Acidifying the drinking water can help to improve the quality of the ‘forgotten nutrient’. Increasing the quality of the drinking water can result in improved performance of the animals, with lower bacterial load in the water and in less chance of the formation of ‘biofilm’ (an organic layer of ‘slime’ in the pipes, in which bacteria and fungi grow).
This article describes the benefits of acidification of drinking water with organic acids and the special importance that it can have for piglets in the post weaning period.
Lowering the pH
Compared to feed, which usually has a high buffering capacity (due to protein sources and minerals), water has a very small buffering effect. The only parameter which can have an effect is the hardness of water. When applying a product which has one single acid ingredient in drinking water, the pH decreases very quickly and if the dosage is too high, the pH can lower too much, leading to a negative result (lower water intake with decreased performance). Therefore choosing a product which has a synergistic formulation of organic acids is more favourable to these single acid products.
These organic acids have a buffering effect which makes the pH decrease slowly. A synergistic mix of organic acids also has a greater antibacterial effect, is more palateable, and is less corrosive compared with a single acid.
How do organic acids work?
The general chemical formula of an organic acid is R-COOH (undissociated form). In this form they have the ability to split off a proton (H+), which lowers the pH of the environment. The pKa value is the pH at which 50% of the organic acids have split off their proton, and is different for each organic acid. Due to the lower pH the growth of pathogenic bacteria (e.g. E. coli, Salmonella and Campylobacter) is inhibited and the growth of beneficial bacteria (e.g. lactic acid bacteria) is stimulated. This pH effect is the only effect that single acids have, on the other hand organic acids also have an antibacterial activity.
The antibacterial activity of organic acids is related to the reduction of pH, as well as their ability to dissociate, which is determined by the pKa-value of the respective acid, and the pH of the surrounding environment. The antibacterial activity increases with decreasing pH-value. Organic acids are lipid soluble in the undissociated form, in which they are able to enter the microbial cell (see figure 1). Once in the cell, the acid releases the proton in the more alkaline environment, resulting in a decrease of the pH in the cell. This influences microbial metabolism inhibiting the action of important microbial enzymes and forces the bacterial cell to use energy to release protons, leading to an intracellular accumulation of acid anions. This accumulation depends on the pH difference across the membrane. Generally the antimicrobial effect of organic acids increases with increasing concentrations.
Figure 1: Antibacterial activity of organic acids
Organic acids exert their antimicrobial action both in the water and in the gastro intestinal tract of the animal. If the water is acidified, the pH in the digestive tract of the pigs will be lowered. This has a positive effect on the digestion especially in the stomach and the small intestines.