The most important factor in a successful cow/calf operation is weaning rate, but there is no good weaning rate without a good conception rate. Conception rates are a numbers game, affected by management decisions and the environment.
A study from the University of Georgia found that to meet production expenses, a cow/calf operation needs to average a calf crop of more than 85%. When it comes to meeting herd conception-rate goals, whether it's an artificial insemination (AI) program, all natural or a combination, the key is a management program focused on health and nutrition.
When it comes to conception rates, by far the most important factor is nutrition. Beef cattle specialists and producers have decades of experience and studies to back up that statement.
Clay Wright, producer and livestock consultant for The Samuel Roberts Noble Foundation, in Oklahoma, believes nutrition is the foundation that sets the stage for failure or success early on.
"From my experience, the biggest wrecks as far as reproductive performance is concerned have come from a lack of understanding of how nutrition drives conception rates," Wright said. "The lack of a solid Body Condition Score [BCS] is the No. 1 cause of low reproduction rates in the cow herd."
The BCS is a score in a numerical system (1 through 9, with 1 being extremely thin, and 9 being obese) that indicates an animal's physical state -- too skinny, too fat or just right. For cattle, "just right" (or average) is generally around a 5 or a 6. Thus, the goal of many cow/calf operators is to have cows at that BCS level come breeding time.
Jason Banta, beef cattle specialist with Texas AgriLife Extension, in Overton, said the ideal BCS depends to some degree on the age of a cow.
"For mature cows that are 4 years old or older, you want a BCS of 5 or greater to optimize pregnancy rates," he said. "For cows that are 2 or 3 years old, you're looking for a BCS of 6 or greater. The BCS at calving is the most important."
Wright notes that to produce a calf every 365 days, a cow has to recover from birth and lactation, and be able to conceive again 80 to 85 days later. He cites field trials out of Texas where only 62% of cows with a BCS of 4 or less were ready to breed again 80 days after calving. That's compared to an 88% readiness rate for cows with a BCS of 5 and a 98% readiness rate for those with a BCS of more than 5. In a second trial, 90% of cows with a BCS of 5 or greater rebred 180 days after calving compared to 50% with a BCS of just 5 and 12% of those with a BCS of 4 or less.
Wright stressed producers should try to match calving season and cows' peak lactation times to the highest, most plentiful forage. He said in many regions, this is the cheapest way to feed a cow and can provide all of her nutritional requirements. It can also help a healthy cow produce good and abundant colostrum, critical in building up a newborn calf's immune system.
Both Wright and Banta recommend defined calving and breeding seasons. Not only does this help ensure nutritional requirements are met, it also makes management simpler as tasks like vaccinations and marketing can be done for the calf crop at one time.
"If you have a year-round breeding season, basically you're always going to have cows at various stages of production," Banta said. "You end up having to feed [at a level] for cows at the highest stage of production. As a result, you end up overfeeding the rest of the herd, which costs you more money in the long run."
Breeding females need to be vaccinated against a lengthy list of illnesses that can negatively affect reproduction, including infectious bovine rhinotracheitis (IBR), bovine viral diarrhea (BVD), leptospirosis (lepto), brucellosis (Bangs or contagious abortion) and the venereal diseases vibriosis (Vibrio) and trichomoniasis (trich).
Not all of those diseases are prevalent everywhere all the time, making it important for producers to work with a consulting veterinarian who will customize a vaccination program to fit their specific operation and environment.
"Having a quality relationship with a large animal veterinarian is just as important as having a good corral or a sound perimeter fence," Wright said. "You might not have anaplasmosis in your county, for example, but maybe it's shown up a few counties over. Your vet will know the biggest threats to your herd."
A big part of having a more productive cow herd is putting wheels under the nonperformers. For cows that do not conceive in an environment where the bull is fertile, and the cow's BCS and health check are positive, culling is often the next step. Many producers cull at a regular time, often before going into the winter when it can cut into profits to carry a nonproductive cow.
"If I've done my job in the partnership, meaning I've protected the cow against disease, given her adequate nutrition and provided an adequate mate, and she comes up open, it probably means she just doesn't fit my resources and management," he said. "If you keep records on cow sales, you'll find it's usually the big cows and the old cows that are not producing."
A large cow producing a lot of milk needs more protein and energy all year long than a more moderate-sized one, Wright said. A big cow is high-maintenance and will try to maintain herself first before using nutrients for reproduction.
A common cull criteria is also age. While it varies across breed, research from The Noble Foundation shows that cows are typically most productive between 4 and 9 years of age. Broken and missing teeth are another indicator it's time to cull an animal, as this can affect its ability to eat and maintain BCS.
When it comes to better dam fertility, longevity and calf survivability, crossbred females have an advantage over purebred animals thanks to heterosis, or hybrid vigor.
Wright describes heterosis as "the added advantage in the performance of a crossbred over the average of its purebred parents."
Traits that drive reproduction are "low" on the inheritable scale, which means improvement in a herd's reproduction rate is generally slow. Wright believes in forcing virgin heifers to "express their fertility" early by limiting their first breeding to 45 days. Those young heifers that produce a calf under that initial pressure have the best chance of being productive contributors to the cow herd.
Let's not forget the bull, which supplies half of a cow's genes. That bull has a huge impact on a herd's conception rates, not just in the case of natural performance but in the genetic performance he has already contributed in the form of his daughters.
"We always think about the cows when we think about reproduction, but the cow needs a bull to get the job done," Banta noted. "You have to have a sound, healthy, fertile and willing bull to produce calves."
Like the cow, a bull should have a moderate BCS of 5 or 6 at the start of the breeding season. Banta stressed the importance of an annual breeding soundness exam (BSE). This should take place 30 to 60 days prior to turnout. A thorough BSE will look at the bull's reproductive tract and check for sperm motility, normal sperm morphology, scrotal circumference and condition of feet and legs.
Banta also said bulls need to be in good physical shape and not be given more females to breed than they are capable of handling.
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