By Matt Lippert

Improved reproductive performance in many dairy herds means producers are more secure in having adequate replacements than in the past. Raising heifers is expensive; crowding heifers in facilities limits performance, and more heifers than needed generates excess manure. There are many reasons to determine the right number of heifers for your farm and stick to that number.

Recently, markets for dairy heifer calves have been low, sometimes not covering the marketing expense.  Black crossbreds, however, are generating high value as newborn calves — $150 to $250 per calf.

With new options, mating decisions and culling outcomes are more complicated than in the past. You must identify which animals should be the future herd mothers. In general, heifers will have the highest genetic merit; however, calving ease from beef sires may be of value in the replacement herd.

You must prioritize calving ease, genetic gain and the specific needs for your herd. Genomic testing and information from your breed association, Dairy Herd Improvement or AI cooperative may all be used to identify which animals to breed to sexed semen, which animals to breed to beef, etc. You may want to keep calves from your older, durable high-producing cows, but that should not be the only criteria. Younger herd members likely will have better genetics; use a genetic ranking to assist with this.

Timing of culling is also a factor. If a beef crossbred calf is born, the marketing outcome was determined nine months earlier and you can act immediately. If you rely on genomic tests, timeliness of the test is important. If you don’t get results until the calf is 6 or more months old, you have lost the savings in labor and feed for a large share of the replacement period.

Optimum number
To determine the right number of heifers to raise, assess what your future desired herd size is. If it is the same size as the current herd, likely you will use your current culling rate as a predictor of future culling. If this is too high, are you currently culling more than needed as a result of having too many replacements?

For example, a 300-cow herd with a 30% culling rate will require 90 replacements. Be sure to account for replacement mortality. In this example, if 10% of those that are alive at 48 hours die or are lost to health problems, you will need 100 replacements kept back each year.

An advantage of early culling is that if you have slugs of calves that challenge the capacity of your rearing facilities, you can use the culling to develop a more steady number of calves of all ages to better utilize the facilities and your labor.

Overculling may not be the worst problem to have. While there are biosecurity concerns with bringing in purchased animals, replacements currently are priced for less than you can raise them — even animals that are well-grown with excellent genetics.

Another way to save on the replacement herd is to make sure they grow well and are bred in a timely manner so the majority calve between 1 year, 10 months and 2 years of age. Just as many dairy producers have improved fertility, they also have done a better job at raising heifers big enough and fast enough.

There is not much to be gained or production even lost by calving younger than 1 year 10 months in Holsteins. Instead of pushing for ever younger age at first freshening, if you have success with getting most heifers bred soon enough, work on improving the consistency of your performance and reducing the number that still calve at greater than 2 years old. Reducing crowding in heifer facilities by raising the right number of heifers may assist with improving fertility in your breeding-age heifers. 

It is not unusual that over 25% of heifers can be sold each year in a herd that is maintaining its size. If sexed semen is used heavily, the number can be much higher. With good planning, you can have a great future herd and minimized cost of rearing.

Lippert is the Extension agriculture agent in Wood County, Wis. This column is provided by the University of Wisconsin-Extension Dairy Team.