The Effect of Solid-State Fermentation on the Nutritive Value of Rapeseed Cakes and Performance of Broiler Chickens

This study aimed to assess the applicability of eleven different products of solid-state fermentation of rapeseed cakes with commercial enzyme additives. Ground rapeseed cakes were mixed with water (1:2) and the enzymatic preparation (0.1%) according to the different variants and fermented at 25 °C for 24 h under anaerobic conditions. For fermentation, different enzymes were used: (1) α-amylase, (2) endo 1,4-β-xylanase, (3) endo-1,3(4)β-glucanase, (4) endo 1,4-β-xylanase, endo-1,3(4)β-glucanase, (5) α-amylase, endo-1,3(4)β-glucanase, (6) 6-phytase, (7) RONOZYME HiPhos 6-phytase, (8) liquid exogenous-6-phytase; and mixed combinations: (9) endo 1,4-β-xylanase, endo-1,3(4)β-glucanase, liquid exogenous-6-phytase, (10) α-amylase, endo-1,3(4)β-glucanase, liquid exogenous-6-phytase, and (11) α-amylase, endo 1,4-β-xylanase, endo-1,3(4)β-glucanase, liquid exogenous-6-phytase. After fermentation, the crude protein content in the products was similar, but the true protein content was significantly higher than in nonfermented rapeseed cakes (p < 0.05). Fermentation significantly reduced (p < 0.05) the levels of phytate phosphorous, raffinose family oligosaccharides, and glucosinolates in the products. In the next step, the most advantageous fermentation product obtained using liquid exogenous-6-phytase was selected in terms of nutritional value, produced on the technical scale, and incorporated into the diets for broilers. Six diets containing 12, 17, or 22% raw or fermented rapeseed cakes, respectively, were prepared. Up to 22% fermented rapeseed cakes did not adversely affect broiler production rates. Replacing raw rapeseed cakes with fermented products improved body weight gain in the grower phase, lowered feed intake in the finisher phase, and lowered the feed conversion ratio in all periods. A level of 22% of naturally fermented rapeseed cakes with liquid exogenous-6-phytase in the diet of broilers could be recommended.