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Pitfalls to monitoring dry matter intakes

John Hibma for Progressive Dairyman Published on 24 May 2018

The single-most important metric for formulating dairy cow diets is knowing how much a cow eats each day. However, the consistent and accurate measuring of dry matter intakes is probably the most elusive component of nutrition management on the dairy farm.

There’s at least a dozen different factors that can affect how much feed a cow consumes every day – management factors such as overcrowding at the feedbunk, reduced cow comfort from poorly maintained freestalls, the amount of time cows spend standing that prevents them from resting and ruminating, feed quality, abrupt changes in the diet, availability of water and inconsistent feeding schedules.

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Then there’s the weather – rainfall, temperature changes, humidity, wind chill and mud.

Some of these factors are simple and straightforward to manage while others are completely out of a dairy farmer’s control. Indeed, it’s possible that every dairy farm could experience one or more of these challenges on a weekly basis.

Add to them the endless cycling of cows entering and leaving the herd and the ever-changing average days in milk (DIM) in corrals and groups – all part of ordinary herd management – and it becomes nearly impossible to accurately measure feed intakes for a herd of cows for more than a few days at a time. Just when we think we’ve got accurate numbers for the nutritionist and the feeder, something changes, and we have to start all over again with revisions.

Maintaining and monitoring dry matter on dairy farms is critical because: 1) Cows have nutrient requirements that, if not met, will affect their milk production as well as other metabolic functions, and 2) with feed costs being the single-largest expense on dairies, over or underfeeding cows can be costly on both ends with excessive feed costs or lost milk revenue as feeding efficiencies diminish.

Besides the variability in feed consumption caused by management and the weather, intakes can also be miscalculated due to incorrect moisture measurement of a high-moisture feedstuff such as corn silage. With many dairy diets incorporating 70 or more pounds of corn silage per cow into a diet, a 2- or 3-point mistake in moisture level calculation can result in an error of over 2 pounds of dry matter as the diet is formulated.

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In a TMR containing 50 percent corn silage that’s wetter than thought to be, means the cows will be eating less dry matter coming from the corn silage and instead be consuming more dry matter coming from expensive concentrates or other forages containing less energy.

This may result in underfeeding 2 or 3 pounds of energy in a diet, which then could decrease milk production by 3 to 4 pounds and also tip the balance of effective fiber in the diet, negatively affecting rumen health.

When targeting a certain level of milk production in a herd, the dairy farmer must have a very accurate idea of the herd’s feed intakes. If the farm expects cows to reach a peak production of over 120 pounds of milk at the beginning of the lactation, time must be budgeted appropriately so cows can spend adequate time at the feedbunk to consume the 60-plus pounds of dry matter needed to produce that much milk.

Where many dairy farmers get into trouble with this dry matter accuracy is underestimating the feed intakes of high-producing cows in their early lactation. Herds of big Holsteins weighing over 1,500 pounds are going to eat a lot of feed if they’re expected to produce 120-plus pounds of milk per day during the first couple months of lactation.

It’s critical to understand that dry matter intakes drive milk production. The more feed a cow can consume, the more milk she can produce. Along with that, maximizing the nutrient density in every pound of feed will improve the overall feeding efficiency in a herd.

Dairies should aim to keep the average milk-to-feed ratio above 1.5 to 1 for the entire herd. Fresh cows should have efficiencies of 1.7 to 1 or greater if possible. Feed efficiency ratios of less than 1.5 to 1 indicate there is room for improvement in the feeding program – and feed intakes may very well be limiting.

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Scales on feeding equipment must be accurate, and checked and/or calibrated on a timely basis. Weigh-backs of feed refusals is also critical in assessing nutrient intakes. Cows eat fairly predictable amounts of feed depending on their size and stage of lactation.

The one thing cows don’t like is abrupt changes in feeds or feed quality. The rumen needs time to adapt to changes in the diet, so those changes must be made gradually. Abrupt changes in forage quality can be especially challenging when trying to accurately manage dry matter intakes.

Neutral detergent fiber (NDF) levels and neutral detergent fiber digestibility (NDFd) can also have a profound impact on total intakes. Changes in NDFd can impact how much forage a cow is able to consume and digest every day. There can be significant differences in NDFd from one forage to another even if NDF and protein levels test similarly.

To stay on top of dry matter intakes, today’s forages should be tested for NDF digestibility as part of a complete forage evaluation.

While computer modeling is sophisticated enough today to deliver very accurate nutrition in support for a given amount of milk production, the models don’t always agree on the predicted dry matter intakes. So relying exclusively on the models for predicted intakes should be avoided.

Errors in predicted and actual intakes make quite a difference in ration costs if there is a 2- or 3-pound discrepancy in predicted feed consumption. Accuracy of dry matter intakes can also be improved with multiple production groups, having cows with similar milk production and DIM so as to keep the nutrient density of the diet more consistent.

In today’s dairy industry, volatile milk prices and feed prices make it imperative to be watching feed intakes and milk-to-feed efficiency more closely than ever before. The temptation to reduce feed intakes in an effort to cut feed costs more often than not will do more harm than good. The best strategy in feeding cows is to find that perfect balance where both feed intakes and milk-to-feed ratios are maximized.  end mark

John Hibma
  • John Hibma

  • Consulting Ruminant Nutritionist
  • Email John Hibma

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