Supplementation of Carbohydrases and Buffered Formic Acid to Broiler Diets Based on Wheat or Maize

The formation of a viscous gut content in the small intestine due to the presence of non-starch polysaccharides in feed can markedly restrict efficient nutrient digestion in poultry. This adverse effect may be mediated through the supplementation of exogenous feed additives. The present study investigated the effects of carbohydrases and a buffered formic acid on growth performance and ileal digesta viscosity in broiler chickens fed a wheat- or maize diet. A 2 × 4 factorial arrangement of treatments with eight replicates per treatment was conducted using 640 Cobb 500 mixed-sex broiler chicks. Factors were diet base: wheat or maize; supplement: xylanase (5,600 TXU/g)/β-glucanase (16,000 TGU/g) mixture (XG), mannanase (M;8,800 TMU/g) or buffered formic acid (FA; 0.42%). On day 21, ileal digesta was collected from 24 birds per treatment (4 birds per pen; 6 replicates), and the digesta viscosity was measured. Overall (d 0 – 21), birds fed the wheat diet were heavier (P = 0.010) than those fed the maize diet, and the maize-based diet resulted in a lower FCR than the wheat-based diet (P < 0.001). All feed additives improved (P < 0.001) weight gain, with no significant difference between the additives. Supplements M and FA improved (P < 0.001) overall FCR compared to the control. A two-way diet × supplement interaction occurred for ileal digesta viscosity at d 21 (P < 0.001). A marked reduction of ileal digesta viscosity due to supplement XG was observed in birds fed the wheat-based diet whereas none of the feed additives altered the viscosity in birds fed the maize-based diet. Collectively, although supplement XG was only effective in reducing digesta viscosity when supplemented in the wheat-based diet, all supplements improved growth performance independent of diet type. This suggests the presence of a mechanism besides viscosity reduction. Understanding the relative contributions of different feed additives in birds fed diets based on viscous and non-viscous grains would further help to develop tailored feeding strategies when multiple additives are used in a single feed formulation.

ACKNOWLEDGEMENT: This study was funded by BASF SE.