Calf housing was the subject of an AHDB winter webinar, with expert advice from the organisation’s lead environment specialist, David Ball.

Pre-weaned calves are too small to generate the ‘stack effect’ to promote ventilation, so air movement must be achieved by other means, said David.

He said: “Research has shown that up to 50 per cent of naturally-ventilated calf houses fall below an acceptable range and this will have a negative effect on calf health. Positive pressure ventilation (PPV) systems are an effective way to achieve good air distribution. It comprises a suspended fan, which draws in external air and delivers it evenly throughout the shed.

“The PPV system must be of a bespoke design that has been calculated to match the dimensions of the installation space. It will remove heat, moisture and dust and pathogens from the calves’ environment. Small particles of bedding, for example, can travel deep into the lungs, causing respiratory tract irritation and an increased risk of bovine respiratory disease due to pathogen transfer. Care should be taken when bedding up, to minimise the disturbance of bedding materials.”

Darlington and Stockton Times: Air movement must be achieved for calves

As well as his advice to provide a well-ventilated environment for calves, care must be taken to avoid draughts, he stressed. A simple way to prevent draughts is to add a piece of belting to plug the gap around the bottom of the pens, including the gates. Calves are highly vulnerable to draughts, which will increase the chill factor, he pointed out.

Measures should be aimed at helping the calf to cope with colder temperatures. These can include using calf jackets and adding heat lamps. Another option is to install a shelf or ‘dog kennel’ in the pen, which will create a micro-environment. Once the temperature falls below 15 degrees Centigrade calves will burn energy to keep warm, reducing growth rates and compromising their disease immunity.

Feeding also plays a role in maintaining optimum calf body temperatures, he added. Calves aged 0-3 weeks should be given an extra 50gms of milk powder per day for every five degrees below 15 degrees Centigrade. Meanwhile, an extra 50gms of milk powder should be allocated to three to six week-old calves for every five degrees below ten degrees Centigrade.

A good standard of hygiene is another essential element, and high ammonia levels can increase respiratory disease susceptibility.

Darlington and Stockton Times: David Ball of AHDB

Improvements to building ventilation will help towards maintaining dry, hygienic conditions and achieving the target 50 per cent relative humidity (RH).

David said: “RH is the amount of atmospheric moisture in the air, relative to the maximum quantity of moisture that the air could hold at a particular temperature and pressure. Warmer air can hold more moisture than cooler air, so a lower RH has an improved capacity to carry additional moisture and will have a greater drying effect.

“At an RH of 70 per cent-plus, there will be little to no pathogen desiccation, while an RH below 50 per cent will inhibit pathogen growth. Buildings should be adequately drained, with the aim of a 5 per cent floor fall. The use of ample quantities of an absorbent bedding will help to maintain the correct RH percentage, along with minimising water usage and controlling the environment with suitable ventilation.”

Where possible, artificial light should replicate natural day light. Lighting should also be optimised in the building, to maximise the calves’ growth rate potential.

“Most of the studies into lighting for cattle buildings have been carried out on adult cattle,” he said. “Nevertheless, the same principles apply. The calves will require 16 to 18 hours of light per day at 200 lux, with six to eight hours per day of darkness, which represents 30 lux.

“This will have the effect of decreasing melatonin levels and increasing the growth rate hormone, IGT-1. Where possible, the daylight hours should be used to replicate natural day light. LED lights with a 4,500-5,500k rating would be suitable.”

A range of elements linked to the calves’ environment can be measured using fairly low-cost instruments, with a simple smoke bomb providing valuable information on air flow in the building, said David.

“A maximum-minimum temperature thermometer is a useful piece of equipment, but a data logger is an even better choice. It can send information about the calves’ environment to a smart phone or pc, and graphs can be created to give a picture of changing conditions in the building. Like all other aspects of livestock husbandry, if it cannot be measured, it cannot be properly managed.”

Ventilation Targets


Stale air: 0.15metres/second at calf level;

Minimum air speed: 0.25m/second at calf level;

Maximum air speed: 0.5m/second at calf level;

Airspace: 6-12 cubic metres per calf;

Minimum four air changes per hour (increase in warm weather).