Pieter Langendijk, senior research scientist with Trouw Nutrition, speaks to The Pig Site about farrowing management and how it impacts piglet deaths during the farrowing process. Langendijk has worked for Trouw Nutrition for seven years focusing on sow R&D, specifically looking at how nutrition can improve sow performance.
“The average sow litter now contains about 18 piglets in highly prolific sows. During the farrowing process, all these piglets must move from where they are positioned in the uterus all the way to the cervix, where they're expelled,” Langendijk said. “The piglets are positioned in a line in the two uterine horns, and they're expelled exactly in the sequence that they're positioned in the uterus. The ones that come out first are positioned closest to the cervix. If we have a litter of 18 piglets, there'll be roughly nine on each side, but to give birth to all these pigs may take a while.”
The piglet sitting at the end of the uterine horn will have to wait until the end of the farrowing process to be born and during that time the piglet will experience uterine contractions. Those contractions serve the purpose of pushing the pigs towards the cervix where they're born. In the process, they also squeeze the piglet, and more importantly, the placenta that the piglet is attached to. The placenta supplies nutrients but also oxygen to the piglet. Every time a contraction passes along the uterine horn and squeezes the placenta, the oxygen supply to that particular piglet is compromised or even inhibited for as long as the contraction lasts.
“For example, if the farrowing process takes five hours, then the piglet that's born last will have to go through that process for five hours which will have a cumulative effect on the piglet,” he explained. “The piglet will experience a reduction in oxygen supply temporarily when there is a contraction. By the time it's born, it will have signs of what we call asphyxia or oxygen insufficiency, which is evident from a low blood pH, so the blood acidifies at high lactate levels. Thus, those piglets are compromised.”
It's a condition that piglets can recover from to some extent, but there's also long-term damage from asphyxia which are evident from, for example, mortality.
“We see that in piglets born in the second half of the litter. At the end of the farrowing process, they have a higher chance for neonatal mortality,” he said. “They also have a compromised gain through lactation, but even after weaning, up to the point where they're sorted, their gain will still be lower than piglets that don't have signs of asphyxia.”
Managing the farrowing process for fewer piglet deaths
Management simply comes down to how to shorten the farrowing process, and that includes reducing stress. Stress is caused by housing, nutrition and handling of the sows.
Housing: For those housing sows in crates where they cannot move around and perform nest building behavior, this affects oxytocin which is the hormone that's responsible for controlling contractions and speeding up the farrowing process. By optimizing housing conditions and improving oxytocin secretion, it’s possible to shorten the farrowing process.
Nutrition: Diets that are low in fiber can cause constipation which is painful for sows and another source of stress. If we can provide a high fiber transition diet that reduces constipation, sows can avoid that source of stress. Research indicates that a transition diet can shorten the farrowing process and reduces the number of stillborn piglets.
Handling of sows: Research shows that when sows were moved during the farrowing process, which normally wouldn’t be done, oxytocin again goes down and the farrowing process is prolonged. Another example of a similar handling stress is from palpating sows during the farrowing process and trying to help sows by pulling out piglets. This is designed to help the sow, but Langendijk questions if it really does. This “help” may also provide a stress into the sows and compromise the rest of the farrowing process. Trouw Nutrition’s data and field studies demonstrated that reducing the number of interventions during the farrowing process can actually help the sow and reduce the number of stillborn piglets.
“In some cases, it's helpful to intervene during the farrowing process, especially when piglets are obstructing the birth canal, but in a large number of cases, it probably doesn't really help,” he said. “People always want to do something; they want action and that's understandable. The interval between two piglets is often the guideline to start intervening. When the interval between piglets exceeds 30 minutes, that's a general rule of thumb to start intervening. However, if you look at our research data, the interval between pigs is really a poor indicator of whether the farrowing process is compromised. If that interval is 30 minutes, I wouldn't really worry. We've seen stillbirths only go up when that interval goes beyond an hour.”
Whether to intervene or not, should be based more on how long the sow has been farrowing in total. For example, if she's been farrowing for two hours, I wouldn't really worry about unless she's showing obvious signs of distress. But if the farrowing process has been going on for four hours, that's when I would really start to think and maybe decide to intervene, but not based on interval between piglets, he said.