You just hired the best nutritionist, purchased a new mixer wagon and payloader and your recent college graduate daughter has come home to run the feeding program, but as far as you can tell things are going downhill fast! What’s up? During these times it’s important to realize there are three rations on the dairy farm:

•one you formulate

•one you mix

•one the cows eat

Are they the same? In order to manage the feeding program and achieve some degree of precision, it’s important to look to Webster for a few definitions:


•Precision is the quality of being reproducible in amount or performance.

•Accuracy is the quality of nearness to the true value.

First, we want our rations to be accurate, and then we seek to achieve precision or reproducibility in the delivery of accurately formulated rations. Dairy cows like to be bored and enjoy repetition and consistency in their feeding programs. To achieve these lofty goals let’s look at sources of variation in the major factors influencing the feeding program on a dairy farm. This [article] won’t solve all your problems, but it should send you on your way to identifying where you can work to achieve better accuracy and precision.

The ration that’s formulated

Optimum information for our nutritionist enables them to accurately formulate rations. The old saying: “Garbage in, garbage out” applies. Here’s the sources of variation under control of the dairy producer listed from field to cow.

In the field

•How many varieties of corn were planted for silage?

A greater number of varieties spreads the risks due to weather or pests. However, if corn is custom harvested it may not be at the optimum for many of them and yield or digestibility advantages may be lost. Keep it simple, and grow varieties well suited to your land resources and environment.

•Is harvest equipment properly maintained to minimize breakdowns during critical harvest times of the year?

Delays of one to several days can have disastrous effects on yield, nutrient content and digestibility of forage.

•Are knives sharp and properly set for desired length of cut to enable good packing yet provide adequate effective fiber?

What’s desirable? It should be as long as possible and still enable good packing or handling in upright silo blowers. About 0.75-inch is a good goal for maximum theoretical cut. Less than 0.5-inch packs well but flies through the cow.

•If a processor is used, are the rollers set close enough to break kernels, cob and stalks?

When custom operators get pushed for time it’s not uncommon to see the rollers come apart. Continuously monitor appearance of the silage during harvest to assure rollers are set close enough (about a dime’s worth in thickness).

Filling the silo

•Piles and horizontal silos

–Adequate numbers of wagons or trucks should be secured to match the cutting rate of the field harvester.

–Assure packing tractors or dozers can keep up with the rate silage arrives at the silo. Remember; fill it in a wedge with thin layers of silage. Well-packed silage shows tread marks and not tire tracks when it’s well- packed.

–Seal the silo to prevent spoilage and accumulation of additional water and exposure to the elements.

•Upright silos

–These usually don’t cause problems with variability as long as the walls and doors are sealed and in good repair.

–Unloaders need to be routinely serviced to assure there are no interruptions in operation requiring abrupt substitution of other silages.

–The silo choice and its structural integrity can have a major impact on variation of nutrient content and quality of silage.

•Horizontal silos

–Although wider and taller silos contribute to lower costs of construction they require high feeding rates to remove enough silage to minimize spoilage. At least 6 inches should be removed daily, regardless of season.

–Spoiled silage on the top and sides must be manually removed every day.

–Multiple varieties stored in one silo increase variation from top to bottom and front to back in the silo.

–Silage unloading practices have a large impact on quality of forage.

The practice of placing the bucket on the floor of the silo and “digging in” results in fissures into the silo face allowing entry of air and causing secondary fermentation and heating. It’s a major cause of deterioration of silage quality.

Silage should be shaved from top to bottom to create a pile of sufficient silage to be used for each feeding. Consider the purchase of quick-attach silo facers to improve silo management. Yes, it takes more time, but it’s a big deal.

•Silo bags enable producers to effectively manage different cuttings of haylage or varieties of small grain or corn silage.

Marking the bag during filling when varieties or cuttings change enables preplanning of ration changes.

–Silo bags should be located on well-drained sites that don’t turn into mud holes.

–Added dirt and rocks lower palatability of the forage and contribute excessive amounts of iron from the soil which can interfere with absorption of minerals.

–Spray the areas around bags with herbicides to eliminate cover for animals which can chew holes in the bags.

–Monitor bags closely for holes and patch them promptly.

•Upright silos provide excellent opportunities for silage management.

Consider sending strips of plastic up the blower as varieties or cutting change. Sample and test forage during filling to enable preplanning of feeding programs.

