Relationships between digestibilities of food components and characteristics of wheats ( Triticum aestivum ) introduced as the only cereal source in a broiler chicken diet

Abstract

1. The aim of the experiment was to establish relationships between chemical or physical characteristics of wheats ( Triticum aestivum ) and digestibilities of food components in broiler chickens fed on wheat-based diets. Twenty-two wheat samples, each differing by their cultivar origin, were included at 550 g/kg in diets offered to male Ross broiler chicks. The other main ingredients were soya bean meal (340 g/kg) and rapeseed oil (68.5 g/kg). Diets were given as pellets. 2. In vitro viscosities of wheats measured as potential applied viscosity (PAV) or real applied viscosity (RAV) varied between 1.91 and 6.03, or between 0.95 and 3.81 ml/g (dry matter basis), respectively. Hardness of wheats varied between 17 (soft) and 95 (very hard), and lipase activity of wheats varied from 1 to 13.6 (relative scale). 3. PAV and RAV values were not significantly correlated with hardness. PAV and RAV values were correlated with (80:20) ethanol:water insoluble.961, 0.932, respectively), with the amount of water retained by cell walls ( r .656, 0.492, respectively), and with lipase activity ( r = 0.600, 0.532, respectively. 4. Hardness was correlated with ash ( r = -0.484), nitrogen ( r = 0.534), mean particle size of wheat flours ( r = 0.631), and specific energy of pelleting ( r = -0.574). 5. Wheat diets were evaluated in two assays with 3-week-old chicks, with 11 diets per assay. In each assay, a balance experiment was carried out using the total collection method. Growth performance was also measured during the balance experiment. 6. In vitro viscosity parameters were negatively correlated with diet AME n .05), lipid digestibility ( P < 0.05) and, to a lesser extent, protein digestibility ( P < 0.05). In vitro viscosity data were positively correlated with food:gain ratio ( P < 0.05) and water loss parameters ( P < 0.05), and were not significantly ( P > 0.05) correlated with starch digestibility. 7. Wheat hardness-related parameters were correlated ( P < 0.01) wi.273, -0.305, 0.212, respectively). 8. Wheat lipase activity was negatively c.179; P < 0.05) and starch ( r = -0.225; P < 0.01) digestibilities and with individual diet AME n ( r = -0.266; P < 0.001). Individual diet AME n .175) with the values calculated by the EU AME n prediction equation (Fisher and McNab, 1987). Among the correlations observed between the individual measured AME n :EU predicted AMEn ratio and wheat parameters ( P .05), the correlation obtained with wheat lipase was the highest ( r = -0.195). The correlations with lipase could be explained in part by strong correlations between lipase and in vitro viscosity parameters.