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To weaning and beyond!

Drew A. Vermeire for Progressive Dairy Published on 20 May 2022

Weaning calves early pays dividends in better calf performance and in saving money by feeding less milk replacer per calf. Here are some guidelines about weaning and taking care of calves after weaning.

The ruminant system and calves …

Most calf people know that calves are born with a rudimentary ruminant digestive system. At birth, the rumen and reticulum are about half the size of the abomasum (true stomach), but in adult cattle, the rumen is about 20 times the size of the abomasum. 



Question: What causes the rapid growth of the ruminant system? 
Answer: Consuming fermentable carbohydrates 

Calf starter feed should have high levels of grain (more than 50%) like corn or barley and should not contain roughages like hay or straw. Fermentation of the starch in grain causes growth of the rumen, reticulum and abomasum where feeds are fermented. Keep in mind that the rumen doesn’t fully develop until 45-60 days after the last milk has been fed, so feeding calves high-quality feed with minimum roughage is important to keep calves growing. 

How do we wean calves? 

Weaning is when we stop feeding milk to calves. Historically, there was debate about whether calves should be weaned gradually over days or weeks, or abruptly weaned on one particular day. In a research setting, it doesn’t really matter. In a practical production setting, we’ve found that it is easier to cut back from twice-per-day milk feeding to once-per-day milk feeding by skipping the morning feeding and only feeding milk in the afternoon. If calves are fed at 7 a.m. and 4 p.m., for example, there is a nine-hour span of time between morning and afternoon but a 15-hour span between afternoon feeding and morning feeding. It is easier to find a calf that is struggling if we skip the morning feeding but check every calf because it has been 15 hours since the last feeding. Generally, we will feed once per day for four to seven days and then stop feeding milk. 

When should we wean calves?

I was at a dairy farm a few years ago where the young calves were kept in a field and attached to plastic hutches with a 10-foot tether. I asked the dairyman “When do you move the calves from this field to group pens?” He answered, “When they start dragging these hutches around the field, we move them.” This strategy might work for that particular farm, but it is not really in the calves’ best interests and is not efficient or economically sustainable. 

Calves should be offered starter feed beginning on day one, and feed intake will gradually increase until calves start consuming 1 pound per day around day 21-24. Our research shows that calves consume about 30 grams of starter feed per day for the first week, 95 grams per day for the second week and 275 grams per day for the third week. The increase in intake is the result of growth and development of the rumen, so it is important to provide small amounts of fresh feed to calves every day. Of course, calves that are sick should not be weaned until they recover from sickness.


The key factors that determine when we wean calves is how much feed are they consuming every day and how much feed have calves consumed in total? There are many “rules of thumb,” with people advising to wean calves when they are eating anywhere from 2-6 pounds of feed per day, but the best rules come from research to evaluate weaning. Research at Kansas State University, led by R.H. Greenwood, showed that the criteria needed to successfully wean calves are:

1. Calves are at least 21 days old.

2. Daily starter intake is at least 1% of the calf’s initial bodyweight.

3. Cumulative starter intake is at least 9% of the calf’s initial bodyweight.

4. Calf has gained at least 12% of its initial bodyweight.

For a 95-pound calf, this means that it is 21 days old, currently consuming 0.95 pounds of calf starter per day, has consumed a total of 8.55 pounds of starter and gained 11.4 pounds, which equals 106.4 pounds current live weight. The results of this research showed that calves weaned according to these criteria (consuming 1% of initial bodyweight) were weaned at 32 days of age. These calves gained more weight and with a lower cost than calves weaned when consuming 1.5% of initial bodyweight (43 days of age) or weaned when consuming 2% of initial bodyweight (45 days of age). The key lesson here is to wean calves early based on daily and cumulative starter feed intake. 


Transition pens

Calves can be moved to transition pens or corrals seven to 14 days after weaning. I am often asked how many calves should be in these pens when the calves are moved from the hutches. The real answer is: The maximum number of calves is however many calves can be well cared for at a time. Can the calf crew find a sick calf out of 10 calves, 25 calves, 50 calves or 100 calves? The simple answer is usually 25-35 calves per pen because most people can find the sick calf in a group this size. 

Calves in transition pens should be fed the same starter feed they received in hutches for the first few weeks. Feed about one-third of the daily allocation in the morning and two-thirds of the daily allocation in the afternoon. It is counter-intuitive to think that the proportion fed makes a difference, but research and experience have both shown that calves perform better when they receive the highest proportion of their daily feed allocation in the afternoon. 

Economics of weaning age

Milk replacer is the most expensive feed the calf will ever consume. Calf hutches are the most expensive facilities the calf will ever occupy, and bringing milk replacer, feed and water to the calf twice per day is much more expensive than having the calf eat grain from a feedbunk and drink water from an automatic waterer. Weaning calves from milk replacer has an immediate savings of milk replacer versus calf starter feed. At our research farm, we are currently spending about $550 per ton for calf starter feed and $3,800 per ton for milk replacer. Replacing 1 pound of milk replacer intake with 1 pound of starter feed intake saves $1.63 per calf per day. 

An often overlooked aspect of weaning is the number of calves that can be raised per year per hutch. If calves are weaned at 60 days and it takes 10 days for cleaning the hutches, we can raise 5.2 calves per hutch per year. If we wean calves on day 35 and still take 10 days for cleaning hutches, we can raise 8.1 calves per hutch per year. For an operation raising 500 calves per year, weaning at 60 days means that we need labor and facilities of 96 hutches, but weaning at day 35 means we only need labor and facilities of 62 hutches. This is about one-third fewer hutches with lower labor and expense. This represents a substantially lower cost per calf raised. Weaning calves early is a key to better calf performance and increased profitability.  end mark

Drew Vermeire
  • Drew A. Vermeire, Ph.D.

  • Nutritionist
  • Nouriche Nutrition Ltd
  • Email Drew A. Vermeire