Birth Weight EBVs are estimates of genetic differences between animals in calf birth weight. Birth Weight EBVs are expressed in kilograms (kg) and are calculated from the birth weight of calves.
Why Should Birth Weights be Recorded?
Calving difficulty has an obvious negative impact on the profitability of a herd through increased calf and heifer mortality, slower re-breeding performance and considerable additional labour and veterinary expense.
Many large studies have shown that the level of calving difficulty in a herd is influenced by many environmental factors and several genetic factors. These genetic factors include such things as calf weight, calf shape, pelvic size and calving “will”. Of these, calf weight is by far the most important factor.
How do I record Birth Weights?
Many different methods are currently used to record calf birth weight. These range from using bathroom scales through to the use of commercially available calf weighing cradles that can be attached to the tray of a utility or the front of a four-wheel motorbike. More recently, calf-catcher devices have entered the market; these have the advantage of allowing the producer to weigh the calf while both are enclosed away from the dam. Several pictorial examples of birth weighing devices are provided overleaf.
For further advice about how to record birth weight, please contact staff at your BREEDPLAN processing centre.
What considerations should be made when recording Birth Weights?
- Birth weight should be recorded for the whole calf crop. Without comparisons to the other calves, "occasional" measurements are of no value and can actually be misleading. Recording birth weight for dead calves is particularly important.
- There are significant fluctuations in the weight of a calf over its first week of life. Therefore, it is important to weigh calves as close to birth as possible. Ideally, measure birth weight within 24 hours of birth.
- Do not guess birth weight or use girth/chest size to estimate birth weight. Either weigh the calves or don't record birth weight.
- A birth management group should be recorded if there are different treatments of the females prior to calving that may affect birth weight. For example, where one group of cows have had different feed availability. A separate birth management group should also be assigned if the weight of the calf has been affected by special circumstances (e.g. premature calves, the dam was sick etc.)
- Some breeders have reportedly been injured by protective cows while weighing calves. It is important to take due care when collecting this information.
How do I submit Birth Weights?
Birth weight information can either be submitted to your Breed Society/Association when submitting your calf registration details or directly to your BREEDPLAN processing centre.
Please contact staff at your Breed Society/Association or your BREEDPLAN processing centre should you have any queries about how to submit this information.
For more information regarding how to record birth weight information or Birth Weight EBVs in general, please contact staff at your BREEDPLAN processing centre.