the epithelia of renal tubules,gills and skin of stressed animals, whereas in controls only red skeletal muscle exhibited an immunopositivity to HSP70 antibody. In trout, immunostaining to HSC70 antibody was found mainly in the epithelia of intestine, gills and skin of both control and stressed animals although the reactivity was generally higher in animals exposed to transport stress. In the same species immunostaining to HSP70 antibody was observed only in red skeletal muscle and epidermis of control animals.