To look at the impact of building design and disease management on a beef and sheep enterprise, leading animal health company, Zoetis, in conjunction with CAFRE and Gleno Veterinary Centre organised a workshop on the Workman family farm at Ballytober Road, Larne.
To set the scene, Darryl Boyd, Beef and Sheep Adviser with CAFRE, took visitors around the farm and outlined the farming policy. The farm’s aim is to produce top quality stock destined for the live-ring in both the cattle and sheep enterprises.
They run 350 suckler cows and the main breed type is a two way cross of Limousin x British Blue. Charolais is the choice of terminal sire producing a calf with great hybrid vigour with the three way cross. A small percentage of heifers are finished on farm with the rest sold in the live-ring as either weanlings or heavier stores depending on time of birth. The British Blue and Limousin are used to breed replacements.
1500 sheep are also kept with policies in place to produce quality breeding replacements for sale in the autumn time with the majority of the male offspring being finished. The two main types of ewe lamb being produced are mules (BFxBLFL) and Suffolk x Cheviots. A number of ewes are also put to Texels to produce an early spring lamb.
Different grazing techniques are used across the farm with rotational grazing being used on the lower more productive land types.
Jamie Robertson, of Livestock Management Systems Ltd, Aberdeen, told those attending the workshop that problems in livestock buildings are usually due to imbalances in one or more of three separate factors – moisture, fresh air and air speed.
Too much moisture supports microbial activity and promotes bacterial growth thus increasing the level of disease and the cost of treatment. High humidity absorbs energy and is also a stress on young calves in terms of heat regulation. There is three times as much moisture generated by urine and faeces as by mouth, thus cleanliness is vital.
Lack of fresh air will also compromise animal health as a result of increased concentration of gaseous emissions in the building and reduced oxygen concentration. A virus will die in five to six minutes when there is 100% fresh air outside – if there is only 50% fresh air in a building it will take 60 minutes for the virus to die. Open doors are not suitable for ventilation, as you lose control of airspeed. Yorkshire board should have 1 or 2 inch gaps in between the boards, whilst the gap in spaceboard should never be greater than one inch. Outlet is ideally provided by a covered open ridge with upstands or can be provided through 15-21 mm gaps in between the roof sheets for stock above 150kgs.
Outlets in pitched roof calf accommodation should be provided with an open ridge and upstands, and fans should be used for provision of fresh air (24 inch Proctor fan and perforated duct) as there is not enough heat produced by the calves to produce a stack effect. Extractor fans should only be used in very low volume buildings.
Fans cost approximately £1/day to run. The perforated duct will go for a length of up to 100 feet and one tube is sufficient for a shed of up to 45ft wide.
Regarding cost of ventilation Jamie gave an example of a replacement ridge in a house which is 60m long costing £100 per metre which is a total cost of £6,000. The improved ventilation meant an increased live weight gain of 10kg for each of the 110 heavy steers in the house, thus in five months, at £2 per kg, this was an extra income of £2200, and the payback time on the investment was less than 18 months. His advice was “build on performance not cost!”
He also warned against inlets becoming blocked by dirt, vegetation or materials stored against them.
Too much air speed is associated with drafts and excessive energy losses which can lead to lower production rates in addition to health problems. Even relatively low wind speeds hitting young calves over a prolonged period of time will “stress” the animal leaving it more vulnerable to disease, particularly pneumonia. Gale breakers are a good way to control airspeed and with 25% void they will still allow plenty of fresh air to come in. Vented tin on the other hand only has a 4.5% void ratio.
Jamie pointed out that around 50% of all naturally ventilated cattle buildings, old and new, are not fit for purpose and went on to outline the check of air inlets and outlets in the building. Most of the time the wind will be driving the ventilation, but when the wind drops buildings have to ventilate through the stack effect. The stack effect relies on negative pressure where hot, stale air moves out of the building through the outlets in the roof. Outlets in the roof are essential, with a simple rule of thumb being 0.04 m2 per 100kg calf and 0.1 m2 per adult animal. The steeper the pitch on the roof the better the outlet at the top will work. If the stack effect is working properly, stale air coming out of the roof will be replaced by fresh air coming in from the sides of the building. Buildings need two to four times the inlet compared to the outlet.
Commenting on temperature control in cattle housing Jamie stated that an average lower critical temperature of a new born calf was around 15˚C and that if this is recognised and managed correctly then daily live weight gain could be increased by 12.5% in the first week of life. Lower Critical Temperature depends not only on calf weight and nutrition, but also on airspeed and whether the bed is damp or dry. Quartz linear heaters can be used to support the body temperature of calves (i.e. set to come on when temp drops below e.g. 7°C), as can calf jackets. This type of support is particularly useful in the dairy industry where calves can’t rely on their mum for heat.
Aurelie Moralis, Veterinary Surgeon with Zoetis outlined the SureCalf® scheme which has attracted a lot of attention due to the blue ear tags in the calves at the marts. She explained that SureCalf® is a pre-conditioning programme aimed at minimising the impact of bovine respiratory disease and improving the welfare of calves as they pass through market. There are three schemes within the programme, based on which vaccine is used, age of the animal, and whether or not it has already been through a winter housing season, but the aim of each is the same - to help minimise the impact of respiratory disease; to help protect the buyer’s investment and to maximise the sale value for the seller.
A demonstration on the ease of intra nasal administration of Rispoval® IntraNasal and Tracherine™ was given by Nigel Brodison from Gleno Vet centre.