What is the term for the act of swine giving birth?

The term for the act of swine giving birth is "farrowing." This word specifically refers to the process when sows (female pigs) deliver their piglets. Farrowing typically involves a series of contractions and is significant in animal husbandry, especially in pork production, as it directly impacts the growth and management of the herd.

Looking at the other options, "birthing" is a general term for the act of giving birth across all animal species and does not specifically relate to swine. "Calving" is exclusively used for the birthing process of cattle, while "gestation" refers to the period of development of the fetus before birth. In this case, farrowing is the precise term that describes the act of swine giving birth, making it the correct choice.