Prioritising youngstock housing is the future

Calf housing on the dairy farm is often not given the priority it deserves. Calves are the future of the herd and their health and performance have a, sometimes hidden, significant impact on the performance of the whole business. It is important to provide them with an environment in which they can thrive, explains David Ball, AHDB’s Senior Technical Knowledge Exchange Manager.

When considering your approach to calf housing, you should start with the requirements of the calf and the farming system rather than the building.

Ventilation

There is an absolute requirement for fresh air in all livestock housing. Calves do not produce sufficient body heat to drive the 'stack effect' where warm air rises, drawing fresh air into the building so air flow must be provided by natural air currents (wind). Suitable openings on all sides of the building are needed to allow airflow from any direction. However, it is also vital to protect the calves from drafts and airflow should never be above 0.2 metres/sec at calf level.

The variety of weather conditions, which our farm buildings must endure, does make it difficult to maintain a constant, steady stream of fresh air in all circumstances. Installing a Positive Pressure Ventilation System (PPVS) can often be a suitable solution to this challenge. A fan drawing fresh air from outside the building is fitted with a plastic tube running 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.

After weaning, calves will ruminate and the heat generated can start to create the stack effect. Housing requirements are therefore different, and they should be housed separately from pre-weaned calves.

Temperature

The design of any calf housing system must consider the fact that calves up to eight weeks old have a reduced ability to regulate body temperature. A newborn calf must burn extra energy when air temperatures are below 10–150 C to maintain body temperature. Once weaned a healthy calf can comfortably cope with temperatures around freezing.

Measures to help calves maintain body temperature could include providing a deep straw bed to allow nesting, providing a sheltered spot within a group pen, the use of lamps, ensuring the diet contains sufficient energy, or fitting a calf jacket.

Relative Humidity

The effect of temperature on calves is compounded by relative humidity (RH%), or how damp the environment is. Cold and damp ‘feels’ colder than cold and dry because the rate of heat loss from a body is greater. The same is true with damp bedding, where the rate of energy loss from a calf to the environment is higher than on a dry bed. Likewise, at warmer temperatures, high RH% will increase the risk of heat stress. Warm, damp environments are also favoured by pathogens, increasing the infection challenge.

RH% levels should be kept as low as possible. Good ventilation will remove stale, damp air replacing it with clean, fresh air, thereby reducing RH%. Bedding should be topped up regularly to ensure the calves have a dry bed and ensure drinkers are not leaking. Floor designs incorporating a 5% fall under bedding and 2% for solid floors should allow for adequate drainage. Any washing of feeding equipment should be done outside the calf housing area.

The temperature felt by a calf is a combination of the ambient air temperature, air speed, and relative humidity (RH%). Controlling these factors will ensure an optimum environment for calf health.

Key questions for planning your youngstock buildings

1. What is the expected maximum number of calves on milk?

You should 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.

2. What are the future plans for the business?
3. What is the preferred feeding system?

Individual buckets, trough feeders, or automatic calf feeders will impact pen layout and size. Minimum space provision is determined by BS 5502 and increases with calf weight. Minimum dimensions for individual pens are 1m x 1.8m up to 80kg and group pens should provide 1.8 m2 per calf up to 85 kg while some Farm Assurance Schemes require up to 3.3 m2 by the time the calf weighs 100 kg.

4. How will pens be cleaned out?
5. What is the optimum location for any new building?

Orientation and shelter from the prevailing wind may be more important than proximity to calving pens or feed stores.