Early weaning permanently compromises gut immune response
Researchers at Michigan State University investigated how early weaning ages affect development of a piglet’s gut and its ability to launch an immune response against pathogens. They also studied how long adverse effects lasted.1
First, investigators focused on the gastrointestinal barrier function of the gut. Several layers in the gut protect pigs against pathogens and toxins. When compromised, the gut becomes permeable, or leaky. Pigs weaned at 21 days exhibited a leaky gut just 3 hours later compared to unweaned littermates.
Next, researchers examined how a later weaning age changed gut permeability. By examining the guts 24 hours after weaning, they found pigs weaned at 18 days exhibited a dramatic increase in intestinal permeability compared to pigs weaned at 28 days. The later-weaned pigs had some injury but much less than the earlier-weaned pigs.
Researchers checked stress responses in both sets of pigs and found the older pigs had higher levels of cortisol than the early-weaned pigs. This indicated weaning is stressful regardless of the age, but how the gut handled it differs by age. A follow-up study checked how earlyweaned pigs handle a second round of stress. Pigs weaned at 16 to 18 days were compared to pigs weaned at 22 to 24 days. The pigs grew to 35 days of age and then were challenged with a strain of E. coli. The earlier-weaned pigs exhibited more severe diarrhea and injury to the gut barrier than the later-weaned pigs. Researchers reported the late-weaned pigs had a robust immune response that is crucial for clearing bacteria. The early-weaned pigs exhibited a suppressed or no response to the challenge. They concluded that any stress occurring at early weaning will alter the overall health of the animal’s gut and will lead to a permanent compromised gut function.
1 Moeser A. Biological and Production Basis of Optimal Wean Age, Allen D. Leman Swine Conference, 2017.