Breeding replacement heifers

I know some of you have been calving, in many cases first calf heifers, during this terrible cold and snowy weather. I realize that cattlemen have had a tremendous work load and stress during this time as the cold east winds just wouldn’t relinquish its grip and unless the new born calves were not attended to immediately some would chill to the point that they couldn’t stand and nurse on their own. I know some have experienced loss but if only those that are critical of us in the cattle business only knew the effort that is put forth to save every calf it would boggle their mind. We not only do it because it is our livelihood but more important we do it because we care deeply concerned about our livestock and their welfare.

Almost every publication and news report talks about the price or value of our cattle and often addresses the topic of rebuilding the cow herd in the United States. Even we have a lot of positive signs to rebuild we still have several parts of the United States that are experiencing drought and in some cases severe snow storms and therefore it appears the rebuilding of the cattle herd may be modest at best. This makes it even more attractive down the road if we have the resources to grow our own cow herd now. We do see considerable more interest in this region retaining and developing replacement heifers. Calls and watching the price of high quality bangs vaccinated heifers tells me we will see considerable rebuilding in this area.

Most decisions have been made on the feeding and management program to develop the heifers, however some time remains for tweaking the system. Obviously if the heifers have not been gaining enough there is still time to catch them up to a desired target weight for breeding For years it was routinely recommended to develop the heifers to achieve 65 percent of their expected mature weight at breeding time or if a heifer that was expected to mature to 1,300 pounds then she should weigh at least 845 pounds to assure good reproduction. Some still make that recommendation which does assure good reproductive performance however research now shows that this often results in a more expensive program than is needed. Ten to 12 years ago Dr. Gene Duetcher now retired from the University of Nebraska West Central Research and Extension Center challenged the 65 percent recommendation and developed some heifers to be bred near 50 percent of their mature weight or close to 200 pounds lighter. Their data found the heifers had very acceptable breeding performance and were developed with much less cost. This work has been followed up by Dr. Rick Funston reproductive specialist, University of Nebraska West Central Research and Extension Center and he writes and speaks on this concept frequently. Dr. Funston states that costs can be cut to least $100 per heifer without sacrificing reproduction plus any open heifer can be sold at a lower breakeven.

The question often arises as the most desirable way to breed heifers. By far the majority of first calf heifers are naturally mated however with innovation and lower labor synchronization programs many producers do use AI (Artificial Insemination) in conjunction with synchronization.

Natural mating is still a viable option especially with increased technology to give more accurate ESDs (Estimated Progeny Differences) for calving ease plus other traits. We see far fewer “wrecks” today than in the past when at times hide color and/or breed seemed to be the major criteria for selecting bulls for breeding heifers. As a result of more attention focusing on EPDs to predict calving ease considerably less heifers are assisted at birth and certainly fewer C-sections.

There are still some major advantages of using proven sires for first calf heifers plus often we can also look at growth traits with accuracy and perhaps maternal and carcass weights. I have felt for years that proven bulls that excel in calving ease and maternal traits are excellent candidates for next year’s replacements. They are often the oldest heifers that are born in the first cycle of calving. Currently with sexed semen perhaps we even have greater opportunities to use this as a source of replacement heifers.

AI is much more feasible today with the use of synchronization programs that allow timed AI. Breed them on a break or week-end when the kids are home from college. One can also hire a nomadic crew that comes through on a given schedule; perhaps all you need to do it keep books when they are being bred. It seems that it is never that simple but fun to think that way. Currently there are many options available that allows a large percentage for the heifers to be bred to superior bulls in a short time period.

The two synchronizing programs that are very popular are the MGA – prostaglandin and the 7 day CIDR norgestmate (GnRH) program. Basically the oldest and perhaps the lowest cost is feeding MGA for 14 days and then giving a prostaglandin 19 days after the feeding of MGA. Breeding can then be done with heat detection or heat detection and breed for approximately 80 hours and then time breed anything not heat detected and give a shot of GnRH.

The 7 day CIDR works similar however the CIDR’s are taken out on day 7 and a prostaglandin is administered at that time of CIDR removal. The heifer can then be heat detected up to 80 hours or some simply breed every heifer between 72 – 84 hours and at the time of breeding each heifer is given an injection of GnRH. The MGH program requires initiation 33 days ahead of time to start breeding while the 7 day CIDR program can be done with less time of initiating the synchronization program. Sound complex and confusing? Help is available in many places. Almost all sire catalogs have these and variations of these programs published in their catalog. Need some help in planning? An excellent spreadsheet planning aid can be downloaded from Iowa States Beef Center web site www.iowabeefcenter.org/esterus_synch.html. All you have to do is put in the date you want to breed and select the program you want to utilize and it will fill in the dates to carry out each procedure. A reproduction web site www.beefrepro.unl.edu also has considerable information on breeding programs. Semen sales representatives and beef extension specialists will also be helpful resources. Best of luck as you make breeding decisions. Also as many go into calving take care and be safe in those low rest times.

Ivan G. Rush is a Professor Emeritus at the University of Nebraska.

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