Decisions today for tomorrow’s cow: maximizing longevity and productivity

Replacing the beef cow on Florida ranches creates opportunities and challenges for ranchers. In this article we will discuss factors to consider when choosing and managing your future cow herd. Decisions you make about your replacement heifers can impact their longevity and lifelong productivity. We will discuss choices you can make while raising your own replacement heifers and also review the pros and cons of purchasing replacement heifers.
When thinking about replacement heifers on your ranch you need to consider two questions: what do I want my heifers to look like genetically and phenotypically and also how can I produce or buy heifers that will last in my cow herd?
Cull Cows:
Lets start with how many heifers you could potentially need annually. The current cull rate in Florida is 15-20%. So, that is your starting point. However, if you are looking to change the size of your herd you should adjust accordingly. Reasons for culling cows include: age, pregnancy status, temperament, other reproductive reasons, poor calves, or physically unsound. This list eludes to some characteristics you should consider in your replacements.
Purchasing versus raising:
Statistically speaking most producers raise their own heifers. However, some purchase heifers because they don’t have the land to raise them separately, they lack the extra labor they need to manage them, they don’t have the time, they don’t want the extra cost of supplementation or feed, they don’t have the appropriate bull power to breed them to or they want to utilize what land they have towards their main cow herd that gives them a quicker return. If a producer only has a few employees they may want to focus on operational improvements, like planting improved forages, maintaining fence lines or roads, or growing alternative crops to supplement income.
The benefits of purchasing go beyond management inputs. Purchasing heifers can give a producer instant improved genetics. Plus, they can be bought to fit right into your calving season preference. They are already bred, potentially docile, are up to date on vaccines and health protocols. These are all things the producer didn’t have to think about or spend time on.
Reasons to retain:
However, 86% of producers do like to grow their own heifers out. They do this because they have always done it, they do it because they can control the genetics, vaccines, nutrition, they can control the breeding season length, and one major plus is that they are acclimated to your system and your environment. For example, if a south Florida producer buys a set of heifers from Georgia those heifers may struggle with the environmental difference between the two locations. They may exhibit a lag in breed, lose weight or even a calf. The same goes for bulls. Bulls raised in the same geographic region can adapt quicker to a new home.
How much does it cost?
So, lets look at the economics behind raising heifers. The major expense is of course the heifer itself. According to the 2019 data a weaned heifer calf value is $1.30/lb If a heifer is weaned at 550 lbs that makes her value to be $715. Following that expense is all the inputs. There are things on this list you probably haven’t thought of as an expense like land rental or taxes. Other things are easy to put on paper because you have an actual invoice or bill to pay for it…like fertilizer inputs to improve your pasture fertility, supplementation, cost of breeding (could be bulls or AI expenses), health expenses, paying for the vaccines and the vet. Other expenses include labor and equipment (tractors, feed bunks, fences, fuel etc). Besides the inputs for each heifer there is also the extra cost of paying for those heifers you have put resources in but will give you nothing in return if they don’t breed. So, including all of those inputs an average heifer in 2019 costs $1,600.
Raising them right:
If you do decide to raise your own heifers lets consider some management practices you will need to factor in. To maximize your replacements all these factors play into their longevity and productivity. Choosing the appropriate weaning weight, selecting the best, breeding at the optimal pubertal age, feeding or supplementing them, and setting them up on the best health foundation with vaccines, vitamins and wormer can give a great platform for your next cow herd.
Separate and supplement!! This process starts with weaning. The average weaning age is 9 months when calves weigh around 500-750lbs. However, some ranchers wean early, at 2-3 months, for a couple of reasons. They may want to give the cows optimal chance to bred back. Removing the calf can jump start her reproductive cycle while also removing the stress of lactation allowing her to put her energy into her body condition and her next calf. Some producers also see a value to weaning at this age to aid in the docility process. Being around people and other stimulation can calm your calves faster and foster a quieter future herd. If you wean calves at this age, you will encounter extra supplementation costs as you will have to feed them longer.
If you wean at 9 months you will be closer to their maturity age and you will not need to feed as long or utilize you pasture space as long. Research suggests you use a 12-16% protein diet as well as a foundation of forage for best results.
Early Weaning study:
In this study, there were 4 weaning processes. One left calves with their mommas until 9 months with no supplementation. One group was weaned at 3 months and exposed to a ryegrass pasture with 1% of body weight of concentrated feed followed by 3 months of bahiagrass with the same amount of feed. The 3rd group was early weaned at 3 months and put on a dry lot with 3.5% BW concentrate. The last group was early weaned and exposed to a dry lot with 3.5% concentrate and then at 6 months moved to a bahia grass pasture with 1% bw concentrate.
The outcome of the study was the calves who were early weaned and put on a dry lot for 6 months with 3.5% bw concentrate had a 78% pregnancy rate opposed to the next closest group of 70%. They reached their pubertal age quicker as well as their mature weight.

