Measuring heifer growth rates is yet another task to squeeze into a day with too few hours in it already, so it is worth the effort? The simple answer is yes! Various studies have now shown a positive correlation between dairy heifer growth rates in the first two months of life and milk yield1. One study found that a 100g increase in average daily gain leads to an extra 225kg of milk produced during a heifer’s first lactation2.
What are the growth targets?
There are a number of different targets to aim for in order to achieve the ideal age of first calving of 24 months. Animals should be 65% of adult body weight at bulling and 90% of adult body weight when they calve.
An average growth rate of 0.8kg/day should be targeted and it is important that enough milk or milk replacer is being fed to allow the calves to achieve this. Some general targets for dairy heifers which are easy to remember include 80kg by 8 weeks or double the birth weight at weaning.
When should growth rate measurements be taken?
In an ideal world growth rates would be monitored every 2 weeks to ensure that calves are growing at a suitable rate to ensure that all heifers will be in calf by 15 months. If it is not possible to measure the calves this regularly then picking certain check points may be another option. AHDB suggest weighing at birth, weaning, one week post weaning, 6 months of age and at breeding. Growth is most efficient in the first 2 months of life so it is important that calves are monitored during the milk feeding stages. Weighing at 4 weeks of age can prove very useful.
How can growth rate be measured?
Using electronic scales is the most accurate way of monitoring calf growth rates. This may not be possible on all holdings, so weigh tapes can be used, particularly in the early stages of life. There are limitations with this form of measurement, but accuracy can be improved if the same person is always responsible for taking the measurements. As the animals become older then height can be used as an alternative to the weigh band. This can be done using a stick across the withers or by marking target heights on a wall.
Growth setbacks can occur at certain times / stages, such as de-horning or weaning, so it is important to manage these events well and keep stress to a minimum. Disease is one of the biggest factors that will impact on growth rates during the first two months of a calf’s life – in particular pneumonia and scours. As well as being one of the biggest causes of mortality in calves, pneumonia is also responsible for reduced growth rates – a case of pneumonia in a calf under 3 months old can lead to an average 2 week delay in age of first calving3.
It is therefore vital that colostrum management on farm is of a high standard in order to give animals the best start to life, and the best opportunity to be protected against illness. Vaccination also plays an important role in disease prevention. Your vet is the best person to discuss disease prevention plans for your farm.
Back to our initial question, why should we bother to measure dairy heifer growth rates? Because these animals are the future of the dairy herd, and if we don’t measure we can’t monitor their performance, or intervene if required. It might be another job but it’s one which will pay you back!
1. Bach A., Ahedo j., (2008) Vet Clin Food Animal 24: 117-138
2. Bach A., (2012) J ANIM SCI 2012, 90:1835-1845.
3. Van der Fels-Klerx et al Livestock Production Science 75 (2002) 157-166
For further information, please see the product SPC, or contact your veterinary surgeon, SQP or Zoetis UK Ltd, Walton Oaks, Dorking Road, Walton on the Hill, Tadworth, Surrey, KT20 7NS. Customer Support 0845 3008034. www.zoetis.co.uk . Always seek the advice of your medicines provider. Use medicines responsibly (www.noah.co.uk/responsible).