Parity's Impact On Productivity

Parity structure of the breeding herd can have a significant effect on efficiency and profitability. The objective of this first in the 2008 quarterly benchmarking series is twofold. First, a comparison of key performance indicators (KPI) from the previous quarter and year will be made with the values observed 12 months ago. And, we will examine performance of sows, by parity, in order to demonstrate

Parity structure of the breeding herd can have a significant effect on efficiency and profitability.

The objective of this first in the 2008 quarterly benchmarking series is twofold. First, a comparison of key performance indicators (KPI) from the previous quarter and year will be made with the values observed 12 months ago. And, we will examine performance of sows, by parity, in order to demonstrate the importance of maintaining proper parity structure in the breeding herd and its effect on the efficiency of a modern pork production operation.

This series is aimed at helping pork producers and managers squeeze greater efficiencies out of their production systems and to reinforce the importance of effectively using accurate production records. Production records combined with benchmarking against the top producers can help identify areas where some fine-tuning may help an operation reach the levels attained by their very best competitors.

We will use pigs weaned/mated female/year (PW/MF/Y) to evaluate our current standing compared to 52 weeks ago. This value serves as a barometer to measure where we're at and where we want to be in the future.

It is important to note that Swine Management Services, LLC, the source of this benchmarking data, has increased the number of farms contributing to this data set from 314 farms in 2007 to 479. This increase is reflected by the increase in numbers of sows from just under 530,000 sows in 2007 to over 800,000 sows currently — an increase of over a quarter of a million sows. This type of increase can skew a year-by-year comparison, but it still provides a good benchmarking target for the industry.

Weaned Pig Averages Edge Upward

The PW/MF/Y values for the most current 52-week period (2008) and comparable data for 2007 are shown in Table 1.

The top 10% of farms in the 52-week summary from the most current quarter reported a 27.07 PW/MF/Y average compared to the top 10% a year ago with 26.95 PW/MF/Y. This reflects 0.12 more pigs, or an improvement of just under 0.5%.

When we look at the same values for the top 25% of producers, a slightly greater increase is seen — 26.02 vs. 25.41, which is a 0.61 pigs weaned difference, or a 2.4% improvement.

The PW/MF/Y average across all farms during the 52-week period showed an increase of 0.20 pigs weaned (22.57 vs. 22.37), an improvement just short of 1%.

This data clearly shows that the best producers keep getting better, and even our average-to below-average producers are still making positive strides toward great efficiency. Producers ranking average or below will need to improve their management skills to more effectively ride out the current economic conditions.

Parity Differences

The second objective of this article is to compare productivity differences among sow parities.

It is generally accepted that maintaining an older sow herd can have positive effects downstream. Pigs from Parity 3 or higher sows perform better than pigs from gilt litters. These positive effects include improved average daily gain or days to market and reduced mortality throughout the nursery and grow-finish phases.

Table 2 illustrates the productivity differences from sows at different parities. To examine these differences we will compare the KPIs of farrowing rate, total number of pigs born, total pigs born alive, percent of litters farrowing less than 7 pigs born alive and number weaned. We will also examine culling and mortality by sow parity.

It is not surprising that Parity 1 females are consistently the poorest producers for all KPIs in this data set up to Parity 5.

The farrowing rate for Parity 1 females is the lowest in this data set, with the exception of sows at Parity 7 or higher. We see a similar trend when examining the number of pigs born and the number of pigs born alive. The exception — sows from Parity 6 and higher have fewer pigs born alive and a greater percentage of litters with 7 pigs (fewer born alive) when compared to the first-litter gilts.

The productivity by parity is not surprising. The fact that Parity 1 and 2 females do not have as many pigs born alive is included in the National Swine Improvement Federation's (NSIF) adjustments for parity for number born alive when conducting genetic evaluations. However, the difference between Parity 1 females and a mature sow (Parity 3 through 5) is not as great as the NSIF adjustments might suggest.

A closer look at the SMS database shows the difference in number of pigs born alive between Parity 1 and Parities 3-5 ranges from 0.35 to 0.66 pigs. The difference between these values and the adjustment factors recommended by NSIF may reflect the SMS database being largely populated with crossbred females, while the NSIF adjustments were calculated for pure line or purebred females, that do not have the heterosis advantage.

Culling Parameters

Sow productivity differences are often used to make culling decisions. Many producers automatically cull sows at specific parities. This is clearly evident in Table 2.

Parity 0 females (selected gilts that have not farrowed a litter) and P1 females have the highest cull rates. Culling in the mature sow parities — Parities 3 through 5 — averaged 10% or less. At Parity 6, culling begins to creep up. Parity 7 and higher sows represent 23.3% of culled sows.

Mortality rates often follow culling trends, by parity. Parity 0, 1 and 2 sows have the greatest mortality rate when compared to all other parity categories. As sows reach Parity 4 and higher, mortality within each parity group begins to decline.

Parity Predictions

Parity distribution not only impacts current production, it will likely influence future productivity and replacement gilt needs. Figures 1-4 illustrate four different herds that have distinctly different parity distributions.

The distribution shown in Figure 1 is generally classified as an ideal parity distribution, which results in a consistent need for replacement gilts. Based on the production information below, the most consistent pig flow is achieved when this “ideal” parity structure is maintained.

Figures 2 and 3 illustrate cases where the producer is relying too much on older sows (Figure 2) or a herd that is too young (Figure 3). Both of these cases are undesirable — but for slightly different reasons.

Figure 2 shows a bulge of older females from Parity 2 through 5. This bulge will move through the herd, eventually causing an abnormally high culling rate and, naturally, the need for a large number of replacement gilts. During the bulge, productivity remains good. But when a high influx of gilts is required, productivity inevitably slips. When high numbers of gilts are needed, selection criteria often become lax, which also hurts productivity.

In the worst-case scenario, an insufficient number of gilts are available, so younger (underage) gilts may be brought in without proper isolation, acclimation and development periods. This may be termed the “death spiral,” because once this trend starts, it is difficult to stop.

Frequently, the parity distribution in Figure 2 leads to the distribution shown in Figure 3, when a disproportionate number of gilts are needed. As the SMS database shows, the number of pigs born alive from gilts is lower than older females. Therefore, commercial herds with a parity structure as shown in Figure 3 will often record fewer pigs born alive, which reduces pig flow and, consequently, does not allow nursery and grow-finish facilities to be used efficiently.

Figure 4 shows the parity distribution of a herd in an expansion phase. Notice the relatively large percentage of females in Parities 1 and 2. This is a necessary evil associated with expansion. Producers should strive to get to the more ideal distribution illustrated in Figure 1 as quickly as possible after the herd expansion is complete.

The Best Get Better

It is clear that U.S. producers are continuing to become more efficient. The SMS database serves as a snapshot of U.S. commercial pork production. The database reinforces that parity productivity differences still exist in commercial sow herds. How we manage these differences will dictate how efficient producers will continue to be.

We need only monitor the ever-changing feed prices to understand the importance of improving efficiencies throughout the production chain. Further changes will continue to challenge our industry.

Next Quarter

The next benchmarking article will focus on sow and gilt breeding criteria. If you have thoughts or questions about how to best utilize this benchmarking information, contact Stalder at or Editor Dale Miller at