As producers walk the profitability tightrope, efficiency is the most important tool to make progress in the balancing act of improving income over feed cost. Lou Armentano, a professor emeritus at the University of Wisconsin, says creating more efficient cows begins with making the right breeding and selection decisions.
Like most aspects of dairying, improving efficiency through selection is complicated. Efficiency can be defined and measured in many ways. As cows and markets evolve, maximizing efficiency is aiming at a moving target. Armentano weighed in on the struggles of nailing down efficiency at Papillon Agricultural Company’s 2016 Dairy Efficiency Summit.
“Defining feed efficiency in an economic form is difficult and not constant. It involves fluctuating market conditions and biological issues related to feed production as well as manipulation of cattle biology and herd structure,” he said.
For most purposes, efficiency is best expressed in terms of energy. Marginal efficiency is the increased yield of milk energy gained with each additional unit of feed energy. Gross efficiency factors in fixed maintenance requirements.
Historically, the industry made tremendous progress in gross feed efficiency by selecting for increased milk yield. Milk production is highly heritable, making it an easy target. As cows produce more milk, fixed maintenance costs become more diluted.
Targeting productivity or body size is oversimplifying
However, as average productivity climbs higher relative to maintenance, gross efficiency is affected less by changes in production. “In cows producing at levels above five times maintenance, it is possible for gross efficiency to become nearly unresponsive,” Armentano explained. “This means future gross efficiency gains through increased production will be less than those we’ve been able to achieve in the past.”
Compounding the dilution effect is digestibility depression, which causes marginal efficiencies to decrease as intakes increase. “In the past, marginal efficiency was assumed to be constant,” Armentano said. “Basically, we used to assume the first pound of feed used for milk production gave the same amount of milk as the last pound. The new NRC (National Research Council) dairy system recognizes digestibility is depressed at higher intakes.”
Like milk production, body size is highly heritable and a frequent topic in the efficiency discussion. The average Holstein today is about 50 pounds larger than one a decade ago.
This trend toward increased body size is negatively impacting efficiency, Armentano said. “In general, bigger cows are less efficient. It takes more to maintain larger animals during lactation and dry periods, and these extra costs are not always offset by additional milk yield.”
The size increase also denotes wasted selection pressure. Selecting for a trait reduces selective pressure on other traits. Armentano noted the trend toward larger cows means we are currently using some selective pressure on increasing size. This reduces the selection pressure usable for increasing milk yield and selects against feed efficiency.
Industry must adjust
“As an industry, the choice should be to stop or reverse the trend toward increased body size. Both producers and bull studs share the responsibility,” he said.
According to Armentano, the way to improve efficiency and reverse the trend toward increasing size is to use residual feed intake (RFI) as a genetic tool. RFI measures feed efficiency at a common production level. Negative RFIs are efficient, and positive RFIs are inefficient.
“To breed cows that are biologically more marginally efficient, we need a measure of marginal efficiency not all tied up in milk. That’s where residual feed intake (RFI) comes into play.”
Although RFI has a relatively low heritability, reasonable progress should be possible with the use of genomics. RFI has other limitations. Negative RFIs do not increase income over feed costs if they cause a drop in milk production. Breeding index weights for RFI and production must therefore be balanced.
Armentano reminded producers there are other ways to influence on-site efficiency in addition to selection. Begin by scrutinizing agronomic practices at harvest, storage conditions and bunk management. Reducing shrink from harvest or purchase to feeding can go a long way toward reducing feed costs.
Precision feeding can also boost efficiency. Consistent, analyzed feeds and an accurate feeding system are a must. Optimizing amino acid balance can cut feed protein costs while improving performance.
“With the right grouping strategy, we can tailor N supplementation to the production level of the cow and limit the use of expensive additives to only appropriate cows,” Armentano added.
Armentano and his colleagues at the University of Wisconsin are optimistic continuous data collection on feed efficiency phenotype along with management changes and selection tools like RFI will allow the industry to advance efficiency at both the cow level and the farm level in the future. 
PHOTO: “As an industry, the choice should be to stop or reverse the trend toward increased body size. Both producers and bull studs share the responsibility.” —Lou Armentano, professor emeritus at the University of Wisconsin. Staff photo.
Mary Grace Erickson is an Indiana-based agricultural journalist. She is providing exclusive reporting for Progressive Dairyman about the Dairy Efficiency Summit which was presented by Papillon Agricultural Company last year in Green Bay and Madison, Wisconsin.
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Mary Grace Erickson
- Agricultural Journalist
- based in Indiana
