The Beef Cattle Institute’s Dr. Bob Larson brings you a series of “cases” employing the use of the Pregnancy Analytics mobile app. Each case will explore a unique herd and examine its reproductive efficiency, strengths, challenges and areas of improvement. The reports (linked below) will lead you through using the Pregnancy Analytics app to utilize the data and practice using it on an actual problem herd.
The case: Diagnosing poor fertility
A herd of 187 commercial cows was palpated on September 19. The herd was split into three breeding pastures and bulls were turned out on May 30. All cows were moved to a new pasture on August 1 to run together with bulls removed. During the breeding season 38 were in the “South Pasture,” 47 were in the “Home Pasture,” and 102 were in the “Webster Pasture.” All heifers and about half the first-calf heifers were in the Webster Pasture.
At preg-check, 59 cows were open (68.5% were pregnant) and 80% of the cows were in moderate body condition (BCS 5 up to 6) while 17% were classified as being in thin body condition. 10.4% of the herd became pregnant in the first 21 days (pregnancies would have been 91 to 112 days), 23.6% in the second 21-day period (79-90 days), 17.6% in the third 21-day period (49-89 days), and 18.7% in the fourth 21-day period (28-48 days). The goal for this herd (and for most herds) is to have at least 60% of the cows becoming pregnant in the first 21 days of breeding.
Something isn’t right here. The poor overall percentage pregnant clearly indicates a problem and the percent pregnant by 21-day interval provides information that the poor reproductive performance continued for the entire breeding season.
To evaluate further, the Pregnancy Analytics App provides a way to easily divide the herd into pertinent sub-groups. When the pregnancy success by 21 days is evaluated by age group, we find that none of the age groups perform well, and the heifers perform particularly poorly. (First-calf heifers are defined as those cows suckling their first calf and being bred for their second pregnancy.)
More information can be found by displaying % Preg Success and finding that while neither the 1st-calf heifers nor the cows performed well the first, second, and third 21-day periods, both these age groups improved slightly the forth 21 days, but still were below the expected 60-70% pregnancy success expected. In addition, the heifers performed very poorly throughout the breeding season.
So far, the information doesn’t narrow the rule-out list. Problems with heifer development, a similar calving pattern last year that results in many cows not calving until after the breeding season has started, and poor bull fertility or Trichomoniasis are all possible contributors to this herd’s poor performance.