May 13, 2021

Dry matter intake of dairy cows impacts milk production

URBANA, Ill. — Monitoring dry matter intake is important for dairymen that are making changes to rations in response to higher corn and soybean prices.

“Dry matter intake dictates nutrient intake, so if we start making changes that lowers dry matter intake, then you may suffer consequences,” said Mike Hutjens, University of Illinois dairy specialist emeritus.

“Optimal milk yield means optimal profitability and high-producing cows make a lot of money,” said Hutjens during a webinar hosted by Hoard’s Dairyman. “Be aware that energy will impact total milk yield and milk components, especially milk fat.”

Not all starch is created equal, Hutjens said.

“Steam flaked corn is the fastest in terms of rate of starch fermentation and dry corn is slow,” he said. “How you process the corn impacts the energy your cow can get out of the pound of dry matter.”

Starch drives feed intake, Hutjens said.

“I like the number to be around 70% of the starch fermented in the rumen, 25% in the small intestine and small amounts in the large intestine,” he said. “To evaluate starch fermentation, look at the particle size, and for dry corn, it should be from 400 to 800 microns.”

Hutjens talked about a ration study that was conducted by the Miner Institute that evaluated three diets — a control diet at 26% starch, a low starch diet at 21.3% using wheat midds or beat pulp and a low starch diet at 21.4% using BMR corn silage.

“The highest dry matter intake was the control diet, and the lowest was the high forage diet, even though it was BMR silage,” he said. “Milk yields were lower on the high forage diet. However, butterfat test was higher on the high forage diet.”

Hutjens advises dairymen to harvest their corn silage at 24% to 36% dry matter.

“That will grow more starch in the field because for every 1% increase in dry matter, you can increase the starch about 1%,” Hutjens said.

“Process your corn silage with a kernel processor and the score should be over 70%,” he said. “I want that kernel crushed.”

Dairy cows have an amino acid requirement, Hutjens said, and metabolizable protein is made up of two factors — how much microbial protein is synthesized and rumen undegradable protein.

“Rumen degradable protein has to be made to microbial protein, and if it does not get converted, it goes into the blood stream as ammonia and to the liver where it is made into blood urea nitrogen,” he said. “If a ration is deficient in rumen degradable protein, urea should be considered.”

Evaluate rumen undegradable protein sources based on cost and the amino acid profile, Hutjens said.

“For lysine sources, heat treated soy products and blood meal are winners, and sources of methionine include corn distillers grain, corn gluten feed and fish meal,” he said.

Currently, Hutjens said, one pound of dry matter in a dairy ration costs 12 cents compared to 10 cents six months ago.

“One pound of dry matter can support two-plus pounds of milk,” he said. “That milk at 18 cents per pound totals 36 cents, so I can make 24 cents per cow per day with another pound of dry matter.”

Dairymen should calculate the feed efficiency of their herds.

“I want that number over 1.5, and if it is below 1.3, you’re going to lose some money,” Hutjens said.

A 70-pound milk herd at 12 cents per pound of dry matter that moves from a 1.4 to a 1.5 feed efficiency that produces the same amount of milk will make 41 cents more per cow per day, he said.

Milk components are an important aspect of a dairyman’s milk check. In February, Hutjens said, protein was twice the value of fat.

“My target is over 5.5 pounds of combined milk fat and protein per cow per day,” he said. “The elite herds in Illinois are over seven pounds, and that’s approaching $3 more per cow per day.”

Hutjens advises all dairymen to know the following feeding economic numbers for their herds — income over feed cost, feed cost per pound of dry matter, feed cost per 100 pounds of milk and the feed efficiency.

“The income over feed cost should be above $10.50 because Illinois dairymen say that’s what it takes for costs,” he said. “I like the feed costs to be under 12 cents per pound of dry matter and the feed cost to be below $7 per hundredweight of milk.”

Hutjens’ target for feed efficiency is over 1.5.

“There are some herds in Illinois that should get out of the milk business because they are not making any more money by running crops through dairy cows,” Hutjens said.

“Be careful and evaluate the economic impact of reducing corn and protein supplements in the ration because you don’t want to give up milk or milk components,” he said. “There are opportunities to look at alternative sources of energy for the ration.”

Martha Blum

Field Editor