Effect of dietary inclusion of different lipid supplements on performance and carcass quality traits of growing beef heifers

The aim of this study was to evaluate the impact of dietary extruded flaxseed and/or rumen-protected lipids on growth performance and carcass quality of growing beef heifers. Sixty-three crossbreed heifers (Charolais X Limousine) were distributed into seven experimental groups, balanced in terms of age and live weight. Diets fed to the groups were isoproteic and differed in both, the dietary lipid source (extruded linseed and/or rumen-protected conjugated linoleic acid) and the supplementation length (90 or 180 days before slaughtering), having the same total amount of lipids and vitamin E, during their finishing period. The results obtained in the present study confirm that in low-protein diets, the inclusion of rumen-protected CLA, alone or in combination with flaxseed, did not bring any evident effect on feed intake, performance and carcass quality traits of growing beef heifers.

Dietary carbohydrate and lipid sources affect differently the oxidative status of European sea bass (Dicentrarchus labrax) juveniles

This study aimed to evaluate the effects of dietary lipid source and carbohydrate content on the oxidative status of European sea bass (Dicentrarchus labrax) juveniles. For that purpose, four diets were formulated with fish oil (FO) and vegetable oils (VO) as the lipid source and with 20 or 0 % gelatinised starch as the carbohydrate source, in a 2×2 factorial design. Liver and intestine antioxidant enzyme activities (catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD)), hepatic and intestinal lipid peroxidation (LPO), as well as hepatic oxidative stress index (OSI), were measured in fish fed the experimental diets for 73 d (n9 fish/diet). Carbohydrate-rich diets promoted a decrease in hepatic LPO and OSI, whereas the lipid source induced no changes. Inversely, dietary lipid source, but not dietary carbohydrate concentration, affected LPO in the intestine. Lower intestinal LPO was observed in VO groups. Enzymes responsive to dietary treatments were GR, G6PD and CAT in the liver and GR and GPX in the intestine. Dietary carbohydrate induced GR and G6PD activities and depressed CAT activity in the liver. GPX and GR activities were increased in the intestine of fish fed VO diets. Overall, effects of diet composition on oxidative status were tissue-related: the liver and intestine were strongly responsive to dietary carbohydrates and lipid sources, respectively. Furthermore, different metabolic routes were more active to deal with the oxidative stress in the two organs studied.