Some scholars believe that the antibacterial effect of zinc oxide is free Zn2+. I don’t agree with this point. The fact is also on my side. If the above point of view is true, then zinc chloride and zinc sulfate can prevent diarrhea, and in fact only zinc oxide has anti-diarrhea effect. Other scholars believe that the surface effect of zinc oxide crystals plays an antibacterial function, so zinc oxide is coated on medical devices, and zinc oxide is also present in some topical ointments. We believe that zinc oxide has astringent effect, can sterilize and accelerate wound healing.
Many people think that the intense stress of weaning causes intestinal damage, and the convergence of zinc oxide is just right. Is this a little taken for granted? If this is the case, the so-called coating of zinc oxide should be better, and I understand that the actual effect is not as we have imagined (perhaps due to experimental design factors).
What effect does zinc oxide have on the intestinal flora?
Within 2 weeks after weaning, zinc oxide significantly inhibited Escherichia coli, but after 2 weeks, the result of intestinal flora was a decrease in lactic acid bacteria, an increase in Clostridium, and a change in the proportion of Enterobacter. Moreover, high zinc diets can lead to the formation of multi-drug resistant E. coli strains.
To what extent this change is affected by the structure of the diet, and to what extent is the effect of zinc oxide, which is hard to say. Let’s restore the “earthquake” that occurs in the intestines after weaning. Under normal circumstances, the main energy source of the small intestine is amino acids, and the large intestine is short-chain volatile fatty acids. After weaning, the small intestine lacks energy and collapses due to a decrease in feed protein digestibility and intense stress. More undigested proteins are poured into the large intestine, providing Enterobacter with a rich diet that allows them to grow vigorously. At this time, it is no longer a “neutral conditional pathogen”, because it meets the conditions of its disease, it is ill. As a result, the short-chain volatile fatty acids that the large intestine wants are gone, the unwanted ammonia, the amines, etc. are too much, and the large intestine also collapses.
The reason why zinc oxide has a good inhibitory effect on weaning diarrhea, I think it plays a role of broad-spectrum antibiotics, more directly, its inhibition of Enterobacter, that is, combined with anti-enzymes to deal with E. coli effect. But unfortunately, E. coli developed multi-drug resistance after 2 weeks. Further observation of the resistance genes of Enterobacteriaceae to tetracyclines, sulfonamides, and quinolones revealed that antibiotic resistance began to increase after 1 week of zinc use. For this reason, the EU has restricted the use of zinc oxide.
Prolonging the use of zinc oxide to 3 weeks to 4 weeks after weaning will reduce the production of short-chain fatty acids at the end of the intestine. This may be an adverse reaction to zinc oxide because pigs use these metabolites as energy reserves. For the colon, 80% of its energy comes from the butyric acid produced by the intestinal microbial fermentation fibers. This also proves that zinc oxide has a longer lasting inhibition effect on bacteria that ferment carbohydrates.