How newborn calves, post-weaned calves and dairy replacement heifers are handled is important to the success and productivity of the dairy farm.
Dr. Rebecca Brotzman is associate outreach specialist for the Food Animal Production Medicine section of the University of Wisconsin-Madison School of Veterinary Medicine and coordinates the Dairyland Initiative. She said planning for grouping, ventilation and feed and water space are all important considerations when it comes to calf and heifer housing.
It is also important that facilities be designed for management — such as headlocks that can be used for vaccination and other veterinary work. Another important consideration is that the buildings work together for the sake of the handlers and the animals.
A calf barn close to the facility that will be used for post-weaned calves will make it easier for both the calves and the handlers when the time comes to move those animals to their next stage.
During a talk at the Professional Dairy Producers of Wisconsin annual business conference last month, Brotzman talked about a 640-cow dairy that was changing its management with the intention of raising all the farm's own heifers on site.
Another of their goals was to preserve pasture access on their small land base for bred heifers.
Brotzman, who grew up on a registered Holstein farm in southeast Wisconsin and worked as a dairy veterinarian for three years, said the first step in any planning process is to crunch the numbers on how many heifer calves are born on the farm each month and each year.
Looking at Dairy Herd Improvement or Dairy Comp 305 data will help farmers get a picture of the size of the facility needed. She added that it's also a good chance to take a look at mortality losses on the farm and determine if the number of calves being lost is too high and why it's happening.
Even without computerized record-keeping systems like Dairy Comp, a calculator can be used to determine the total cow herd, the number of freshenings per year and the percentage of heifer calves born. This information helps arrive at the size of a calf barn.
Calculating 40 percent above the average weekly rate of calvings allows for calving "surges" and nursery cleaning time.
On the farm she was using to illustrate her talk, the total heifer inventory was 702 with roughly 30 heifer calves born per month. Most of their heifers had calves by 23 months of age and were then moved into the milk cow housing.
Another consideration in creating a plan for a nursery is how long the calves will be in there. At the farm Brotzman was working with, they wanted to keep their heifer calves in there for 10 weeks.
That means if they had seven calves per week and wanted to plan capacity for 30-40 percent over that, they would need to calculate for 9-10 calves per week, she said, or a capacity of 90-100 calves in the nursery at any given time.
Beyond the calf nursery barn, post-weaned calves and heifers are generally housed in age groups. At her example farm, that meant 36-40 heifers per month in age groups.
As much as the calculations are important in doing this kind of planning, Brotzman said it is also important to just stand back and compare real numbers and determine "does it make sense?"
The post-weaned calves and transition calves should be housed in bedded pack pens that are small enough to keep the calves in a range of size with their pen mates.
"The range in weight should be no more than 100 pounds," she said. "That generally means an age range of two months or less."
She suggested these transitioning calves be limited to 10 calves or less per pen. "Smaller groups are preferable. About six calves per pen is about right to get calves to learn social behavior while limiting feed bunk competition."
These smaller groups ensure that all the calves have access to feed.
For heifers that have made the transition away from milk and into the social structure of group pens, some farmers and heifer growers are using freestalls that are properly sized and indexed to the younger animals.
Brotzman said that in these groups, it is advisable to limit their range in weight to 200 pounds and about four months in age.
In the pre-breeding group — about 10-12 months of age — it's important to have facilities to be able to vaccinate them. Breeding age heifers — from 13-17 months of age — should be housed in a facility where it's easy to breed them and check them for pregnancy.
Bred heifers — those that are 18-23 months of age — should ideally be in a facility that allows for a second pregnancy check.
Brotzman said one of the next questions that will need to be answered in planning calf or heifer raising facilities is whether or not they will be naturally ventilated or mechanically ventilated. Mechanical ventilation can be in several forms; tunnel ventilation or cross-ventilation systems are common.
Natural ventilation requires the building to be free of what are called "wind shadows" — places where no air circulates because of the closeness of other buildings. Brotzman said 75 feet away from other buildings is considered the gold standard for avoiding wind shadows.
Natural ventilation also requires at least 12-foot sidewalls that are at least 50 percent open. Open ridges are another way to add to the natural ventilation, she said.
Split curtains allow for finer control of the wind inside these barns, she added.
Advantages of the naturally-ventilated building are that it has the lowest input cost and the lowest operational costs. Automatic controls can be used to help manage the side curtains on this kind of barn.
Another advantage is that they are simple to operate. The only real disadvantage is that they require space between buildings.
Younger calves are still susceptible to respiratory infections even in naturally-ventilated barns, she said. Sometimes tunnel ventilation is needed to add to the natural ventilation.
One of the systems used to mechanically ventilate barns is the so-called tunnel system, where one end of the barn is filled with fans to pull air through the facility.
Brotzman said the inlets need to be correctly sized and located to draw in fresh air throughout the entire barn.
There are more complex questions when it comes to using this kind of barn: it can be difficult to keep the barn ventilated but not frozen during the cold winter months; the air tends to move more freely in the feed alley; and power backup systems must be in place in case there is a loss of electricity.
There is also the question of where to put the youngest animals in this kind of barn, she said. "Should they be at the coldest end or the exhaust end?"
Cross-ventilated barns are generally lower pitched in their rooflines, and fans are installed along one sidewall. In these barns, one advantage is the decreased building footprint. "You can put all your animals together without worrying about the wind shadows."
In these kinds of barns, the managers have total control over ventilation, but that is also the downside, she said. They also require backup generators in case of a power outage.
Another disadvantage is the air tends to move in the transfer alley, and these barns can be difficult to tweak and work with in colder weather.
In addition to how the barn is ventilated, it's important to make sure there is enough space for animals to drink and eat. Adequate space for the entire group needs to be built into the design, and the designers should make sure younger animals can reach the feed bunk or the waterer.
A bedded pack is a good, flexible option for younger groups of calves.
Some farmers have reported having a sloped concrete floor to a drainage base results in the use of 50 percent less bedding, she said. That's because this kind of design keeps bedding dry.
Whatever else goes into the design of calf and heifer housing, Brotzman said farmers should make sure it's easy to clean and easy to bed.
It's also important to make it is safe to sort and move calves and heifers for procedures like vaccinations, treatment, reproduction and hoof trimming.
Dairy farmers in Wisconsin can visit www.thedairylandinitiative.vetmed.wisc.edu and get a free two-year subscription to the information generated by the veterinarians.