Effect of maize conservation technique and phytase supplementation on total tract apparent digestibility of phosphorus, calcium, ash, dry matter, organic matter and crude protein in growing pigs

Two experiments were carried out to investigate the effect of different maize conservation techniques and phytase addition on coefficients of total tract apparent digestibility (CTTAD) of phosphorus (P), calcium (Ca), ash, dry matter (DM), organic matter (OM) and crude protein (CP). In the first experiment, 9 growing pigs were allotted to a triplicate 3 x 3 Latin square design to measure CTTAD of P in three different maize conserves. Maize was either dried (dried maize), ensiled after milling (maize silage) or tight-closed-stored as whole grain (TCS-maize). Diets consisted of the differently conserved maize alone supplemented with amino acids and a mineral and vitamin source. To achieve P-deficient diets, no P was added. In experiment 2 same experimental design, diet composition and feedstuffs were used as in the first study. However, in this study diets were supplemented with 750 FTU phytase kg(-1) diet from Schizosaccharomyces pombe. To evaluate the effect of phytase supplementation, results of both experiments were pooled for statistical analysis. The obtained results show that the CTTAD of P was greater (P < 0.0001) when maize was fermented compared with dried maize (0.42 in maize silage, 0.37 in TCS-maize, 0.28 in dried maize). The CTTAD of P was enhanced in all conservation types through phytase addition (0.46 in dried maize, 0.55 in maize silage and 0.52 in TCS-maize) (P < 0.0001). Moreover, CTTAD of Ca was higher in the fermented maize groups (P < 0.0001) compared with dried maize. However, it was not influenced by phytase supplementation. The CTTAD of DM and OM were not influenced by fermentation. The CTTAD of CP was lower in fermented maize (P < 0.05) compared to dried maize, whereby this effect was more pronounced in maize silage. However, the CTTAD of DM, OM and CP were not influenced by phytase supplementation. In conclusion, maize fermentation in the form of ensiling increases CTTAD of P in growing pigs. Therefore lower P supplementations are required and P excretions with manure can be reduced. Although CTTAD of P is improved when phytase is added, fermentation still offers advantages compared to dried maize. (C) 2013 Elsevier B.V. All rights reserved.