But at what cost?

High-milk cows pay a biological penalty relative to cows with lower milking ability. This penalty occurs in two ways:

Additional feed required

• Higher-milk cows require more nutrients to support their higher milk production.
• Higher-milk cows have higher maintenance requirements. Which means they require more nutrients year-round than a similar-sized cow with lower milking ability. This is believed to be related to a greater visceral organ mass relative to empty bodyweight.

Diminishing returns to additional milk
A study conducted at University of Nebraska – Lincoln (UNL) had three groups of cows with similar body size but with different levels of milking ability.

They found that the importance of the dam’s milk in increasing weaning weight was greatest for calves from the low-milk group and least for the high-milk group.

• In the low-milk group, each 11.8 pounds of additional milk that the cows gave equated to 1 additional pound of calf weaning weight.
• The medium-milk group required 15.2 added pounds of milk from the dam to produce the same 1 additional pound of calf weaning weight.
• The high-milk group needed 52.6 pounds of dam milk to produce that 1 additional pound of calf weaning weight.

High-milk cows are less efficient
An analysis of the biological and economic efficiency for the three levels of milk production in that same UNL study found that the low-milk group was not only more biologically efficient (calf weight and total feed energy required), but were more economically efficient as well (income and expenses).

The researchers ended their paper by stating “Recommendations to use breeds of cattle with high milk levels as dams in commercial production and to select for higher milking ability in beef breeds already with an adequate milk level are questionable.”

How has the industry responded?
What has happened in the industry in the 20 years since those researchers cautioned us against adding higher-than-necessary levels of milk in a beef cow herd?

There has been a strong genetic trend for increased milk in virtually every major beef breed except those that originated as dual-purpose breeds.

In Angus cattle, for example, the average milk EPD has increased from approximately 6 pounds in 1990 to 23 pounds in 2013.

At least we are getting heavier calves as a result of the increased milk, right?

Maybe so, but you would be hard-pressed to find the data to support it. Three major collections of cow herd performance records show virtually no increase in average weaning weight over the last 20 years.

How can this be?
Limited forage resources appear to be the likely culprit.

In an Oklahoma study, cows with the highest milking ability actually gave less milk than cows with average milking ability as forage quality declined during the summer.

The decline in nutritive value of forage had greater effects on higher-milking cows than the cows with average milk yield.

Not surprisingly, the researchers reported that there was an interaction between cow size and the level of milk the forage could support.

They stated, “There seems to be a practical maximum sire milk EPD for heavier cows, above which increases in daughter milk yield do not occur, with the maximum effective sire EPD becoming smaller as cow size increases.”

What does all this mean?
The obvious answer is that it is possible to get too much milking ability in your herd.

Cows with higher levels of milking ability cost you more to feed than those with lower milking ability.

Not only that, but in cows where milking ability is too high to be supported by your feed resources, you may actually see them wean lighter calves. Increased costs, lower returns – now that is bad news.

It may also mean that you need to stop selecting for increased milking ability.

Given the research findings, and the genetic trend of the nation’s cow herd, it is very likely that your cow herd is near the practical maximum for your ranch.

Unfortunately there is no one-size-fits-all milk EPD that will work for every ranch. It depends on cow size, available feed resources, how and when you market, and many other factors.

What can you do?
Look over your cow herd and your records for clues.

High-milk cows often have lower body condition scores than low-milk cows. There is also a tendency for high-milk cows to have longer calving intervals, later calving dates and lower calving percentages than cows with lower milking abilities.

Look over the milk EPDs of your bull battery and compare them to your weaning weights. Be careful though, weaning weights vary considerably due to environmental conditions.

Consider growth EPDs as well. It is possible that higher weights may be due to more growth rather than more milk.

Our industry has a long history of crazy trends that take a long time to recover from; let’s not make milking ability become one of those trends. 

References omitted due to space but are available upon request. Click here to emial an editor.

—Excerpts from University of Nebraska – Lincoln BeefWatch website

PHOTOS
PHOTO 1: A study has shown that low-milking cow groups can be more efficient both biologically and economically. Photo by Kevin Brown.

PHOTO 2:  While EPDs for milking traits have increased in recent years, that hasn’t translated to heavier weaning weights in calves.

PHOTO 3: Cows with high milking ability will cost more to feed, and may have longer calving intervals. Photos by Ryan Curtis.