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What is calving distribution?

With bulls entering breeding pastures in the weeks ahead, cattlemen can easily understand the impact of a good overall herd conception rate on their bottom line. However, another reproductive measurement that can directly affect ranch profitability is calving distribution. 

The opportunity

While pregnancy checking may give us a good indication of our conception rate (equal to the number of cows pregnant divided by the number of cows exposed), we will likely need to wait until calving to get a better feel for our calving distribution. 

So, what is “calving distribution,” and why should you be concerned with it? Calving distribution is a look at the cycles of your breeding season in which each of your calves was conceived. If you have a 60-day breeding season, you have roughly three 21-day cycles in which to get your cows bred. If you keep track of calves’ birthdates, you can generate the calving distribution of your herd. You can now look at the percentage of your calves that were conceived in each of the three breeding cycles in the 60-day breeding season.  

The payback

You may be asking yourself, “Why would this matter?” A few years back, Harlan Hughes put together a graph (displayed in Figure 1) showing the relative profitability of when a calf is born within the calving distribution of a herd. It is primarily driven by weaning weight. Older calves weigh more and are generally worth more.

Hughes, 2005

I have heard ranchers talk of herds in which 65 to 85 percent of calves were born in the first 21 days. It is entirely possible that those herds on the lower end and higher end of the percentage scale have the same conception rate, yet one is likely to be more profitable. Let's say both herds consist of 100 cows and 95 percent of the cows were pregnant. If the ranchers were only measuring conception rate, they are likely to be equally happy at this point. Let’s also say 3 percent of the calves or fetuses were lost by the time they were weaned. This leaves us with 92 live calves per herd to sell at weaning. 

Will the paychecks for both herds be the same? Probably not. The second herd had 18 more calves born in the first cycle than the first herd (92 x 65% = 60 calves versus 92 x 85% = 78 calves). If those 18 calves gained 2.5 pounds per day for an extra 21 days before they were weaned, they have added 945 pounds more pay weight than the first herd. That could result in over $1,500 more in your pocket. Additionally, that herd probably has more cows conceiving in the second cycle. Each cow that conceives a cycle earlier can add about $83 more to your bottom line. Regardless of when a cow conceives, the cost to carry her for a year will essentially be the same. She should just as well conceive earlier and deliver a heavier calf in the fall.

What can I do to impact calving distribution?

Pre-breeding nutrition, genetics and management are the tools you have available that will affect both conception rate and calving distribution. Fortunately, you still have time to make adjustments before your 2019 calves are conceived.

Starting today, for most spring calving herds, you should be two weeks to a month ahead of turning your bulls out. Nutritionally, you want to ensure that more than adequate levels of protein, phosphorus, trace minerals and vitamins are available to your herd, bulls included. 

Just last fall, CRYSTALYX® introduced their new line of Blueprint® supplements, a beef industry first. The CRYSTALYX Blueprint premium nutritional program is based on the total replacement of inorganic trace minerals with highly bioavailable Bioplex® organic trace minerals. Bioplex trace minerals are provided in a form that is as close to nature as possible. It is easily absorbed and readily metabolized by animals.

The CRYSTALYX Blueprint line promotes environmental responsibility and targeted nutrition by feeding the right levels of highly bioavailable trace minerals without the potentially harmful effects of overfeeding less available inorganic forms, which may be excreted into the environment. CRYSTALYX Blueprint supplements are an easy way to provide protein, phosphorus, organic trace minerals and vitamins in a block supplement that’s available to your herd around the clock. Contact your local CRYSTALYX dealer today for more information on Blueprint and other great products that might benefit your herd.


Hughes, Harlan. “Increasing your profits: Part III.” Beef magazine. April 1, 2005