Milk is clearly a good thing in the beef cowherd.
By Jay Jenkins, UNL Extension Educator
Milk is clearly a good thing in the beef cowherd. Heavier milking cows produce heavier calves.
But at what cost?
High milk cows pay a biological penalty relative to cows with lower milking ability. This penalty occurs in two ways:
1) Additional feed required
• Higher milk cows require more nutrients to support their greater milk production. (NRC, 1996)
• Higher milk cows have higher maintenance requirements. Which means they require more nutrients year around than a similar sized cow with lower milking ability. (Ferrell and Jenkins, 1984) This is believed to be related to a greater visceral organ mass relative to empty body weight. (Jenkins et al., 1988)
2) Diminishing returns to additional milk.
A study conducted at UNL (Lewis et al., 1990) 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 one additional pound of calf weaning weight.
• The medium milk group required 15.2 added pounds of milk from the dam to produce the same one additional pound of calf weaning weight.
• The high milk group needed 52.6 pounds of dam milk to produce that one 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/total feed energy required), but were more economically efficient as well (income/expenses) (van Oijen et al., 1993).
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 cowherd?
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 six 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 cowherd performance records show virtually no increase in average weaning weight over the last 20 years (Kansas Farm Management Association; North Dakota Cow Herd Appraisal Performance Software Summary; and the New Mexico, Oklahoma, Texas Standardized Performance Analysis Summary).
How can this be?
Limited forage resources appear to be the likely culprit.
In an Oklahoma study reported by Brown et al. in 2005, 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 that 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!