It's easy for clubs to cross the line with supplements HORSE placenta is fine, as is the oil from an emu's belly. Deer antler is a no-go zone. As for calf's blood, it's okay as long as injections are given at six-hour intervals. Any sooner, and you're in the World Anti-Doping Agency's bad books. The world of sport science can be a wacky and mysterious place where boundaries are often pushed in the search for every available edge. How else do you explain Manchester United hitman Robin van Persie turning to placenta fluid to heal an ankle injury or Paula Radcliffe breaking the world marathon record after using oil from an emu's belly to treat injuries? The line is often crossed, in the case of Lance Armstrong, with sinister motives in mind. Occasionally, ignorance can bring the fall. Just ask golfer Vijay Singh. A three-time major winner and former world No 1, Singh is serving a six-month ban for using a deer-antler spray to promote muscle growth. The company that sells the product, Sports With Alternatives To Steroids (SWATS), harvests the deer antlers from New Zealand. Singh found himself in trouble because the product contains IGF-1, which is on WADA's prohibited-substances list. Not only has he suffered the shame of a suspension, but he has become the butt of jokes across the golfing globe (one wag suggested Singh took the substances while on a stag night). Now it's Essendon's turn in the spotlight, under investigation from the AFL and ASADA over supplements given to players last season. The club yesterday confirmed it had sacked sports scientist Stephen Dank, who came to prominence five years ago when he was credited with introducing rugby league to the benefits of calf blood. With Dank in tow, Manly became the NRL leader in sports science. Their methods were shrouded in secrecy. Dank declined interview requests, heightening his reputation as a man of mystery. Calf blood, used to promote faster healing from injury, was only the start. Dank talked about DNA-testing players, although the plan didn't go further due to the cost. Sea Eagles officials yesterday remembered Dank as a man who liked to push the envelope, often trialling his own products. That said, they insist he never crossed the line and there is no suggestion he has done anything illegal at Essendon. After leaving Manly, he headed to Cronulla but the marriage was short-lived and ended in acrimony when Dank fell out with the club's medical staff. He was used by other clubs before finding a home in the AFL at Essendon. That marriage now appears to have turned sour as well. After a disappointing season, the club yesterday approached the AFL with concerns over supplements given to its players. Given Dank's history, rugby league will watch with interest.