Fig. 1

Pork production is a tiered multiplication and breeding pyramid. Diagram of the steps of pig production starting at the nucleus, multiplier, producer and final commercial pig for consumption. Each step of the pyramid is approximately 1 year and multiplication factor for each generation shown on the left. The red portion of the pyramid that is owned and operated directly by genetic nucleus (GN) providers; blue section represents independent producers under contract with genetic providers for sale to other producers; and gray portion represents customer operations for their internal use. According to the USDA, in March 2022, there were 72. 2 million pigs in production, producing approximately 120 million for processing annually (https://www.nass.usda.gov/Newsroom/2022/03-30-2022.php). Six million pigs make up the breeding population consisting of nucleus, multiplication and commercial levels. Maternal (dam lines) and paternal (sire lines) are shown on the right of the pyramid and describe at the bottom of the figure