30 Pigs/Sow/Year: Now What?

Optimizing sow productivity, longevity, and offspring performance.

by Brad Lawrence, PhD, Senior Manager – Global Swine Innovation Lead, NOVUS

Achieving 30+ pigs per sow per year was once a lofty goal, but today it is a fairly common achievement thanks to genetic improvements in litter size.

However, are pigs weaned per sow per year really the ultimate target for financial sustainability?

Data by Gruhot et al. (2017) would suggest that while pigs per sow per year is certainly a contributing factor, the ultimate target should be the optimization of pigs per sow lifetime, which is achieved by sows reaching parity four and beyond.

Achieving the pigs per sow per year goal has coincided with an increase in sow mortality over the past decade. The appearance in North America of pelvic organ prolapses as a significant industry issue and reason for euthanasia and lameness continues to plague the industry. Additionally, piglet quality from gilt litters and increased litter size are concerns.

What if pigs weaned per sow per year, as well as pigs weaned per sow lifetime (and ultimately pounds of pork produced per sow lifetime), could be enhanced with a greater than 18:1 return on investment? Research indicates this may be achievable.

pigs standing in mud
Photo Credit: deyanarobova/iStock/Getty Images Plus photo

Gilts - Beginning with the End in Mind

Gilts are the foundation of the breeding herd. Reviews by Patterson and Foxcroft (2019) as well as Faccin et al. (2022) have, during the gilt selection process, highlighted the need to consider factors such as gilt birth weight, litter size the gilt came from, and sex ratio within the litter the gilt came from.

In addition to boar exposure to stimulate puberty, weight at breeding should be considered, with a target weight of 135 to 160 kilograms (~297.6 to 352.7 lbs.).

However, as pointed out by Faccin et al. (2022), the growth rate of modern gilts can be associated with increased locomotion and structural issues if gilts are too heavy at breeding.

This leads some producers to either restrict nutrition or feeding levels during gilt development, which can lead to negative consequences for mammary development.

What if gilts could be developed to their full growth potential without negative consequences to their structural health and therefore longevity?

Research is demonstrating the importance of trace mineral sources for gilt development and the breeding herd on the longevity and lifetime productivity of not only the sows but also the offspring.

Traditionally, inorganic trace minerals, often in sulfate form, have been used due to their low cost. New forms of trace minerals, including those as metal-methionine hydroxy analog chelates (MMHAC), which result from coordinate covalent bonds of the mineral with two molecules of methionine hydroxy analog, are shown to provide a high return opportunity to improve sow and offspring performance as well as sow welfare.

Decoux et al. (2012) reported that from weaning to first farrowing, the total removal rate was nine percent lower when 50 percent of the zinc (Zn), copper (Cu), and manganese (Mn) were supplied in the MMHAC form.

Gilt mortality for the same period was 28 percent lower when 50 percent of Zn, Cu, and Mn were provided in the MMHAC form.

Of removals through first parity, 13.8 percent were for locomotion or lameness in the 100 percent sulfate mineral treatment, compared to only 8.9 percent when 50 percent of the trace mineral was in the MMHAC form (Table 1).

Table showing trace mineral source impact on gilt removals
Table 1. Impact of trace mineral source on gilt removals from weaning through first parity. From Decoux et al., 2014.

Of the 70 gilts per mineral source evaluated for lameness, the research did find that gilts supplemented with 50 percent of the mineral in the MMHAC form had a lower gait score, further supporting the benefits minerals in the MMHAC form have on structural development and mobility.

These observations of reduced lameness in gilts fed a portion of their trace minerals in the MMHAC form are supported by more recent unpublished findings where MMHAC increased the percent of growing pigs without lameness symptoms using ractopamine HCl as a growth stimulant.

These results support the use of MMHAC minerals as a portion of the total trace minerals in gilt development to support mammary development while optimizing structural health.

Achieving More Pigs per Sow Lifetime

While Gruhot et al. (2017) indicated economic return was optimized at parity four to five, what this reflects is the impact of the number of weaned pigs on fixed costs.

At the time of analysis, the data from Gruhot et al. (2017) would indicate that approximately 40 to 50 pigs per sow lifetime would need to be achieved for optimal financial return.

Costs, of course, have increased over the past decade. However, assuming 50 pigs per sow lifetime as a target and 13 pigs weaned with modern sows, we still need to retain as many sows as possible to parity three or four. Results from a large field evaluation in Spain (Barea et al., 2019) highlight the importance of trace mineral sources in helping achieve this goal (Table 2).

Table showing impact of trace minerals on key performance
Table 2. Impact of trace mineral source on key performance parameters. From Barea et al., 2019

Data from 28 sow farms with an average size of 1,500 sows per farm was evaluated over two years.

When only 50 ppm Zn, 10 ppm Cu, and 20 ppm Mn in the MMHAC form were included in the diet, retention of sows to parity three was 74 percent, compared with 67 percent for sows fed all inorganic Zn, Cu, and Mn.

Additionally, MMHAC sows weaned 0.6 more pigs per litter. The data was also used to calculate pigs weaned to parity three, with the sows fed the MMHAC minerals producing nearly four more pigs due to more pigs weaned and a greater percentage of females reaching parity three.

A lower replacement rate contributed to more sows reaching parity three. Approximately 50 percent of the replacement rate difference was due to the MMHAC herds having lower sow mortality. The other 50 percent of the replacement rate difference was due to a lower culling percentage in the MMHAC herds, with about 20 percent lower culling due to lameness in the MMHAC herds.

Achieving More Pork Produced per Sow Lifetime

The goal is not only to produce more pigs but also to produce high-quality pigs that will survive and arrive at market.

This starts with minimizing the number of low-birthweight pigs (Feldspausch et al., 2019), which can increase as litter size increases (Beaulieu et al., 2010).

Findings from a study conducted by Zhao et al. (2011ab) indicated that sows fed trace minerals in the sulfate form saw an increase in the percentage of pigs less than one kg (2.2 lbs.) at birth with increasing litter size.

However, when sows were fed 50 percent of their Zn, Cu, and Mn in the MMHAC form, the percentage of pigs less than one kg (2.2 lbs.) did not increase as litter size increased.

This data indicates that sow trace mineral sources (as MMHAC) impact pig development. It has an influence on low birthweights, can impact pre-weaning mortality, and improves the opportunity for more primary market-weight pigs.

Furthermore, research by Jang et al. (2020) demonstrated that feeding 50 percent of the mineral in the MMHAC form positively impacted offspring muscle development during gestation and resulted in lower markers of gut inflammation at weaning. Zhao et al. (2011c) followed pigs wean-to-market from the trial by Zhao et al. (2011ab) and observed that in a fixed-time system, pigs from sows fed the MMHAC minerals were two kg (4.4 lbs.) heavier.

Additionally, mortality was 16 percent lower, resulting in approximately eight more pigs reaching market per 1,000 placed (Figure 1).

graph showing sow trace mineral source and wean-to-market
Figure 1. Sow trace mineral source impact on offspring wean-to-market

More Pigs per Sow Lifetime Improves Returns

More pigs marketed per inventoried sow or per sow lifetime drives down fixed costs.

Research shows that sow trace mineral sources impact the key performance parameters that are important for driving cost out of the system, optimizing revenue, and therefore improving returns.

Bradley V. Lawrence, PhD

Dr. Lawrence works with a team of in-house Novus researchers and experts to develop and execute the swine research program that focuses on optimizing sow lifetime productivity, pig performance, and survival, as well as production sustainability, all supported through intelligent nutrition. He also works with the global strategic marketing and business development teams.