The efficacy of 2 phytases on inositol phosphate degradation in different segments of the gastrointestinal tract, calcium and phosphorus digestibility, and bone quality of broilers

Abstract

The anti-nutritional effects of dietary inositol phosphates (IP6 through IP3) have been recognized in broiler chickens; however, inositol hexaphosphate (IP6) is more potent than the lower IP esters. The efficacies of 2 commercial phytases, a Buttiauxella sp. phytase (BSP) and a Citrobacter braakii phytase (CBP) at 500 and 1,000 FTU/kg, were studied on IP6–3 concentrations in the crop, proventriculus + gizzard, and distal ileum digesta, and ileal IP6 disappearance in broilers at day 22. Apparent ileal P and Ca digestibility, and bone quality at days 22 and 33 were also measured. Female Ross 308 broilers (n = 1,890; 30 birds × 7 diets × 9 replicates) were fed corn-soy-based crumbled diets. The 7 diets included a primary breeder recommendation-based positive control diet (PC); the PC marginally reduced in available P by 0.146% and Ca by 0.134% of the diet, (NC1) or moderately reduced by 0.174 and 0.159% of the diet, respectively (NC2). Other diets were the NC1 + BSP or CBP at 500 FTU/kg (NC1+500BSP and NC1+500CBP) and the NC2 + BSP or CBP at 1,000 FTU/kg (NC2+1,000BSP and NC2+1,000CBP). Each of the NC1 and NC2 had distal ileum IP6 disappearance similar to that of PC, but each had lower P digestibility and the majority of measured bone quality parameters than the PC. The ileal IP6 levels were decreased by 52.0 and 32.7% for NC1+500BSP and NC1+500CBP, respectively, relative to NC1 and by 73.6 and 50.9% for NC2+1,000BSP and NC2+1,000CBP, respectively, relative to NC2 (P < 0.001), with a similar effect for distal ileum IP6 disappearance. Overall, phytase in the NC diets increased P digestibility, and femur breaking strength and cortical bone mineral density at days 22 and 33. Overall, each of the phytases at each dose degraded IP6–3 across the gastrointestinal tract segments to increase P digestibility and the P and Ca utilization in bone. However, dietary BSP at 1,000 FTU/kg was most effective. Supplemental phytase degrades phytate to decrease the anti-nutritional effects in a dose- and phytase-dependent manner.

Impacts of dietary calcium, phytate, and phytase on inositol hexakisphosphate degradation and inositol phosphate release in different segments of digestive tract of broilers

“…The pattern of lower IP esters varied depending on phytase, Ca, and PP, but significant increases in IP3 and 4 were observed due to phytase inclusion. However, in another trial, IP4 was found to be most influenced by 500 or 1,000 FTU Buttiauxella phytase/kg inclusion, whereas there were no differences in ileal IP3 concentration between phytase and non-phytase treatments (Bello et al., 2016 ). In addition, no differences were found in ileal IP4 concentration between birds fed phytase ( A.niger or E. coli phytase at 500 FTU/kg) and non-phytase diets (Zeller et al., 2015 ).…”

“…Even though in birds fed high PP diets (0.34%) there was more IP5 remaining in both the crop and Prov+Giz, a similar pattern of increases in IP3 concentration was seen at both PP. However, recent (Menezes-Blackburn et al., 2015 ) in vivo (Walk et al., 2014 ; Bello et al., 2016 ) studies showed IP ester production may be different among phytases. For example, Walk et al.…”

A novel consensus bacterial 6-phytase variant completely replaced inorganic phosphate in broiler diets, maintaining growth performance and bone quality: data from two independent trials

“…(2020b) . The breaking strength of the tibias was measured by the 3-point bending test using an Instron Universal Testing Instrument, as described by Bello et al. (2019) .…”

“…Their efficacy has been clearly demonstrated (see, e.g., reviews by Selle and Ravindran, 2007 ; Dersjant-Li et al., 2015 ; Abd El-Hack et al., 2018 ) and they are commonly used in animal diets. Studies have revealed complex physical and chemical relationships occur in the gastrointestinal tract ( GIT ) between phytate, phytase, minerals, and other nutrients ( Ravindran et al., 2008 ; Amerah et al., 2014 ; Li et al., 2016 ; Sommerfeld et al., 2018 ; Bello et al., 2019 ). These must be taken into account when formulating diets with phytase to achieve maximum efficacy while maintaining nutritional balance.…”

Safety evaluation of a novel variant of consensus bacterial phytase

“…For example, a current generation 6-phytase derived from Buttiauxella sp. and dosed at 1000 FTU/kg can achieve 76–92 % ileal phytate degradation in broilers [ [12] , [13] , [14] ] and 76 % ileal phytate degradation in pigs [ 15 ]. Nevertheless, new phytases with further enhanced activity and more desirable biochemical and thermal properties continue to be sought.…”