Heat-treatment, phytase and fermented liquid feeding affect the presence of inositol phosphates in ileal digesta and phosphorus digestibility in pigs fed a wheat and barley diet

Abstract

The aim was to evaluate the effect of heat-treatment, microbial phytase addition and feeding strategy (dry feeding v. fermented liquid feeding) on degradation of phytate (myo-inositol hexakisphosphate, InsP 6 ) and formation and further degradation of lower inositol phosphates (myo-inositol pentakisphosphate-myo-inositol bisphosphate, InsP 5 -InsP 2 ) at the distal ileum of pigs. Furthermore, the apparent ileal digestibility/degradability (AID) of phosphorus (P), InsP 6 -P and calcium (Ca) and the apparent total tract digestibility (ATTD) of P and Ca were studied. Pigs were fitted with a T-shaped ileal cannula for total collection of digesta at 2 h intervals during an 8 h sampling period after feeding the morning meal. Each period lasted for 2 weeks: 8 days of adaptation followed by 3 days of total collection of faeces and 3 days of total collection of ileal digesta. The experiment was designed as a 4 3 4 Latin square with four pigs fed four diets. A basal wheat/barley-based diet was fed either as nonheat-treated or heat-treated (steam-pelleted at 908C). The heat-treatment resulted in an inactivation of plant phytase below detectable level. Diet 1 (non-heat-treated basal diet fed dry); diet 2 (heat-treated basal diet fed dry); diet 3 (as diet 2 but with microbial phytase (750 FTU/kg as fed) fed dry); diet 4 (as diet 3 fed liquid (fermented for 17.5 h nighttime and 6.5 h daytime at 208C with 50% residue in the tank)). Chromic oxide (Cr 2 O 3 ) was included as marker and ATTD was determined both by total collection of faeces (ATTD Total ) and Cr 2 O 3 (ATTD Cr ). InsP 6 was completely degraded in diet 4 before feeding resulting in no InsP 6 -P being present in ileal digesta. InsP 6 -P concentration in ileal digesta decreased with increasing dietary levels of plant or microbial phytase in pigs fed the dry diets. Consequently, AID and ATTD of P and Ca were greatest for pigs fed diet 4 followed by diets 3, 1 and 2. The ATTD of P depended on the used method as ATTD Total of P was 72%, 61%, 44% and 34%, whereas ATTD Cr of P was 65%, 52%, 38% and 23% for diets 4, 3, 1 and 2, respectively. In all pigs the ileal concentration of InsP 5 -InsP 2 -P was extremely small, and thus unimportant for maximisation of ATTD of plant P. In conclusion, fermented liquid feeding with microbial phytase seems to be an efficient approach to improve ATTD of plant P compared with dry feeding. This opens up for further reductions in P excretion.

Animal production for efficient phosphate utilization: from optimized feed to high efficiency livestock

“…The activity of phytase depends mainly on pH, temperature, dose, and diet composition [24][25][26][27]. Phytase supplementation has mostly been studied in monogastric animals, and improvement of the P digestibility has been observed in Animal production for efficient phosphate utilization Kebreab, Hansen and Strathe 873 [33,34] poultry [21,28 ] and swine [22,29]. However, there is a wide variation in the effect of phytase added at the same phytase dose and type of diet [30], contributing to its unreliability in diet formulation.…”

“…The use of fermented liquid feeding or soaking of dry feed for swine is a method to pre-digest phytate before feeding. When the feed is mixed with water, phytate will be subjected to degradation by microbial or plant phytases [33][34][35][36]. The degree of phytate degradation depends on phytase concentration in the plant, addition and type of microbial phytase, soaking or fermentation time and whether or not the cereal was heat-treated before mixing into the ration [34].…”

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

“…Phytase is dormant in dry conditions but is activated to degrade phytate in wet conditions. Thus, use of liquid feeding seems to be a promising strategy to further enhance the P digestibility compared with dry feeding due to the initiation of the phytate degradation in the tank before feeding (Liu et al, 1997;Lyberg et al, 2006;Blaabjerg et al, 2010b). However, more knowledge about the potential of liquid feeding without and with microbial phytase is needed.…”

Effect of particle size and microbial phytase on phytate degradation in incubated maize and soybean meal

“…Thus, there is an increased focus on maximization of the efficacy of phytase to improve P digestibility further by 'pre-digestion' methods (soaking, fermentation) (Pedersen and Stein, 2010;Blaabjerg et al, 2010a) and feed processing (grinding, pelleting, heat treatment) (Oryschak et al, 2002;Pedersen and Stein, 2010;Blaabjerg et al, 2010b).…”

“…Liquid feeding with the presence of endogenous phytase or microbial phytase addition has been shown to improve P digestibility in pigs because of the degradation of phytate before feeding (Lyberg et al, 2006;Blaabjerg and Poulsen, 2010;Blaabjerg et al, 2010b). However, the effect of liquid feeding on the degradation of phytate depends on the type of feed, feed processing, phytase activity and soaking/ fermentation time (Carlson and Poulsen, 2003;Blaabjerg et al, 2010a).…”