Digestibility of macronutrients, energy and amino acids, absorption of elements and absence of intestinal enteritis in Atlantic salmon, <i>Salmo salar</i>, fed diets with wheat gluten

Apparent digestibility coefficients (ADCs) of macronutrients and energy, and apparent absorption coefficients (AACs) of amino acids and elements were assessed in an experiment with 0.9 kg Atlantic salmon reared in saltwater tanks. Duplicate groups of fish were fed five diets, where 0, 6.25, 12.5, 25 and 50% of crude protein (CP) from fish meal (FM) was replaced with CP from wheat gluten (WG). In Experiment 2, triplicate groups of 0.9 kg salmon were fed a FM diet, a diet with 15% of CP from FM replaced with extracted, toasted soybean meal (SBM), and a diet with 35% of CP from WG, for 18 weeks. Experiment 2 was designed to determine whether WG caused pathological changes in the intestinal epithelium, and if a diet with 35% of CP from WG could support rapid growth. There was a trend toward increased ADC of fat and energy in the diets with WG, and the diet with 25% WG was ranked significantly higher than the FM control. The ADC of CP and AACs of all amino acids except alanine and lysine increased significantly with increasing proportion of dietary protein from WG, and the results indicate that absorption of individual amino acids from WG was between 94% and 100%, WG is low in lysine, but the results indicate that the requirement for lysine was nearly met and the requirement for other essential amino acids was met even with the highest WG inclusion level, due to high dietary protein concentration and the supplementary amino acid profile of FM. There was no reduced absorption of Ca, P or Mg in the salmon fed diets with WG. The absorption of Zn was higher in all the diets with WG than in the FM diet. The fish doubled their weight during Experiment 2, and there were no significant differences in growth among dietary treatments in salmon fed the WG, FM or SBM diets. No indication of intestinal pathology was seen in the salmon fed the FM or WG diets, while 60% of the examined fish fed SBM had SBM-induced changes in the mucosa of the posterior intestine

Fitase na alimentação da tilápia do Nilo (Oreochromis niloticus). Desempenho e digestibilidade Phytase as feeding for Nile tilapia (Oreochromis niloticus). Performance and digestibility

Este experimento foi realizado para avaliar os efeitos da adição de diferentes níveis de fitase (0, 500, 1500 e 3000 unidades de fitase ativa [UFA]/kg de ração) em dietas para a tilápia do Nilo (8,88 ± 0,02 g). Todas as rações foram fornecidas até saciedade durante 45 dias. O nível de fitase baseou-se nos parâmetros de desempenho e digestibilidade e foi estimado pelos modelos quadrático e/ou LRP ("broken line"). De acordo com os resultados obtidos com os níveis de fitase, o modelo LRP apresentou o melhor ajustamento de dados. A suplementação de fitase aumentou o desempenho, a retenção de minerais nos ossos, a digestibilidade da proteína e a disponibilidade de cálcio e fósforo. Os melhores resultados de desempenho, retenção de minerais nos ossos e digestibilidade foram obtidos com 700 UFA/kg de ração.<br>This experiment was carried out to evaluate the effects of addition of different levels of phytase (0, 500, 1500 and 3000 units of active phytase [UFA]/kg diet) in the diets for Nile tilapia (8.88 ± 0.02 g). All diets were fed to satiation daily for 45 days. The phytase level determination was based on the performance and digestibility parameters and was estimated by the quadratic and/or the broken line models. The broken line model showed a better adjustment for phytase levels according to the observed results. Phytase supplementation increased performence, bone minerals, protein digestibility and calcium and phosphorus availability. The best results of performance, bone mineral retentions and digestibility were obtained with 700 UFA/kg of diet