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Nutrition: Risky Business

17:02PM Nov 28, 2011


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Every day on a dairy farm, we decide what to feed the cows, how much to feed them, which cows should be fed which feeds, and how to mix and present the feed. With every one of these decisions, there is an element of risk as to what will happen to milk production and feed costs. Good decisions result in good things happening to milk and/or milk component production. Bad decisions cost in loss of milk production, cow health and, usually, higher feed costs.
The major risk areas in nutrition fall into three categories: diet formulation, ration delivery and forage quality. However, these are not independent of one another and a low risk in one area can result in a high risk in another.
For example, suppose forage quality is marginal and the nutritionist formulates a diet at the lower guideline level for fiber and forage. The risk is that grain will be overfed, with loss of milk components and possible laminitis.
This risk can be reduced with good on-farm diet mixing and feeding management: keeping feed in front of cows all the time; frequent push-up of the ration; no overmixing to reduce particle size; not having too long a particle size to promote feed sorting; adequate bunk space so cows can eat at the same time; and consistency in feeding times.

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Another example of risk is feeding one total mixed ration (TMR) to all cows. This is a simple feed mixing program with no concern about which cow gets which mix of feed.
While this may save time, there are risk assessments that should be made before implementing the practice. For instance, at what level of milk production and dry matter intake is the nutritionist going to formulate the diet?
A high-production diet will substantially increase feed cost across the herd, and low-producing cows may become overconditioned. If the diet is formulated for a level of milk production that is too low, early-lactation cows may become deficient in energy, limiting production and affecting reproduction.
To illustrate the feed cost increase with one group TMR across the herd, assume a farm has three groups of cows (80 first-lactation cows, 100 high-producing cows and 70 low-group cows). Milk production is 75 lb. per day for first lactation, 90 lb. per day for high production and 65 lb. per day for low production.
Dry matter (DM) intake is 50 lb. per day for first lactation, 60 lb. per day for high production and 50 lb. per day for low production. The total feed cost per day for feeding the one high-production TMR to all cows at $0.13 per pound of DM is $1,755.
If a separate TMR is formulated for each group based on its nutrient requirements (feed cost of $0.13 per pound of DM for the high group, $0.12 for first lactation and $0.10 for the low group), the total daily feed cost for milking cows is $1,590. Feed cost is reduced $165 per day by feeding three different rations instead of one ration to all cows.
Using this same herd for an example regarding forage and feed mixing risks, what happens if the feeder isn’t concerned about the accuracy of weighing feed into the mixer?

What’s the risk of feeding 200 lb. more haylage in the low group diet than the formula specifies? First, there is the increased cost of feeding 200 lb. more haylage. Second, there will be a dilution with forage of nutrient concentration in the diet, and cows eating the same amount will have a lower energy intake and probably decreased milk production. A conservative estimate for this example would be 3% less milk.

Third, the extra forage feeding will deplete inventories more quickly, which may mean buying some higher-priced feed later in the feeding year to replace the used-up inventory.
With each step in the nutrition program, there are various risks. Every dairy should do a risk assessment analysis to identify the main areas causing low production and/or high feed costs. Once the risk areas have been identified, an action plan should be developed to reduce or eliminate the risk.
JIM LINN is an Extension dairy nutrition specialist with the University of Minnesota–St. Paul.
You can contact him at