Calf Rearing Facilities
By Andrew Robinson (Locum vet winter 2008)
A good winter project for those of you that may actually have some spare time on your hands at the moment is to get your calf rearing facilities into tip top condition before the first calves have arrived. Time and effort spent now can go a long way towards reducing extra unwanted time and effort treating sick calves in spring.
Healthy animals are the result of a combination of: an active immune system, a comfortable environment and low exposure to nasty bacteria and viruses. It is not uncommon for us to see good calves getting scours, navel infections and pneumonia as a result of less than optimal living conditions. The next few paragraphs will give some tips on creating a good calf rearing environment, hopefully using what you have already got rather than having to start from scratch.
Shed design is important. Firstly, the shed should be facing roughly north to allow for maximum sunshine and protection from the colder winds. If necessary, the front of the shed can be protected from northerly winds by placing large straw bales or wind cloth along the front. Test the ability of the shed to keep out drafts by going into the pens on a windy cold day, kneel down to calf level, take off your jacket, thick jersey and woolly hat (there is no need to get completely naked) and see how long it takes to get cold. Be aware that there does need to be an air flow through the shed but the breeze should be above calf level and going from front to back, not across the pens.
If the calf shed has pens two or more deep, a central race is necessary to allow access to all calves without having to climb through other calves pens. Ideally calf pens should be twice as deep as they are wide to provide areas of sun and shade and allow for better protection from the wind. Some people put solid divisions between each pen, usually using straw or chipboard, to prevent the spread of infection from pen to pen.
Adequate and appropriate bedding is absolutely crucial to successful calf rearing. Each year the bedding needs to be removed and replaced up to a depth of 20cm. The base material should be free draining (e.g. shingle or sand) and the deep layer of bedding should be an absorbent material such as wood shavings or saw dust. Depth is the key here. As the calves move around they can churn under the dirty top layer continually revealing a clean (or at least less contaminated) bed to lie on. A deep layer of bedding will also soak up other free water that is lying around. Calves’ drinking from stagnant, contaminated puddles is a recipe for disaster and this also applies to the calf paddocks. In an extreme example, calf deaths were associated with pooling of septic tank overflow in the calf paddock.
During the winter, while the calf sheds are empty and the old bedding has been removed, a heavy spray of an industrial strength disinfectant over the entire shed, including at least 2 metres up the walls, will help eliminate infection carrying over from the previous season. Also spray all of the calf rearing equipment (feeders etc). Remember to water blast the pens before spraying. During the calf season a product such as Virkon can be carefully sprayed around the pens on a regular basis without causing a problem to the calves. A boot washing facility or foot bath with a good disinfectant in it should be in place at the entrance to the calf shed or in the central race. If possible have one feeder per pen (this speeds up feeding anyway) and don’t mix them. Diseases such as calf diphtheria can be spread by feeders.
Know which pen will be your sick calf pen. It should have either solid fencing around it or some space between that pen and where the healthy calves will be. A separate shed is better still. Sick calves go into the sick pen but not back to their original pen once they are better. Where do you put them then? Unfortunately, in many situations they may have to go back to their original pen as other free pens are not available. If the calf only had something like nutritional scours then obviously this would not be a problem. Infectious scours (e.g. Rotavirus) are a different story and ideally the calves would either stay in the sick calf pen or go to a new, empty pen once they have recovered. In an outbreak of scours a bit of thought may be required to keep healthy and sick calves separate. Pens set aside for new healthy calves may be needed for the sick calves. Older calves may be put outside and their pens converted to sick pens. If that does happen just remember to be as hygienic as possible and use the Virkon spray around the pens, even daily. Feed and treat sick calves last and thoroughly disinfect clothes and equipment after each feed. Even better have a pair of old overalls and boots to put on in the sick calf pen.
Use an all-in-all-out system. This means that there is no mixing of individual calves or ages of calf. Gradually fill a pen with new calves then move onto the next pen. Those calves stay together in that pen until weaning. To avoid overcrowding, know how big each pen is and allow between 1.5m2 per calf (for new born Jerseys) to 3m2 (for ready-to-wean Friesians). There should be no more than 20 calves per pen (most pens will only hold around 10) and 100 calves per shed.
Have a separate area for bobby calves to be picked up. The end of the drive tends to upset passing tourists and it doesn’t have to be far away from your calf shed or even physically removed from your calf shed. It just needs to be a pen where bobbies can be put for pick up that keeps the truck and driver away from the healthy replacement calves. Remember if the truck driver does inadvertently bring an infectious disease into your calf shed, it ends up creating a lot of heartache for you, not the truck driver. You have the final say over the biosecurity of your calf sheds and it isn’t over the top to be vigilant about it.
Make sure each pen will be able to provide unlimited clean water, meal and roughage (hay or straw) to all of its calves from day one. Water and meal troughs should be off the ground to prevent faecal contamination and the hay/straw should be hung from nets.
You will never eliminate all of the bacteria and viruses from your property, but by reducing their numbers and providing a good environment for your calves to live and grow, infectious diseases can be minimised.
Treating Calf Scours
Treating calf scours is a time consuming, frustrating business and the first thing to remember is that even though you will do your best you may not save them all. One of the first questions to ask when a calf gets scours is “Is it a nutritional or infectious scour?” A nutritional scour is often what’s called a ‘happy’ scour. The calf will often look otherwise healthy and still have a good appetite, although not always. Nutritional scours are usually the result of: a sudden change of feed (like colostrum to milk or milk replacer), a sudden change in feed volume (like twice day feeding to once day feeding), or mixing problems with milk replacer. Changing brands or types of milk replacer can also cause a nutritional scour. Usually giving the calf 24 hours off milk and replacing those feeds with good quality electrolytes is all that is needed to stop the scour.
