Maximizing the output from any given facility is key to the profitability of pork production.

For the finishing herd, maximum output from a barn is defined as the maximum total weight of pigs that fall within the target market-weight window that the packer demands. A major factor determining total output from any facility is the floor space allowed for each animal or, in other words, the number of pigs that are placed in the building. Optimizing floor space is critical; giving the animals too little or too much floor space will result in either poor animal welfare or reduced output. 

Recently, there have been some major changes in grow/finish management, including the widespread adoption of technologies such as wean-to-finish systems, larger group sizes and all-in/all-out management, which have implications for defining the optimum floor space for a given situation. Therefore, it is opportune to revisit the optimum floor space to use in commercial facilities.  In practice, the space will be situation specific, depending on the facility’s characteristics, as well as the weight of pigs that the packer wants.

There are several factors that you should consider when deciding how many pigs to put into a particular building. These include:

  • Based on a significant body of historical research, U.S. recommendations for the floor space needed to maximize growth rates are around 7.5 square feet per pig. Producers have generally allowed less floor space than this to maximize the total weight of pigs produced from the facility.
  • Results of recent University of Illinois studies suggest that the floor space needed to maximize growth rate is less than predicted from historical studies. The Illinois studies, which were carried out in commercial, wean-to-finish facilities with conventional group sizes (~32 pigs per pen), suggest that the minimum floor space to maximize growth is 6.5 square feet per pig, or about 13 percent less than the traditional recommendation.
  • With single-stocked, wean-to-finish facilities, floor space typically only becomes limiting toward the late-finishing period, such as in the last two to four weeks before pigs are shipped. Therefore, this late-finishing period needs consideration. 
  • Most producers will ship pigs from a facility over a number of weeks. Obviously, the floor space available to the remaining animals increases when pigs are removed from the pen. Depending on how many pigs are removed, this can eliminate floor-space restrictions on growth.
  • In fact, we have shown in several studies that the performance of the remaining pigs increases substantially when the larger pigs are removed. The timing and number of pigs to ship in the first cut are critical decisions that will influence the facility’s ultimate output. The other consequence of removing pigs from the barn is that pigs may be dealing with restrictive floor spaces for a very short time.
  • The move to large finishing groups has important floor-space implications. In theory, the floor space that maximizes output declines as group size increases. However, the research has not been carried out to prove this concept.
  • The ventilation system’s capacity is critical to determining the maximum number of pigs to place in a facility. If you decide to increase the number of pigs, then the maximum ventilation needs to be checked to ensure that it’s adequate for the proposed animal load.

Deciding on the number of pigs to place in a given facility is critical to determining system output and is a complex decision involving all of the factors outlined above. Our research has suggested that the optimum floor space to use in modern production facilities is less than historical recommendations, and stocking more pigs in a barn can help offset higher production costs. However, as with all other aspects of pork production, barns with increased stocking density require management for successful operation.