A Yielding Animal is any animal which produces a product that can be harvested and used. This can be the animal itself, such as in meat-yielding pigs, or a byproduct of the animals, such as wool from sheep and fertilizer from cows. Usually, the product must be self-sustainable and self-replicating; you cannot continually harvest meat from a cow, but you can shear a sheep every season. This means that the term "yielding animal" is usually used in conjunction with a specific product: "milk-yielding animal," or "wool-yielding animal." While bird feathers can be harvested from from normal molting, it is harmful to the bird to pluck the feathers directly, and so birds are not usually referred to as "feather-yielding," but instead as "meat- or egg-yielding," the feathers being a side product. Different sectors of agriculture may use the term in different ways, but most yielding animals are domesticated and kept on farms or homesteads; few wild animals are considered "yielding" (with the notable exception of hunted animals such as deer and turkeys) because they are not kept and harvested on a specifically regular basis. In other words, a wild boar would not be considered "yielding" except as when hunted, but a domestic pig is considered yielding, because it is raised and fed to harvest its meat.