Over the past few years we’ve seen demand for fuel-efficient cars skyrocket.

The same idea holds true for feed efficiency in the dairy cow. As feed prices have climbed higher and milk prices dropped, producers have reevaluated diets and management practices to improve their herds’ feed efficiency value. Getting the most production response from each pound of feed can directly influence herd performance, health and cash flow. We have also learned that while improved production efficiency is the goal, other areas will impact efficiencies outside of the ration.

There are two milk production numbers that can be used in the feed efficiency calculation:

• Adjusted-corrected milk (ACM) removes variability in the milk production calculation by adjusting for days in milk of the herd, fat test of the milk and percent of heifers in the herd. ACM will likely be the best number to utilize for monitoring herd efficiency, but can be more difficult as each value must be more closely monitored.

• Energy-corrected milk will likely serve as the best parameter for monitoring efficiency at the pen level. When evaluating pen-level variables, days in milk and percent of heifers will likely be similar throughout individual pens.

The feed efficiency equation must be tracked regularly to be meaningful, and results should be compared to internal herd data rather than other dairy operations. Use the equation in Figure 1* to measure feed efficiency at the pen level.

While there are limitations to calculating and utilizing the feed efficiency value, it does provide fundamental insight on how your cows are responding to their diet. Any information we can gather on how much cows are eating is important for formulating rations. Feed efficiency is one tool we can use to collect this data.

A tough calculation
While nutritionists can agree calculating feed efficiency is important, there are many reasons the calculation can be hard to measure, maintain and use as an indicator of cow performance.

• Intake measurement. To calculate feed efficiency, you must know dry matter intake (DMI) per cow. This data is collected by dividing total pounds of feed consumed by the number of cows in the pen, but it must also account for leftover feed by measuring weighbacks. When it is not possible to measure actual pounds of feed refusals, an estimate should be made before the next feeding. Furthermore, dry matter analyses must be completed on the refusals to account for environmental and weather effects. For example, during hot weather conditions, feed is often higher in moisture from feedline cooling systems. This means weight alone will not accurately quantitate feed refusals – dry matter content of the refusals must be determined as well.

• The individual cow. Animals will respond to the same ration differently, which means feed efficiency will vary also. Many factors influence individual feed efficiency including age, stage of lactation, environment and genetic potential.

• Variable results. Much like fuel rating will vary depending on how the car is handled and where it is driven, feed efficiency is affected by external factors. Some of the factors that impact feed efficiency we have control over, like the ration we formulate. Other factors, like weather, we have little to no control over and can make feed efficiency extremely variable.

• Indirect performance monitor. Just as days open is one of many indicators of reproductive performance, feed efficiency is one indicator of the success of a dairy’s nutrition program. While the calculation can be helpful in making decisions, feed efficiency alone does not display the full picture of how well cows are responding to their diet. Recognize that this number does not direct one to the cause of the problem; it merely identifies that an opportunity exists.

Putting feed efficiency into action
Translate the feed efficiency value to usable information by understanding what the data tells you and then by making action plans to move forward.

• Use efficiency as a guide. Because feed efficiency can be so variable, use the calculated value as a guide, not as the only measurement of ration quality and herd performance. If you hit an acceptable range – from 1.4 to 1.6 – your herd meets the goal for feed efficiency standards. Remember that individual pens will vary outside of this range based on weight loss or gain and milk production levels. Monitor feed efficiency values at least monthly to observe how the herd is responding to the ration.

• Consistent measurement. For consistency sake, measure feed efficiency the same way every time you calculate it. Use the same milk production value, collect feed refusals at the same time and have the same person determine refusal amounts and dry matter to get an accurate reading.

• Focus on specific cow groups. High-producing cows are a good group to closely monitor as they are in peak performance and use their diet, rather than fat reserves, as their main nutrient source. Fresh cows may have feed efficiency of 1.8 or greater because they are mobilizing body reserves and eating fewer pounds of dry matter.

On the other hand, cows in late lactation that are not producing high milk, but regaining bodyweight, can have efficiencies as low as 1.3. When these feed efficiency levels decline, it may suggest there is a problem when in actuality cows are performing optimally. Because feed efficiency is unique to each operation, progress should be assessed internally rather than compared to other operations. One herd may be able to improve efficiencies by a larger percentage, while another makes the same changes and realizes a different end result.

Know what the results mean. Feed efficiency is a good measure of how well the diet is utilized by the animal to produce a maximal amount of milk given the quantity of feed consumed.

Rate of passage and rate of digestion are the two opposing forces in the digestive tract that determine where and to what extent a feed source will be utilized by the cow. While optimal efficiency is often associated with extensive feed breakdown by rumen microorganisms, the feed that escapes the rumen will go on to be digested in the small intestine for use by the cow. Diets formulated to balance highly rumen-degradable feeds with feeds designed to bypass the rumen provide strategic delivery of nutrients to the cow to maximize feed efficiency.

• Forage quality. Feeding high-quality forages can directly influence feed efficiency. High-quality forages often move through the cow faster, which makes other feeds, like straw, critical to slow the passage rate and improve feedstuff utilization.

• Feed ingredients. Specially formulated feed ingredients have been created to increase rumen microbial growth, allowing for additional breakdown of each pound of feed and a higher feed efficiency value. Beyond that, there is also recognized value in providing feeds intentionally designed to bypass the rumen in order to supplement what the cow cannot deliver through fermentation.

• Identify potential ration solutions. Monitoring feed efficiency can bring current ration challenges to the forefront and drive changes to the diet. By identifying potential problems in the ration, you can work with your nutritionist to make changes that can have a positive effect on cow performance and feed efficiency.

Troubleshooting with feed efficiency results
Use the information you glean from the feed efficiency calculation as a troubleshooting tool and to identify where potential opportunities may exist for your herd. While feed efficiency may not direct change, it can suggest change is needed. The calculation can help to open up a dialogue between you and your nutritionist to discuss the possible value of strategic feeding of byproducts, or rumen-protected nutrients, and the application of new technologies in nutritional supplements.

Much like a car with improved fuel efficiency, how we handle and care for our herd will have a great impact on feed efficiency. Many variables will influence cow performance, but the ration is a key driver of how cows will convert nutrients to milk. Use feed efficiency as a process control tool to monitor and evaluate the performance of the feed program as part of the quest for peak herd performance. PD

*References and figures omitted but are available upon request at editor@progressivedairy.com

Bill Prokop
Veterinarian
Attica Veterinary Associates
wjprokop@midwaynet.net