Published: November 30, 2007 11:54 am            

Pork Professor: Sow health, longevity at risk during periparturient period

Originally published in the November 30, 2007, print edition.

There is uniform consensus on the importance of sow longevity in breeding herds.

Animal welfare and economic concerns as well as low employee morale are some of the consequences of poor sow longevity. The benefits associated with improved sow longevity include larger litters with heavier pigs, fewer unproductive days, acquired immunity to herd diseases, higher sow salvage value and lower replacements costs.

Generally, reproductive efficiency determines how long a sow stays in the herd. However, a sow may be removed from the herd for production or health-related reasons.

Periparturient period (a few days prior to farrowing and including lactation) is often a high-risk time. Reproductive inefficiency directly results in poor sow longevity.

Health problems can affect longevity both directly and indirectly. Severe health problems may cause immediate removal of a sow from the herd. Indirectly, health problems can affect feed intake or subsequent reproductive performance of the sow depending upon the health problem and cause sow removals eventually.

Producers often face a dilemma as far as sow removal decisions are concerned. It is relatively easy to decide when a healthy animal should no longer be retained on economic grounds.

Given our housing systems, especially in large herds, it is a practical challenge to observe and record the health problems of all females every day. In most cases sows receive individual attention around the time of farrowing. This facilitates recording of health problems such as lameness, downer and prolapse, in addition to disease symptoms such as off-feed, vulvar discharge, fever, diarrhea and respiratory problems.

However, there is great difficulty in objectively quantifying the extent of compromise in welfare due to a health problem so that a decision to remove or retain can be made — although it may be possible to assess whether the welfare of an animal is compromised or not.

The emerging question then is, is it worth to increase longevity just for the sake of it?

Arguably, factors influencing sow removals are not consistent and often the removal of a female pig is not dependent on its biological performance alone. The criterion used for deciding on sow removals may not be equally applied to all females present in the herd at a given point of time.

For instance, although sow culling is a voluntary decision, producers may be reluctant to remove a periparturient sow considering the productivity losses associated with such removals. However, the effect of retaining sows with health problems in the subsequent overall performance of the herd is seldom evaluated.

Health problems as a reason for poor sow longevity in breeding herds itself is infrequently assessed.

We analyzed the data on periparturient health problems, farrowing interventions, length of lactation, lactation feed intake, farrowing performance and sow longevity collected from a commercial swine breeding herd in the U.S. Midwest.

Data from this pork checkoff-funded study were analyzed to understand association of risk factors with sow longevity within 35 days after farrowing or before the next parity. The production performances of the sows that were retained (with or without health problems during the periparturient period) in their subsequent parity were compared to evaluate the removal decisions.

Lameness was the primary reason for the removal of sows within 35 days post-farrowing. Reproductive problems were the major reasons for sow removals before next parity.

The results indicated that the likelihood of removal from the herd within 35 days post-farrowing or before another farrowing decreased with increasing number of live born piglets and increasing average LFI. Sows that did not have lameness or other periparturient health problems were less likely to be removed from the herd before 35 days post-farrowing compared to other sows.

A younger parity (less than 5) was also found to be protective as far as longevity is concerned. Similarly, the risk of removal before another farrowing was less for non-lame sows compared to lame sows.

Interestingly, sows retained with periparturient health problems had reduced longevity and fewer live born piglets. Also, fewer numbers of such sows had another farrowing compared to those retained with out any periparturient health problems.

Besides the adverse effects of factors such as higher parity and a low LFI and health problems on sow longevity, this study indicated that retaining sows despite lameness and other health problems during the periparturient period may adversely affect the overall herd performance in the long term. This is suggestive of a reexamination of removal decisions taken after farrowing.

        

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