As any beef producer knows, once calves are shipped in the fall, the next big item on the agenda is preg-checking the mother herd. It’s a routine all too familiar. The cows are brought into the corrals and ran through the chute. The local veterinarian is on hand, usually with a trusty ultrasound machine, and the fate of the cows are determined. Bred cows get to stay on the company payroll, while those that are open or bred up too late, are shuffled on down the line.
Its pretty simple really – it doesn’t pencil out to continue feeding open cows. But what if you could get more out of preg-checking? Dr. Megan Igo, a large animal veterinarian that services southwest Montana while working for Beaverhead Veterinary Clinic in Dillon, Mont., explains that vets can offer their clients more information, depending on when you choose to pregnancy check your herd.
For her senior paper while wrapping up veterinary school, Igo decided to look at the accuracy of fetal aging with ultrasounding. To do this, Igo and her mentor, Dr. Brad De Groot, checked over 600 mixed-aged cows from all around southwest Montana.
They were trying to determine at what point during development of the fetus a veterinarian can be most accurate in their predictions. Igo and De Groot didn’t want to just tell their clients the cow was open or bred, they wanted to be able to provide a more realistic determination as to when that cow would calve.
“In the data that we collected, it was most accurate when the calf fetus was at 90 days old. Similar studies have been done with similar results. We recommend to people that the best time to do fetal aging is somewhere between the 60- to 100-day window,” Igo explained.
For the study, a calving period was determined by the producer and the veterinarians ultrasounded the cows to find out if they had bred up in a timely manner and were on track to calve within the allotted period. A seven- to 11-day window of variation, in either direction, was accounted for.
There are different ways to determine fetal aging, but most commonly, a measurement of the calf’s skull can determine its age. Positioning of the fetus is crucial when it comes to taking those measurements. If the fetus is older than 100 days of age, it starts moving further down into the cow’s abdomen, making it less accessible.
Armed with proper information, Igo says producers are better able to assess their needs come calving time. How much help will be needed, laying out pasture rotations and having a better chance of mitigating neo-natal diseases are all topics that can be answered.
“Our main goal is to give producers the information so they can prepare for the upcoming calving season. It is important for us as veterinarians to act as a resource for producers,” Igo said.
Igo also emphasized how preg-checking can be an excellent time for a veterinarian to assess herd health for a producer. There is a slew of topics that producers and veterinarians can discuss on preg-checking day, including mineral and vaccine programs, deworming protocols and body condition scores. It is a great opportunity for a veterinarian to lay eyes on the herd so they are better prepared to offer assistance later on.
“I think people sometimes forget there are other reasons that preg-checking is important,” Igo stated.
Igo wants people to understand, if nothing else, that veterinarians are first and foremost a helpful and very useful tool for producers, so don’t be afraid to take advantage of their knowledge and expertise.
Fall works might all be just about wrapped up across the region, but it’s important look ahead to next year and remember the 60- to 100-day window is best for accurately determining fetal aging.