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MMN January 2024 – Spring Block Calving: How does your Herd Measure Up?

12 January 2024

Measuring reproductive performance of the herd can allow comparison between years, areas for improvement can be identified and you can check the effectiveness of management changes made. Regular measuring and monitoring allows the business to respond quickly if performance is not at the desired level. It provides the opportunity to identify which aspects of the system are limiting the performance of the herd and therefore changes can be targeted.

In a spring block calving herd, measuring calving performance can be quite simple when the correct data is collected. Data that can be collected over the calving period includes:

  • Planned start of calving date.
  • Actual start of calving date.
  • Date the last cow calves.
  • Calving details – including date, assistance required, stillbirths and calf deaths post 24 hours.
  • Cow exits – date of cow sold, death or culled and reason.

Once calving has finished and data has been collected, then key performance indicators can be easily calculated in a spreadsheet to determine whether the herd is meeting its targets. A key calving performance indicator for block calving herds is cows and heifers calved within the first 6 weeks as a percentage. This is simply calculated from the number of cows and heifers calved in the first 6 weeks divided by the total number of cows and heifers due to calve x 100. For example:

100 cows and heifers calved    x 100 = 83%

120 cows and heifers in-calf

Following calving, the next area to investigate is how well the cows and heifers get back in calf. Two key performance indicators which can be monitored are the 6-week in-calf rate and the empty rate. Again, both of these indicators can be easily calculated; the 6 week in-calf rate is defined as the percentage of heifers and cows which get pregnant within the first 6 weeks of the mating period. The empty rate is defined as the number of cows that are confirmed empty during pregnancy testing. Further key performance indicators which can be utilised include the 3-week submission rate (%), conception rate (%) and herd replacement rate (%). The table below shows suggested fertility targets for block calving herds.

Table 1. Targets for the main performance indicators measures in block calving herds

Excellent: top 5% performer or aspirational target
Good: Top 25% performance
Average: Industry average where available

Source: AHDB


Determining how the herd compares to targets can then allow you to make decisions about what areas need improving to bring your indicators up to the target set for the herd. Setting achievable targets for your herd is important and evaluating and comparing your herd’s current reproductive performance against industry targets will give you the opportunity to determine which areas are achievable for the business. It is important to consider whether meeting a target is easily achievable for the following year. If you are far from the target then setting smaller, more achievable goals each year may be a more viable (and moral- boosting) option.

Discussing results and proposed targets with your team and advisors can help ensure that targets are achievable. Regularly reviewing targets throughout the year is key to making sure the business is making good progress and timely decisions can be implemented if required. Individual herd targets will need to be updated as they are achieved or if anything changes within the system which may impact the success of the target. If you are heading towards spring calving, then this is an excellent opportunity to collect data to determine your herd performance and compare it against industry targets.

Dr Cara Campbell,; 01586 552502

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