Improve your profits by lowering open rates in first calf heifers

Posted on by
Retrieved: December 9, 2019, 1:24 am

This is a guest post written by Karin Schmid, Beef Production Specialist with the Alberta Beef Producers.

Young cows are investments. And like investments in a stock portfolio, they need to be monitored and their management needs to be periodically adjusted if they’re going provide you with your desired return.

While the average cost of raising a bred heifer in 2018 was $1,840, the most expensive (or valuable, depending on your perspective) cow in the herd is the one that has just had her first calf, because she hasn’t had a chance to recoup any of that investment through the sale of her calf yet. You’re hoping she has a second calf, and a third, and many more to pay for and profit from that investment, but first she has to breed back for the second time.

We ask quite a lot of these first calf heifers. Even while they are still growing, they’re expected to raise a calf and rebreed back on time. Their energy and protein demands are going to be 10 to 20 per cent more than those of mature cows, but at the same time, they are only physically able to consume about 80 per cent as much dry matter as mature cows. Mature cows tend to be more aggressive at the feed bunks or in extended grazing situations, outcompeting these younger cows for the highest quality feed.

On top of this, the post-partum interval (the period after calving before cycling starts again) is longer in first calf heifers, generally at least 80 days and up to over 100 days, compared to 50-60 days for mature cows. This is a very tight window for a first calf heifer to rebreed and remain on a one-year calving cycle given a fixed gestation length of about 283 days. This post-partum interval will be lengthened further by poor body condition, diets lacking sufficient protein and/or energy, calving difficulty, or trace mineral deficiency.

These factors all contribute to a relatively high open rate for first calf heifers. The Western Canadian Cow-Calf Survey reported a 12% open rate in heifers in 2017, while the 2015/16 Ontario Cow-Calf production survey was slightly higher at 14.5%

How much does it cost to have 12 first calf heifers out of a hundred cow herd not return to have a second calf?

If we assume that each first calver:

  • Cost $1,840 to get to the bred heifer stage,
  • Cost $926 to maintain for that next year until we find out she’s open at preg checking in November (92% of $1,007 to keep her for a year, AgriProfit$ production cost 2017),
  • Her calf sold for $1,254 (550 lbs at $2.28/lb, Canfax Nov. 2017 avg. price) and
  • Her salvage value is $1,262 (1450 lbs at $0.87/lb, Canfax Nov. 2017 avg. price),

We’ve lost $250/head, or $3,000 on the whole group of 12 open first calvers.

So, how do we make sure that we’re setting ourselves up for rebreeding success? By ensuring all the “stocks” in our breeding portfolio are optimized.

The three top dividend payers are:

  • Body Condition,
  • Nutrition, and
  • Timing of Breeding.

Setting up first calf heifers for reproductive success should start Keep a close eye on their body condition score (BCS). They should be maintained at 3 to 3.5 using the 5-point scale pre-calving to post-breeding. Previous research has demonstrated that first calf heifers with a BCS of 3 at calving subsequently have pregnancy rates over 90 per cent regardless of weight gain per day. Those first calf heifers with a BCS of less than 3 at calving, even while fed to gain at 1.8 lb/day, had pregnancy rates of below 70 per cent.

It is easier to make sure body condition scores remain optimal by feeding first calvers separately from the mature cow herd as they head into winter. This allows for specialized supplementation programs, reducing the competition from mature cows. It also avoids wasting money by managing the entire cow herd to meet the first calf heifer requirements and overfeeding the mature cows. Within three weeks of calving, first calf heifers voluntarily reduce their daily feed intake by up to 17%, likely due to the size of the feturs reducing physical space in the rumen, emphasizing the importance of a high-quality, energy dense ration for this class of cattle.

While ensuring optimum body condition will have a beneficial effect on rebreeding first calvers, research also indicates that it matters whether they are on an increasing or decreasing plane of nutrition prior to rebreeding. Even if the first calvers aren’t visibly losing body condition, weight loss may be occurring that will negatively impact pregnancy rates. Hands-on body condition scoring will help detect differences before your eyes register a significant change.

Post calving, first calf heifers need a high energy and protein diet (at least 62% TDN and 11% CP), which is unlikely to be achieved on a forage diet or early season grass without some form of supplementation. Feed testing is the only way to tell how much and what type of supplement needs to be provided.  Feed testing allows more strategic feed use, allowing the use of poorer quality feed when nutrient requirements are lower earlier in gestation, and saving higher quality feed for closer to calving and rebreeding. In addition, it will help identify any potential nutrient deficiencies. Many soils in Canada are low in copper, and increased open rates as a result of copper deficiency will show up in first and second calvers before the rest of the herd is affected. Feed or water high in minerals that can bind copper, like sulphur or molybdenum, can also cause issues.



According to the 2017 Western Canadian Cow Calf Survey, only 14% of respondents bred heifers at least 14 days earlier than cows. In Quebec, 16% of herds over 40 head 22% of herds with less than 40 head bred their heifers earlier than their mature cows. With a post-partum interval of 80-100 days in first calf heifers, any additional time given to overcome that period is going to be beneficial (remember on average, cows need to be bred within 80-85 days of calving to maintain a one-year calving interval). Breeding your replacement heifers at least a cycle (21 days) earlier than the cows by artificial insemination or putting a bull out with the heifers earlier is going to help ensure they are back in estrus when it’s time to rebreed.  Ideally, they should calve again in the first 21 days of the next calving season.

Research from the U.S. Meat Animal Research Centre (MARC) on over 16,000 heifers demonstrated that those heifers that calved in the first 21 days of the calving season were more likely to have four more calves than those first calvers that calved in second or third 21 days of the calving period. The early calvers also consistently weaned heavier calves.

Data from the Western Canadian Cow Calf Surveillance Network indicates that pregnancy rates in heifers from herds that started their breeding season in July or August were 5% lower than those that started their breeding season in June or earlier (87% vs. 92%), a trend that was also apparent in mature cows. This confirms anecdotal reports of conception rates falling as calving seasons move later in the year. If energy demands of peak lactation and rebreeding are highest in July and August, the same time as forage quality is generally declining, these decreased pregnancy rates may simply be due to a lack of adequate nutrition during this critical time period. Heat stress in certain areas in July and August may also play some role in these observations. However, reductions in pregnancy rate from later breeding seasons may be offset by labour, marketing, or facility considerations that favour later calving and breeding.  This trade off will have to be evaluated by each individual producer to determine what is best for their operation.

A “survival of the fittest” approach to first calf heifer management may seem like a good way to improve conception rates, but every cull cycle leaves dollars on the table.  Survey results in Western Canada also indicates it doesn’t work. Conception rates for all females have decreased by over 3.5% since 1998. Providing these young cows with the management they need to succeed reproductively by managing body condition score, fine tuning their nutrition program, and optimizing breeding time is an investment strategy that will pay off.

Learn More:

Reproductive Failure, Beef Cattle Research Council.

Different Approaches/Same Goal For Winter Management Of Heifers (Blog Post), Beef Cattle Research Council. 2017.

Boosting The Calf Crop Percentage In Your Beef Herd (Webinar), Beef Cattle Research Council, 2014.

Click here to subscribe to the BCRC Blog and receive email notifications when new content is posted.

The sharing or reprinting of BCRC Blog articles is welcome and encouraged. Please provide acknowledgement to the Beef Cattle Research Council, list the website address, www.BeefResearch.ca, and let us know you chose to share the article by emailing us at info@beefresearch.ca.

We welcome your questions, comments and suggestions. Contact us directly or generate public discussion by posting your thoughts below.

Leave a Reply

Your email address will not be published. Required fields are marked *