–Generally silage is very consistent coming out of an upright silo providing that doors are well-sealed.

–Silage variability can be excessive in bottom unloading silos when shifting from one cutting or variety to another. Forage sampling and analysis is critical to reducing variability of TMRs and achieving the nutritional balance for the herd or group.

•Obtain a representative sample.

Some tips for good sampling:

–Take a large initial sample (5 gallon bucket) and subsample from it.

–Send a maximum of 2 pounds to the lab.

–Keep it stored in a freezer or refrigerator until shipping and double-bag it.

–Send it by UPS, FedEx or Express mail to assure quick shipping. Time is money and waiting for more than a few days for results will cost money.

•What analysis?

Here’s where lots of producers try to cut corners by ordering the least expensive analysis. This may be adequate if there is poor control over formulation, mixing and feeding. However, more detailed tests such as the CPM analysis enable the nutritionist to learn more about the forage and do a better job of predicting responses to rations with the new forages. The NDF digestibility (30 hour) will help identify those silages with higher relative digestibility. Likewise, mycotoxin screens should be run on suspect forages.

•On-farm screening

•Sample silage weekly to measure DM percentage. Dry matter can be determined by several devices on the farm.

–Changes in moisture indicate impacts of weather on the silo face or movement into a new cutting or variety.

–As moisture changes make initial adjustments to the ration and send samples for more complete nutrient analysis

•Particle separators are an inexpensive, simple tool to aid in ration problem diagnoses.

–A “shaker box” can reveal the physical nature of the forage and provide the nutritionist with an idea of how the forage will behave in the rumen.

The ration that’s mixed

The formulation arrives from the nutritionist and is given to the feeder. What assurances are there `it’s been implemented properly?

Sources of variation affecting accuracy and precision

•Is the ration listed in feed order with the aggregate of weights listed as ingredients are added?

•Is the feed order relevant to the type of mixer? Normally forages are added first.

•Is the feeder well trained?

–Adjustments made to horizontal silo weights when it rains or when the number of cows in the group changes.

–Mixing time adequate, but not too long.

–Feeder evaluates feeds as they are being added.

–Manages the silo face well?

•Scales on mixer wagon are evaluated periodically (weekly)?

•Evaluation of the final mix

–Nutrient analysis of the TMR (sampling errors are common)

–Run a particle separator on the mix at three different locations along the bunk to determine separation or poor mixing is not a problem.

•Consider the use of feed management software to track operator performance.

Should you consider feed management software? Some of the important features enable the manager to evaluate:

•loading accuracy

•delivery accuracy

•operator accuracy

•track dry matter intake by herd or pen

•trace inventory

•compute feed costs and income over feed cost

•remote communication between the TMR wagon or truck and the office

•Internet download of information to consultant

The key advantage of feed management software packages is a means to reliably evaluate the accuracy and precision of the ration delivered to the cow or groups of cows.

The last ration on the farm – the one the cows eat

This is probably the toughest one to evaluate for precision and accuracy because the cows don’t tend to follow instructions very well. It’s the one where the manager may have the least control. The principal problem is sorting of ingredients by the cow. This can be evaluated by using the particle separator to evaluate the TMR at three or more locations along the feedbunk and repeating this every few hours between feeding. If sorting is a problem results will vary as time after feeding increases. Other measures used to evaluate what the cows eat include:

•The ultimate measure of what the cows eat is their performance. Track milk production and milk composition daily and report this to the nutritionist.

•What percent of the cows are chewing their cuds or eating (should be 60+%)?

•Evaluate their manure. If you observe a large portion of undigested forage particles in the manure there are problems with the ration.

How similar are the rations on your dairy?

Accuracy and precision begin with accurately describing what the nutritionist has to work with. This includes providing the nutritionist with estimates of quantities of each forage available and timely evaluation of quality. The next ration conforms to the first when equipment is functioning properly and personnel are well-trained. Consider the benefits of timely evaluation of ration mixing by implementing the use of feed management software.

Finally, let the cows’ production and behavior provide the final indication of accuracy and precision of their ration. These procedures involve a lot of common sense and are just important as the latest technological breakthrough of a feed additive or injection. PD

References omitted but are available upon request at

—From 2006 Virginia State Feed Association and Nutritional Management Conference Proceedings