beef to (the) heel like a Mullingar heifer

Chubby or fat, especially in the legs. Usually said of women, it refers to cattle bred in Mullingar, a town in County Westmeath, Ireland. Primarily heard in Ireland. I think I need to go on a diet, I've gotten beef to the heel like a Mullingar heifer since my pregnancy. I don't know what's wrong with other men, I like a woman who's beef to heel like a Mullingar heifer.