Putting preg check results to work

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SDSU Extension

BROOKINGS — Pregnancy check day is one of the most important days on the ranch.

“It is the day when cattle producers find out which cows are pregnant and how many calves they can expect during calving season,” explained Taylor Grussing, SDSU Extension cow/calf field specialist.

With this in mind, Grussing posed the question. “Now that the veterinarian has left the yard and the open cows are sorted off, what’s next?”

Before throwing the pregnancy check list on the pickup dashboard, never to be looked at again, she encouraged cattle producers to reflect on the results. “Take some time to sort through the list to uncover valuable information such as breeding season management and what to expect for the upcoming calving season,” Grussing said.

Below Grussing shared tips to analyzing preg check results and how to most effectively utilize the data.

“Records such as pregnancy and cull rates are critical in that they give insight into management areas that affect reproductive and economic success of the herd,” Grussing said.

Analyzing preg check results

First start by finding the following information:

• Number of cows at the start of breeding season.

• Start and end dates of breeding season.

• Cow death loss, culls, non-breeders.

Utilizing pregnancy check results and the above information to determine the following:

1. Pregnancy rate: To figure this, take the number of pregnant cows and divide it by the number of cows exposed to breeding. Once you have this number, multiply it times 100.

Pregnancy checking can determine the overall fertility of the cowherd. “If pregnancy rate is lower than desired, areas such as type of breeding program and bull-to-cow ratio should be analyzed to pinpoint where adjustments are needed,” Grussing said.

She encouraged cattle producers to also evaluate pregnancy rates by sorting cows into age groups to determine if a certain age group is falling out of the herd, such as 2-year-olds or old cows.

2. Pregnancy distribution: To figure this, sort the cows based on the number of cows that became pregnant during days 1 thru 21 of the breeding season, days 22 thru 42, days 43 thru 63, days 64 thru 84, and 85 or more days after the start of the breeding season.

“Analyzing pregnancy distribution can be used as a guide to prepare for the calving season,” Grussing explained. “Not only can the barn be ready by the time the first calf hits the ground, but you can also determine when the majority of the calves will be born and adjust labor and feed resources accordingly.”

For example, Figure 1 shows the pregnancy distribution from a cowherd where 66 percent of cows became bred during the first 21 days of the breeding season.

The strength of the cowherd in Figure 1 is that over 80 percent of calves will be born during a 40-day period resulting in a larger, more uniform calf crop to take to market.

3. Culling rate: To figure this, take the total number of cows that died, were open or sold and divide it by the number of cows exposed to breeding. Then, take this number and multiply it by 100.

If a greater than normal cull rate is observed, Grussing said a cattle producer’s records can help them identify what may have gone wrong.

“Start by assessing the body condition and health records as poor nutrition or sickness could be reasons for more open cows,” she said. “Keeping track of culling rate will help determine the number of replacement heifers needed to maintain herd size.”

Grussing added that if bulls become injured early in the breeding season, more cows will likely be bred during the second or third cycle.

Reproductive diseases, such trichomoniasis (trich) can also be spread if an exposed bull is carrying the disease or if a neighboring bull with trich jumps the fence and joins the herd for a period of time. “While cows can clear the infection, bulls remain positive for life and throughout the breeding season and cause loss of pregnancies,” Grussing explained.

Figure 2 shows what the pregnancy distribution may look like if a bull injury went unnoticed or if a herd was exposed to trich during the breeding season.


By keeping consistent records, from year-to-year cattle producers will begin to create benchmarks unique to their herd. These can be used for comparisons and performance analysis.

If cowherd records are sparse, industry averages or benchmarks such as CHAPS (http://bit.ly/2iDPsUu) can be utilized for initial comparison until more years of records are collected.

Figure 1. Pregnancy distribution shows when and how many cows were bred during the breeding season. SDSU Extension graphic
Figure 2. Pregnancy distribution of a cowherd with bull injury early in the season and a trich infection resulting in more open cows at the end of the season. SDSU Extension graphic