To address the problem of manure-based environmental pollution in the pork industry, we have developed the phytase transgenic pig. The saliva of these pigs contains the enzyme phytase, which allows the pigs to digest the phosphorus in phytate, the most abundant source of phosphorus in the pig diet. Without this enzyme, phytate phosphorus passes undigested into manure to become the single most important manure pollutant of pork production. We show here that salivary phytase provides essentially complete digestion of dietary phytate phosphorus, relieves the requirement for inorganic phosphate supplements and reduces fecal phosphorus output by up to 75%. These pigs offer a unique biological approach to the management of phosphorus nutrition and environmental pollution in the pork industry.
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We thank the staff at Arkell Swine Research and T. Archbold in the Department of Animal and Poultry Science for their assistance. This research was supported by funding from Ontario Pork, Ontario Ministry of Agriculture, Food and Rural Affairs, Food Systems Biotechnology Centre (University of Guelph) and the Natural Sciences and Engineering Research Council of Canada to C.W.F. and J.P.P.
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Golovan, S., Meidinger, R., Ajakaiye, A. et al. Pigs expressing salivary phytase produce low-phosphorus manure. Nat Biotechnol 19, 741–745 (2001). https://doi.org/10.1038/90788
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