Livestock building design and diseases associated with poor ventilationThursday 27 September 2012
VENTILATION, VENTILATION, VENTILATION - if there was a televised housing improvement show for cattle then this is what it would be called as air flow is the single most important factor when considering animal health and building design.
According to livestock health specialist Jamie Robertson clean air must be able to flow in and out of a building at all times, taking with it bacteria and viruses that are inevitably present in the environment. This should be balanced with providing a habitable temperature within the building to maximise growth. New builds should be designed accordingly but there is usually scope to considerably improve most existing farm buildings.
It was with this approach that the key note speaker from Aberdeen University gave his opinion on what small improvements could be made to the housing at a livestock programme demo event organised by Cumbria Farmer Network held at Wincham Hall, Millom.
Kindly hosted by the Capstick family and aimed at beef producers, the event focused on the farm’s cattle housing, accommodating 350 head of cattle in buildings that have evolved over the past 38 years to their present form.
Speakers on the day (click on the links below to go directly to what they had to say):
- Jamie Robertson - Building design alterations to improve animal health
- Pfizer vet Dan Griffiths - Diseases associated with poor ventilation
- Rick Browne from Browne and McKinney vets - "Early colostrum is the most important factor"
- Rob Hitch of Dodd and Co - tax relief on new builds
Dan spoke about infectious viruses and bacteria in the environment and explained how there was no way of eradicating them and so managing the balance between natural immunity and challenge to the system was the way to reducing the amount of disease.
A number of ways to reduce the amount of challenge were put forward:
- Ventilation in housing – bugs exhaled by the cattle need to be able to move out of the environment.
- Hygiene – keep bedding dry, water troughs clean and isolate incoming animals.
- Management – mixing different ages, sizes and overstocking will increase the amount of disease.
- Preventative medicine – vaccination will help to dampen down the spread of disease although will not eradicate entirely.
- Cull infected animals.
In balance, a number of ways to help increase immunity were put forward:
- Colostrum – good colostrum received as soon as possible is vital to long term health. Six hours after birth a calf is only able to absorb half of the goodness and by twenty four hours this reduces to nearly zero.
- Control of common diseases – scour early on increases the chances of getting pneumonia and where BVD is present it is excreted which then passes easily to the rest of the herd.
- Good, healthy well balanced diet – improves overall health.
- Preventative medicines – vaccines to boost the immune system and increase the chances of being able to fight off disease.
- Selection of better mothering abilities when choosing for breeding.
Rick started by saying that he rarely visits Whicham Hall which is testament to their cattle management system.
Rick enforced the earlier point made by Dan that early colostrum is the most important factor in disease prevention. He said that it is essential for the calf to receive at least six pints of quality colostrum over six hours and that it is vital that farmers should observe strong suckling ability in the calf over this time period. The calf must be seen to suckle for an established period of time.
It is better for the calf to receive from the mother and that good mothers should be selected for breeding. A cow with too much milk on calving will be likely to produce diluted colostrum, this is more of a problem in dairy cows than suckler cows where the colostrum is usually thick. Colostrum levels should be around 20 and calves with problems are often tested with levels as low as 2.
If the calf suffers from scour this will reduce the amount of colostrum absorbed still further.
Cows due to calve should be housed as cleanly as possible. Reducing the amount of dirt and bacteria on the teats will help to reduce the amount of infection transmitted to the calf.
Rick also said that buying in replacement heifers is a big issue for introducing disease into the herd, especially BVD. Herds should be checked for BVD status.
Jamie started by saying that, on average, 50% of farm buildings have not been built for their current purpose and are usually, therefore, not fit for purpose. However the scope for change is quite substantial. The Capstick family gave background on three of the farm's buildings, how and what they were used for before Jamie made his suggestions.
Building 1 – housed 60 suckler calves or 40 older cattle.
In this building the suckler cows did well initially but when young stores and fat cattle were mixed problems were seen at around the six to seven months stage. Jamie Robertson explained that this is a classic problem when mixing occurs. The older animal has better immunity, the younger is more susceptible to disease and replicate the virus quickly.
