I never had foal that was not accepted by their mother...but I have experienced many a momma beef cow that was apprehensive in accepting a calf, particularly a twin. In that situation I have used Vick's Vapor Rub around the mother's nose in addition to rubbing it down the middle of the calf's back...this distorts the sense of smell of both parties. Some people profess that extracts of vanilla work in the same fashion.
In addition, I had a neighbor who had a foal whose mother had no intentions of providing any typical mothering mannerisms, let alone be the source of food. She actually hated her baby and would attempt to kick, bite and strike every chance she had. Our vet quickly was able to provide a powdered milk replacement (although quite expensive), specifically designed for horses. My neighbors were dedicated to raise this baby, which they did with flying colors. Needless to say, momma went down the road!
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