How low can we reduce crude protein in a simple corn-soy diet by using free amino acids?
When I asked the late Dr. Dave Baker, my Ph.D. mentor at the University of Illinois, this question, he gave me two numbers: 2 and 4. He said 2% if the feed is reformulated by anyone, and 4% if the formulator is a Ph.D. nutritionist who knows about amino acid nutrition.
This was 25 years ago, and valine and isoleucine were still in the experimental phase; in fact, our lab was working on new amino acids, and my thesis was on valine. Since then, a lot has happened.
Today, we are facing the problem of diets for broilers with protein levels that are too low because free amino acids have proliferated, and they are competing strongly with locally produced protein sources. We will assume for the sake of this conversation that quality is not an issue, because quality can become an issue for all ingredients, and this is a different conversation. Today, the conversation and research is about meeting non-essential amino acid requirements and the serine-equivalent concept in broiler nutrition. But some research and experience has indicated we may have overdone it with how low we have gone with reducing natural protein sources.
So, to follow up on my previous blog, and close the conversation based on the conference I had with a group of broiler producers from which I drew this month's blogs, I was asked to provide actual numbers about soybean meal and crude protein levels in broiler feeds for modern genetics. I am not sure my answer pleased everyone, but that is neither my goal nor my job.
As a nutritionist, I have my own norms – which I will not disclose – just like any other nutritionist. Suffice it to say that I prefer a balance between soybean meal (or any other good quality protein source) and free amino acids for broilers, but not for all species. Some have even considered a proposal by an amino acid company to completely replace soybean meal. I do not have the experience on something like this, and relevant research says that, even with modern low-protein broiler feeds where we still use soybean meal and too much free amino acids, we will have some problems. I believe these problems can be resolved, but whether the end result will bring about the cost savings advocated is something that needs to be demonstrated in practice.