By Gilda V. Bryant
Photos by Della Ehlke, Montana
Replacement heifers are the hot topic of discussion in many coffee shops and sale barns. By paying attention to supplements, body condition and smart management strategies, producers will be able to give heifers exactly what they need to be profitable additions to the herd.
Aaron Stalker, Ph.D., Animal and Food Science professor at Brigham Young University-Idaho, reports there are six minerals frequently lacking in beef cattle diets in the United States. Phosphorus (P), magnesium (Mg) and sodium (Na) are macrominerals, needed in larger amounts and are listed on mineral bags as percentages. Trace minerals, also known as microminerals, required in much smaller amounts, are listed as parts per million (ppm). Copper (Cu), zinc (Zn) and selenium (Se) are essential trace minerals that tend to be deficient in American herds.
Phosphorus, a major building block of bone and teeth, is also essential for cell growth and energy utilization. Since cattle need phosphorus in relatively large amounts, it can be expensive to supplement. When cattle graze on green grass and vegetative forage, they usually receive adequate amounts of this mineral, and supplements are unnecessary. Around 85 percent of phosphorus is stored in the skeletal structure, and animals can pull this mineral from their bones when needed if it is unavailable in their feedstuffs.
“If cattle are grazing large, remote pastures in the summertime, it can be challenging and expensive to deliver phosphorus,” Stalker explains. “One good strategy is to not feed phosphorus when cattle are grazing green grass. Then, in the wintertime when we’re feeding cows and heifers, we can add phosphorus to the diet to replenish their stores. Heifers are still depositing bone, so their phosphorus requirement is relatively higher than a mature cow. They can still draw on their bones as a reserve.”
Magnesium is essential for energy metabolism, DNA function, and the transmission of nerve impulses. It also activates at least 300 different enzymes. Adequate levels of magnesium prevent grass tetany, which is usually only a problem in early spring. If needed, include it in a mineral supplement in the spring, but take it out the rest of the year to save money.
Sodium, a component of salt (sodium chloride) should be available to cattle all year because forages tend to be low in this mineral. Sodium is necessary for the nervous and muscular systems to work well, and also promotes appetite and body condition.
Copper and zinc are trace minerals that work together for healthy immune function, growth and reproduction. Zinc is vital for skin and hoof health as well as male reproduction. Both of these elements are stored in the liver, until utilized by the animal when needed. Stalker reports it is not necessary to feed them year round. Use the same strategy as was recommended for phosphorus, providing them in the winter months. Selenium, strictly regulated by the USDA, is required for normal growth, fertility and the prevention of diseases, such as scours and mastitis. Selenium amounts vary widely in the U.S. Check with a local expert for accurate advice about whether or not to include selenium in mineral supplements.
Stalker recommends maintaining growing heifers in a separate pasture with the best grass because they are still growing, and have higher nutritional requirements than mature animals. Providing supplemental trace minerals to these developing heifers is a good idea, especially if forages are not sufficient to meet their rate of growth.
“Multiply the number of animals by the amount of the formulated intake,” Stalker explains. “Then figure how often you want to refill the mineral feeder. Put out only the amount that’s been formulated. If you put out four days’ worth of mineral and they eat it in two, then wait until the four days are over to feed more, rather than feeding them as much as they will eat. Minerals are expensive and proper management can go a long way to help with the bottom line.”
If heifers develop a copper, zinc or selenium deficiency, consider feeding chelated minerals, also known as organic minerals. These treated minerals bypass the rumen’s microflora to be efficiently absorbed in the small intestine, where they are utilized by the animal.
“My recommendation is that people not feed organic trace minerals unless there’s a particular situation where rapid absorption of trace minerals is important,” Stalker advises. “There’s no need for organic trace minerals if you’ve got an adequate trace mineral for your developing heifers. However, if you’ve got animals that are susceptible to getting sick, they have a place.”
Hydroxy trace minerals, a new category of innovative supplements, look promising for use in cattle. A unique chemical composition protects copper, zinc and manganese (Mn) in the rumen so they can be absorbed in the lower intestine.
Heifers often require additional protein and energy, which are essential for their growth, development and successful breeding. Cotton seed cake, range cubes or alfalfa hay are affordable sources of these nutrients. Energy and protein given at least 40 days before breeding are essential for successful pregnancies in heifers.
Stalker recommends that heifers calve around two years of age because waiting longer than that is not economically efficient. A cattle operation is more profitable if heifers calve on their second birthday.
“Underdeveloped heifers are a problem, but so are overdeveloped heifers,” Stalker explains. “Overdeveloping can affect the mammary gland development when fat tissue is deposited in the mammary gland. This can reduce the lifetime performance of the animal in terms of milk production. She won’t produce as much milk as she’s genetically capable of because of the fat that was deposited in the udder while developing. It’s a balancing act. Underdevelopment and overdevelopment are both unacceptable. We want to have reasonable, appropriate growth rates.”
It all ties together
Mark Ehlke and his family run Ehlke Herefords, a registered Hereford operation tucked in the scenic Big Belt Mountains of Montana. Most of his spring-born heifers are developed in a nearby feedlot where they receive appropriate amounts of minerals, vitamins, energy and protein. They gain roughly a pound and a half a day. When they are ready to breed, they will receive a round of AI, then return to the ranch, where they are exposed to bulls.
“We’ve added a fall calving group of heifers that are developed on a separate protocol,” Ehlke explains. “They’ll be weaned, then turned out on grass, usually in March. They’ll have the basic mineral program the cows are on. We’re always in communication with our vet as far as any deficiencies or anything we can do better. As a rule, we bump up the protein with a little additional Vitamin E [with a lick tub] about 40 days prior to breeding.”
Applying tried and true strategies, such as checking bone structure and docile dispositions, Ehlke prefers his heifers to maintain body condition scores ranging between five or six. He breeds them when they weigh 55 to 60 percent of what their projected mature cow weight will be. To avoid a wreck, these Hereford heifers, cows and bulls are regularly monitored.
“We don’t want them too fat by any means,” Ehlke reports. “The bone structure and all the phenotypes is an ongoing evaluation. Most anything that doesn’t fit our goals will never be in the replacement pen. They will be moved out to the commercial feeder.”
Ehlke looks for heifers that will be good mothers, producing the right quantities of milk. They must display docile dispositions enabling cowboys, and their working animals to move safely among them. He says that many of his customers run cattle in pastures that contain thousands of acres. He wants an animal with sound feet and legs that can travel in larger pastures, work for a living and get that calf raised.
“Do your homework,” Ehlke advises. “The heifers should go out and do their job if you’ve done your part. [Genetics] are just one part of the equation. You have to use the visual aspect and all of the production history. It all ties together.”