The effect of raw, hydrobarothermally treated and fermented rapeseed cake on plasma biochemical parameters, total tract digestibility and gut function in laying hens

This study evaluated the effects of inclusion of raw, hydrobarothermally treated and fermented rapeseed cake (RRC, HRC and FRC, respectively) in diets fed to laying hens. Hydrobarothermal treatment decreased the hydroxyglucobrassicin and neoglucobrassicin content of rapeseed cake (RC), whereas fermentation significantly reduced the content of all glucosinolates (GLS) and phytate phosphorus (PP) concentration. Both HRC and FRC increased the serum concentrations of total protein (TP) and globulin (GLB), compared with group C. Group HRC hens had desirably lowest blood triacylglycerol (TAG) levels and aspartate aminotransferase (AST) activity. Group FRC hens were characterized by the lowest alkaline phosphatase (ALP) activity, and the highest concentrations of phosphorus (P) and triiodothyronine (T3). Regardless of its form, RC improved ether extract (EE) digestibility, and decreased dry matter (DM) digestibility and calcium (Ca) retention. In comparison with group C, RRC, HRC and FRC decreased cecal digesta weight and enhanced the activity of bacterial α-galactosidase and ß-galactosidase; HRC also increased ammonia concentration in the ceca and reduced β-xylosidase activity. The activity of α-glucosidase and α-arabinopiranosidase was highest, and the activity of bacterial β-glucuronidase was lowest in the ceca of group FRC hens. The cecal concentrations of acetic acid, propionic acid, and total short-chain fatty acids (SCFA s) were highest in birds fed a diet containing RRC and lowest in group HRC. In conclusion, RC fermentation considerably reduces the concentrations of GLS and PP. A diet containing 20% FRC is more recommended than diets containing RRC and HRC because it exerted a beneficial effect on metabolic parameters and intestinal function in laying hens.