We have had a cold and wet start to our calving season! The veterinarians at Prairie View Veterinary Clinic have been very busy with calving calls doing anything from correcting calves that are presenting abnormally, to C-sections, to uterine prolapses and much more. With all that time spent in the field with our producers, we get to talking about the trends of this year’s calving season.
One of the things that producers often ask us is, “Are the calves bigger than normal this year?” Our answer is typically yes, they seem to be. Many researchers, veterinarians and producers alike have a few theories as to why this happens.
First, is the cold winter we have had. According to US Climate Data, we have been 11 degrees colder between January and March than average. This results in livestock having to eat more to maintain their core body temperature.
In general, for every degree the wind chill is below 32 degrees (cow’s lower critical temperature), their energy requirements increase by 1 percent. If the cattle are wet, their energy requirement increases by 2 percent per degree below 59 degrees.
Sudden changes in rations are not recommended but it would be good to do smaller increases in energy before the storm and extend this a few days after the storm to help the cattle make up the energy they lost.
So, what does this have to do with the baby calf? When cattle eat more, the fetus will get more nutrition, and can then grow bigger.
Changes in Blood Flow
Second, is that during the cold weather, cows will tend to have less blood flow to their extremities and more to their core. And where does the baby grow? Right in the middle of their core. More blood flow means more nutrients being exported to the calf which means more growth is possible.
Third, cows are most likely getting less exercise during the cold weather and storms because ranchers have them close to home in feedlots or large pens. When cows aren’t exercising like they do in the summer, they get couch-potato bodies just like we do! So even if the calf would be normal sized, they might get the calf half way pushed out and get too tired to continue.
So how much bigger will the calves actually be?
In 1999, there was a Nebraska Beef Report titled “Climate Affects Calf Birth Weights and Calving Difficulty” with data that shows for every 1 degree decrease in average winter temperature, there is a 1 pound increase in birth weight. That means an 11 pound increase in calf birth weight than normal.
Although we are not convinced that this theory holds true for us this year, we think that a half a pound increase per degree below normal would make sense. That means that this year, calves have been an average of 5.5 pounds heavier than normal is what we have actually been seeing.
Our observations have not been statistically proven but may shed some light for producers who think they are having bigger calves this year.
As always, call Prairie View Veterinary Clinic anytime with all your calving questions and needs!
Questions? Send email to Eric Knock, DVM, at firstname.lastname@example.org or send mail to 321 E. 14th St., Miller, SD 57362. Eric Knock owns and operates Prairie View Vet Clinic in Miller, Redfield, Wessington Springs and Highmore, S.D.