Ventilation was shown to be the biggest problem with this building. When the wind is blowing the air flow through the building is moving constantly, removing viruses and bacteria with it out of the building. When the wind drops, the air is unable to move out of the building as there is not enough open ventilation in the roof space and a solid back wall creates an area of static warm air at the back of the building where the cattle tend to be. Moisture and heat levels rise and the survival times for the bacteria increase dramatically.
To improve ventilation in this building, Jamie Robertson suggested the following:-
- Start at the top of the building. As a general rule of thumb 0.1 square metres of hole per animal, eg 40 animals = 4 square metres of hole in the roof.
- Create air flow space at the back wall of the building by opening up ventilation space at the top of the wall and beneath the boarding.
Jamie explained that older, slate roofed buildings often provided better ventilation through the gaps and holes between the slates.
Jamie said that getting the balance right is essential as too much wind through a building, lowering the temperature will slow down finishing times as the animal requires more energy to keep warm thereby reducing profit margins. Increased bedding costs tend also to be seen in poorly ventilated buildings as moisture levels increase.
Jamie was faced with concerns farmers had about rainfall coming in the holes created in the roof to increase ventilation. He explained that 60 inches of rainfall would produce six cubic metres of water over a 12 month period, although this seems a lot it should be remembered that this is over one year and not all at once and when it is compared to 1.2 tonnes of moisture produced by cattle a day this seems little in comparison!
If ventilation is increased to the correct amount, the number of cattle kept in a building can be increased.
Building 2 – This was a lean-to onto Building 1, open fronted with cleaning out area and feed area at the front and bedded area at back. The building contained seven month old suckler calves.
Jamie asked where in this building the cattle spend most of their time and was not surprised to learn that it was at the front in the open area. He said that on the whole cattle like to be outside and that a healthy growing beast will not be cold at -20 degrees. Problems are often caused by cattle being inside too much.
The building had a rough earth floor, not concrete. Jamie Robertson explained the benefits of this as he explained that the moisture was able to soak away and not be absorbed into the bedding as it would on a concrete floor. A wet floor makes a damp building and a cold building which takes energy away, the air is not warm and so does not rise taking the bugs with it out of the building.
Jamie suggested cutting a 12 inch slot along the wall between building 1 and building 2 with Yorkshire boarding on the gable ends above ear height. Air speed control should be above the animal’s height.
If your building is sound then ideally gable ends should be solid with ventilation in the roof, however if there is doubt over the stability of the building then take out the gable ends instead.
Jamie was asked about the materials used for roofing and he said that tin was the worst material as tin sheets heat up the air temperature underneath them quickly and it then drops very quickly upon cold night temperatures producing massive variation in air temperatures and problems with condensation.
Building 3 - home made, timber framed, built on sand, with the capacity to hold 50 young cattle (around 400 kilos) or 60 older cattle.
Jamie pointed out the space boarding at the back of the building and said there needn’t be more than an inch space between the boards. He was asked about the height of the building and explained that it was fine for the age of cattle, but on the whole high buildings were unsuitable for young animals as they tend to be too cold. The air flow is driven by the heat of the animal and if they are too cold then air is unable to rise out of the building.
Air must be able to move out of the building and if the age of the building means that its structure cannot be changed then a fan and duct system could be considered.
Jamie concluded that ventilation was the most important factor in building design. Clean air must be able to flow into and out of a building at all times taking with it bacteria and viruses that are inevitably present in the environment. This should be balanced with providing a habitable temperature within the building to maximise growth. New builds should be designed accordingly but there is usually scope to considerably improve most existing farm buildings.
In the video below Jamie explains a few more alterations that can be made to buildings:
Rob started by pointing out that buildings contribute more to the profitability of a business than anything else such as machinery or equipment and yet very little is done to promote this in the industry unlike the numerous sales pitches there are for new products, machinery or equipment.
As far as tax relief goes for buildings, Rob said that structural changes made by the farmer himself such as creating air flow spaces in roofs, removing boarding, simple flooring changes or cutting holes in buildings are extremely unlikely to be eligible for any form of relief even if animal welfare is taken into consideration, however he agreed that these alterations made would be advantageous for the profitability of the business.
Changes to the roof, fabric of the building or changes to improve the building are all considered ineligible for tax relief.
However, there is likelihood that tax relief would be considered for improvements made to drainage in floors such as removing a flat floor and replacing it with a sloping one.
Report by Rosslyn Balding - Cumbria Farmer Network