By Dr. Bob Larson
The BCI Pregnancy Analytics App was released in the fall of 2016 and is being used by veterinarians and beef producers to enhance monitoring and evaluating cowherd breeding season success. Veterinarians know that being able to visualize the percentage of a cowherd that becomes pregnant each 21-days of the breeding season can provide important information to identify the contributing causes for situations when a lower than desired percentage of the herd becomes pregnant, or to identify areas for improved reproductive efficiency. Until now, collecting and evaluating that information while at the chute during preg-checking has been difficult. Data entry for the BCI Pregnancy Analytics App is even easier than using a paper-and-pen method and has the benefit of data analysis that is as powerful as a chute-side computer.
Beef cow reproduction is limited by two key factors, the first being a relatively long period of infertility following calving and the second being that only 60% to 70% of successful matings between a fertile bull and fertile cow will result in a viable pregnancy at the time pregnancy status is determined a mid-pregnancy. We know that approximately 30% to 40% of fertile matings result in either failure of fertilization or death of the early embryo, but in most situations, the cow will express heat and ovulate a fertile egg about 21 days after her last heat and have another 60 to 70% probability of conceiving and maintaining a pregnancy. Fertile cows that have three opportunities to be bred by a fertile bull in a breeding season (each with a 65% probability of a successful pregnancy) will have a 96% probability of being pregnant at the time of a preg-check about one-half way through pregnancy.
If nearly all the cows in a herd calved early enough so that they have resumed fertile cycles by the start of the next breeding season, and the bulls are fertile and able to successfully mate, then the ideal pregnancy pattern would have about 60% to 65% pregnant in the first 21 days of the breeding season, 85% to 90% pregnant by the 42nd day of breeding, and about 95% pregnant after 63 days of breeding.
Herds that only have 50% of cows cycling by the end of the first 21-days of the breeding season are expected to have no more than 30 to 35% of the herd become pregnant in the first 21 days (60 to 70% pregnancy success from the mating of fertile cows to fertile bulls) and the pattern will be flatter and longer than the ideal pregnancy pattern. The magnitude of non-pregnant cows at the end of the breeding season will depend on the length of the breeding season. Even if the breeding season is limited to 63 days, at least 80% of the cows are expected to be pregnant if the problem is confined to issues of cows resuming fertile estrous cycling during the breeding season. A magnitude of non-pregnant cows that exceeds 20% of the herd is not likely due to cow-problems alone and either bull problems or a combination of cow-problems and bull-problems should be investigated.
Poor pregnancy success due to bull problems can often be detected at the time of preg-check by using the pattern to identify a substantial decrease in the pregnancy success by 21-day periods. Because previously fertile cows rarely become infertile over a short period of time, but bulls can suddenly become less fertile due to testicular, penis, or leg problems, any time that reproductive efficiency suddenly decreases during a breeding season, bull problems should be considered likely.
The only data required by the Pregnancy Analytics App is the dates for the start and end of the breeding season and an estimate of the fetal age for each cow’s pregnancy. Additional information such as cow id, cow age, body condition score, and breed (or other descriptor) can be added to enhance the value of the preg-check information.
The veterinarian and producer can decide whether to share the cow data with BCI or not. No herd identifiers are available to BCI – so even if you share the data we can’t identify any person with the herd. If you agree to share the data, BCI will have access to the cow information (% pregnant, % with each BCS, starting date for breeding season, etc.), but not the producer or veterinarian information. By submitting the data, the herd’s data is compared to a benchmark created from all the submitted herds or a benchmark of the herds submitted by that veterinarian/clinic. If you choose not to submit the data to BCI, the app works the same, but there is no benchmark for comparison.
After preg-check data is entered, projected calving dates are generated and graphs are created to display the distribution of the upcoming calving season. These pregnancy patterns can help identify the most likely contributing factors when investigating herds with lower than desired percent pregnant.
The BCI Pregnancy Analytics App can serve as a valuable tool to assist veterinarians and producers improve reproductive efficiency of beef herds. By the start of 2017, the Pregnancy Analytics App has been downloaded nearly 800 times and over 250 herds with nearly 7,000 cows have already been entered and permission given to be uploaded into the BCI database. The BCI Benchmark is calculated to illustrate the level of reproductive success needed to be in the top one-third of the database. At this time, the Benchmark indicates that to be in the top third of herds, 63% of cows become pregnant during the first 21 days of breeding, 19% become pregnant in the second 21 days, 9% become pregnant during the third 21 days, 3.5% become pregnant in the fourth or greater 21 day periods, and 5.5% of the cows in the herd are open.