Reproduction is often called the most important element for cow-calf operations – because without a successful breeding program there is no live calf to sell.

In early December, Colorado State University hosted its bi-annual Robert E. Taylor Memorial Symposium with the focus of this year’s program on improving the understanding and application of reproductive technologies, including AI, estrus synchronization and factors affecting male fertility.

Over 20 speakers were featured on the two-day program. Following are highlights from some of the presentations. Audio, power point and summary write-ups of all of the speakers can be found online at the newsroom at www.appliedreprostrategies.com.

As we move into calving season for most Midwestern cow-calf operations, Rick Funston, University of Nebraska Extension reproductive physiologist, reminded participants of the importance nutrition plays on reproductive performance.

Funston said that research indicates, “It is better to have cows and heifers in good condition before calving than to play catch up after calving.” He recommended that cows be in a body condition score (BCS) of 5 to 6 prior to calving.

To that end, he said, “Balanced nutrition is the key to optimizing production.” On his list of nutrients to consider were protein, energy, minerals, vitamins and water. Some tips that he highlighted to achieve this balance:

• Minerals and vitamins must be balanced in the diet to optimize reproductive performance. Funston recommended that mineral supplementation is critical 45 days prior to calving, through the breeding season and prior to weaning.
• Consider water quantity and quality when balancing diets.
• Be cautious about overfeeding nutrients as it has been shown to delay puberty, lower ovulation and lower conception. However, Funston acknowledged that there is a misnomer that feeding cows protein too extensively prior to calving increases dystocia. But he says research has proven otherwise. “It may increase the birth weight slightly, but there is no impact on calving difficulty.” To avoid overfeeding, he reiterates that the rule of thumb for a herd should be a BCS of 5-6 prior to calving.
• Consider feeding fat as a prepartum supplement. Funston reported on multiple research studies that indicate feeding fat – from sources such as sunflowers to ethanol by-products – about 60 days before calving can improve pregnancy rates in beef cow herds.

Lastly, Funston emphasized that there is no quick fix for reproduction challenges brought on by poor nutrition. He said, “There is no magic feed ingredient that exists to compensate for a diet deficient in any of the mentioned nutrients or poor BCS.”

Jim Graham of Colorado State University emphasized that cow-calf producers should take heed of Breeding Soundness Exams (BSE) and the information they provide to evaluate bull fertility prior to breeding season next spring. He says all three components of the BSE – the physical exam, the health evaluation and the semen analysis – are important.

Graham suggests that producers should cull the bulls that fall in the lowest 15-20% of the BSE exam. “Remember the most important thing is fertility and getting cows bred,” he says. Thus, culling bulls based on BSE results such as a small scrotal circumference or low motility is a step toward improving herd fertility. “This is a very cost-effective approach,” Graham adds.

Graham also discussed the status of sexed semen in cattle. He explains that the only way to sex semen reliably is based on the different DNA composition of the X and Y chromosomes – the X chromosome is 3.8% larger than the Y. “That’s not very much,” Graham says.

While the sexing process does produce safe, viable sperm and calves, Graham reports that sorted sperm are very different than non-sorted due to the pressure of going through the flow cytometer. “Sex sorted cells swim differently; die more quickly and have more damage,” he says.

Because of the fertility differences in bulls, he adds that semen from some bulls cannot be sorted. “Some don’t take the stain through the sorting process or because of the added damage to the cells after sorting, they won’t freeze.”

Thus, Graham believes sexed semen will likely continue to be available only in small numbers.

George Perry, assistant professor in beef reproductive management at South Dakota State University, addressed the question of why beef herd pregnancy rates can vary so much.

He attributes the variation to management, saying, “Management can affect the outcome of artificial insemination (A.I.) or natural service breeding.” And he emphasizes to cow-calf producers, “Little mistakes can add up to a big impact on fertility.”