When cows just aren’t performing the way they need to be, the ration often takes the blame. Your nutritionist may need to make some adjustments, but before they do, it might be a good idea to take a look at what is happening to that ration when the formulation moves from theory to practice.

Freelance Writer
Tamara Scully, a freelance writer based in northwestern New Jersey, specializes in agricultural a...

You may have the right ration, but that ration may not be what your cows are consuming.

William Prokop, DVM, director of operations at the Cornell University Ruminant Center, discussed the many ways a good ration can go wrong in his presentation, “When bad things happen to good rations,” during the Penn State Dairy Nutrition Workshop last November.

Prokop has many years of experience as a dairy consultant and has seen many reasons why the ration fed is not the same as the ration prescribed. When performance is down, ask yourself what else could be wrong, and don’t assume it is the nutritionist’s problem, he urged.

“If the ration worked before, do we know why?” he asked. “If it doesn’t work, why? Lack of repeatability tells me we’re missing something.”


Rations are quantitative, as well as qualitative, in nature, Prokop said.

The dairy nutrition models offer quantitative data. Models allow for precise utilization of nutrients, enhanced nutrient management and amino acid optimization. If the data that is input into the model is correct, the formulated ration is, theoretically, optimized for cow performance.

Qualitative aspects arise with management, however, and can significantly impact even the best ration formulations.

Input problems

“Nine times out of 10, the problem with the ration” is not the model, but the management, Prokop said, although no model is perfect. “They’re robust, but they have limitations. They are not autopilot. You have to think about the results. You can’t just plug data in.”

Bodyweight is the factor that makes the models work and is the most important metric. Even trained nutritionists misjudge bodyweight by underestimating the actual weight of dairy cows by more than 300 pounds, as shown in recent Cornell studies. Estimating weights by sight is not an accurate basis for diet formulation.

“It can really impact what kind of performance you get,” he said. “If things don’t make sense, go back and double check yourself on weights.”

Using one cow to represent an entire herd is not going to get you the correct ration. Each pen should be represented by an average weight. This can be achieved by loading the pen into a trailer and weighing it.

“Cull cows are not representative of the herd,” Prokop reminded participants.

Target weights for heifers play an important role in ration formulation and shouldn’t be overlooked. The net energy (NE) and net protein (NP) in the ration need to change with physiology and aren’t static as cows grow.

Dry matter and dry matter intake adjustments often get neglected. Improper results from dry matter determination can cause many ration concerns. Errors in calculating starch and neutral detergent fiber (NDF) levels often occur.

Variables such as who enters the data, how many samples of each feed are taken, which feeds are analyzed and even the weather during sampling can all affect the dry matter calculations.

“Weekly analysis of feeds is paramount” for dairy producers, Prokop said.

Feeding errors

Increasing efficiency and decreasing variability in feeding operations makes the nutrition models work better, but there are many common ways in which the actual ration fed can vary significantly from the ration formulation.

A management goal should be “to make the system so intuitive and so easy to follow” that everyone can execute the job properly and do it consistently. Management has to show that proper ration formulation is important, or employees won’t be motivated to do their best work.

Lack of consistency can be due to many factors. Equipment issues such as improper maintenance and worn parts will impact the proper mixing of rations. All parts should be replaced on the manufacturer’s schedule, even if they still look good.

Surfaces that lose their polish are no longer mixing accurately, due to changes in friction. One way to determine if equipment is mixing as it should be is to throw candy gummy worms into the ration and see if they are distributed evenly after the mixing protocol is followed.

Human error also plays a role in mixing, and not following the established protocol can lead to very inconsistent rations. Weekend feeders are often responsible for mixing errors. Improper training of employees who don’t time the mixing correctly or add ingredients in the wrong order can compromise feed mix integrity.

Data readily available on the farm can show that a problem exists but often isn’t utilized. Feed mixer time stamps can point to problems, for example, but are often not examined, Prokop said.

Measuring ration samples from the feedbunk, using a tool such as the Penn State particle separator, before the cows eat can help determine if the ration is being properly mixed. Although time-consuming, it is a good process control and is a way to demonstrate the potential for variability to employees.

Cow refusals can be due to spoilage concerns. Inventory control, so feed is fresh and the supply is adequate, helps to ensure that substitutions aren’t being made and keeps things consistent. Feed needs to be delivered to the cows on time and pushed up frequently, so it is always available to them.

Sorting can mean that the cows aren’t consuming the fiber you assume they are. Excessive sorting by the cows can result in nutrition concerns. Manure analysis can help determine what is being digested – or not – and can be an important tool in determining if rations are being fed correctly.

“All cows will sort to some degree; it’s a matter of how much the ration will allow for it,” Prokop said. “Not all of the cows are eating the same thing,” impacting herd performance.

Cow comfort

Miner Institute research has shown that the comfort of dairy cows impacts rumination. Mitigating stress and keeping cows physically and emotionally comfortable and healthy will allow the “phenotype expression of genotype,” he said.

Comfortable cows will produce more milk. Changes in cow environment – type of stalls, bedding, noise or light, animal density, temperature – can all impact performance, even when the ration stays the same.

“Putting the needs of the cow first, over the needs of the outfit,” is a best practice to optimize the performance of the ration, Prokop said.

Management practices are the key to getting the most out of a properly formulated ration. If things aren’t going well, don’t blame the nutritionist. Take a look around and see if the diet being fed is actually the same as the diet formulated or if other concerns could be causing a good ration to have poor results.

The steps to managing a potential ration problem – or any other process on the dairy – is to recognize variation’s negative impact and work to improve consistency.

“It’s not just the ration” that impacts performance, Prokop said. “What we want is process control and continuous improvement.”  end mark

Tamara Scully, a freelance writer based in northwestern New Jersey, specializes in agricultural and food system topics.