By John Deen, DVM, PhD, MBA, University of Minnesota Swine Group
Mortality rates are highest in the farrowing room, whether it be for pigs or sows. When we include stillbirths, it is not uncommon to see three-quarters of growing pig mortality showing up before weaning. If we take this risk on a daily basis, a pig is 20 times likely to die on a day in the farrowing room than a day subsequent to that. Based on this higher risk, we have studied both stillbirth rates and preweaning mortality rates in great detail. We know that there are factors such as birth weight, colostral intake, facility design and facility factors that lead to higher and lower preweaning mortality rates.
The rates of mortality for sows are also much higher in the farrowing room than in breeding or gestation. We can see daily rates that are eight times as high in the farrowing room than in breeding and gestation. The difference is that there has not been a particular emphasis on the study of this aspect of sow mortality in the same way that preweaning mortality has been emphasized as a separate category of mortality versus post weaning mortality.
With the levels of mortality seen in the farrowing stall, it may be useful to understand the processes that lead to sow death, as well as leading to additional compromised sows at time of weaning. There are additional pressures on the sow through parturition and lactation that appeared to result in a proportion of sows that are unable to cope with the added physical requirements. Moreover, it may be worth questioning whether the physical environment in the farrowing stall is too biased toward the piglet rather than the stall. Though the studies are limited, it may be useful to start viewing the farrowing stall as a point of intervention to reduce sow mortality rates.
Here are a few factors that are worth considering as we try to help the sow survive and thrive in the farrowing stall.
Lameness: In our work a sow that is lame at entry into the farrowing stall has a 40% higher mortality rate, even if the lameness appears to be minor. Moreover, these sows are also much more likely to be compromised at weaning so that they are culled at a higher rate.
Analgesia: Though it is particularly true in lame sows, there is a positive effect of long-acting pain control in sows. Behaviorally, these sows are more likely to get up and eat and drink shortly after farrowing. Unfortunately, here in the United States no such product is registered for use in sows.
Off-feed events: We have shown that even one day off feed can significantly increase the mortality rate and decrease the quality of sows at weaning.
Heat: Hot, humid nights particularly result in higher sow mortality in the farrowing stall.
Farrowing difficulties: Slow parturition is also an indicator of a sow that is having difficulty in coping and predicts higher levels of mortality.
As any good herdsperson will point out, these are not independent subjects. The real problem is when these factors start coming together. A lame sow going into a farrowing stall during hot weather is much more likely to see those off-feed events and have trouble farrowing. It is in the multiplicative aspects that we truly identify at-risk sows. It is a cascade of events that leads to sow death in many cases, and catching sows in early stages of difficulty may be our best chance of providing an efficient intervention.
However, there may be a need to also change some of our emphases in pig rearing. I would argue that there is a greater emphasis on reducing preweaning mortality in the farrowing room than reducing sow mortality. An illustration that I use in this argument is asking what is the optimal temperature for a farrowing room, especially when the sows are farrowing? The answers that I receive are usually more closely correlated with piglet comfort than with sow comfort — sows would do best at a temperature of 60-65 degrees F.
Farrowing rooms are already places of intense activity and focus, and redirecting some of that effort toward the comfort and well-being of the sow may have real returns.