Soybean molasses has a positive impact on the pelleting process and physical quality of dairy feed pellets

Abstract

The influence of soybean molasses (SBMo) addition in dairy cow feed on the pelleting process and pellet quality was assessed in this study. For purpose of optimising production process of dairy feed pellets the SBMo content was varied at three levels (30, 60 and 90 g/kg) together with moisture content (MC – 130, 150 and 170 g/kg) of mash prior the pelleting process and sieve opening diameter (SOD – 5, 6 and 7 mm) of the hammer mill that was used for grinding of dry ingredients. The SBMo and required amount of water were added by a two-phase nozzle during mixing of ingredients and pelleting was done using a flat die pellet press. Experimental runs were performed according to Box-Behnken experimental design. The determined responses were: specific energy consumption (SEC), quantity of fines (QoF), pellet hardness (PH), pellet durability index (PDI) and bulk density (BD). Significance of input factors and their interactions, corresponding contributions and sum of squares were determined by using the statistical method of analysis of variance (ANOVA). Addition of SBMo decreased the SEC, PH and BD, and higher MC also decreased the SEC, PH and BD. The increase of SOD decreased the BD. The strongest contribution on SEC had the addition of SBMo (64.1%), while the strongest contribution on BD originated from the MC (71.2%). Models obtained in this research were used to optimise the input parameters in order to get the minimum SEC, maximum PH and maximum BD. The results of the optimisation for the input parameters were: SBMo content = 89.9 g/kg, MC = 130 g/kg, and SOD = 6.0 mm; and for the responses were: SEC = 33.9 kWh/t, PH = 12 Kahl unit kg, BD = 595.1 g/L. The obtained results showed that inclusion of SBMo at level of 90 g/kg could lead to the reduction of SEC and without significant influence on the pellet physical quality.