Importance of calving distribution and planning for synchronization |

Importance of calving distribution and planning for synchronization

Ivan G. Rush

Beef Specialist, UN-L Panhandle Research and Extension Center

I hope everyone is braving the late winter weather as well as possible. I know conditions are really tough in much of the northern high plains causing stress on cows, calves and people. I am always hesitant to discuss calf losses due to blizzards as I am fearful someone that is not familiar with the cattle industry or those that are opposed to our industry, will pick up those comments and exploit them as “see those cattlemen are not caring for their cattle.”

My wife and I have been Ag Pen Pals with a 4th Grade Class in Grand Island, NE, which we often still think of as rural Nebraska and one of the most frequent questions is if we have shelter for all cattle when we have cold and bad weather. We know of the tremendous effort that cattlemen put out in all kinds of weather and conditions, at all hours of the day and night to care for the livestock. We do that partly because it is crucial for our profits but also it is because of our passion to properly care for the animals. It is unfortunate that we can’t convey this message to those that are not informed and make wrong assumptions.

As many spring calving programs are in some phase of calving now it may be time to reflect on how well you did last year in getting the cows bred in a timely manner. Perhaps one of the most important statistics that we can collect is the number or percentage of calves that are born in the first 21-28 days of the calving season. A large number of calves in the early part of the season concentrates calving, thus labor, plus provides a larger group of uniform calves at weaning. Additionally, if all calves are weaned on the same day in the fall, weaning weight will be heavier if the majority of the calves are born earlier in the calving season.

Assuming the calves gain around two pounds per day then calves that are 30 days younger will average 60 pounds lighter at weaning. Dr. Kris Ringwall at NDSU has analyzed tons of data through the CHAPS program, continually showing graphs for the weaning weights of the calves that are born in the first, second and third 21 days of the calving season. Weaning weights decreased around 45-70 pounds as the ages decreased each 21 day period. Calving distribution also indicates overall reproductive performance. Usually the number of open cows is higher when the calving season is strung out, not only for this calving season but subsequent calving seasons. Many factors contribute to late calves but assuming no major disease problem, cow condition and bull power are major factors to consider.

For those that breed yearling heifers utilizing synchronization, now is the time to start planning the synchrony program, especially if MGA is utilized. The MGA feeding needs to be initiated about 34 days before you intend to breed the heifers. That involves 14 days of feeding of MGA at 0.5 mg./hd./day and then giving the prostaglandin injection 19 days after MGA feeding is stopped.

Some have preferred to use CIDRs, especially when delivering MGA daily to the heifers is not feasible. The use of CIDRs can be initiated closer to the time of breeding than the MGA/prostaglandin program. CIDRs arguably appear to be about equal in success, however, is slightly more costly. There does appear to be an advantage of CIDRs in cows partly because the difficulty for some to uniformly deliver MGA to cows under range conditions.

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Iowa State University has developed an excellent spreadsheet to aid in planning a successful synchronization program and is for sale at their web sight ( Many beef specialists and semen sales representatives have the software and would be willing to assist in selecting and developing the details of the desired program.

In closing, I know Mother Nature has dealt some tough hands to deal with so here’s hoping for some warmer and more pleasant days ahead so we can see the calves run over the hill with their tails over their heads. It will get better. I just I wished I knew when.