Have You Herd — Future Success Through Heifer Development, by Sydney Smith

By SYDNEY SMITH N.C. State University -- ANS 402 Beef Management

Future Success Through Heifer Development

The development of replacement heifers is an extremely important process for beef producers. These heifers are the future of the herd, and they will ultimately determine the profit margin of the operation. It is vital that producers manage them well by providing them with all their needs. These heifers should be managed closely throughout each stage of life, including pre-weaning, weaning, and post weaning. It is important that proper nutrition is provided for each stage of life, target weights are reached, and the heifers are bred early in the breeding season when compared to the cows of the herd. These are practical ways to best develop replacement heifers.

The only way for a heifer to reach her target weight and perform to the best of her ability is to provide her with proper nutrition. Nutrition should be adjusted to cater to each stage of life, as seen in Figure 1. During pre-weaning, the heifer should be putting on weight, but not to the point where she is losing efficiency. If the heifer gains too much weight during pre-weaning, her milk production later in life will not be able to reach its original capability. Producers should keep watch on her body condition score (5-7 recommended) to ensure that she does not gain excess weight. The goal should be to keep the heifers at a body condition score of about five or six prior to breeding.

The next stage of life, weaning, is a stressful time for the heifer. Stress can cause a loss of appetite and, therefore, loss of weight. The best way to support the heifers and combat this issue during weaning is by providing them with all their nutritional needs. High quality feed is a must during this stage of life! To prevent the heifers from turning away from feed, give them something palatable. Grain should be fed along with high quality hay (Poore). The producer can feed a sweet feed by adding molasses to the grain (Poore). Sweet feeds are more palatable to the calves. Trace minerals should also be added to the grain. An optional but beneficial additive would be an ionophore. An ionophore is a feed additive such as monensin or lasalocid (Selk). These ionophores are rumen modifiers and help grow the heifers. Studies prove that heifers can also reach puberty at an earlier age if ionophores are utilized. Body weight is a large determining factor in the start of puberty. In most cases, the higher the body weight, the earlier the heifer will reach puberty, as shown in Figure 3. In some studies, ionophores have also been shown to help heifers that are prone to bloat (Selk). This additive, with its long term benefits, can be extremely effective in the development of heifer calves.

Figure 1. This is an example of nutritional requirements for growing medium framed heifers that are at different body weights (Rayburn)

Target weights are tangible goals to reach when it is time for breeding. If she meets her target weight, she is a desirable heifer. Each breed has different target weights. Mature body weight predictions should be based on the specific herd as well as the specific breed standards. Once the target weight is determined, the needed average daily gain (ADG) can be calculated. The weight can be put on at a constant rate or gradually depending on the nutrition plan, as seen in Figure 2. Each method has advantages and disadvantages. The constant rate of gain method will use the least amount of energy and supplemental feed (Arthington). The other two methods will use more energy when they are at the levels of increasing gain but may need less supplementation overall (Arthington). If this is the case, feed costs may be reduced depending on the price of the feed utilized. The slow gain method may be beneficial to the growth of the heifer later in life, but it is a risky method. The heifer may not reach her target weight in time and will have a delayed onset of puberty. Each producer should make their decision based on the resources they have. If she reaches her

Figure 3. Shows how body weight impacts the start of puberty, with both Bos taurus and Bos Indicus breeds being represented (Arthington)

The post weaning period is the time leading up to breeding. The heifers should be at least 65 percent of their mature weight by the time they are bred (Extension). To do this, producers should compare their growing heifers to industry standards but, more importantly, to the mature cows within their herd. This goal helps to ensure that the heifer will be able to carry and sustain a calf. During this growth stage, supplemental feed may be required if pasture is not enough. Forage analysis should be done for pasture and hay on a regular basis. Hence, the producer knows exactly what is being fed to the animal and what supplementation needs to be provided. This is also a great time for the heifer to catch up if she lost weight during the weaning period due to stress. Proper nutrition is critical in each stage! If the heifer is not receiving proper nutrition, then she cannot reach her target weight. target weight, then she has a better capability of carrying and delivering a calf. The most important thing is that the heifer reaches this target weight by the time she is bred!

The most important piece of replacement heifer development is getting her bred. To be a productive replacement heifer, she must produce a calf. The heifers of the herd should be bred before the cows of the herd. The recommendation is to breed them about 30 days before the rest of the herd (Wells). When breeding replacement heifers, it is important to select for calving ease and good maternal traits. The effectiveness of your replacement heifer program will be revealed during the breeding season and later during the calving season.

The last step for a producer to have an effective replacement heifer program is to keep detailed records of their heifers. Records should include dates, identification numbers,

Figure 2. Shows the ways in which weight may be gained, each method has advantages and disadvantages (Arthington)

administration of vaccinations, administration of medications, heat detection dates, breeding dates, and any other important information pertaining to the heifers. The heifers should be treated for parasites and provided with the necessary vaccines along with the boosters for those vaccines. Recommended vaccines include high quality modified live viral respiratory, blackleg, vibriosis, leptospirosis, and brucellosis (Wells). Although necessary vaccinations will vary for each herd, it is important to talk with your local veterinarian. Developing replacement heifers with intention will lead to future success within your herd! References

Arthington, John, and Philipe Moriel. “Targeting ADG of Developing Replacement Heifers Using Age and Body Weight.” AN305/ AN305: Targeting ADG of Developing Replacement Heifers Using Age and Body Weight, 12 October 2021, edis.ifas.ufl.edu/ publication/AN305.

Extension, Parker Henley Oklahoma State University. “Heifers Should Reach Target Weight before Breeding Season.” The Eagle, 17 May 2021, theeagle.com/news/agriculture/ heifers-should-reach-target-weight-beforebreeding-season/article_a2cbb9b8-aed811eb-9006-afee0d5c5ecf.html.

Poore, M.H.. “Animal Science - Nutrition for Developing Replacement Heifers.” NCSU, projects.ncsu.edu/cals/an_sci/extension/ animal/nutr/mhp96-3.htm.

Purinamills.com. “Tips To Build Replacement Heifers: Purina Animal Nutrition.” Purinamills.com, 2 March 2020, www.purinamills. com/cattle-feed/education/detail/tips-to-buildsuccessful-replacement-heifers.

Rayburn, Ed. “Nutrient Requirements for Beef Cattle - WVU Extension Service.” Nutrient Requirements for Beef Cattle, West Virginia University Extension Service, September 2013, extension.wvu.edu/files/d/4095370d9c6c-4448-a092-862a676b2713/beef-cattlenutrient-requirements.pdf.

“Replacement Beef Heifer Development.” Mississippi State University Extension Service, extension.msstate.edu/publications/publications/ replacement-beef-heifer-development.

Selk, Glenn. “Using Ionophores in Replacement Heifer Diets.” Beef2Live, beef2live. com/story-using-ionophores-replacement-heiferdiets-0-119228#:~:text=%22Ionophore%22%20 is%20the%20generalized%20name,programs%20 for%20replacement%20beef%20heifers.

Wells, Robert. “Getting First Calf Heifers Ready for the Breeding.” Beef Magazine, 16 December 2011, www.beefmagazine.com/ americancowman/genetics/0219-calf-heifersbreeding.

Have You Herd article written as a portion of ANS 402 Beef Management course requirement at N.C. State University Department of Animal Science. The opinions of Sydney Smith are not necessarily those of N.C. State University or Dr. Carrie Pickworth.

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