Ask The Vet

Base Supplement Decisions on Data

Is the supplement you use appropriate for your operation at this time, under these conditions? (PF photo by Karl Wolfshohl)


We farm in southern Virginia. What is your opinion on protein tubs? We use the 24% protein tubs. They weigh about 200 pounds. Our hay this year was cut late, and our cows started calving in March.


First, let's go through a few basics. Why are cows able to primarily live off forage? They have a rumen, and this is what makes cattle, sheep and goats different from simple-stomach animals such as humans and pigs. Microorganisms in the rumen break down fiber in forages that simple-stomach animals can't use. The process produces volatile fatty acids that are used nutritionally.

Some forages do not have enough readily available nutrients to feed the rumen bugs. This is where tubs and liquid feeds come in. Most of these supplements contain energy and a combination of natural proteins and nonprotein nitrogen (NPN) or urea. Microorganisms in the rumen use this energy and natural protein to digest fiber in forages, turning it into carbohydrates or energy for growth. Not only can they take nondigestible carbohydrates (fiber) and use them for energy, but they can hook NPN onto carbohydrate molecules to make proteins. The bugs eventually move into the abomasum where they are digested. This process extracts energy and proteins from forage faster so forages "pass through" the cow quicker, allowing them to eat more.

There are many forms and formulations of tubs and liquid feeds. Some less-expensive tubs have higher moisture content, are less nutrient dense and provide lower-quality nutrients. Cattle may eat more of these blocks but receive less nutrition. It's important to analyze how much it costs to feed any supplement on a "per-head per-day" basis. Consider how cattle perform on that supplement. A less-expensive supplement can cost more to feed and lead to lower production, directly affecting profitability.

Ask yourself if the supplement you use is appropriate for your operation. Get your hay tested, so you know its nutrient quality. If it's low in total digestible nutrients and crude protein, traditional supplemental feed may be a better alternative than a protein tub.

Lastly, if you use these products, always start them while cattle are still in good body condition. The ideal is probably a body condition score (BCS) of 6. If the average BCS is anything less than a 5 at calving, traditional supplemental feed is the better way to increase BCS.

If you're working with growing cattle, including "wet 2-year-olds" trying to grow, calf, raise and breed back, tubs and liquid feeds alone often won't provide adequate nutrition.

It all comes back to the data. Test your hay. Establish a BCS on those females. Then, analyze nutritional goals and choose the best way to reach them. Don't forget the resources you have in your herd veterinarian and Extension. These unbiased sources will help you make the best choices for your unique operation.