Seeing double: Calving twins
The frequency of twins during calving, according to USDA surveys, is estimated in about 2 percent of pregnancies, more common in dairy breeds. The result of either a double ovulation or, less commonly, an early embryo will split into two, resulting in identical twins.
Some cows and cow families are more apt to produce twin pregnancies though some years seem to result in a higher percentage of twins. This could be a result of a cow in really good body condition score at the time of breeding or a number of environmental factors that could play a role.
According to Dr. Bob Larson at Kansas State University, one twin is often not as vigorous. There are differences between placentas in terms of nutrient transfer and the birth itself can affect the calves depending upon which twin is where in the birth canal, especially in the case of dystocia.
Calving difficulties can make twins rather frustrating, especially when the birth of the first twin is complicated, putting the second twin at risk. Dr. Kathy Whitman, DVM, said solving twin calving problems is a matter of untangling more than being too large.
“The calves are not too big, they’re just in a jumbled mess,” she said. “If one is not coming right after another, they may be trying to come at the same time and that’s when they get a little tangled.”
Dystocia is common in twins and is one more reason not to encourage it as a production method. Whitman, who owns Bov-Eye Veterinary Services, said she has seen research operations that select for twins to gather data on the method and it is certainly not ideal.
Twins can pose a managerial challenge for producers if a twin is either abandoned or simply not thriving and must be removed from the cow. Whitman said while some more mature and experienced cows may be able to raise twins, she typically recommends one twin be grafted onto another cow if possible.
“If we’re doing well and not losing any calves, which hopefully we’re not, we may have bottle babies and that becomes a logistical challenge more than anything,” she said.
The grafting process depends on the nature of the cow, sometimes requiring a bit of sedation for the cow to calm her for the process of allowing the calf to safely nurse while she may be in a headcatch or even hobbled. Having her milk in the calf’s system helps the calf smell like the cow he or she is being grafted to. Products like Orphan-No-More claiming powder can also help the calf smell like the cow, but Whitman said she recommends it in tandem with other methods for a successful graft. Some producers will skin the cow’s dead calf and tie the hide to the new calf. She said she doesn’t discourage this method if it works for the producer but said it can be challenging.
“The biggest thing is to protect that calf from being hurt by the new cow and some cows are just not nice and you can’t use them, but for the most part, I think we’re pretty successful putting them in a head catch and letting the calf nurse,” she said. “If we do that for a day or two, with some other chemical restraints it’s successful in my experience.”
Another managerial consideration is culling a twin heifer when the time comes. Larson said exposure to testosterone in the uterine environment results in freemartinism in about 90 percent of heifers born twin to a bull calf. Whitman said if a client is making a decision to cull a calf to avoid twins and is without a feeding option, culling heifers born to a bull is her recommendation.
As rebreeding time approaches, the nutritional needs of a cow who raised a single twin don’t differ from the rest of the females though keeping all the cows in good body condition is a best practice. Whitman said cows should be in good body condition at calving time as well to avoid problems. Cows allowed to raise twins would require some additional protein and energy but would be managed separately to avoid the other cows overeating.
“Regardless of whether they have twins or singles, if they’re increasing in body condition towards the breeding season, those cows breed back better,” she said. “We definitely don’t want fat cows at calving but we do want to have cows that are stable and as they increase body condition, that increases reproductive efficiency.” ❖
— Gabel is an assistant editor and reporter for The Fence Post. She can be reached at email@example.com or (970) 768-0024.
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