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High levels of dietary phytase increase growth and nutrient digestibility in young broilers

Kailyn Beaulac1, Mike Bedford2, Andrew Van Kessel1, Karen Schwean-Lardner1, Michael Kautzman1, Dawn Abbott1 and Henry Classen1

1University of Saskatchewan, 2AB Vista Marlborough

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Outline Literature review

Phytate

Implications for monogastrics

Phytase

Development of the digestive tract

Phytase efficacy and age

Experimental procedures

Results and discussion

Conclusion

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Major storage form of phosphorus (P) in plants

Myo-inositol ring accompanied by up to 6 phosphate anions

Phytate

Cowieson et al., 2004

1

234

5 6

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Monogastric Nutrition Phytate anti-nutritional properties

Mineral availability (Cheryan, 1980)

Cu2+ > Zn2+ > Ni2+ > Co2+ > Mn2+ > Fe3+ > Ca2+ (Graf and Eaton, 1990)

Protein availability (Selle et al., 2012)

Direct

Indirect

Other

Starch/lipid availability (Selle et al., 2012)

Reduced digestibility and increased endogenous losses

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Monogastric Nutrition

Thompson, L. 1987

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Phytase Classified by optimum pH – acidic, neutral, alkaline

Acid phytases are used primarily (Mullaney and Ullah, 2003)

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Phytase Effects

Improves mineral availability

P and trace minerals

Improves amino acid digestibility

Improves energy availability

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Dosage Effects

Shirley and Edwards, 2003

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Development of the Digestive Tract Intestinal growth initiates within

24 h of feed ingestion(Sklan, 2001)

Changes in morphology occur within the first 10 days (Sklan, 2001)

Villus height

Villus width

Crypt depth

Goblet cell development – 3 d pre-hatch (Uni et al., 2003)

Initiation of mucin secretion and innate barrier function

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Phytase efficacy and bird age Improves digestibility and absorption of nutrients that

would otherwise be excreted in young birds?

Endogenous amino acid losses are 2X greater in young birds (5 d) compared to older birds (15 d)

(Adedokun et al., 2007)

Mucins and biliary secretions are high in certain amino acids Reduces the nutrient requirements for the formation of digestive

secretions?

Improve the digestibility of digestive secretions?

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Objective To examine the effects of high levels of dietary

phytase on the nutrient digestibility, gastrointestinal development, and performance parameters of young broilers (5 and 20 d)

Hypothesis Increased hydrolysis of phytate will result in improved

nutrient digestibility, enhanced gastrointestinal tract development and improved performance in young (5 d) vs older (20 d) broilers

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Experimental DesignBasal diet formulation

Ingredient %

Wheat 51.11

Soybean meal 24.00

Canola meal 10.00

Wheat bran 5.00

Canola oil 5.94

Endo-xylanase (Econase) 0.01

Titanium oxide 0.30

Analyzed phytate content (0.96%)

Treatments

Phytase level 0 FTU

500 FTU

1500 FTU

3000 FTU

Gender Male

Female

Standard Management Practices

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Experiment 1

Evaluate the effects of high levels of phytase on the

morphology of the gastrointestinal tract and digestion

characteristics of young chicks (0-5 d)

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Data Collection Performance Data (0 and 5 d)

Pen body weight and feed consumption

Excreta Collection (5 d)

AME

Digesta Collection (5 d)

Phytate digestibility

Terminal ileal amino acid digestibility

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Data Collection Tissue Collection (5 d)

Heart, liver, pancreas, and yolk sac weight

Gizzard pH

Lengths and weights of the

digestive tract

Histology (1, 3, and 5 d)

Duodenum, jejunum, and ileum Villi height, villi width, and crypt depth

Examined at 0 and 3000 FTU/kg

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Experiment 2

Evaluate the effects of high levels of phytase on the

performance and digestibility of broiler chicks to 20 d

of age

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Data Collection Performance Data (0, 5, 10, 15, and 20 d)

Pen body weight and feed consumption

Excreta Collection (20 d)

AME

Digesta Collection (20 d)

Phytate digestibility

Terminal ileal amino acid digestibility

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Data Collection Tissue Collection (20 d)

Heart, liver, and pancreas weight

Gizzard pH

Lengths and weights of the digestive tract

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Statistical Analysis Proc mixed (SAS 9.3)

4 X 2 (phytase X gender) factorial arrangement for performance and digestibility

2 X 3 (phytase X age) factorial arrangement for histology

Analyzed covariance and normality

Regression analysis for level

Proc reg – linear; Proc rsreg – quadratic

Differences were considered significant when P ≤ 0.05

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Results and Discussion

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Phytate Digestibility * quadratic

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Body Weight Gain * linear

quadratic P = 0.06

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Feed Consumption * linear

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Feed Conversion Ratio * quadratic

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Tissue Weight * quadratic

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Histology

Ileum

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Apparent Metabolizable Energy

* linear

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Amino Acid Digestibility * linear

All amino acids increased in a linear fashion

10%

7%

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Amino Acid DigestibilityAmino acids high in endogenous secretions

Mucin amino acids Cysteine

Proline

Serine

Threonine

Biliary amino acids Glycine

Essential amino acids

Arginine

Histidine

Isoleucine

Leucine

Lysine

Methionine

Phenylalanine

Valine

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Amino Acid Digestibility * linear

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Hypothesis Increased hydrolysis of phytate will result in

improved nutrient digestibility, enhanced gastrointestinal tract development and improved performance in young (5 d) vs older (20 d) broilers

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SummaryParameter 5 d 20 d

Phytate digestibility

Body weight gain

Feed conversion ratio

Tissue weights

Histology

AME

Amino acid digestibility

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Summary High levels of dietary phytase result in:

More consistent hydrolysis of phytate in both 5 and 20 d old broilers than at low levels of phytase

A positive response in performance in both performance and digestibility at 20 d of age, but only a response in digestibility at 5 d

REJECT HYPOTHESIS

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Conclusion Despite less effect in 5 d old broilers, the use of

high levels (super-dosing) of phytase in broiler diets has considerable promise

Almost all phytate P is consistently made available

Improved utilization of other minerals

Improved energy and amino acid availability

More consistent response to phytase use

Economics?

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Acknowledgements

Thank you to all the Poultry Centre staff and other members of the Poultry Science group at the University of Saskatchewan

NSERC IRC Sponsor Organizations

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Questions?