Is it permissible to dispose of a ram, by selling it, gifting it, or slaughtering it, after it had been designated for free insemination for the sake of Allah?

It is permissible to make an endowment (waqf) of an animal, and this is the view of the majority of jurists. The endowment is established through an explicit utterance or through an implicit one accompanied by the intention. So, if you say: "I have endowed this stallion," or "I have dedicated it," or "I have made it a sabil (endowment for public use)," it becomes an endowment. However, if you say: "I have given it in charity," or "I have forbidden it (for personal use)," or "I have made it perpetual," it does not become an endowment unless an explicit term is adjoined, such as saying "a perpetual charity (sadaqa mawqufa)," or if it is described with the characteristics of an endowment, such as "it is not to be sold or gifted," or if the intention of endowment is present. It is permissible to dispose of the stallion by gifting or selling it as long as it is not an endowment. If the endowment is valid, it is not permissible to dispose of it in a way that would take it out of the endowment.