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Conception rate versus calving distribution

With bulls going into breeding pastures every day now, cattlemen easily understand the impact of a good conception rates on their bottom line.  Another measure that can directly affect ranch profitability, is calving distribution. 


While pregnancy checking may give us a good indication of what our conception rate is (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 I be concerned with it?  Calving distribution is a look at which cycle of your breeding season each of your calves are born in.  If you have a 60 day breeding season, you have about three, 21 day cycles, to get your cows bred.  If you keep track of the birthdates of your calves, you can then generate the calving distribution of your calves.  You can now look at the percentage of your calves that are born in each of the 3 breeding cycles in this 60 day breeding season.  

The Pay Back:

Why would this matter? A few years back Harlan Hughes put together a graph 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.

Figure 1. Profit Index by 21 Day Calving Interval

Figure 1. Profit Index by 21 Day Calving Interval

I have herd ranchers tell of herds where 65% of the calves are born in the first 21 days, as well as herds where 85% of the calves were born in the first 21 days.  It is entirely possible that both of these herds have the same conception rate, yet one is likely to be more profitable.  Let’s say both herds are 100 cows and 95% of the cows were pregnant.  If the ranches were only measuring conception rate, they are likely to be equally happy at this point.  Let’s also say 3% of the live calves were lost by the time they were weaned.  This gives us 92 live calves per herd to sell at weaning. 

Will the checks for both herds be the same?  Probably not.  The second herd has 18 more calves born in the first cycle than the first herd (92 x 65% = 60 calves & 92 x 85% = 78 Calves).  If those 18 calves gain 2.5 pounds a day for an extra 21 days before they are weaned, they have added 945 pounds more pay weight than the first herd.  That could total over $1,500 more in your paycheck.  And that herd probably has calves moving from the 3rd cycle to the 2nd cycle as well.  Each cow that conceives a cycle earlier, can add about $87 more to your bottom line.  Regardless of when a cow conceives, the cost to carry her for a year, will be pretty much the same.  She just as well conceive earlier, and deliver a heavier calf.

How Can I Affect Calving Distribution?

Nutrition, genetics and management are the hurdles you have to cross.  You may still have time to take a good run at some these before your 2017 calves are conceived.

Nutritionally, you want to ensure that more than adequate levels of phosphorus, trace minerals and vitamins are available to your cow herd.  CRYSTALYX® Breed-Up® Max Supplement is an easy way to provide these in a mineral block that’s available 24/7.  Breed-Up® Max contains higher levels of trace minerals and vitamins (200% of NRC) as well as Bioplex® trace minerals which are better absorbed, stored and utilized by the animal than inorganic mineral sources.

For your bulls, CRYSTALYX® Breed-Up® Omega also contains Bioplex® trace minerals.  Additionally, it contains omega-3 fatty acids which have been shown to improve semen quality and sperm motility.

You have just crossed the first hurdle.