Participants in last week’s Range Beef Cow Symposium enjoyed a “peek under the curtain” at potential advancements in reproductive technology from George Seidel, PhD., Colorado State University distinguished professor of biomedical sciences.
Over his years at CSU’s Animal Reproduction and Biotechnology Laboratory, Seidel has led cutting-edge research in cattle reproduction, including estrus synchronization and the development of sexed semen. He says that in some situations, technology can improve the speed and efficiency of meeting reproductive goals, which include:
- Getting cows pregnant as close to the optimal time as possible. For most herds, non-pregnant and late-pregnant cows are the most costly problem in the operation.
- Genetic improvement to meet productivity goals and improve profits.
- Improve convenience and efficiency objectives such as shortening the calving season, introducing the polled trait and decreasing dystocia.
- Experimenting with new approaches, which, if nothing else, can help keep owners and employees interested and motivated.
Looking back, Seidel notes that prior to the 1950s, there was no frozen semen, no disposable tools for AI, no EPDs, no estrus synchronization, no embryo transfer and minimal vaccination for reproductive diseases. Since then, a number of technologies have come in to routine use with significant impacts. Seidel lists his top-10 in chronological order.
- Artificial insemination: The oldest on the list, Seidel describes AI, using superior semen, as the most powerful reproductive-technology tool for most applications.
- Electroejaculation: Essential for breeding soundness exams
- Vaccination against reproductive diseases
- Cryptopreservation of sperm
- Readily available hormones for estrus synchronization: progesterone, GnRH, prostaglandin F-2-alpha, FSH and others
- Body condition scoring
- Expected progeny differences
- Ultrasound for ovarian status, pregnancy, sexing, pathology of uterus ovary and testis
- Sexing embryos, fetuses and sperm
Sex is one of the most important genetic traits, and sexed semen currently is available for use in beef cattle. Seidel notes, though, that sexing semen is about 90 percent accurate, cost per semen dose is $15 to $20 higher than for conventional semen and fertility is about 10 percentage points lower, even with ideal management. One practical application for beef producers is to use sexed semen to breed heifers to have heifer calves with first-service AI. This could reduce dystocia while speeding genetic improvement, as heifers typically have the best genetics in the herd.
Looking to the next five to 10 years, Seidel says procedures such as ovulation synchronization and sexing semen will become more refined, fetal programming better understood and genomics more readily applicable.
In the longer term, Seidel expects transgenic manipulations, also called biotechnology or genetically modified organisms (GMOs), to become more common in livestock. In the crop world, 90 percent of the corn and soybeans grown in the United States are GMOs, but none of the cattle. These tools are so powerful they cannot be ignored indefinitely for production purposes, he says.
One potential application, used along with sexed semen, would be to link genes for cattle growth to the “Y” chromosome. This could allow production of male calves that grow rapidly and efficiently after birth, while also keeping cow mature size and maintenance requirements low.
Using sexed Semen, Seidel speculates that it could be possible to build a production system that essentially eliminates the need for a cow herd by having each heifer replace herself with a heifer calf. Weaning calves at three months of age, feeding the dams for three months then sending them to slaughter would require only slightly more nutrients per animal than currently used for raising replacement heifers, with no cow herd to maintain. Because reproductive efficiency would be less than 100 percent, some females would need to remain in the herd to produce a second calf.
Such a system would need some bulls, but not very many. In any case, Seidel says optimizing bull genetics will become interesting as genomics will allow selection at the embryo stage or earlier. Bull embryos could be produced by in vitro fertilization and screened with genomic testing from biopsies to producer thousands of new genotypes each week. Cells of selected embryos could be multiplied and further modified using transgenic technology. Scientist then could clone nuclei from those genetically improved cells to produce new embryos for transfer to recipients to produce bulls needed for semen production.
It’s a brave new world.