Lipidic and proteic absorption in digestive tract of tropical fat snook (Centropomus parallelus, POEY 1860)

The tropical fat snook Centropomus parallelus is a species of recognized ecological importance and with a high economical potential for fisheries and aquaculture. The investigations of digestive tube morphology in association with their feeding abilities are fundamental to improve techniques for aquaculture feeding procedures. Sudan black staining and Perl`s method were used to evaluate their absorption capacity of fat and protein respectively. The Sudan black stain was performed 12 h after the ingestion of lipids. The lipids are intensely absorbed in the ceca epithelium and less intensely in the intestine and rectum. The Perl`s method was performed 12 h after the ingestion of ferritin. The proteins are absorbed only in the rectum. This is the first description of fat and protein absorption ability by the digestive tube of fat snook. These data enhance the possibility of the addition of macromolecules in rations that can show a diversity of physiological effects. The histological implications of each segment of the digestive tube in association with fish biology are further discussed. (C) 2010 Elsevier B.V. All rights reserved.

Metabolic changes in ruminant calves fed cation-anion diets with different proportions of roughage and concentrate

Two experiments were carried out with twenty-four male weaned Holstein calves to verify the influence of different dietary cation-anion concentrate and roughage proportions on calves metabolism. In the first experiment, calves were fed rations with -100, +200 and +400 mEq cation-anion balance/kg of dry matter, containing 60% of roughage and 40% of concentrate. In the second experiment, calves (117.6±20.8 kg average weight) received rations with similar dietary cation-anion balance but in diets of 40% roughage and 60% concentrate. As the dietary cation-anion balance became more positive, there was a quadratic response of blood pH in both diets with 60 and 40% roughage. A linear increase following increased dietary cation-anion balance was observed on bicarbonate concentration, carbon dioxide tension, carbon dioxide partial pressure and urine pH on both experiments, while anion gap decreased linearly. Blood urea nitrogen and base excess increased quadratically according to increased dietary cation-anion balance on 60% roughage, whereas those same parameters showed a linear increase on 40% roughage. Growing ruminant metabolism both in cationic and anionic diets was modified when the roughage:concentrate ratio was altered.