Optimising youngstock housing should be further up the list of producers’ priorities, particularly if they want their future milkers to get off to the best possible start.
TEXT ALIX MORLEY
Calf housing is not always given the priority it deserves, even though healthy and well-grown replacement heifers are key to the successful future of the herd. Heifer health and performance has a significant impact on the performance of the whole dairy business.
AHDB’s David Ball says it’s vital to provide calves with an environment in which they can thrive. “When considering calf housing, producers should start looking at the requirements of the calf and rearing system, and wider herd management, rather than the building.”
Fresh air is key to good health, and good ventilation is vital in all livestock housing. “Calves do not produce sufficient body heat to drive the ‘stack effect’, which is where warm air rises and draws fresh air into the building. Airflow must be provided by natural air currents or wind,” he says. “Suitable openings on all sides of the building are needed to allow airflow from any direction. But it is also vital to protect the calves from drafts. So Airflow through the building should never be above 0.2m/second at calf level.”
The UK’s varying weather conditions does make it difficult to maintain a constant, steady stream of fresh air through buildings all year round. So installing a positive pressure ventilation system (PPVS) can be one suitable solution. This comprises a fan, which draws fresh air from outside the building, that is fitted with a plastic tube that runs the length of the building with suitably placed holes along it to ensure fresh air is delivered to the whole building. “It is essential in these situations to provide a means of escape for the stale air through the roof,” stresses Mr Ball.
After weaning, calves will be ruminating and begin to generate more body heat, which can start to create the desired stack effect. “Housing requirements are different at this stage, so weaned calves should be housed separately from pre-weaned calves,” he adds.
Body temperature
Calf-housing design must take into account that calves aged up to eight weeks old have a reduced ability to regulate body temperature. “Newborn calves burn extra energy to maintain their body temperature when air temperatures fall below 10°C,” says Mr Ball. “Once weaned, a healthy calf can comfortably cope with temperatures around freezing point.”
Steps can be taken to help young calves maintain body temperature during cold weather. When temperatures drop below calves’ lower critical temperature (LCT) they divert energy away from growth and maintaining immunity to keep warm. Calves less than three weeks old should be fed an additional 50g of milk replacer per day, or 0.33 litres per day of whole milk, for each 5°C temperature drop below 15°C. Providing deep straw bedding, to allow nesting, and a sheltered spot within a group pen, can also help. Producers can use heat lamps, ensure calf diets contains sufficient energy, and fit calf jackets.”
The effect of temperature on calves is compounded by relative humidity (RH), or a damp calf-house environment. “Cold and damp ‘feels’ colder than cold and dry, because the rate of heat loss from a body is greater,” says Mr Ball. “This is also seen with damp bedding, where the rate of energy loss from a calf to the environment is higher than with a dry bed.” When the temperature is warmer, high RH will increase the risk of heat stress. Warm, damp environments also allow pathogens to thrive and increase the infection challenge.
“So RH levels should be kept as low as possible,” stresses Mr Ball. “Good ventilation will remove stale, damp air replacing it with clean, fresh air – reducing humidity. Bedding should be topped up regularly to ensure that it’s dry, and check that drinkers are not leaking. Floor designs incorporating a 5% fall under bedding to ensure liquid can drain from under the straw, and 2% for solid floors with no additional bedding, should allow for adequate drainage, and feeding equipment should be washed outside the calf-housing area to, again, ensure the environment remains as dry as possible.”
The temperature felt by a calf is a combination of the ambient air temperature, air speed, and relative humidity. Controlling these factors will ensure an optimum environment for calf health.
Calf housing can be difficult to optimise and easily overlooked in favour of more pressing jobs. But time and investment here will pay dividends when it comes to the quality of heifers entering the herd. Producers will reap the rewards for their efforts,” adds Mr Ball.
Key planning questions
● What is the expected maximum number of calves on milk? Allow for calves to remain in their pens for two weeks after weaning. Weaning, moving pens, and mixing groups are all stress factors for calves, so these events should be staggered.
● What are the future plans for the business? Will, for example, calving pattern change? Will beef calves be sold or reared?
● What is the preferred feeding system? Individual buckets, trough feeders, or automatic calf feeders will impact pen layout and size. Minimum space provision increases with calf weight. Minimum dimensions for individual pens are 1m x 1.8m for calves up to 80kgLW. Group pens should provide 1.8m2 per calves up to 85kgLW.
● How will pens be cleaned out?
● What is the optimum location for any new building? Shelter from wind may be more important than proximity to calving pens or feed stores. What is the expected maximum number of calves on milk? Allow for calves to remain in their pens for two weeks after weaning. Weaning, moving pens, and mixing groups are all stress factors for calves, so these events should be staggered.
● What are the future plans for the business? Will, for example, calving pattern change? Will beef calves be sold or reared?
● What is the preferred feeding system? Individual buckets, trough feeders, or automatic calf feeders will impact pen layout and size. Minimum space provision increases with calf weight. Minimum dimensions for individual pens are 1m x 1.8m for calves up to 80kgLW. Group pens should provide 1.8m2 per calves up to 85kgLW.
● How will pens be cleaned out?
● What is the optimum location for any new building? Shelter from wind may be more important than proximity to calving pens or feed stores.
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