Managing for milk level in your cow herd is similar to determining whether the porridge is too cold, too hot, or just right, says the University of Nebraska's Rick Rasby.
Too little milk in the cow herd equates to lighter weaning weights, which impacts dollars generated in the cow-calf enterprise. But low milk level in a cow herd should result in lower feed costs.
High milk level equates to heavier weaning weights, but can increase feed inputs and thus cow costs. As milk potential increases so do nutrient needs. Cows with a high milk level have a greater need for pounds of protein, pounds of energy (TDN), ounces of mineral, etc., to be consumed daily to meet those needs compared to cows with a low level of milk potential.
A number of years ago, the University of Nebraska developed three groups of cows similar in weight but differing in level of milk produced.
Cows in the moderate level of milk gave 28% more milk than the cows in the low level of milk group. Cows in the high milk level gave 46% more milk than cows in the low milk group.
As you'd expect, the feed for lactation between the three groups differed. Cows in the moderate and high level milk groups needed more feed to stay in similar weight and body condition compared to cows in the low level of milk group.
More interesting is that feed during gestation was greater for cows in the moderate and high level of milk groups compared to cows in the low level of milk group. This indicates that even when cows with different milk-producing abilities weren't lactating, milk potential increased nutrient needs.
In addition, feed requirements in the feedlot were greater for the offspring of dams that had higher milk potential. Data from the U.S. Meat Animal Research Center in Clay Center, NE, indicates cows with greater potential to produce milk also have a greater percent of their body weight as heart, liver, and lungs. So the greater nutrient need for non-lactating cows and for their offspring in the feedlot may be a result of having to maintain more heart, liver, and lungs, which are highly active tissues.
If cattle are asked to produce in a lush environment, then cow mature weight and level of milk is less of a concern, but carrying capacity will be reduced. If feed resources are limited, cow weight and milk production need to be carefully scrutinized, as both not only impact nutrient requirements but also feed intake. Cows bred for a high level of milk production have higher nutrient requirements even when not lactating.
So how big should your cows be and how much milk should they give? It depends, Rasby writes. Match cow size and milk level to your feed resources.
"From an economic standpoint, the greater number of cows that can be grazed on a given forage base and meet their nutrient needs from the grazed resource base, the greater the profit potential of the enterprise," Rasby says.
-- Rick Rasby, University of Nebraska-Lincoln