After numerous meetings and roundtable discussions, I am certain of only one thing — when it comes to culling rates, no one agrees. Unfortunately, lenders and investors look closely at this number and can draw some improper conclusions unless the details are investigated.
Culling has a major impact on a farm. Milk production, expansion efforts and profitability/cash flow are all negatively affected when cull rates are too high.
How do you define cull rate?
Most agree that culling is the removal of a cow from a herd. However, people calculate cull rates in very different ways. Is it just sales and slaughter, or do you include deaths? And do you divide by lactating cows, all cows on the farm, or herd size at a specific point in time?
Instead of calculating a cull rate, I prefer to look at cull-risk and herd-turnover rate.
Cull-risk = # animals culled per year/Some population at risk
Herd-turnover rate = # of animals culled per year/Average # in herd + # culled
In addition, I look at deaths and culls separately, because the reasons underlying each of these categories may differ dramatically. If you do look at culling, keep it standardized and be certain that your support team understands what you mean when you discuss cows leaving your herd.
An ideal cull rate
Based on various economic models, many experts advocate a 20 percent to 30 percent cull rate as ideal. While a starting point, I think each farm needs to determine its own ideal cull rate.
To do that, I would look at:
The number of milk cows needed.
Availability of replacements.
Cow value vs. value of a heifer if sold.
Value of culled animals.
Milk production needed per day to meet farm expenses per cow.
With this information, you can look at each animal in the herd and compare her profitability to that of a potential replacement.
Why and when cows leave
Work with your veterinarian to determine why and when cows leave. Most farm records indicate that about one-third of all culls leave in the first 100 days in milk and another third leave at 300+ days in milk. Obviously, those leaving in the first 100 days have a more negative impact than those leaving at the tail end.
Why do they leave? Metabolic problems, fresh cow mastitis, traumatic dystocia—the list goes on.
Correlate the data, and you should find answers as to why cows leave. Use that information to develop strategies and procedures to keep a lid on future problems.
Use culling as an economic tool
Ideally, culling should be an economic decision: Remove one animal to replace it with one that is more profitable. However, there are no guarantees that a new heifer will produce, and experience has shown that cull rates in purchased replacements often range from 15 percent to 25 percent before 60 days in milk. In addition, removing one cow and getting another is not always practical—and often poses additional biosecurity concerns.
All of these factors need to be reviewed when evaluating the culling practices on your farm. Utilize the experts and your management team to understand where you are, what factors affect your farm, and how to use culling as a positive economic tool for your business.
Jim Brett is a practicing veterinarian in Montezuma, Ga.