The effects of dietary soybean saponins on growth and performance, intestinal histology and immune response of first feeding rainbow trout Oncorhynchus mykiss
The purpose of these studies was to determine the effects of diets containing water/alcohol extracts from soybean meal (SBM) on growth and performance, intestinal histology and specific and nonspecific immune parameters of juvenile rainbow trout. The first study evaluated seven experimental diets containing SBM, SBM after extraction, soy protein concentrate (SPC), SPC after extraction, SBM saponin extract, SBM flavonoid extract and Quillaja saponin (0.171%), and casein-gelatin based control diet. The second study evaluated SBM, SBM after extraction, SBM carbohydrates, SBM flavonoid extract, SBM saponins, SBM lipids, and negative control (containing 50% of casein-gelatin). Diets were formulated to have one half of the casein-gelatin replaced by soybean protein or supplemented with methanol/water extracts in amounts equal to the amounts found in 50% protein replacement. All female rainbow trout were subjected to feeding experiments beginning at first exogenous feeding. After initial feeding trials fish were maintained on experimental diets until vaccination. In the first study fish were vaccinated at 13 weeks by intraperitoneal injection of 0.1ml Furogen vaccine (AquaHealth Ltd) to examine specific humoral antibody responses and non-specific mucosal immune responses. In the second study fish were vaccinated after reaching an approximate mean individual weight of 5 grams (different chronological ages) with Furogen Dip vaccine (AquaHealth Ltd) and sampled to determine specific antibody responses in plasma and mucus and to examine histological changes in the posterior mid-intestine. Fish fed diets containing SBM, SBM after extraction, SPC, SPC after extraction and SBM carbohydrates exhibited lower growth than fish fed the control diet. Fish fed the saponin, lipid and flavonoid fractions performed similarly as control. Fish fed soybean saponins had higher specific plasma antibody levels after intraperitoneal vaccination but not after immersion vaccination. Dietary soybean saponins did not result in histological changes in the posterior mid-intestine consistent with soybean induced enteritis. It is concluded that purified soybean saponins, when included in the diet at a level of 0.24%, do not cause reduced growth and performance or pathological changes in the posterior intestine consistent with soybean induced enteritis. Additionally, dietary soybean saponins can augment the specific antibody response following intraperitoneal vaccination.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:soybean meal soy protein concentrate saponin soyasaponin rainbow trout oncorhynchus mykiss immune response antibody immunoglobulin posterior enteritis aeromonas salmonicida
Date of Publication:01/01/2005