By John F. Grimes
For spring-calving beef herds, the breeding season is currently or soon will be underway. Many decisions have already been made in terms of the genetic makeup of the 2018 calf crop. Natural herd sires or sires to be used through artificial insemination have been selected. Mature cows have been retained and replacement heifers have been introduced to the breeding herd. Hopefully the genetic decisions that have been made will prove profitable when next year’s calf crop is sold.
Nearly every beef specialist or researcher that I am familiar with will tell the cow-calf producer that reproduction is the most economically important trait in beef cattle. Numerous studies have shown that reproduction is several times more important than growth or carcass traits. Simply put, genetic superiority in any trait doesn’t matter if the beef female doesn’t get bred and deliver a live calf for the producer.
How can the cattleman evaluate the reproductive performance of the herd? I would suggest three key areas to evaluate. They are as follows:
- Calf Crop Percentage: This would be the number of calves weaned divided by the number of cows exposed divided by 100.
- Distribution of Calving Dates: This would be a picture of how calving dates are scattered across an existing calving season.
- Pounds of Calf Produced Per Cow Exposed: This would be the weaning or sale weights of heifers retained as replacements or feeder calves sold.
Can the producer improve reproductive performance in the herd? Compared to growth and carcass traits, reproductive traits are more are more lowly heritable. Changes in reproductive efficiency are most easily made by management changes or the impacts of crossbreeding through heterosis. Over time, progress can be made by selecting and culling for reproduction.
Nearly every management decision associated with the cow herd is simplified and improved with a shorter calving season. Herd health, nutritional, and reproductive management are much easier when all cows are in a similar stage of production. Restricting the breeding season to 60 to 90 days will produce a more uniform calf crop which enhances marketing opportunities. It is easier to match up your forage supply with the nutritional demands of your herd when all animals are in a similar production cycle. Vaccination programs are more effective when animals in the breeding herd are in a similar reproductive status.
A more concentrated calving season is important for the smaller or part-time producers who have major time restrictions in their daily lives. I don’t know of any producer that enjoys the stress and worry of calving season over an extended period of time. This is especially true if calving season comes during inclement weather and you are away from the farm for long stretches of time during an average day.
A shorter calving season will eventually lead to greater efficiencies in reproduction rates. Palpate shortly after the conclusion of the breeding season and cull heifers and cows that don’t conceive within your given calving season and don’t look back. Keep daughters of the cows that get 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.
Probably the production group that is the most consistently mismanaged in the typical cow-calf operation is the replacement heifer. An ideal scenario would be for the replacement heifers to be managed as a separate group until after they’ve had their first calf. In smaller herds, heifers retained as replacements are often managed with the mature cows from first breeding through first calving. As a result, these heifers may not receive the proper nutrients to meet their dietary needs.
Keep in mind that replacement heifers should be at 60%-65% of their expected mature weight at 15 months of age. They should also be at least 85% of their expected mature weight when they calve for the first time as two-year-olds. These heifers should be bred before the mature herd. This allows the producer to better supervise the first-calf heifers at calving and allows them more time to start cycling and get bred back as two-year-olds. This scenario sets up the replacement heifers to have realistic chance to become productive members of the herd.
Management of the bull power needed to adequately cover the number of cows in the herd is a key component to reproductive success. The appropriate bull to female ratio will vary on a variety of conditions such as the bull’s breed, age and body condition, the nature of the pasture situation, and the length and seasonal timing of the breeding season. A longstanding rule of thumb for a proper bull to female ratio would be one female per months of the bull’s age up to 36 months of age. There are instances where producers will turn out multiple sires over a larger group of cows. Do not assume that number of matings per sire will be spread out evenly across the herd. Research has shown there be various levels of dominance expressed across a multiple sire pastures in terms of the number of calves sired by each bull in a pasture.
What are some reproductive goals for the beef herd that the cow-calf producer can strive to achieve? Consider the following targets:
- 90%-95% in heat in the first 21 days of the breeding season. Note: This will be virtually impossible to achieve in anything longer than a 60 day breeding/calving season.
- 70% conceive on the first breeding.
- 90% or greater conception at the end of a shortened breeding season.
- Less than 5% difficult or assisted births.
- 90% of cows bred wean a calf.
Achieve these reproductive goals and you will be well on your way to future profitability with your cow-calf enterprise.
Source:osu.edu