Organic acids have been used extensively for the last decade as a viable alternative to antimicrobial agents now banned in Europe and the rest of the world. Still, despite their widespread use, there are six important questions that many livestock producers continue to pose to technical personnel. Unfortunately, there is no consensus regarding their answers, but if you know what to look for, one might find the incentive to search for the answer or a better product.
1. Which organic acid is best?
This is the toughest question, especially when the person asked is selling organic acids! The reason we don't have a clear answer to this question is because there is no longer public funding of research to compare side-by-side all available organic acids. The fact that the perfect organic acid will differ according to overall diet composition only makes things worse.
2. How much organic acid is required?
Research conducted in the 1990s indicated for organic acids to fully replace antibiotics in their growth promoting effects, inclusion rates should exceed 1 percent and they might be as high as 2 percent. Yet, modern commercial practice calls for no more than 0.5 percent inclusion rates, with some being as low as 0.01 percent. Why the difference? The answer is two-fold. Adding large amounts of organic acids makes the animal feed prohibitively expensive. Also, modern livestock diets are formulated to be gut-friendly, which reduces the need for high levels of organic acids. However, this is just a hypothesis to which I ascribe based on my own practical experiences.
3. Why not add inorganic acids?
Both phosphoric acid and hydrocloric acid (but not sulfuric acid) when used at very low concentrations have been shown to be as effective as organic acids. Perhaps, the answer has to do with the highly corrosive effects of these inorganic acids, or because they cannot be branded as efficiently as the organic ones. But, they do work!
4. Single acid or blend?
There are so many single organic acids that work just fine, and yet, there are certain blends that are equally effective. In fact, it has to do with the desired effect. In my own feeds, I use two acids: one for acidification and the other for taste and improved digestibility. If I were to make a diet for a lactating sow, for example, and I needed to acidify the urine, I would certainly use a totally different single acid.
5. Pure acids or salts?
Most pure acids can be corrosive, yet highly effective at smaller dosages. Salts are not so corrosive, but you need a higher dosage to get the same antimicrobial effect. This is because not 100 percent of an acid salt is acid! In addition, pure butyric acid smells so awful that feed mill workers refuse to work! Nowadays, there are certain versions of butyric acid that "stink" less.
6. Coated or not coated?
It depends on the desired function and the nature of the acid. Some acids become ineffective as soon as they reach the stomach. Others work better. Still, some straight acids offer a stronger response. When it comes to butyric acid, coating is the only solution to its offensive nature. Personally, I have not used any coated products, because I have not seen any convincing evidence of their benefits. However, other nutritionists wholeheartedly vouch for them!
I believe it is evident that we use organic acids mostly based on limited information and much personal experience. It would have been great if we could clarify the field, but I don't believe this is going to happen anytime soon. Until then, common sense and trial-and-error are the only means to answer the above six questions.