“We can improve feed efficiency by improving how we feed, breed and manage cows,” says Mike VandeHaar of the department of animal science at Michigan State University. VandeHaar was a presenter at the 4-State Dairy Nutrition and Management Conference held this summer in Dubuque, Iowa.

What is feed efficiency? VandeHaar defines it simply as “to produce a lot of milk for the amount of food a cow eats during her lactation.”

However, VandeHaar is not a supporter of using the milk-to-feed ratio in making feeding decisions. VandeHaar says, “We should focus on maximizing milk income after subtracting the cost of feed. Grouping cows according to their nutritional needs can help us optimize efficiency and profitability.

This will enable cows in early lactation to be fed diets that maximize milk income and cows in later lactation to be fed diets that optimize milk income while minimizing excess body condition gain.

“Feeding a single TMR across lactation can never maximize production and efficiency,” he adds.

VandeHaar says while most farmers recognize that grouping cows according to their feed needs will increase feed efficiency and profitability, it does require more work and management. “You simply must implement effective grouping strategies or you won’t be able to feed optimally for cows at various stages of lactation.”

He notes there are several recent studies that back up the idea of nutritional grouping. Some producers are resistant to the idea that moving cows from group to group will create a drop in milk production.

“Generally, however, this drop is only for a few days,” VandeHaar counters. “Furthermore, if a late-lactation diet is balanced with plenty of digestible fiber and only 12 to 15 percent starch, cows may not drop in fat-corrected milk at all. Instead they partition more of their feed energy to milk instead of body fat.”

The number of rations on any farm depends on many factors, but his recommendation is to have at least three rations based on the following feeding goals:

• Fresh cows should be fed for optimal health, and expensive supplements are warranted.
• Cows in peak lactation should be fed for maximum milk; because their intake is limited by rumen fill, they should be fed minimum-fiber diets (about 27 percent NDF) with plenty of digestible starch to maximize energy intake.
• Cows in later lactation should be fed to optimize milk and body condition; they should be fed less fermentable starch and more fermentable fiber to promote dividing of nutrients toward milk instead of body tissues (minimize fattening).

The decision on when to switch cows from the early to late-lactation diet should be based on body condition, parity, milk yield and reproductive status, VandeHaar says. “Of these, perhaps the most important benchmark for switching to the lower- starch ration is whether a cow has achieved a body condition score of 3.”

Overweight cows are more susceptible to health problems at next calving, resulting in less saleable milk and followed by increased body fat mobilization, impaired fertility and extended lactation intervals.

Other general guidelines he recommends include that cows in late lactation should be fed lower-protein diets, expensive supplements are most useful in early lactation, and cheap feeds are best used in late lactation.

He added, “We need to stop selecting for big cows just because we like big cows. If they produce more milk, fine. But for the past few decades, we have selected for big Holsteins even if they did not produce more milk because almost every type trait is correlated with bodyweight and stature.”

Although poor feed efficiency usually decreases profitability, VandeHaar says maximizing efficiency will not necessarily maximize profitability – feed costs do matter. “Expensive energy sources like fats usually improve feed efficiency but sometimes decrease profitability.

Cheap bulky feeds may decrease efficiency but improve profitability, especially in late lactation. Feeding extra protein usually decreases efficiency of protein use but sometimes, even if the protein is expensive, it might improve profitability if it enhances production.”

He added that feeding these groups of cows optimally requires that cow responses to diet changes be carefully recorded. “The optimal diet to prevent overfeeding while maximizing milk is hard to predict. You must monitor your cows.

“Monitoring the actual response is essential for optimal farm management,” he says. “High production is almost always more important for high profitability than is low feed cost, but managing feed costs is still prudent.”

He urges producers to choose feed based on actual financial returns, and he says computer models cannot accurately predict cow response. “Some nutrition programs attempt to formulate diets using a mathematical model for profit maximization.

However, in real life, it is virtually impossible to accurately predict how a diet will affect appetite, nutrient partitioning, and milk yield and components. Feed intake and cow responses must be measured to determine if diet changes are returning profit.”

Improved feed efficiency occurs because as cows produce more milk relative to their bodyweight, the percentage of feed used for maintenance decreases.

A cow’s maintenance requirement is defined as what she needs to maintain her bodyweight and condition. As a cow produces more milk relative to her bodyweight, the percentage of feed used for maintenance decreases.

If a Holstein cow eats enough to maintain her bodyweight (about 10 Mcal of net energy) and produces no milk, her feed efficiency is 0 percent. If that same cow eats 20 Mcal of net energy, half of her feed is used for maintenance and the remainder is used to produce milk (2X).

As she eats more, the portion used for maintenance becomes a smaller percentage of total feed intake, which increases efficiency.

“Cows at about 4X intakes are close to maximum feed efficiency. Elite cows (producing more than 30,000 pounds per lactation) are already near, at or possibly above the optimal multiple of maintenance for maximal efficiency during lactation,” VandeHaar explains.

“We are not likely to continue to make major advances in feed efficiency simply by increasing milk per cow. Instead, we also must focus on how to get more milk from each unit of feed.

“Efficiency and maintenance does vary considerably among cows,” he says.

VandeHaar says most cows already have the genetics for high production. He and his colleagues believe that genomic tools should allow for direct selection for feed efficiency in the future. Greater efficiency will improve profitability and environmental sustainability, he says, but continued focus on production, health and fertility will continue to be important for farm profitability.

Feed efficiency is only one factor that influences profitability, he observes. More milk per cow reduces the portion of total farm expenses that are fixed, so even when a cow reaches optimal production to maximize efficiency, economics will still favor higher production per cow to dilute out the fixed expenses on a dairy operation.

VandeHaar also notes that increasing feed efficiency is generally good for the environment.

“We can feed more people with fewer resources and less negative environmental impact. Improving efficiency of milk production by using new technologies seems the responsible thing to do for the environment, at least in the foreseeable future and at least until average milk production exceeds 30,000 pounds a year for the average Holstein.” PD

Kelli Kaderly-Boylen is a freelance writer based in Waterville, Iowa.