In Ireland, the two greatest causes of death in calves under one month of age are calf scour and pneumonia.
Post-mortem data shows that a common problem with these calves is that they have failed to receive a sufficient level of passive immunity.
During the recent Teagasc/Animal Health Ireland (AHI) CalfCare webinar, the key areas to consider for reducing the prevalence of these issues were discussed by vet and assistant professor with UCD School of Veterinary Medicine Catherine McAloon; vet with AHI Michelle McGrath; and research officer with Cork Regional Vet Lab Ciara Hayes.
Two pillars of prevention
The control and prevention of calf scour and pneumonia can be divided into two pillars. Pillar one involves reducing the disease pressure in the calf’s environment.
This includes a well-designed calf-rearing shed with good ventilation and drainage, adequate space allowance for calves, a sufficient level of clean, dry bedding and attention to detail around hygiene in terms of feed and feeding.
The ability of the calf to absorb these antibodies decreases every hour from birth
Pillar two focuses on maximising the calf’s own immune system. It is important to remember that a calf is born without any protective immunity.
They therefore depend entirely on the quality and quantity of colostrum fed in the first few hours of life to provide them with a sufficient level of antibodies for the first three to four weeks of life, until their own immune system develops.
The ability of the calf to absorb these antibodies decreases every hour from birth and has stopped completely by the time the calf is 24 hours old. It is therefore important to follow the 1–2–3 rule of colostrum management.
Measuring colostrum quality
It is recommended that farmers test the quality of the colostrum being produced on their farm. This can be easily done using a Brix refractometer. At a cost of less than €30, it is a good investment on all farms.
Simply place a few drops of colostrum on the glass prism, ensuring the entire surface is covered, close the cover and ensure there are no air bubbles in the sample. Hold the device perpendicular to a light source to look through the lens.
Colostrometers work using specific gravity and the result can be affected by the temperature of the colostrum sampled
The scale on the refractometer ranges from 0 to 30.
The higher the reading from the colostrum, the better the quality, with a minimum value of 22 required to be deemed sufficient.
Colostrometers are also used on some farms.
However, they are not as accurate as a Brix refractometer. Colostrometers work using specific gravity and the result can be affected by the temperature of the colostrum sampled.
If testing colostrum highlights a quality issue on farm, there are a number of options for farmers.
Immediately, for the calf that is to be fed the colostrum, the best option is to have a backup of high-quality colostrum stored on farm for use in such situations.
Surplus high-quality colostrum can be stored in the freezer for up to a year without quality being affected.
Thawing colostrum should be done in water no hotter than 50°C, so as not to damage the antibodies during the process.
Longer-term, you need to look at the cow’s diet
Where this is not available, another option is to feed more of the lower-quality colostrum to try to get a sufficient level of antibodies into the calf. This is not always possible though, as calves may not be physically able to consume enough colostrum.
Longer-term, you need to look at the cow’s diet. Is the overall silage quality good enough? Are intakes at a sufficient level? Is the crude protein level of the diet 12% or greater?
Once a cow calves, she immediately changes from producing colostrum to producing milk. Therefore, the quality of the colostrum is highest at the time of calving. Where colostrum is to be collected, it should be done as close to the point of calving as possible.
Hygiene when collecting colostrum is very important, as a high bacteria count in the sample will reduce the calf’s ability to absorb antibodies.
There should be a designated container which is only used for collecting colostrum. Always wash all equipment thoroughly between uses.