Effects of high moisture airtight storage of barley with exogenous enzymes on phosphorus digestibility of barley fed to pigs alone or in combination with soybean meal

Abstract

The aim was to study the effect of storage (high moisture airtight (HMA) storage vs. dry storage) and a combination of phytase, xylanase, β-glucanase, and protease on nutrient solubility and digestibility of barley. Experiment 1 studied the effect of HMA stored barley at 29%, 35%, and 40% moisture and enzyme combination to define the optimum moisture level for the maximum nutrient solubility of barley. The ‘35% moisture’ was chosen for HMA storage of barley because this treatment (without or with enzymes) enhanced phytate degradation (31–73%) and the solubility of P (125–177%), nitrogen (N) (95–125%) and protein (56–68%) compared to dry storage (P < 0.05) and at the same time seemed to prevent a loss of energy and N (ammonia) by microbial fermentation. In Exp. 2, 6 female growing pigs (43 ± 2 kg) were used per diet (8 diets, 48 pigs) in a 12-d nutrient digestibility study to assess the effect of HMA stored barley at 35% moisture and enzyme combination on coefficient of total tract apparent digestibility (CTTAD) of P in barley fed alone or together with soybean meal (SBM). Also, HMA storage of barley at ‘35% moisture’ without and with enzyme combination enhanced phytate degradation (43–58%) and P solubility (2.5–3.3 fold) (P < 0.05). Thus, HMA stored barley (solely endogenous enzymes) enhanced CTTAD of P to almost the same extent as dry stored barley with enzyme combination (endogenous enzymes plus added enzymes) in the barley diet (45–49%) and the barley-SBM diet (15–25%) (P < 0.05). Adding the enzyme combination to HMA stored barley achieved the greatest increase of CTTAD of P in the barley diet (70%) and the barley-SBM diet (36%) (P < 0.05). The inclusion of the enzyme combination to HMA stored barley tended to enhance the calculated CTTAD of P of SBM (29%) compared with no enzyme combination (P = 0.06) due to the lower endogenous enzymes activity in HMA stored barley. It is necessary to add the enzyme combination to enhance P digestibility of SBM when fed together with HMA stored barley. Overall, HMA storage with enzyme combination is a potential method to enhance P digestibility of barley in pigs to reduce the dietary need for inorganic P addition and P excretion to the environment.