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Erin Cook knows what it takes to keep calves healthy at weaning. In fact, the calves that Cook manages at Aurora Ridge Dairy in Aurora, N.Y., sail through weaning with flying colors. That’s because Cook knows that in order to keep calves healthy, she has to minimize stress.

So, Cook practices what the weaning textbooks preach. That includes waiting five days to move calves into a group pen after they come off milk and keeping group size small — no more than seven animals per pen. Once they move to a group pen, calves continue to eat their familiar pelleted starter while Cook gradually increases the amount of dry hay in the diet. Plus, she spreads out stressful events, like weaning and vaccinations.

A little extra pampering keeps the calves from “crashing” after weaning because, as Cook says, “it can be a real disaster” if you stack too many stressors on the calves.

Learn why you, too, should lessen stress at weaning.

Stress hurts gains
When a calf is stressed at weaning, she diverts energy away from growth, says Sam Leadley, a calf-care specialist with Attica Veterinary Associates in New York. When that happens, average daily gain falters -— even in calves that don’t get sick after weaning.

Leadley has documented this loss in average daily gain. On one occasion, he followed the growth rates of a group of 100 calves. The calves were weaned at about six weeks of age. Thanks to good weaning-management practices, none of the calves got sick. However, during the week after weaning, each calf gained a quarter of a pound less per day than expected -— a loss of 1.75 pounds of gain during that week. (Please see “Weaning stress impacts gains,” on page 32.)

Just think if those calves would have developed pneumonia or coccidiosis after weaning. “Then the effect would be multiplied,” Leadley points out.

Calves being weaned are under stress. Add in a change in feed, new housing and even a vaccination or two, and you have the recipe for mega stress on those calves. This scenario sets the stage for a domino effect that can topple calf health and productivity. That’s why it’s so important to keep stress at weaning to a minimum. The more stress you pile on the calf, the worse the situation can become.

Avoid the post-weaning crash
Stress elevates cortisol levels. Elevated cortisol levels suppress the calf’s immune system. When that happens, bacteria and viruses that normally reside in the body rise up and cause the calf to get sick -— often three to five days after weaning.

“Stress can suppress the immune system to a degree that normal bacteria and viruses can cause problems,” says Lance Fox, technical services veterinarian with Alpharma Animal Health. The concept isn’t that much different than what happens to a student who is cramming for a test. When the pupil starts “stressing out” over an upcoming test, it lowers the body’s normal defense mechanisms, Fox explains. This, in turn, allows the herpes virus that causes cold sores — a normal inhabitant of the body — to strike. The result is a painful cold sore.

Think about how many times you have seen calves “crash” within a week after weaning. Not all calves succumb to stress. However, when they do, they become ideal candidates for illness, particularly respiratory diseases, like pneumonia. Stress at weaning also can trigger coccidiosis.

These effects of stress often become so commonplace that you don’t perceive them to be a problem. Have you become accustomed to the sound of calves coughing after weaning? If it happens every time you wean calves and move them into a group pen, then maybe you have. 

However, medicating a pen of calves that fall ill after weaning shouldn’t become so routine that you think it’s normal. Instead you should take action to minimize the stressors that threaten your calves’ health at weaning. (Please see “Reduce weaning slump” at right.)

Minimize medication cost
The cost of treating calves that fall victim to weaning stress can add up fast.

Leadley has seen instances where producers treated almost all post-weaned calves for respiratory illness.

On one dairy, they treated 40 newly weaned calves for respiratory illness per week, Leadley explains. At a cost of $7.50 per antibiotic treatment, times three doses per calf, treatment cost equaled $22.50 per calf. The total cost to treat 40 calves amounted to a whopping $900 per week.

Think about it, in a 1,000-cow dairy, with 50 percent of all heifer calves getting sick after weaning, the treatment cost would be $5,625 per year (250 calves x $22.50). That’s money you wouldn’t need to spend if you took steps to minimize weaning stress.

So, the question you must ask yourself is “why wouldn’t you want to minimize stress at weaning?” Especially when doing so can save thousands of dollars in unnecessary treatment cost and improve calf performance.

Reduce “weaning slump”

It’s less than a week after weaning. calves don’t thrive, they go off feed, you hear coughing, and some calves scour. Sounds like a classic case of “weaning slump.” To prevent it, you need to minimize stress. Here’s what you can do:

  • Make sure calves are eating 2 pounds of starter each day for at least two days in a row before weaning.
  • Offer plenty of fresh, clean water.
  • Wait at least one week after weaning to move calves into a group pen.
  • Spread out stressful events like vaccination, dehorning and moving to new housing.
  • Group heifers by body size, if possible.
  • Keep group size small -— at a level that allows you to give each animal individual attention every day.
  • Provide adequate bunk space per animal.
  • Keep calves on the same diet after moving them into a group pen. Gradually introduce diet changes.
  • Don’t move calves during extremely hot or cold weather.
  • Provide good ventilation to decrease respiratory disease.
  • Consider using a broad-spectrum antibacterial or a coccidiostat.