The state Senate voted 34-23 Friday to give final approval to a one-year ban on a hormone used to boost cows' milk output, making Minnesota the second major milk-producing state to do so. The Minnesota House passed the ban Thursday 68-59 despite protests from the state's dairy farmers that the action would put them at a competitive disadvantage. The measure follows a similar one approved by the Wisconsin Legislature last month. Minnesota and Wisconsin combined produce about 24 percent of the nation's milk. Rep. Chuck Brown, who led the charge for the moratorium in the Minnesota House, said he has received assurances that Gov. Rudy Perpich will sign the measure into law. Under the legislation, non-medical use of bovine growth hormone, known as BGH or bovine somatotropin, would be banned for a year. The protein is a synthetic version of a hormone that naturally appears in cows and is expected to win approval of the Food and Drug Administration for commercial use later this year. Brown and state Sen. Steve Morse urged the ban, saying more time is needed to study the potential effects of the drug on animals and humans. The legislation would keep the ban in effect as long as Wisconsin enforced a similar moratorium or if a consortium of states representing at least 40 percent of the nation's milk production adopted a ban on BGH. The Wisconsin Legislature approved a temporary moratorium last month that is awaiting the signature of Gov. Tommy Thompson. He has not said whether he will sign the measure. The companies that produce the hormone, Monsanto Agriculture Co., Eli Lilly Co., Upjohn Co. and American Cyanamid, have lobbied against such measures, saying the hormone has been more than adequately tested. Supporters of the synthetic hormone, including dairy farmers, a pharmacist and a veterinarian, took issue with opponents' contentions that the drug may not be safe and argued against legislative impediments on new technology. ``There's no credible evidence that there's any health hazard,'' said Rep. Jim Girard. ``This is just another tool to allow farmers to increase their production.'' Rep. Harriet McPherson likened BGH to milk machines, embryo transplants and other technological advances that have increased milk production.