By Jon Holt, PhD, North Carolina State University Assistant Professor and Extension Swine Specialist
Live weight of market pigs in the United States continues to rise. With finishing pigs becoming increasingly larger it is important to consider that pig performance can be adversely affected by a shortage of feeder space. Feeder space can influence feed efficiency by affecting the pigs’ access to feed. So how do we determine the correct amount of feeder space needed?

A literature search for this information may lead to more confusion than answers as recommendations are not abundant and often lack consistency. Part of the reason answers are limited in this area is because there is very little research that has been conducted on proper feeding spaces for finishing pigs. Traditional recommendations would be four to five finishing pigs per feeder space. However, this does not take into consideration the dimensions of the feeder or the pig.

Research in the United States has concluded that for finishing pigs around 200 pounds one feeder space is adequate for 10 pigs (Brumm, 2004). European recommendations add a little more detail by recommending one space for every four pigs weighing 220 pounds and that feeder space should be 3 inches per pig (12 inches total for four pigs). The National Swine Nutrition Guide gives a slightly smaller recommendation of 2 inches of feeder space per pig space in a pen (8 inches for four pigs). But does any of this consider dimensions of the pig besides its weight?

Related:Are finishing hogs getting enough space?

Brumm (2004) points out in his review that the feeding space required for a 265-pound pig would be about 13 inches using the following guidelines.

Shoulder width (cm) = 6.1 x body weight (kg)^0.33 and,
Feeding space (cm) = 1.1 x shoulder width

If we apply those guidelines to the other recommendations above, we would find that a 200-pound finishing pig would have a shoulder width of about 10.6 inches and therefore a feeding space allowance of 11.66 inches. It would appear that there is some agreement in the recommendations on the size of the feeder space, but still large variability in recommendations on how many pigs can be placed on each feeding space. Depending on recommendations above, a pen of 20 pigs could require anywhere between 23.3 inches (10 pigs per space, 11.66 inches per space) and 60 inches (four pigs per space, 12 inches per space) of feeding space. This is an important economic consideration as producers want to maximize the use of equipment and pen size while still maximizing feed efficiency. More research is certainly needed to bring clarity as well as consistency to feeder space requirements of finishing pigs, especially as we see heavier, faster growing animals in production facilities.

Work at the University of Minnesota (Li et al, 2017) suggests that feeder space allowance is not as simple as applying size and space ratios to a group of finishing pigs. Li et al (2017) suggest that the optimal feeder space allowance is the maximum number of pigs that can share a feeding space without a reduction in performance of the pigs. While this is an important measure of feeding space, it is also difficult to measure as it would be a dynamic number in various production settings and have many factors involved. These researchers found that time spent eating was key to determining the optimal feeder space requirements for finishing pigs. Factors that affected time spent eating included mash versus pelleted diets and dry versus wet-dry feeders. The researchers found that time spent eating was greater for pigs fed mash compared to pellets and also greater for dry compared to wet-dry feeders (Li et al, 2017). The increased time feeding led to increased feeder occupancy rates in those circumstances.

In their study, pigs were allotted to treatments based on feeder occupancy rates from 80, 103 and 125% based on time spent eating, with 125% representing a crowded feeder situation. Across both feed form and feeder type (dry versus wet-dry) the researchers found that increased feeder occupancy rate decreased average daily feed intake and average daily gain. Li et al (2017) recommended a feeder occupancy rate of 80% for maximum production in commercial settings based on eating behaviors of the pigs.

So how does this compare to previous recommendations?

In the study by Li et al (2017), finishing pigs were about 204 pounds on average, housed in pens of either 11, 14 or 18 and provided a feeder with a 15-inch feeder space and fed a mash diet. Using the shoulder width method, a 204-pound pig would only require 11.66 inches of feeder space and if this is enough for 10 pigs under some recommendations, then Li et al (2017) may have given slightly more feeding space allowance than necessary for maximum production.

In an attempt to bring all these calculations onto the same scale, calculating the feeder space allowance per pig may help illustrate the point. The earlier recommendation of 10 pigs per feeder space (Brumm, 2004) and 11.66 inches of feeder space (calculated using the shoulder width method) allows 1.16 inches of feeder space per pig. Li et al (2017) found the greatest ADG at 1.36 inches of feeder space allowance per pig, yet decreased performance at 1.07 inches of feeder space per pig. As noted earlier, the National Swine Nutrition Guide recommends 2 inches of feeder space per pig when feeding a mash diet. Therefore, it appears that regardless of the methods used to determine the optimal feeder space allowance for overall performance of finishing pigs, there is a range of 1.1 to 1.36 inches of feeder space per pig to maximize production, when feeding mash feed. More work is necessary to refine these recommendations further, especially with different feed forms.

As feed efficiency becomes more important and market weights keep increasing, consider the factors associated with eating behaviors and feeder space allowance in your production setting to make sure equipment and facility usage are being maximized.

References

Brumm, M. Understanding feeders and drinkers for grow-finish pigs. Paper presented at Memorias del X Congreso Nacional Produccion Porcina; June 13, 2010; Mendoza, Argentina.

DeRouchey, J.M. and B.T. Richert. Feeding systems for swine. 2010. National Swine Nutrition Guide. U.S. Pork Center of Excellence. Chapter 29, pp 255-269.

Li, Y.Z., K.A. McDonald, and H.W. Gonyou. Determining feeder space allowance across feed forms and water availability in the feeder for growing-finishing pigs. J. Swine Health Prod. 2017; 25(4):174-182.