Michigan State University Extension specialists say it’s always best to start with the youngstock because feeding dairy heifers for two years and having them turn out to be below average is a waste. In any culling plan, it is necessary to have criteria by which you select animals for culling. The problem with criteria is that some farmers will always be able to find an excuse for making an exception for this individual or that one. At the start, let me suggest you use criteria, but that you set a limit, that is, you plan to cull at least 80% of the animals that fit the criteria. By setting a limit, in this case 80%, you curtail making excuses for some individual animals to only 20%.
Consider these criteria for culling dairy heifers:
1. Calves that have been treated for pneumonia at least twice. These animals will have reduced lung capacity and are unlikely to be highly productive cows.
2. Heifers that lag their birth group pre-breeding. Go through and look at the birthdates of the heifers in the pre-breeding pen, and select animals that are one to two months older than the majority of heifers in the same pen. If you have moved heifers up in pens based on size, then these selected individuals are animals that have lagged in weight gain in the first year of life and are unlikely to become productive later.
3. Heifers that did not conceive after two services. Though it is natural to want to give heifers another chance to become pregnant, they should be very fertile, and those that don’t conceive at this stage are not likely to become better at conceiving later in life. It is a waste of feed and money to continue to give these heifers more chances.
4. Look at cow families, and note the families that result in more below-average offspring. You may consider three daughters or granddaughters and if two out of three were below average, cull out this next generation now. Genomics and bull data can also provide information to select out the families that will not perform well.
After starting with the heifers, you should also consider culling the less productive cows. Cull to reduce the herd size to a number you will have forage to support. Track inventories throughout the harvest season, and adjust it by the amount and quality of any purchased. Keep comparing inventory and cattle numbers.
Consider these criteria for culling cows:
1. Cows that have been treated for mastitis twice in the lactation. These individuals are more likely to develop mastitis again.
2. First-lactation animals that have been bred three times and are not confirmed pregnant and multiparous cows that have been bred four times and are not confirmed pregnant. You have to draw the line somewhere.
3. Cows open at 225 days in milk. Even if you could get them bred after this point, you will have a long lactation and, more likely, a fat cow by dry-off.
4. Cows by their second test (50 to 70 days in milk) that are the lowest of the group of 10 that calved around the same time. When you look at animals as a cohort (a group defined by going through something around the same time), you have a comparison group. Consider culling the least productive members of the group once they have passed their lactation peak, and put them on a do not breed list.
Within any herd of cattle, there are those that, because of genetics, past health events or other individual characteristics, will not be as good as their herdmates. Yet, they may eat just as much and return less for it. To make your herd more profitable and to save on limited resources such as feed, it is important to identify these animals as early as possible. It doesn’t mean they aren’t good animals, but even average animals won’t help you achieve above-average results.
Culling early as heifers means you will cull without knowing the full future of the animal. However, culling early saves the most potential loss. Having good criteria provides confidence you are culling the animals most likely to be below average.
Culling criteria should also be a call to solve problems. If too many animals are selected for not meeting the breeding criteria, then have a professional check your technique, evaluate your program, and make sure it is fine tuned to get the results you need. If too many calves are selected for culling based on pneumonia treatment, then evaluate the environment and vaccination protocols. Likewise, a high incidence of repeat mastitis cases may indicate a need to re-evaluate mastitis prevention practices. Sometimes it is not the fault of the animal that she doesn’t measure up; sometimes it’s the fault of people.
Culling is selection for improvement. Limited forage may force you into increased culling and that may be the silver lining of this crisis. By applying culling criteria, you are setting the herd up for lower costs and higher returns and establishing a pattern to be continued in good years or bad. 
—Excerpts from the Michigan State University Extension website, June 28, 2019
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Phil Durst
- Senior Educator, Dairy and Beef Cattle Health and Production
- Michigan State University Extension
- Email Phil Durst
