There are important differences between protein supplementation on low-octane forages and high-octane forages.
I make this differentiation from low-octane forages and difficult environments because in them it is imperative to supplement with protein for cattle to thrive and produce good sustainable profits.
High-octane forages in the dormant season present a different scenario.
In high-octane environments it is valuable to evaluate a protein supplementation program before embarking on it. It's value would be as a tool to increase our profits by allowing us to increase stocking rate.
In those environments with good-quality forages, the cow can cope with low protein content by increasing intake of dry matter without a corresponding increase in production. She is able to "overeat" to get the protein she needs. Good-quality forages would be not highly lignified and would have grown in a low-rainfall area, typically with cool nights in the growing season.
However, if we supplement the lacking protein the animals can then reduce dry matter intake thanks to a better digestion of the fiber. That's because the nitrogen needs of the rumen microbes are met by the protein supplement.
You can test this by feeding extra protein and observing the fibrous material in the manure. If no extra protein is needed then the particle size in the manure will stay the same, even with the protein supplement. That tells you it will not be cost effective to feed it.
Remember that rumen microorganisms in cattle need around 8% protein content in their dry matter intake to be able to digest fiber efficiently.
Another way to determine whether cattle need protein supplementation is by checking the pH of the urine or the blood urea nitrogen levels. When the pH of the urine is below 7 it indicates protein is deficient in relation to available energy. When it is above 7.5 it indicates protein is in excess of available energy in the ration or forage.
Available energy is the thing that matters, as it is a reflection of digestion. Sometimes the energy is there but is not available due to the forage being lignified.
Let’s consider a 1,200-pound cow with a 2.5 % dry matter intake: She would consume 30 pounds of dry matter per day. If protein is deficient, at 5.7 %, and the cow can overeat an extra 40% above normal then she would be eating 42 pounds per day dry matter and able to consume the pounds of protein she needs per day to digest said forage.
However, those 12 pounds of extra dry matter per cow per day may be important if the amount of forage is limiting or there is a shortage of alternative feeds.
It also means 40% more cows could be carried in the same area if protein was not a limiting factor and/or can be supplemented economically.
Another way to reduce the amount of protein supplement needed is to have the cow pregnant and in late lactation by the time protein becomes a limiting factor.
In fact, the timing of calving and breeding season become very important in reducing costs in any cow/calf operation. I will write about the importance of the calving season next blog.