VANCOUVER, Canada  - The world’s first “test-tube” meat, a hamburger made from a cow’s stem cells, will be produced this fall, Dutch scientist Mark Post told a major science conference on Sunday. Post’s aim is to invent an efficient way to produce skeletal muscle tissue in a laboratory that exactly mimics meat, and eventually replace the entire meat-animal industry. The ingredients for his first burger are “still in a laboratory phase,” he said, but by fall “we have committed ourselves to make a couple of thousand of small tissues, and then assemble them into a hamburger.”