Maximizing nutrient utilization is at the heart of profitability for a dairy farm. A cow fed a highly digestible diet will produce more milk on less feed and excrete less manure. “The only way to really affect profit is by improving efficiency of production,” said Elliot Block, senior manager of technology for Arm & Hammer Animal Nutrition. One way to be more efficient is to consider ways to maximize the nutrients fed.

The cow will benefit from eliminating excess feed in her system. It costs the cow something to get rid of or store any excess nutrients. For example, if overfed protein, it will cost the cow energy to excrete it. Long-term effects of too much protein can also harm the cow’s health and reproduction.

Producers could feed high amounts of protein all the time to ensure the cows are always getting what they need, Block said, but that could cause an increase in disease incidence and decrease the cow’s longevity.

If more nitrogen can be captured in either the milk or the body of the cow or calf, less will be excreted into the environment.

On a 5,000-cow dairy, the reduction of 2 percent manure is impactful, Block said. Anything that improves the efficiency of use will mean less for the environment.


To reduce total manure, a dairy producer must provide the most digestible feeds. A diet with 50 percent digestibility means 50 percent will come out the back end of the cow. A diet with 50 pounds of dry matter would result in 25 pounds of manure.

If digestibility is increased to 60 percent, that would result in five less pounds of manure to handle and most likely an increase in production or general health of the cow.

Block added, “There are lots of minerals that are potential pollutants. They are typically overfed as a comfort factor.” One way to increase the efficiency of minerals like calcium, phosphorus and sulfur is to just stop overfeeding them.

Bottom line
Achieving proper nutrient utilization is important to maximize the profit margin on milk. So is allocating money to providing the proper nutrients.

Producers are looking for the maximum feed input with minimum cost.

“This is not necessarily done finding the lowest cost per ton of feed,” Block said. “It should be calculated by finding the lowest cost per unit of nutrient that is needed.”

A wild example he uses is sawdust versus soybean meal. While sawdust provides the lower price per ton, it does not adequately provide nutrients the cow can utilize. Therefore, even if it is more expensive per ton, the soybean meal is more cost effective when considering cost per nutrient.

Know the variability of the ingredients, too. If you take something like blood meal where there is a lot of variability – from 10 to 15 percent digestibility all the way up to 90 percent – it does not make sense to compare those values at similar price points.

How to determine utilization
It is difficult to achieve maximum utilization without taking some measurements.

Lab tests on starch and forage can give an indication on digestibility, but that doesn’t guarantee the digestibility in the cow.

“That’s a relative thing,” Block said. “There are other factors that influence digestibility, such as the environment, water availability, water quality, heat stress, cold stress and feeding behavior.”

Taking manure samples can also provide direction on the lack of digestibility based on fecal starch content. He is not a big advocate of visually appraising manure for digestibility of corn or other grains. If it is done, it must be on a comparative basis and not a one-glance analysis.

Milk-urea nitrogen tests are another indicator. If MUN levels are increasing, it could mean protein is being overfed or wasted – either the amino acids are not balancing or there is an energy shortage. If the levels are decreasing it means efficiency is being met (as long as milk protein levels remain high) or protein is being underfed.

Analysis of what the cow is excreting through milk and manure is just a start. To truly be able to determine digestibility is to have a handle on what is being fed.

“The only way to have a benchmark is to know what’s going in the front end. Then you have better knowledge of what’s coming out the back end, too,” Block said.

He added, “In a business that is so cost driven with no control of input costs and milk costs, how can you operate and improve profitability margin if you don’t know what’s going into the cows?”

You do not have to do weighbacks every day to accomplish this. Instead concentrate on knowing the actual dry matter content of what is being fed. Keep track if the feeder is mixing the right ration, he says.

For instance, in a 50:50 ration (for simple math purposes) that uses 10 tons of grain, you should see 20 tons of feed disappear. If you track that amount and how many cows you are feeding you can get a fairly decent handle on feed consumed over time. Measuring weighbacks just once a week can help solidify those numbers. PD

Karen Lee