Katie Fitzgerald of Bishopton Veterinary Group discusses how to improve calf survival

CALF-REARING has received much attention in recent years, however, there is still much room for improvement.

National bodies have identified calf health as an area of importance, highlighting calf survival as an area of concern.

A recent study of BCMS data from 2010-2019 showed that about six per cent of registered dairy heifer calves died before reaching three months of age. This represents not only a significant economic challenge, but also reduces the rate of genetic improvement in herds that are therefore able to make fewer voluntary culls.

It is not exclusive to dairy calves, with mortality in beef cross calves of about four per cent, representing a significant inefficiency in beef calves originating from the dairy sector.

Despite numerous industry initiatives focusing on calf-rearing, it is concerning that the mortality rate has remained very consistent over this time period. This study also highlighted variation in mortality rates associated with both month of birth and temperature at the time of birth for male and female and dairy and non-dairy calves.

This suggests that there are optimal environmental conditions associated with survivability, if housing was able to replicate these optimal conditions all year round, we may see a reduction in calf losses.

Colostrum is Key

Colostrum management is widely acknowledged as the critical starting point for good calf health, however, a recent survey showed that 20 per cent of calves had failure of passive transfer of maternal antibodies.

Failure of passive transfer is associated with higher rates of scour, pneumonia and mortality, and long term effects include increased age at first calving and detrimental effects on colostrum. The principles of ensuring a calf receives an adequate volume (ten per cent of body weight) of good quality colostrum as soon after birth as possible (within six hours) are widely understood.

Use of refractometers to measure quality of colostrum prior to feeding is now commonplace on British dairy farms and many farms use total proteins to monitor the success of their colostrum management.

Recent evidence suggests that increased emphasis should be placed on the handling of colostrum to ensure it not only contains an adequate concentration of antibodies, but reaches the calf in a hygienic state.

Bacterial contamination of colostrum not only presents calves with a pathogenic challenge, but also reduces the absorption of antibodies in the gut and can lead to failed passive transfer. A recent study showed that a third of colostrum samples were too dirty.

Contamination can occur at any stage of the colostrum harvesting and feeding process. Dirty teats, dump buckets or feeding equipment, as well as poor storage techniques can all contribute to high bacterial loads in colostrum being fed to calves.

Use of hot water to clean colostrum collection equipment could reduce the bacterial count in colostrum by as much as 50 per cent and use of a disinfectant such as hypochlorite could further reduce this count. Handling of colostrum following harvesting is also an important factor, especially in warmer weather when bacterial counts can rise if the colostrum is not fed immediately.

Any colostrum that is to be stored for later feeding should be chilled rapidly and warmed up prior to feeding. Pasteurisation is a useful tool for reducing bacterial counts but must follow a suitable protocol to prevent damage to the crucial antibodies.

Maximising Growth Rates

There is a well-supported evidence base documenting the benefits of maximising pre-weaning growth rates in both dairy replacement and beef calves. Many factors are known to be associated with improving growth rates, however, many of these are associated with significant economic costs of implementation and the relative importance of these different factors are often hard to elucidate.

A large-scale study assessing different calf rearing practices across the UK has highlighted several factors most strongly associated with improvements in growth rate. These include volume of milk fed, shed temperature in the first month of life and pen hygiene.

Data loggers can be useful in understanding daily and seasonal fluctuations in temperature in your sheds, allowing you to make judgements on when and how to alter your management to reflect this.

As with any aspect of animal health, monitoring your performance at critical control points can allow you to gain a better understanding of your performance and help identify areas that can be improved.