Selecting the right heifers as replacements for the keep pen doesn’t need to be a complicated decision. Look at clear indicators such as those who were born during the first 21 days of calving, those who were treated for bovine diseases, and those who gained a steady 1.5 to 1.8 pounds a day.
Experts from the University of Nebraska and Zoetis offer valuable information and insights on how setting a heifer up for long-term success starts in her first two years of life.
The dust has cleared, the steer calves are loaded and gone to market. Now, your attention turns to the heifer replacement pen. How you manage that heifer now can set her up for a long, productive life — or failure in her first two years.
Selecting Heifers as Replacements
The first step in heifer development is selecting the right heifers for the keep pen. The time during the calving season when the heifer is born is the most important factor in determining her lifetime productivity, said Rick Funston, PhD, professor and reproductive physiologist with University of Nebraska, during the 2018 Feeding Quality Forum in Omaha, Nebraska.
“The biggest driver in cow profitability is when she was born in the breeding cycle,” said Dr. Funston. “Heifers born in the first 21 days of the calving season stay in the herd longer and wean heavier calves than heifers born in the second or third 21 days of a calving season.”
The first heifers to sell should be any heifer you treated for bovine respiratory disease as a nursing calf, according to Che Trejo, DVM, Beef Technical Services at Zoetis.
“We simply can’t reverse the lung damage after that point, and she isn’t a good replacement candidate,” Trejo said.
Preventing Disease Challenges
The next step is making sure the heifers are protected from reproductive diseases, so they have the best chance of getting bred in the first 21 days.
“It’s a shift in protecting her from respiratory disease before weaning to protecting her from reproductive disease going forward,” said Dr. Trejo. “We want to get at least 45 days past weaning before we give the first dose of modified-live virus (MLV) reproductive vaccine. The timing of brucellosis (bangs) vaccination lines up well to give the first dose in most herds.”
Dr. Trejo recommends giving two doses of an MLV reproductive vaccine prior to the heifer being bred for the first time. He suggests that producers use a vaccine, like BOVI-SHIELD GOLD FP® 5 VL5 HB, that protects against the following diseases:
- Bovine viral diarrhea (BVD) Types 1 and 2 viruses
- Infectious bovine rhinotracheitis (IBR) virus and IBR abortions
- Campylobacter fetus (vibrio)
While most MLV vaccine labels indicate that the second dose of vaccine should be given at least 30 days prior to breeding, Paul Walz, DVM, PhD, College of Veterinary Medicine Auburn University, suggested at least 45 days prior to breeding to allow two heat cycles before breeding, during his Feeding Quality Forum presentation.
In both cases, the timing allows the heifer to have a complete immune response to the vaccination without any interference during breeding.
Nutrition and Target Weight
Adequate nutrition is critical during the heifer’s development, as well as throughout and after breeding for improved pregnancy rates. However, nutrition continues to play a key role throughout pregnancy with the ultimate goal of producing strong, vigorous calves. Traditionally, the recommendation is for heifers to reach 65 percent of their mature weight by the time they are ready to breed, said Dr. Trejo. More recent research has looked at a lower target weight (55 percent of mature weight) and its impact on breeding rates.1
Research suggests there is some impact on artificial insemination (A.I.) conception rates, but there was not a significant difference in overall pregnancy rates between heifers developed to 55 percent of mature weight and 65 percent of mature weight.1
“If you have the flexibility to keep more heifers than you need, then put some pressure on the heifers to breed in a lower nutritional plane,” said Dr. Trejo. “Ideally, we will develop heifers to gain between 1.5 and 2.2 pounds per day. The key is to keep her growing throughout pregnancy, her first calf and rebreeding for a second.
“Ideally, we need a heifer development strategy until they have their second calf,” said Dr. Trejo. “They aren’t cows yet because they are growing and developing, along with growing a full set of teeth.”
Dr. Trejo reiterates the following tips for developing heifers:
- Select older heifers, born in the first 21 days of the season
- Don’t keep any heifers treated for BRD as a nursing calf
- Administer two doses of a modified-live virus vaccine with fetal protection prior to breeding
- Target 1.5 to 1.8 lbs/day gain so heifers attain at least 55 percent of mature weight by breeding time
For more information on selecting vaccines in your heifer development program, talk with your Zoetis representative or local veterinarian, or visit FetalCalfProtection.com.
1Hall JB, Cummings, Glaze Jr. JB. Heifer nutritional development and the target weight debate, in Proceedings. Applied Reproductive Strategies in Beef Cattle 2016; 131-144.
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