Effects of increasing dose of a novel hybrid bacterial 6-phytase on apparent total tract nutrient digestibility, release of free myoinositol, and retention of Ca and P in pigs

Hyunjun Choi and Sung Woo Kim

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North Carolina State University, Raleigh, NC

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Phytate P in plant feedstuff

• Phytate P
• Phosphorus (P) is mainly in a form of phytate in plant feedstuffs.
• Phytate is indigestible to pigs due to lack of endogenous enzyme to hydrolyze phytate.

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Phytate P in plant feedstuffs

(Selle and Ravindran, 2008)

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Phytase

• Phytase
• Hydrolyzed phytate in plant feedstuffs, which reduces the P excretion and inorganic P supplementation in feeds.
• Prevented mineral chelation in the GIT of pigs
• Known to increase the absorption of myoinositol
• Improved the growth performance in pigs fed Ca and P deficient diets

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(Madrid et al., 2013; Lu et al., 2019; Moita and Kim, 2022)

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Phytase sources

• However, the degree of hydrolysis of phytate depends on the levels of phytase and the properties of various phytases.
• 6-phytase could be more efficient in P utilization than 3-phytase
• Greater number of positions to hydrolyze.
• Bacterial phytase has a higher stability and improved activity under a wider range of conditions than fungal phytase
• pH and temperature

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(Igbasan et al., 2000; Dersjant Li et al., 2020; Saleh et al., 2021)

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

A hybrid phytase

• A hybrid bacterial phytase is composed of subunits from multiple bacterial origins using enzyme engineering methods.
• Hybrid bacterial phytases are shown to have high resistance to pH, temperature, and proteases, potentially providing enhanced efficacy in the GIT of pigs.
• Considering enhanced efficacy, a hybrid bacterial 6-phytase could be effective at traditional levels compared with other phytases

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(Rodrigueze et al., 2000; Tomschy et al., 2002; Elkhalil et al., 2007)

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Hypothesis

• It is hypothesized that the dietary supplementation of a hybrid bacterial 6-phytase could increase the Ca and P utilization in a Ca and P deficient diet, increase the absorption of myoinositol, and improve growth of pigs.

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Objectives

• To investigate the effects of increasing doses of a hybrid bacterial 6-phytase on the apparent total tract digestibility of energy and nutrients, retention of Ca and P, and plasma level of free myoinositol in pigs
• To estimate the optimal 6-phytase supplementation levels in pigs

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Materials and methods: animals, diets, and experimental design

• Fifteen pigs (21.5 ± 1.4 kg BW) were used in a triplicate 5 × 5 Latin square design: 5 dietary treatments and 5 periods in each Latin square
• Basal diet: Ca and P deficient diet
• Ca: 0.22% and P: 0.17% unit below the requirement by NRC (2012)
• Experimental diets: 5 dose levels of phytase
• 0, 500, 1,000, 1,500, and 2,000 FTU/kg
• Hybrid bacterial phytase (BASF Corporation, NJ, USA)
• Source organism: a hybrid with Hafnia, Yersinia, and Buttiauxella
• Production organism: Aspergillus niger

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NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Materials and methods: composition of the basal diet (NC)

¹ SID = standardized ileal digestible

² STTD = standardized total tract digestible

¹ Others included poultry fat, sodium chloride, vitamin premix, and mineral premix.

² Phytase was supplemented at the expense of corn.

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Materials and methods: feed allowance and sample collection

• Feed allowance:
• 9% of metabolic body weight (BW^0.75) of each period
• Provided 2 equal meals at 0800 and 1700 h
• Pigs had free access to water.
• Sample collection
• A 5-d adaptation and 5-d total collection periods
• Feces (marker to marker procedure)
• Urine sample (Time-based procedure)
• Plasma sample (d 10 of each period)

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NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Materials and methods: chemical analyses

• Chemical analyses
• Diets: DM, GE, N, EE, NDF, ADF, Ca, and P
• Feces: DM, GE, N, Ca, and P
• Urine: GE, N, Ca, and P
• Plasma: free myoinositol level

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NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Materials and methods: calculation

• Apparent total tract digestibility (ATTD) of P, %

= [(Pi – Po) / Pi] × 100

• Pi = P intake (g)
• Pf = fecal P output (g)
• Retention of P, %

= [(Pi – Pf – Pu) / Pi] × 100

• Pu = urinary P output (g)
• Digestibility and retention of GE, Ca, and N were also calculated using the same equation.

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NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Materials and methods: statistical analysis

• Statistical model
• Fixed effect: dietary treatment
• Random effects: rep, animal within rep, and period within rep
• Mixed procedure
• Orthogonal polynomial contrasts (linear and quadratic)
• NLMIXED procedure
• One-slope broken line analysis
• Statistical significance: P < 0.05; tendency: 0.05 ≤ P < 0.10.

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NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: ATTD of Ca and P

Linear: <0.001

Quadratic: <0.001

Linear: <0.001

Quadratic: <0.001

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: Retention of Ca and P

Linear: <0.001

Quadratic: <0.001

Linear: <0.001

Quadratic: <0.001

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: Free myoinositol level in plasma

Linear: <0.05

Quadratic: <0.05

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: ATTD of energy and nutrients

Linear: 0.775

Quadratic: 0.318

Linear: 0.142

Quadratic: 0.659

Linear: 0.409

Quadratic: 0.402

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: metabolizable energy (ME) in diets and N retention

Linear: 0.202

Quadratic: 0.319

Linear: 0.409

Quadratic: 0.402

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: optimal phytase level on ATTD of Ca

P value: Overall model: <0.05 Asymptote: <0.05

Slope: <0.05

y = 92.1 – 0.019 (668 –x) where x is less than 668 (SE = 65; P <0.01)

Optimal phytase level: 668 FTU/kg

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: optimal phytase level on retention of Ca

P value: Overall model: <0.05 Asymptote: <0.05

Slope: <0.05

y = 91.4 – 0.021 (668 –x) where x is less than 668 (SE = 69; P <0.01)

Optimal phytase level: 668 FTU/kg

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: optimal phytase level on ATTD of P

P value: Overall model: <0.05 Asymptote: <0.05

Slope: <0.05

y = 80.1 – 0.027 (780 –x) where x is less than 780 (SE = 86; P <0.01)

Optimal phytase level: 780 FTU/kg

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: optimal phytase level on retention of P

P value: Overall model: <0.05 Asymptote: <0.05

Slope: <0.05

y = 78.2 – 0.029 (773 – x) where x is less than 773 (SE = 93; P <0.01)

Optimal phytase level: 773 FTU/kg

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: optimal phytase level on free myoinositol in plasma

P value: Overall model: <0.05 Asymptote: <0.05

Slope: 0.063

y = 22.8 – 0.015 (705 –x) where x is less than 705 (SE = 212; P <0.01)

Optimal phytase level: 705 FTU/kg

22.8 µmol/L

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Results: growth performance

Linear: 0.027

Quadratic: 0.535

Linear: 0.053

Quadratic: 0.585

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Conclusions

• Supplementation of a hybrid bacterial 6-phytase at a range of 650 to 800 FTU/kg feed provided the optimal efficiency in improving apparent total tract digestibility of Ca and P, retention of Ca and P, plasma levels of free myoinositol of pigs compared with pigs fed a Ca and P deficient diet.
• Supplementation of a hybrid bacterial 6-phytase improved growth performance compared with pigs fed a Ca and P deficient diet.

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NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE

Thank you!� Thoughts? Questions?

Acknowledgment:

NC STATE UNIVERSITY

DEPARTMENT OF ANIMAL SCIENCE