By Robert Fears
It is hoped that you had an opportunity to attend the Cattle Raisers Convention and Expo in Fort Worth at the end of last month. It was a great event for enjoyment, education, and meeting old and new friends.
Dr. Brad Lindsey, Ovitra Biotechnology, gave one of the outstanding presentations in the School for Successful Ranching. His presentation was titled, “Optimizing Reproductive Efficiency in the Breeding Herd” and contained information gathered through 35 years of field experience helping ranchers solve reproduction problems in their beef cattle herds. This article provides a summary of Lindsey’s presentation.
“At some point, ranching operations have experienced periods of inconsistent or low pregnancy rates or other reproductive associated problems,” said Lindsey in his introduction. “Most producers desire more cow pregnancies, fewer calf losses, and faster genetic improvement. To realize these desires, it is now possible, and in most cases necessary, for cow-calf operators to adopt and implement techniques used by seedstock producers.”
Preparation for the breeding season
Essential prerequisites for optimizing reproductive efficiency include the placement of a permanent and unique identification on each animal, which provides the basic means of keeping accurate records on the animal.
Reproduction parameters to record would include age, weight, body condition score (BCS), age at puberty, age at first calving, calving dates, ease of calving, birth weights, breeding exposure method and dates, pregnancy status, weaning weights and any other measurements that will help determine female performance.
Cows with a low BCS at calving require a longer post-partum interval to rebreed than do cows with a good BCS, which makes this measurement especially important.
Once a good record keeping system is in place, it is time to evaluate which breeding methods will improve the herd genetics most efficiently. Options include natural breeding, artificial insemination (AI) and embryo transplants (ET). If natural breeding is utilized, it is important to select herd sires that will elevate the genetic value of potential replacement heifers, stock enough bull density to ensure each cow is serviced and perform breeding soundness exams (BSE) on all bulls before putting them into service.
For AI, choosing the optimal sires to complement the genetic line of each dam is easier when good record keeping is in place.
Successful breeding requires good nutrition and animal health programs. Analyze the nutrient content of pasture forage and hay. Based on animal nutritional requirements, use these analyses to choose vitamins, minerals, and supplements to overcome any nutrient deficits in the forage and hay.
Consult a veterinarian to select appropriate vaccines and internal and external parasite treatments. Integrate a defined calving/breeding period with good nutritional and herd health programs for more efficient breeding and economical management.
Implementation and maintenance of breeding strategies
Prior to the implementation of a breeding program, it is a good idea to pre-screen heifers, dry cows, and wet cows to determine reproductive cycles and thus, their capacity for breeding. This pre-screening will also reveal whether the nutritional program is a success or a failure.
Rectal palpation or ultrasound of cows and heifers will determine their breeding soundness and allow sorting for synchronization.
For herds with a history of low pregnancy rates and abortive issues, blood sampling is recommended to determine if pathogens such as Leptospirosis and Neospora are present. Selection of breeding-eligible females should also be based on genetic merit and ranch goals such as raising replacement heifers or herd sires, developing calves for the feedlot, or providing recipient females for embryo transfer.
After a reproductive screening, sort the breeding-eligible females into groups that can be managed and fed similarly. Then implement the schedule of reproductive techniques required to accomplish the breeding goals. If females are to be artificially inseminated, select a synchronization protocol that best matches the animal’s reproductive status and management capabilities, especially estrus detection periods.
Determine the number of necessary clean-up bulls and the timing and length of the exposure period. Schedule an appropriate method and time for pregnancy detection and determine whether attempts should be made to rebreed open females and if so, how, and when.
Essential to an improved breeding program is the placement of permanent and unique identification on each animal to help keep accurate records.
Select definitive dates for termination of the breeding period and weaning of calves. After pregnancy detection and again after calving, review breeding/calving records and cull those cows that did not breed, calve, or that produced calves that did not meet genetic goals.
Set a high standard for culling cows with bad teeth and/or udders, and certainly resist the temptation to keep open females for the next breeding season. Cows that breed early or on time each year will typically have a higher index of fertility. Inversely, cows that calve in the second half of the calving season are more likely to have a lower index of fertility.
Long-range reproductive strategies for additional genetic gains
Once the above-described practices have been perfected, a cow-calf producer might want to look at some other long-range reproductive strategies for additional genetic gains.
The producer’s targeted market dictates whether bull or heifer calves are of equal value or if one has greater value than the other.
Ultrasound fetal-sexing, which is possible at 60 to 100 days of gestation, provides advance identification of calf gender. This information allows for advanced planning and/or marketing a future calf crop. It is now possible to artificially skew the gender-ratio by utilizing sex-sorted semen in AI and/or multiple offspring embryo transfers (MOET) programs.
If producers simply want to propagate more of their own within-herd genetics, this can also be accomplished through MOET techniques applied to the existing breeding program.
Females with superior genetics and production histories can be selected and utilized as embryo donors and subsequently super-ovulated and mated with complementary sires to produce embryos. The embryos, fresh-collected or frozen, are transferred to females in the herd with a lower genetic value. This yields more calves with superior genetics and accelerates herd improvement through shorter generation intervals. A normal lifetime’s worth of offspring is produced from one donor animal in one breeding season. Utilization of embryos from within-herd genetics offers a more aggressive alternative to AI because it optimizes the genetics of both the sire and dam.
Outside-herd genetic integration into the existing breeding program is yet another way to rapidly improve herd genetics.
Frozen embryos from superior or novel genetic donor cows are typically purchased from another producer at a lower cost than purchasing those same animals and then obtaining embryos from them. Additional ways to acquire outside herd genetics are to purchase an embryo collection of a particular donor, lease the potential embryo donor(s) for the purpose of producing embryos or enter into a donor/embryo partnership arrangement.
“Producers must do their homework in order to prepare for the breeding season,” said Lindsey in summary.
“They must then implement their breeding plan with strict monitoring and post-season decisions that eliminate problem breeders and facilitate breeding proficiency. Adoption and implementation of these reproduction strategies will ultimately result in more pregnancies, fewer calf losses, and faster genetic advances in breeding herds.
“Progressive management is a prerequisite for the implementation of aggressive techniques such as utilizing sexed semen and/or MOET. Collectively, these strategies will result in much faster propagation and major improvements in the genetic merit of breeding herd females and their calves.”
Optimizing Reproductive Efficiency is excerpted from the April 2019 issue of The Cattleman magazine. Join today to start your subscription.
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