What if all of the worlds major religions (Christianity, Judaism, Islam,) apart from some of the Dharmic religions which already do, had prohibitions on the consumption of most or all meats, with the exceptions of Fowl, such as Chickens, Turkey, etc. and seafood, like Fish, clams, Crabs etc.
You can assume that their are some denominations that are totally vegetarian and don't eat any meat and some that are less so, allowing for the consumption of fowl, fish, and perhaps one other type, excluding large animals, but the ones that allow the consumption of more than that are very small minorities.
While the three Abrahamic religions and Hinduism and Buddhism must remain major religions, you can come up with one to three additional major religions, but they must all share the same trait of not allowing the consumption of most meats.
The OTL major religions don't have to be exactly the same either, different denominations may develop or dominate and they may spread geographically differently then OTL.