John F. Grimes, OSU Extension Beef Coordinator
Calving season is underway to some degree for many producers. If you have not started your calving season, you likely will soon. Calving time is an exciting period for producers as they are seeing the results of their genetic choices and management decisions coming to reality. Warmer weather and green pastures will develop in the coming weeks. The calf crop will grow and develop quickly through the spring and summer months. While this is taking place, the producer will set the 2019 calf crop motion with the onset of the breeding season.
Before the start of this breeding season, I would encourage producers to critically evaluate the production goals for your herd. Do the type of cattle that you produce adequately target your chosen market? If you sell your calves as feeder calves in the fall, your goal should be to sell as many healthy feeder calves with excellent weaning weights as possible. If you retain ownership after weaning and finish your calves to harvest weights, your priorities will be post-weaning gain, yearling weight, and carcass traits. If you are producing replacement females, emphasis should be placed on early puberty, moderate mature size, and milk levels that can be adequately supported through available feed resources.
I do believe these stated goals match up with the targeted production endpoints. However, I do not believe they are the production traits of the highest importance. Before we can attempt to reach these production endpoints, we must get the female bred and have her deliver a live calf. A producer may have access to top genetics and proper management techniques to give them the opportunity to reach their production goals. However, these will be wasted resources without high fertility and solid calving ease.
A producer should expect excellent reproductive performance (90% + conception rates) from a properly developed heifer. If she is adequate in size (60-65% of mature weight at puberty), been involved in a sound health program, and has been exposed to a fertile bull or bred artificially with high quality semen, there is little reason that she should not become pregnant in a 60 – 90 day breeding season. Similar conception rates should be expected from mature cows that are in body condition score 5-6 (on a 9-point scale) at calving and gaining weight after calving until breeding.
A shorter calving season will eventually lead to greater efficiencies in reproduction rates. Pregnancy status should be determined within 60 days after the conclusion of the breeding season through rectal examination, ultrasound, or available blood tests. Cull heifers and cows that do not conceive within your given calving season and don’t look back. Keep daughters of the cows that are bred early each calving season. If necessary, buy bred females that calve within your desired window to replace the open females. Implementation of these practices will certainly improve your herd’s reproductive performance over time.
Once the female is bred, calving ease comes to the forefront. I do not know of a single producer that wants to experience difficulties during calving season. The primary negatives associated with calving difficulties are potential calf death loss and a slower return to cycling with females. The primary question is how do you determine or interpret calving ease? When making genetic selections, do you prioritize an animal’s actual birth weight, Birth Weight EPD, Calving Ease Direct (CED) EPD, or Calving Ease Maternal (CEM) EPD?
Two factors that increase the probability of dystocia are calf birth weight and pelvic area of the dam. Actual birth weight of an animal may not be the best indicator of future calving difficulties as many environmental factors can influence birth weight. Birth Weight EPD predicts an animal’s ability to transmit birth weight but not the potential for calving difficulties.
The CED EPD predicts the average difference in ease with which a sire’s calves will be born when he is bred to first-calf heifers. It evaluates both birth weight and calving ease scores. The CEM EPD predicts the average ease with which a sire’s daughters will calve as first-calf heifers when compared to daughters of other sires. Each point of difference with each of these EPDs indicates the expected difference in the percentage of unassisted births. For example if Bull A has a CED of +15 and Bull B’s CED is +5, you would expect Bull A to have 10% less assisted births with first-calf heifers than Bull B. Remember that these EPDs are based on a first-calf heifer scenario and not mature cows.
A common complaint that I hear from some breeders today is that we may have carried the emphasis on calving ease too far. Research has shown that a typical beef female is capable of having 7% of their body weight in calf. This means that a 1,200 lb. cow is capable of having an 84 lb. calf and a 1,400 lb. cow could deliver a 98 lb. calf. Contrary to popular belief, not all commercial cows weigh 1,200 lbs. and I’m not so sure we need to see plenty of 100+ lb. calves out of our bigger cows!
Some believe that we have lowered calf birth weights to the point that we are sacrificing calf survivability and future performance. I realize that we have some harsher environments where lighter calves may struggle with extreme heat or cold. The individual producer should decide what weight is appropriate for their environment. However, greater calving ease does not mean you have to sacrifice animal performance or carcass merit. All major breeds have databases that can help any breeder identify animals that excel in multiple economically relevant traits.
Excellent reproductive performance and calving ease in any herd will go a long way towards increasing potential profitability in any beef herd. Once the producer has mastered these areas, we then can discuss what production traits should be prioritized to best achieve your marketing objectives.
Source: Ohio Beef Cattle Letter