Search

A 14-week trial was conducted to investigate the effects of antinutritional factors ( ANFs) commonly present in soybean ingredients, singly and in combination, on Atlantic salmon ( Salmo salar L.) fed from start-feeding. The experimental diets consisted of a negative control fish meal diet ( FM), and a positive control diet with 167 g kg−1 soybean meal inclusion ( SBM) and four diets based on the FM diet supplemented with 2 g kg−1 soya-saponins ( SAP), 1.5 g kg−1 isoflavones ( IFL), 0.3 g kg−1 phytosterols ( PHS) or a mixture of these ( MIX). Fish fed the SAP diet showed significantly higher growth performance than those fed FM, while the IFL treatment significantly decreased growth performance of salmon fry. Fish fed the IFL diet had significantly lower maltase activity and higher trypsin activity in proximal intestine than fish fed the FM diet. Histological differences were observed in the liver of fish fed the IFL diet, characterized by reduced size of the hepatocytes. Fish fed the PHS and IFL diets showed the highest frequencies of skeletal deformities among the six treatments. In conclusion, the results indicate that purified isoflavones may negatively affect growth performance, intestinal function, liver metabolism and bone formation of salmon fry. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of sparteine, a lupin alkaloid, on growth and organ histology in rainbow trout. Eight diets with increasing concentrations of sparteine (0, 50, 100, 250, 500, 1000, 2500 and 5000 mg kg−1) were fed to triplicate groups of 61-g fish for 62 days. Survival was not affected by the dietary treatments. Weight gain, feed conversion efficiency and feed intake decreased in a quadratic manner for sparteine levels above 100 mg kg−1. No effects were observed at inclusion levels ≤100 mg kg−1. Whole-body lipid and dry matter was depleted in a quadratic manner, while protein and ash were not affected. No tissue alteration attributable to sparteine alkaloid intake was found in liver, kidney, spleen or mid and distal intestines. At sparteine levels above 1000 mg kg−1 of diet, the weight of the intestines and the liver relative to body weight decreased, whereas the weight of the spleen increased. These effects were likely associated with low feed intake and starvation. These results indicate that dietary sparteine alkaloid primarily reduced palatability, but did not impair the health of the fish. The level of sparteine should be kept below 100 mg kg−1 in trout diets to ensure rapid growth. [ABSTRACT FROM AUTHOR]

Plant ingredients contain antinutritional factors that may affect fish growth performance and health when included in their diets. The present work aimed at studying the effect of two soy purified antinutrients, saponins and phytosterols, on growth, intestinal morphology and immune response of on-growing sea bream. Fish were fed one of seven diets for 48 days: control diet (fishmeal and fish oil based) and six experimental diets containing low (0.1%) or high (0.2%) levels of soya saponins, low (0.5%) or high (1.0%) levels of phytosterols or a combination of 0.1% saponins +0.5% phytosterols or 0.2% saponins +1.0% phytosterols. At day 15 and at the end of the trial pyloric caeca (PC) and distal intestine (DI) samples were collected for histological evaluation. At the end of the trial plasma was sampled for cholesterol analysis and DI was sampled for gene expression of immune and functional genes. Saponins and phytosterols did not affect fish growth, feed utilisation or plasma cholesterol levels. Histologically only a mild increase in the number of eosinophilic granular cells in the PC after 15 and 48 days of feeding in fish fed 0.1% saponins and 0.5% phytosterols, respectively. Gene expression of immune related genes was not affected by the presence of dietary antinutrients. Sea bream in grow-out phase showed high tolerance for saponins and phytosterols either alone or in combination, thus indicating an ability to cope with dietary plant feedstuffs containing such antinutrients, at least within the concentration range used in the present study. [ABSTRACT FROM AUTHOR]

The use of plant ingredients in aquafeeds for piscivorous fish species is a reality that exposes fish to a number of antinutritional factors present in plants. The present study is the first to evaluate the effect of two purified antinutrients, saponins and phytosterols, in sea bream juveniles. For that purpose, seven diets were formulated: a control diet (fishmeal and fish oil based) and six experimental diets containing low (1 g kg − 1 , SapL) or high (2 g kg − 1 , SapH) levels of purified soya saponins, low (5 g kg − 1 , PhytL) or high (10 g kg − 1 , PhytH) levels of purified phytosterols or a combination of 1 g kg − 1 saponins + 5 g kg − 1 phytosterols (SapPhytL) or 2 g kg − 1 saponins + 10 g kg − 1 phytosterols (SapPhytH). Fish were fed for 48 days in order to evaluate growth performance, feed utilization, plasma cholesterol, and gut health as assessed by histomorphological evaluation and gene expression profiling of immune and functional markers. Fish fed the diets PhytH, SapPhytL and SapPhytH showed better feed utilization and PhytH and SapPhytH showed higher protein utilization than the other groups, although this was not reflected in improved growth performance. Histomorphological analysis of the distal intestine revealed increased variation in supranuclear vacuole sizes after 48 days of feeding diets SapH, SapPhytL and SapPhytH and increased number of intraepithelial leukocytes in response to all dietary treatments except SapL and SapPhytL. Although juvenile sea bream growth was not affected by dietary inclusion of saponins and phytosterols, the results indicated some disturbances of the intestinal mucosal structure that could compromise function and/or protection from potential dietary antigens or opportunistic pathogens. [ABSTRACT FROM AUTHOR]

Abstract: The effect of pea protein concentrate in diets for Atlantic salmon on growth performance, nutrient digestibility, carcass composition, blood chemistry, histology of the gastro-intestinal tract (GIT), and physical feed quality was investigated. A 12-week study was conducted using triplicate groups of Atlantic salmon with 0.16 kg initial weight kept in seawater. The dietary treatments consisted of one control diet based on high-quality fish meal (FM diet), one control diet containing 200 g kg−1 soybean meal (SBM diet), and two experimental diets containing 200 g kg−1 pea protein concentrate with either 350 or 500 g kg−1 crude protein (PPC 35% CP and PPC 50% CP diet), substituting for fish meal protein. There were no significant differences among dietary treatments for weight gain or feed intake, but there was a tendency (P <0.07) toward a lower feed conversion ratio in fish fed the PPC 50% CP diet. There were no differences in the digestibility of protein, fat, starch and most essential amino acids between the fish fed the FM and the PPC 35% CP or PPC 50% CP diets, but the PPC diets gave lower energy digestibility. The SBM diet gave reduced digestibility for protein, fat, starch, essential amino acids, and energy compared with the FM and the PPC diets. Also, feeding the PPC diets had no effect on body composition, while the SBM diet reduced (P <0.05) the content of carcass fat and energy compared with the FM diet. Feeding the PPC diets did not induce morphological changes in the intestine, or affect the size of the GIT. Brush border maltase activity and fecal trypsin activity were unaffected. Feeding the SBM diet increased the size of the stomach, decreased the size of the distal intestine (DI), induced morphological changes in the DI, reduced brush border maltase activity, and increased fecal trypsin activity compared with the FM and PPC diets. In conclusion, pea protein concentrate was shown to be a promising new protein ingredient for salmonids and could replace 20% of high-quality fish meal protein in the feed without any adverse effect on growth performance, carcass composition or histology of the DI. [Copyright &y& Elsevier]