Maternal Matters: post calving herd management - knowing when to cull

Culling is a valuable tool to improve the herd's performance by removing cows that are not performing well and are costing, rather than earning the business money.  

Knowing when to cull

There are two points during the suckler calendar when culling decisions can be made most usefully. The first is at pregnancy diagnosis.

Is the cow in calf and predicted to calve inside the target calving period?

The next time culling decisions can be made is after calving when you should consider the following:

  • Does her historical performance, and that of her calves, justify her staying in the herd?
  • Did she require assistance during calving or getting the calf to suckle?
  • Temperament at calving
  • Is she in good health?

Calculating replacement rate is an effective way of understanding culling practices in the herd. Approximately 16% of cows should be replaced each year. A lower replacement rate can reflect increased cow longevity, with lower overall costs and higher lifetime productivity.

However, after around eight years of age, cow productivity declines, and older cows can be replaced by heifers. A high replacement rate indicates either health or fertility problems. Where this is the case, it is important to analyse further why breeding animals are culled from the herd to find where problems exist.

Calculate your replacement rate using our KPI Express Calculator

Cow mature size

Suckler cows in the UK have been increasing in size over time. When breeding heavier cows, we make a trade-off in terms of whether the cost of keeping a heavier cow outweighs the extra value she provides by producing heavier offspring and having a higher cull value.

Ideally, cows should wean at least 45% of their mature size. This figure can be calculated using the KPI Express Calculator.


Research by AbacusBio International on behalf of AHDB, QMS and HCC, has used industry data to create a model of UK beef production systems. This model demonstrates how an increase in mature size affects other traits of economic importance and how these changes influence costs and revenue on farm.

The team at AbacusBio compared the cost of producing cows with a mature weight of 651 kg compared with those with a mature weight of 751 kg. Heavier cows did benefit the modelled farm through higher cull cow revenue and by producing offspring with higher carcase revenue and quality.

However, heavier cows have higher costs in terms of maintenance feed and replacements. They also suffer from a decrease in fertility, potentially producing fewer offspring in their breeding lifetime. Heavier cows require more land than lighter cows, resulting in a reduced stocking density on farm.

Once you combine all these factors, the cost of production is higher for heavier breeding females, and therefore, profitability is poorer.

Find out more on this study.

Discover our Optimising suckler herd fertility for better returns guide

Learn more about: Assessing efficiency of breeding enterprises