Enviropig

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Enviropig Richard Wolfe
2
Introduction

• - Increase food production without degrading the
  environment.
• - Manure is used as a fertilizer.
• - Monogastric (single stomach) animals, pigs and
  chickens produce high phosphorus manure.
• - Not able to digest plant phytate

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Introduction

• - Can not remove the phosphorus from phytate.
• - Up to 80 of the P in the plant based feed is
  found in phytate.
• - Phosphorus is supplemented to diet to achieve
  optimal growth.

4
Introduction

• - Required dietary supplements cause excess P in
  manure.
• - Run off from using manure as fertilizer adds
  excess P into streams and rivers.
• - Algal blooms, oxygen depletion, death of fish
  and aquatic animals
• - Phytase is an enzyme that releases P from
  phytate
• - Used transgenic mice to deliver E.coli phytase
  into digestive tract through salivary glands.
• - Shown E.coli phytase added to poultry diets was
  effective.
• - Pigs that produce salivary phytase require
  almost no supplement and excrete 75 less P.

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• - Pig eats food
• - As pig chews phytase released
• - Phytase and food swallowed
• - Phytase enzyme activated
• - Phosphorus absorbed
• - Low P manure excreted

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Results

• - 4,147 embryos were microinjected.
• - PSP/APPA transgene (parotid secretary protein
  promoter linked to the E.coli appA phytase gene)
• - DNA extracted from blood and tail used to id
  with PCR
• - 33 transgenic founder (G0) pigs produced.
• - 14 produced 5 to 6000 U/ml of phytase in their
  saliva at 7-11 days
• - 15 produced lt 5 U/ml.
• - 4 produced an undetectable amount.
• - 1U phytase 1 micro mol phosphate released
  from phytate per min
• - Transgene copy number was 35 for WA line, 2 for
  JA

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• - Tested to see if salivary phytase promotes
  digestion of P
• - Selected transgenic G1 WA with median salivary
  phytase 2,420 U/ml
• - Fed soybean meal containing 53 phytate P
• - Only source of P

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• - P in manure reduced 75 in weanling transgenic
  pigs
• - P reduced 56 in growing-finishing transgenic
  pigs
• - Almost all of the dietary P was digested and
  absorbed

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• - Second test to see if salivary phytase promotes
  digestion of P
• - G1 pigs fro JA line fed standard diet
• - No supplement of inorganic P
• - Fecal P reduced by 64 67 compared to
  non-transgenic pigs
• - Average salivary phytase 190 U/ml
• - Growth rate transgenic pigs was 145.8 days to
  reach 100kg
• - Non-transgenic was 147 days and they received P
  supplement

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• - High phytase activity detected in parotid,
  sublingual, and submaxillary salivary glands
• - Low but substantial activity in stomach and
  duodenal contents
• - Comparable tissues of non-transgenic pigs
  contain no detectable amount

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• - Images correspond to Table 2
• - Parotid and submaxillary glands show staining
  of phytase protein
• - No staining in transgenic muscle
• - No staining of non-transgenic parotid

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• - 55 kDa phytase protein found in B,C,E,F,G
• - Levels of F,G lower
• - Mass of D higher

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Discussion

• - Phytase activity present in saliva varied from
  5 6000 U/ml due to position of transgene
  insertion
• - A transgenic pig producing 2-5 U/ml of phytase
  will satisfy the dietary requirement of P
• - The transgene copy number was only determine
  for two lines of transgenic pigs, can not
  determine if related to phytase expression
• - Shown that salivary phytase enables digestion
  of phytate P and no P supplement is required
• - Also, P in manure is reduced up to 75
• - Have not detected any deleterious effect on
  health or performance

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References

• 1. Golovan SP,et al Pigs expressing salivary
  phytase produce low-phosphorus manure. Nature
  Biotechnology. August 2001, 19, 741-745.
• 2. Phytate picture. http//www.food-info.net/uk/qa
  /qa-fp162.htm.
• 3. Enviropig image. http//www.uoguelph.ca/envirop
  ig/.