Effect of increasing dose level of a novel consensus bacterial 6-phytase variant on phytate degradation in broilers fed diets containing varied phytate levels

Dersjant-Li, Y.; Christensen, Trine; Knudsen, S.; Bello, A.; Toghyani, Majid; Liu, S.Y.; Selle, Peter H.; Marchal, Luc

doi:10.1080/00071668.2021.2000586

Cited by 6 publications

(2 citation statements)

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“…Given the capacity of PP to complex with mineral cations in the digestive tract ( Selle et al, 2012 ), which limits its availability for digestion, the hypothesized mode of action for this phytase is the early, rapid, and extensive hydrolysis of phytate to lower IP esters in the upper digestive tract. The low pH optima (pH 3.5–4.5 in vitro), wide pH range of activity (pH 2.0–5.0) ( Christensen et al, 2020 ), and extensive hydrolysis of IP 6 to IP 2 observed in vitro and in vivo ( Christensen et al, 2020 ; Dersjant-Li et al, 2021 ) of PhyG support this thesis. The degree of improvement (above NC) in P retention with 1,000 FTU/kg (+24.9% units) is consistent with the degree of improvement in ileal P digestibility (+25% units) recently observed in 21-d-old broilers fed Pi-free diets containing similar PP content (3.45 g/kg) with 1,000 FTU/kg of the same phytase ( Dersjant-Li et al, 2021 ).…”

Section: Discussionsupporting

confidence: 61%

“…The low pH optima (pH 3.5–4.5 in vitro), wide pH range of activity (pH 2.0–5.0) ( Christensen et al, 2020 ), and extensive hydrolysis of IP 6 to IP 2 observed in vitro and in vivo ( Christensen et al, 2020 ; Dersjant-Li et al, 2021 ) of PhyG support this thesis. The degree of improvement (above NC) in P retention with 1,000 FTU/kg (+24.9% units) is consistent with the degree of improvement in ileal P digestibility (+25% units) recently observed in 21-d-old broilers fed Pi-free diets containing similar PP content (3.45 g/kg) with 1,000 FTU/kg of the same phytase ( Dersjant-Li et al, 2021 ). Although total tract retention does not equate to digestibility as it includes P excreted via urine, comparative studies of the two measures for evaluating P availability from Pi sources have suggested comparable results ( Shastak et al, 2012 ).…”

Section: Discussionsupporting

confidence: 61%

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Effects of a novel consensus bacterial 6-phytase variant on the apparent ileal digestibility of amino acids, total tract phosphorus retention, and tibia ash in young broilers

Dersjant-Li¹,

Abdollahi

Bello³

et al. 2022

Journal of Animal Science

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The effect of a novel consensus bacterial 6-phytase variant (PhyG) on apparent ileal digestibility (AID), of amino acids (AA) and phosphorus (P) utilization in young broilers when added to diets with high phytate-P (PP) content without added inorganic phosphate (Pi) and deficient in digestible (dig) AA and metabolizable energy (ME) was investigated. A total of 256 Ross 308 male broilers were assigned to 4 treatments (8 birds/cage, 8 cages/treatment) in a completely randomized design. Treatments comprised a positive control (PC, 2,975 kcal/kg ME, 3.7 g/kg dig P, 2.83 g/kg PP, 8.4 g/kg Ca, 10.6 g/kg dig lysine), a negative control (NC) without added Pi (ME -68 kcal/kg, crude protein -10 g/kg, dig AA -0.1 to -0.4 g/kg, Ca -2.0 g/kg, dig P -2.2 g/kg, Na -0.4 g/kg, vs. PC), and NC plus 500 or 1,000 FTU/kg of PhyG. Test diets were corn/soy/rapeseed-meal/rice-bran-based and fed from 5 to 15 d of age. Ileal digesta and tibias were collected on d 15. Excreta was collected during d 12 to 15 to determine P retention. The NC (vs. PC) reduced (P < 0.05) P retention (-10.4% units), tibia ash (-14.3% units), weight gain (-109g), feed intake (-82g) and increased FCR (from 1.199 to 1.504), confirming that NC is extremely deficient in nutrients and energy. Phytase addition to the NC linearly (P < 0.001) improved performance, but not fully recover to the level of the PC due to the severe nutrients/energy down spec in NC. Phytase linearly increased P retention (P < 0.001), tibia ash (P < 0.001), AID of dry matter (P < 0.05), nitrogen (P < 0.01), gross energy (P < 0.05) and all 17 individual AA (P < 0.01). At 1,000 FTU/kg, phytase increased (P < 0.05) P retention vs. PC and NC (+14.5 and +24.9% units, respectively) and increased tibia ash vs. NC (+13.8% units), equivalent to PC. The NC decreased AID of Cys, Gly, Thr and Met vs. PC (P < 0.05). At 1,000 FTU/kg, phytase increased AID of all 17 AA vs. NC (P < 0.01), equivalent to PC. At 1,000 FTU/kg, AID AA responses (above NC) ranged from +4.5% (Met) to +15.0% (Cys), being maximal for essential Thr (+10.4%) and Val (+8.2%) and non-essential Cys (+15.0%) and Gly (+10.4%). The results highlight the efficacy of PhyG at a dose level of 500 to 1,000 FTU/kg in young broilers for improving the ileal digestibility of nitrogen, AA, and energy alongside P retention and tibia ash. The performance data emphasize the need to consider digestible nutrient intake as a response variable in exogenous enzyme studies.

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