This past week I’ve been working on a presentation for the China Swine Science Conference in Xiamen, China on September 17-20. My topic – optimal farm size for profit in pig farming.

Talk about a challenge. While somewhat limited, the most recent data that I’ve seen generally suggests profit per cwt sold generally is not related to size of the sow unit(s). In other words, big is not necessarily better or worse. In the United States, size (pigs per site or sows per breeding site) is most often related to zoning regulations at some point in the pig flow and/or pig health considerations.

The US-EPA definition of an animal unit is 2.5 pigs weighing greater than 55 lb. For pigs under 55 lb, the definition is 25 pigs per animal unit. A 1000 animal unit basis for many township, county and state regulations is the reason so many grow-finish and wean-finish sites have capacities of 2450 pigs.

If we go backwards from this number, if the desire is to fill a facility with pigs that vary only 7-8 days week in age, this means we need to wean almost 2500 pigs every week for a single fill wean-finish site. The option is to co-mingle pigs from smaller breed-wean sites if pig age is an absolute criteria for filling a site or we need to let the age spread widen if the breed-wean site is smaller.

If we have a 5200 sow breed-wean site, once it is up and running with a stable parity distribution and weaning 24 pigs per inventoried female (females enter the inventory for this computation at time of first mating), this becomes 124,800 weaned pigs per year or 2400 weaned pigs per week. If the breed-wean unit is smaller than 5200 females there is more variation in age at typical grow-finish and wean-finish facilities.

Many industry outsiders ask why our sow units have to be so big. It’s all about pig flow downstream beginning with the regulatory process. Producers know the local and state zoning and manure regulations and make good faith efforts to go beyond the rules and regulations. At the same time, they will generally construct facilities that capture the economics of size for such items as wells, roads, electric supply, etc. that are site specific and not size specific.

All-in and more importantly all-out management dictates that age spread at the time of placement be relative tight (most strive for a 10 day spread in age or less) so that when all-out happens at sale time, there aren’t too many open pen days that are being paid for while the last pigs in the facility grow to market weight. With current production contracts, grow-finish spaces average $0.10-0.12/day and nurseries average $0.08-0.10/day. Keeping spaces full of pigs is an economic advantage and the ability to source enough pigs at one time to fill in a relatively short time is an economic edge that can’t be denied.