NW (left with cows, no supp) EWPAST (ryegrass+con 1%) EW180 (drylot 3.5% BW) EW90 (dry lot 3.5%…bahia +1% conc)
Day 90 (early weaning) 306 lbs 297 lbs 361 lbs 376 lbs
Day 180 (normal weaning) 467 lbs 392 lbs 577 lbs 476 lbs
Day 335 (Breeding season) 712 lbs 643 lbs 800 lbs 720 lbs
Age at puberty (days) 429 lbs 418 lbs 298 lbs 358 lbs
Body weight at puberty 753 lbs 674 lbs 629 lbs 643 lbs
Pubertal heifers (% total) 30% 40% 100% 80%
Pregnant heifers 60% 50% 78% 70%

The oldest and heaviest heifers in a calf crop were born from cows that calved early in the calving season. Although reproductive traits are considered low in heritability, heifers from reproductively sound cows should not be overlooked. Heifers that are the heaviest are more likely to reach puberty sooner compared to lighter weight counterparts. By selecting 20 – 25% more heifers than you’ll need, you can cull late breeding or open heifers to offset production costs.
Emphasis should be placed on animals with more internal volume and capacity, natural muscling and fleshing ability. Traits to look for are: spring of rib, depth of rib, natural thickness and shape down the top, thicker quartered, and width through the stifle.
Frame score is easily determined and should be used in the heifer selection process to eliminate those that do not fit predetermined production goals. Selecting heifers with frame scores of 4 to 6 will result in mature cow weights of 1100 to 1250 pounds.
Calves with poor disposition may be a physical risk to anyone who handles them. Not only do they pose a danger, they may display decreased performance as compared to their calmer counterparts.
Femininity is exhibited by a longer, more refined head that is sharper about the poll. Females should possess a long, trim neck and be smooth about the shoulders.
Replacement heifers are costly to develop and the goal is to keep them in the herd as long as possible. These females must be structurally sound in their feet and legs.
In order to maximize your investment it is expected heifers calve at 24 months. This means she should conceive at 13-14 months. Some producers push their herd to breed earlier than this at 12 months. In order to achieve either one of these goals adequate nutrition is required. Heifers usually achieve puberty at 55-65% of their mature body weight. This is an easy method to presume heifers have achieved puberty. Another method is to utilize reproductive tract scoring to determine if the females are in fact ready to bred. The scale is 1-5 with 5 being most mature. Research indicated tract scores with a 4-5 show 20-30% higher pregnancy rates.
One caveat in Florida is the influence of bos indicius genetics to increase heat tolerance. Bos indicus influenced heifers do not achieve puberty as early as the English breeds. Making it even more difficult for Bos indicus and Bos taurus crossbred heifers to become pregnant and calve at 24 months of age.
When considering your breeding cycle it is wise to start your heifers earlier than your regular cow herd. This is done for a couple of reasons. One is it may take a few extra cycles to get the heifers bred depending on their reproductive maturity. The other reason is when they have produced and weaned a calf again it, may take them a couple of heat cycles to rebred. This is because they are still growing at 24 months. They need to continue to increase their body weight while growing a calf.
Use low birth weight bulls as the heifers are not full grown when they calve and do not need the extra stress of a large calf. Something else to consider it to use younger, lighter bulls as the heifers are not at mature body weight and this will reduce the stress of breeding. Be aware of selecting bulls for this singular reason as this can limit your genetic potential and future use of the bulls. 1 bull can cover 25 females.
Herd Health:
This is a simplified breakdown of a heifer development health protocol. Please consult your veterinarian for a custom protocol appropriate for your herd. It is advisable to provide your replacement heifers with the best health foundation prior to starting their reproductive journey.

Vaccine Period of Vaccination
Clostridium 3 months prior to weaning
IBR Weaning and prior to breeding
BVD-P13 Weaning and prior to breeding
BRSV Weaning and prior to breeding
Brucellosis 4-12 months
Vibriosis Weaning and prior to breeding
Leptospirosis Weaning and prior to breeding

Raising replacement heifers has unique challenges and it is different for every producer. The future of your cow herd depends on these management decisions to give you the next best thing for your operation. Keep in mind to select what you want your cow herd to look like, separate and supplement to reach their max potential. To achieve puberty as early as possible look for at least 55-65% of mature body weight. And vaccinate to give them their best chance.

Lancaster,P., C. Prevatt, and J. Artington. EDIS Archive. Improving the Productivity of Beef Heifers in Florida. AN132.
Moriel. P. 2018. Nutrition at Early Stages of Life Determines the Future Growth and Reproductive Performance of Beef Calves. EDIS AN335.
Hersom, M., T. Thrift, and J. Yelich. 2018. Culling and Replacement Rate in the Beef Cow Herd. EDIS AN323.


Posted: March 26, 2021

Category: Agriculture, Livestock, UF/IFAS, UF/IFAS Extension, UF/IFAS Research
Tags: Beef Cattle Nutrition, Cattle Selection, Feeding Cattle, Heifer Development

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