Canadian scientists have genetically engineered an eco-friendly pig whose manure may contain 20 to 50 percent less phosphorus than normal pigs, potentially reducing soil and water pollution. The scientists say their “enviropigs” are likely the first animals engineered to help cope with environmental problems. The new pigs could abet pork producers in raising more pigs under strict environmental regulations for phosphorus. The enviropig is at least four years away from commercialization and would need regulatory approval from the Canadian government.