Microbial phytase addition resulted in a greater increase in phosphorus digestibility in dry-fed compared with liquid-fed non-heat-treated wheat–barley–maize diets for pigs

Abstract

The objective was to evaluate the effect of microbial phytase (1250 FTU/kg diet with 88% dry matter (DM)) on apparent total tract digestibility (ATTD) of phosphorus (P) in pigs fed a dry or soaked diet. Twenty-four pigs (65 ± 3 kg) from six litters were used. Pigs were housed in metabolism crates and fed one of four diets for 12 days; 5 days for adaptation and 7 days for total, but separate collection of feces and urine. The basal diet was composed of wheat, barley, maize, soybean meal and no mineral phosphate. Dietary treatments were: basal dry-fed diet (BDD), BDD with microbial phytase (BDD + phy), BDD soaked for 24 h at 20°C before feeding (BDS) and BDS with microbial phytase (BDS + phy). Supplementation of microbial phytase increased ATTD of DM and crude protein (N × 6.25) by 2 and 3 percentage units (P < 0.0001; P < 0.001), respectively. The ATTD of P was affected by the interaction between microbial phytase and soaking (P = 0.02). This was due to a greater increase in ATTD of P by soaking of the diet containing solely plant phytase compared with the diet supplemented with microbial phytase: 35%, 65%, 44% and 68% for BDD, BDD + phy, BSD and BSD + phy, respectively. As such, supplementation of microbial phytase increased ATTD of P in the dry-fed diet, but not in the soaked diet. The higher ATTD of P for BDS compared with BDD resulted from the degradation of 54% of the phytate in BDS by wheat and barley phytases during soaking. On the other hand, soaking of BDS + phy did not increase ATTD of P significantly compared with BDD + phy despite that 76% of the phytate in BDS + phy was degraded before feeding. In conclusion, soaking of BDS containing solely plant phytase provided a great potential for increasing ATTD of P. However, this potential was not present when microbial phytase (1250 FTU/kg diet) was supplemented, most likely because soaking of BDS + phy for 24 h at 20°C did not result in a complete degradation of phytate before feeding.

Fermentation of rapeseed meal, sunflower meal and faba beans in combination with wheat bran increases solubility of protein and phosphorus

“…The present high phytase activity of wheat bran and low or non‐detectable activity in rapeseed meal, sunflower meal and faba beans agrees with previous studies . Cereal phytases are not active in the dry‐stored dormant grain but are activated to release P from phytate in moist conditions during germination, resulting in increased P solubility . It should be emphasized that the assessment of phytase activity in dry as well as fermented samples was performed after 65 min of incubation, permitting partial activation of the enzyme in dry‐stored samples.…”