Putting Preg-check Results to Work
Evaluate management decisions by analyzing pregnancy rates.
The day you pregnancy-check is one of the most important days on the ranch as it is the day when we find out which cows are pregnant and how many calves we can expect come calving season. So now that the veterinarian has left the yard and the open cows are sorted off, what’s next? Before throwing the preg-check list on the dashboard, never to be looked at again, try to reflect on the results. Take some time to sort through them to uncover valuable information to assist with breeding-season management and what to expect for the upcoming calving season.
Analyzing your 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 and non-breeders.
Pregnancy rate (%) — (number of cows diagnosed pregnant ÷ number of cows exposed at breeding) ✕ 100
Preg-checking can determine the overall fertility of the cow herd. 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. Also, evaluate pregnancy rates by sorting cows into age groups to see if a certain age group is falling out of the herd, such as 2-year-olds or old cows.
Pregnancy distribution — (number of cows that became pregnant during days 1-21 of the breeding season, as well as during days 22-42, days 43-63, days 64-84, and Day 85 or later.
Analyzing pregnancy distribution can be used as a guide to prepare for the calving season. 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, Fig. 1 shows the pregnancy distribution from a cow herd where 66% of cows became bred during the first 21 days of the breeding season.
The strength of the cow herd in Fig. 1 is that more than 80% of calves will be born during a 40-day period, resulting in a larger, more-uniform calf crop to take to market.
Culling rate (%) — (number of cows died, open or sold ÷ number of cows exposed to breeding) ✕ 100
If a greater than normal cull rate is observed, records can help 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. Keeping track of culling rate will help determine the number of replacement heifers needed to maintain herd size.
In addition, if bulls become injured early in the season, more cows will likely be bred during the second or third cycle. Reproductive diseases such as 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 cause loss of pregnancies. Fig. 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.
Benchmarks
Records such as pregnancy and cull rates are critical in that they give insight into management areas that affect the reproductive and economic success of the herd. Keeping consistent records from year to year will allow benchmarks to be created unique to each herd, which can then be used for comparisons and performance analysis. If cow herd records are sparse, industry averages or benchmarks such as Cow Herd Appraisal Performance Software (CHAPS) can be utilized for initial comparison until more years of records are collected.
Resources
The Beef Management and Reproductive Score Card and 2017 SDSU Extension-sponsored Integrated Resource Management (IRM) Red Books are available to assist producers in year-round recordkeeping needs. Contact an SDSU Extension beef team specialist for a 2017 IRM Red Book (limited supply available) and assistance in collecting and analyzing production records.
Editor’s Note: Taylor Grussing is a cow-calf field specialist for South Dakota State University Extension.