Weaning can be one of the most stressful occurrences for the pig, said Dr. David Rosero with The Hanor Company in Franklin, Ken. The pigs have abrupt maternal separation, a different food source, co-mingling, pathogens, and other stressors. Enzyme activity also is reduced.
"Any stress that happens early in life (at weaning) has long-term consequences from the standpoint of disease risk and severity," Rosero said.
If pigs are weaned earlier, the intestinal barrier is disrupted. Rosero reported that early-weaned pigs had higher intestinal permeability compared to those that were weaned later and the long-term consequences were amplified.
"Pigs were compromised at 16 or 18 days when they were exposed to an E. coli challenge, but at 10 days old, we didn't see a dramatic increase in their intestinal permeability," Rosero said. "On immune response, at 16 and 18 days of age, they're not able to respond to a pathogen challenge but when they were weaned at 20 days of age, they had a much higher immune response to an E. coli challenge.
"Response to weaning is immediate and acute, and we've learned that it has long-term consequences," Rosero said.