Not all sources of protein are created equal. Evaluate your sources compared to what cows need.

Intense genetic selection has given us cows that are metabolic athletes,” said Dr. Bill Chalupa, University of Pennsylvania College of Veterinary Medicine. “There’s a drive to increase milk production rapidly after a cow calves, and inadequate nutrition not only compromises the acceleration of milk production but can adversely affect [the cow’s] health and future reproduction.”

Speaking to milk producers assembled at the 2005 MFA Dairy Innovators Seminar, Chalupa added that cows in late gestation often pull protein from their own tissues to meet the requirements of the fetus. When a cow calves, she needs to replace these protein losses from her own body, plus acquire the protein she needs to produce milk.

But not all protein is created equal. As late as 1978, National Research Council (NRC) recommendations were based simply on crude protein. Then, researchers began to look at the importance of absorbed protein, from so-called bypass protein and rumen-degraded sources. Later, scientists focused on amino acids, those building blocks of protein.

There are 20 known amino acids that occur in protein, 10 of which are considered essential. These cannot be synthesized in the animal’s tissue, but must be fed. Most important are lysine and methionine.

“We want to grow as much bacterial protein in the rumen as possible, and that takes fermentable carbohydrates,” said Chalupa. “Rumen bacteria will grow on sugars but not on silage; the ensiling process has already turned carbohydrates to acids.

“Amino acids can help increase milk faster and stimulate a higher peak milk production,” he added. “If you have a market that pays a good premium for protein, lysine and methionine levels can be increased profitably. Net amino acid requirements are based on pounds of milk and the protein content of that milk, both of which can be measured reliably.”

The ideal lysine-methionine ratio is 3:1. That is, three units of lysine are needed for each unit of methionine. And lysine is the limiting factor. If lysine levels are not at about that 3:1 ratio, methionine does not work.

“Optimum milk protein is obtained with 2.5 percent methionine and 7.3 percent lysine,” said Chalupa. “It’s hard to reach these concentrations without single sources of methionine and lysine. And, because milk protein seems to be dramatically reduced when rations provide less than 2.1 to 2.2 percent methionine [as a percentage of metabolizable protein] and 6.0 to 6.5 percent lysine, these levels are considered minimums. Obviously, formulating rations for lysine-methionine balance costs more, but this can boost both milk production and milk protein content.”

It’s not always easy to feed high-producing dairy cows, said Dr. Jim White, MFA ruminant nutritionist. “You need to focus on increasing dry-matter intake. It’s crucial to try to increase the energy and protein a cow takes in, and that makes digestibility more important.”

A dry, pregnant cow needs 2.4 pounds of protein per day. But once she calves and is producing 88 pounds of 3.5 percent butterfat milk, her protein requirement nearly quadruples, to 9.8 pounds of protein.

Soluble protein (which is not the same as degradable protein) should make up 5 to 6 percent of dry-matter intake, and 28 to 32 percent of crude protein. Examples of highly soluble protein are urea or wet silage.

Rumen degradable protein (RDP) is rapidly degraded in the rumen. Examples are alfalfa silage, barley and soybean meal. RDP in the ration should be 10 to 12 percent of total dry-matter intake, and 60 to 66 percent of crude protein. Rumen undegradable protein (RUP) is protein that is not degraded by rumen bacteria, such as blood meal, fish meal or corn grain. RUP in the diet should be 5 to 7 percent of dry-matter intake and 34 to 40 percent of crude protein.

“Getting milk out means getting feed in,” said White. “Happily, the milk you get out is more than the increase in dry-matter intake. Increased dry-matter intake nearly always results in more milk, which will more than pay for the additional feed.

“Your goal in protein nutrition should be to maximize microbial protein synthesis,” White added. “Ensure that high quality protein reaches—and is absorbed by— the small intestine. If lysine and methionine are the two most limiting amino acids, then increasing rumen microbial production gives the biggest bang for the buck.

“The best approaches for increasing amino acid availability for milk production are to increase feed intake, optimize rumen fermentation and supplement protein to that part of the diet that escapes rumen fermentation,” he continued. “Rumen-protected feedstuffs that contribute the largest amount of amino acid contain a high percentage of amino acids and have high rumen stability and high intestinal digestibility. It would be helpful if they also were cheap, but they rarely are.

“Protein feeding has a big impact on cow performance. Protein feeding and production tend to be positively correlated,”  White summed up.

Calf raising takes a new turn

A Holstein heifer that calves the first time at 24 months of age should weigh 1,250 pounds. If she weighed 100 pounds at birth, that means the heifer must gain 1,150 pounds in 730 days, or an average 1.6 pounds of gain per day of age.

“That doesn’t leave much time to waste on limiting feed intake or growth—at any stage,” said Chuck Hubbert, MFA feed division. “Limiting growth early in the process not only requires more weight gain later on, but also hampers the heifer’s immune system.

“For every 100 pounds of post-calving body weight below 1,250 pounds, 600 pounds of first lactation milk potential is lost,” added Hubbert, who has helped dairy producers design calf-raising programs.

Hubbert looks at calf raising as a total program, from birth to 12 weeks of age. A baby calf should get two feedings of high quality colostrum (first milk), either from the calf’s mother or from another cow known to be disease free.

“Don’t feed pooled colostrum, transition milk or waste milk,” he urged. “A newborn calf should get three quarts of colostrum as its first feeding, within one hour, and again 12 hours later.

“Remove the calf from the cow as soon as possible after birth and dip the navel with a 5 percent iodine solution,” he added. “Have a clean, dry maternity pen that is disinfected between uses. Cold stress can be a challenge. Calves less than 21 days can chill when the temperature drops below 42 degrees, and Missouri has 105 days per year when temperatures don’t reach 42 degrees.”

Hubbert is excited about several new trends and products that help successful calf raising. One of these is “Cow’s Match,” a milk replacer developed by Land O’ Lakes, that contains 28 percent protein and 20 percent fat.

“Feed a high protein, high energy milk replacer twice each day, and keep a supply of clean, fresh water in the pen after the second day,” Hubbert continued. “Make calf starter feed available from day two, but don’t feed any hay.”

During the last week on milk replacer, reduce the feeding to once per day, to ensure more consumption of good calf starter feed and make an easier transition to weaning. Continue feeding calf starter—but no hay—until the calf is 12 weeks old.

“Calves started on this system can be up to 44 pounds heavier at weaning compared with conventional calf milk replacer programs,” said Hubbert. “Getting calves off to this kind of start can reduce the age at first calving by 2 months.”