Infectious scours like Rotavirus, Cryptosporidium, Coronavirus, Salmonella and E.coli will normally cause a sick, dehydrated looking calf. Contrary to popular opinion it is not possible to diagnose which bug is causing the problem just by the smell and colour of the scour. Faecal culture is needed on at least three scouring calves in an outbreak situation to get a picture of what is causing the problem. To increase the chance of getting a meaningful result only take samples from calves that haven’t been treated with antibiotics (e.g. penicillin, Scourban or Trisulfin tablets). Getting a diagnosis is important for several reasons. Firstly, some of the treatments differ slightly for different bacteria or viruses. Secondly, some of the bugs will infect people and make them sick, especially children. This happens more often than you might think and examples include Salmonella and Cryptosporidium infections. Thirdly, knowing what is causing the problem can help in forming a prevention programme for next season e.g. using Rotavec in the cows pre-calving.
The most important treatment for infectious calf scours is still fluid/electrolyte replacement. If the calf has stopped drinking then it needs to be tube fed. A 40kg calf that has lost 10% of its bodyweight in lost fluids will need 4 litres just to correct the dehydration. This level of dehydration is not unusual in scouring calves. Add in the normal day to day needs of about 4 litres and that calf needs 8 litres of fluid in 24 hours. A calf can only take in 2 litres per feed so that means, ideally, 4 feeds of fluids in 24 hours. In most cases giving the calf 3 feeds every 24 hours over 2 to 3 days will correct the dehydration, but remember that 3 is the absolute minimum number of daily feeds for a scouring calf, twice daily is too little. You can check the level of dehydration in the calf by gently pulling down the bottom eyelid and looking at the gap between the eyelid and the eyeball. In a normal calf there is almost no gap (check a healthy calf first for comparison) and as the calf gets more and more dehydrated the eyeball will gradually sink away from the eyelid.
When it comes to electrolytes you generally get what you pay for. The better quality products such as ‘Revive’ have ingredients which give a fast and slow release of energy as well as correct the major electrolyte and acid imbalances that occur in scours. Cheaper products only provide some basic electrolyte replacement and a short term energy burst. As a general rule, if the calf is sick enough to need tube fed then use a better quality product. If the calf is still drinking then you can fill a feeder between milk feeds with a more basic electrolyte product and let the calf drink ad lib.
New research has shown that keeping the calf on milk during a scour episode may actually speed up the recovery process as opposed to having 2 to 3 days of straight electrolytes. This is due to the milk having excellent energy levels, some localised gut protection activity and the correct proteins and amino acids to aid healing and stimulate the calf’s immune system. A standard fluid replacement programme for scouring calves is outlined below:
Day 1: Electrolytes (Morning) Milk (Lunch time) Electrolytes (Evening)
Day 2: Milk (Morning) Electrolytes (Lunch Time) Milk (Evening)
Day 3: Milk (Morning) Electrolytes (Lunch Time) Milk (Evening)
An alternative approach would be to give the calf 3 or 4 feeds of electrolytes on the first day and then go onto the above programme for days 2, 3, and 4.
Products such as Scourban and Trisulfin tablets may be used in conjunction with fluid/electrolyte replacement but should not be used on their own. Scourban has a ‘binder’ in it called kaolin which helps reduce the amount of scour. This will reduce the degree of dehydration, which is good, but may also aid in the build up of the bacteria/virus in the gut, which is bad. The antibiotics in these products are of questionable value. Not only do they kill the ‘bad’ bugs, but they kill the good ones as well and, also, the main cause of infectious scours, Rotavirus, isn’t killed by antibiotics at all. Having said all that, a calf with a very bad scour will be vulnerable to what’s called ‘secondary’ bacterial infection. This is the rapid growth of unfavourable bacteria in the gut as a result of damage to the gut lining from the initial infection. Antibiotics, both in the oral or injectable form may be of some value here. Confusing I know, so when do you use these products? There is no right or wrong answer (sorry!) but our recommendation is not to use them unless the scour is bad and the calf is visibly ill. There are other products such as ‘Bobby binder’ that have kaolin and electrolytes but no antibiotics in them which are useful in some situations especially, as the name suggests, in bobby calves where antibiotic products such as Scourban must not be used.
Another antibiotic free product that is regaining popularity is Bentonite. It is a type of clay dug out of, mainly, North America and has been used for medicinal purposes for centuries. It is chemically inert so it doesn’t actually ‘do’ anything but toxins and viruses are drawn into the pores of the clay which is then passed out in the faeces. Because it is not a scientific product there isn’t a lot of trial work data on bentonite but positive farmer testimonials, and the fact that it almost definitely doesn’t do any harm, mean that some may want to try it. Just pour some into a separate meal feeder and let the calves eat it ad lib.
The vet clinic has an ‘intensive care’ area set up for treating sick and/or scouring calves. This may only be considered for more valuable or special (pet!) calves but if you want to do your best for a sick calf we can certainly do a lot more to try and save it than the basic oral fluids and antibiotics that can be given on farm.
For an outbreak of scours, veterinary input can be invaluable so please include us when trying to control and treat this stressful problem.