Litter size at birth and pre-weaning mortality (PWM) have increased significantly in U.S. commercial swine herds in recent years. PWM surveys conducted on commercial units across the U.S. suggested that low birthweight and low body temperatures in the early period after birth were two of the major predisposing factors.
Recent research by Katherine Vande Pol and Naomi Cooper, graduate students in Dr. Michael Ellis’s lab at the University of Illinois, carried out in collaboration with The Maschhoffs in company facilities, set out to better understand the effect of piglet birth weight on body temperature changes post-farrowing. Through six studies carried out under typical farrowing house conditions involving a total of 1,032 sows and 13,208 piglets, they also evaluated how interventions such as drying, warming and oxygenation could be applied to mitigate temperature loss and potentially increase piglet survival.
A part of Pork Checkoff’s sow-lifetime productivity project, these studies confirmed that all piglets experience a significant decrease in body temperature after birth. However, the decline was much greater in low-birthweight piglets (3.3 lbs.).
Without drying or warming intervention, piglets experienced a very large decline in rectal temperature within the first hour after birth (approximately 8 degrees Farenheit on average). Low-birthweight piglets showed the largest decline (approximately 11 degrees Farenheit on average).
“The drying and or warming of piglets significantly reduced this temperature decline, with the effect being greatest in the low-birthweight piglets,” Ellis added.
Researchers evaluated drying and warming as independent acts but found the best response occurred when combined. Also, all of the drying and warming methods were more effective in lightweight piglets than for their heavier littermates.
“Although drying and warming of piglets was highly effective at minimizing the extent and duration of the temperature decline after birth, we were surprised that it had no effect on overall pre-weaning mortality,” Ellis said. “However, the study was carried out between April and November, and during the cooler months, when farrowing room temperatures were close to the set point (72 degrees Farenheit), drying and warming substantially reduced mortality levels by 2.6 percentage units. In contrast, during the hotter months, when farrowing room temperatures were much higher, this approach had no effect on mortality levels.”
Placing piglets in an oxygen-enriched chamber for 20 minutes after birth increased blood oxygen but did not benefit body temperatures. In fact, those piglets had a lower temperature leaving the chamber than piglets that remained with the sow. Researchers also found that colostrum intake was not impacted by any of the interventions nor by piglet birthweight.
A final study, involving 800 litters and more than 10,000 piglets, evaluated whether drying and warming piglets at birth impacted pre-weaning mortality. It revealed that the practice did not impact pre-weaning mortality overall, the same was true for piglets within the birthweight categories.
Although drying and/or warming of piglets at birth was highly effective at reducing the magnitude of post-natal body temperature decreases in these studies, the practices had no effect on pre-weaning mortality levels in piglets of any birth weight.
“Drying and warming is a potential approach to reducing pre-weaning mortality during the cooler periods of the year, but not under hotter conditions,” Ellis said.
Other researchers included The Maschhoffs R&D Group of Caleb Shull, Omarh Mendoza, Beau Peterson and Clint Schwab; and Clay Lents of the U.S. Meat Animal Research Center.
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