Evaluating Ingredients – Protein in the Rumen and Small Intestine Part 3
For part 3 of how to evaluate ingredients, I’m switching over to ruminants. In parts 1 and 2, I focused on poultry and how changes in the levels of major nutrient categories (crude fiber and total fat levels) affected metabolizable (think useful for productive purposes) energy of the complete diet.
Ruminants are more complex because of their digestive structure, and in particular, the rumen. While poultry and birds have a difficult time with tough-to-digest fiber, the vast microbial populations that naturally inhabit the rumen are designed to degrade various structural carbohydrates (fibers) and produce useful compounds that benefit the animal (as well as the microbes themselves). This adds complexity as it is often said that you are actually feeding the “bugs” in the rumen, as well as the animal.
There are entire university courses taught on ruminant digestive physiology, but you can understand some key points that are useful when trying to pick from a basket of available ingredients for feeding these specialized animals, especially dairy and beef cattle, sheep and goats, that have been used to help humans for thousands of years.
So, back to the idea of feeding the rumen microbes and the cow – as much as animal nutritionists have tried to push the boundaries, this fundamental aspect of all ruminants will always regulate and have a great impact on feeding strategies. Like all animals, cows have nutrient requirements for amino acids (from protein ingredients in the diet) in order to perform normal functions, and also, to support elevated production of food, like milk.
Alternatively, in order to maximize productivity, such as achieving increased milk production, amino acids from protein that are rumen undegradable are needed. Proteins that escape the rumen and enter the small intestine (often called rumen by-pass protein) can be absorbed and immediately contribute to milk production, but only if they are highly digestible.
It is this balance between rumen degradable protein and rumen by-pass protein that must be understood and controlled. Often, dairy nutritionists will include a source, or several sources, of by-pass protein in the ration. As discussed on our blog before, extruded/pressed (ExPress®) soy meal is an excellent source of highly-digestible by-pass protein for dairy cows that are often pushed to their limits.
So, once again, I bring up least cost formulations, which only do one thing – minimize costs. You have to understand the true values of ingredients in order to maximize productivity while minimizing feed costs. Speak with us about evaluating ingredients for your dairy or ruminant operation.