Numerous terms are used to describe pigs of various ages, sexes and ultimate purpose, such as sow, boar, piglet, sucker, weaner, baconer, porker, chopper and stag. When a young pig is up for sale, or being shown, however, it usually is referred to as a barrow or a gilt. These terms define not only the sex of the pig, but also its ultimate potential purpose.

A gilt is a young female pig. In common use, gilt is used to refer to a pig that has not yet been bred, whether only a few months old or approaching a year. Technically, however, the term gilt is defined as a female pig that is less than six months old. A gilt is intact, or capable of breeding and producing young, and her reproductive organs are not surgically or chemically altered.

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