Weak calves can result from multiple factors, but weather and inadequate nutrition are at the top of the list of causes.
“Bad weather and cows with poor nutrition can lead to stressed calves with less vigor,” says Karl Hoppe, North Dakota State University Extension Service livestock systems specialist at the Carrington Research Extension Center.
Some calves are born weak, possibly unable to stand, or lack the energy to nurse. The calf may survive if the producer helps it nurse, provides it with another source of colostrum, and takes it to a warmer place (pickup cab, barn or calf heater).
Colostrum is a form of milk that cows produce in late pregnancy. It contains energy, protein, fat, vitamins and antibodies to protect newborns against disease until their own immune system is functional.
Weak calves can result from disease but usually not immediately after birth. However, placental infections, such as fungal infections from moldy feed, can lead to a reduced nutrient flow to the unborn calf. While this usually leads to smaller calves at birth, it can explain some weak calves, research shows.
“Good feeding management that provides balanced nutrition to the cow can help prevent weak calves,” Hoppe says.
A study at the University of Idaho found fewer cases of weak calf syndrome when the mothers were fed a higher level of protein 60 days before calving.
The researchers reported that cows receiving late-gestation rations with more than 10 percent crude protein had offspring with a 0.6 percent incidence of weak calf syndrome, while cows receiving rations with less than 10 percent crude protein had calves with an 8.5 percent incidence of weak calf syndrome.
Cows with a body condition score of 3 or 4 are more likely to have offspring with weak calf syndrome than cows with more body fat, Hoppe notes. The lack of body fat isn’t the only issue involved, although it is a good physical indication.
“When protein content in feeds is low, it indicates other nutrients also may be less than required,” he adds. “These nutrients include calcium, phosphorus, copper, zinc and selenium.”
He encourages producers to:
- Provide pregnant cows with a vitamin and mineral supplement
- Get the ration they are feeding their cows tested for nutrient value. A feed test will identify if the energy and protein content of the ration is adequate. If energy and protein are low, changing the ration immediately might help reduce the risk of weak calves.
- Invite a neighbor or other producer to provide an unbiased evaluation of their herd’s body condition score. The goal should be a body condition score of 5 or 6 at calving, with no ribs or backbones visible.
However, even a healthy, well-conditioned cow fed a balanced ration can give birth to a weak calf in poor weather conditions. Windbreaks, bedding and barns can help offset some weather stress.
Another issue is that although well-fed cows in good body condition seem to have fewer problems with weak calves, some producers fear calves will be too big at birth and have dystocia, or a difficult birth, when the cows are fed well.
“Usually, that’s not a problem because a well-fed cow can expel the calf quickly and less mortality is observed,” Hoppe says. “If calf size is a consideration, look for bulls with calving ease traits to solve the problem. Don’t do it with inadequate feed.”
Having a veterinarian necropsy a dead calf can help determine causes of weak calves. Calves with minimal fat reserves are indicative of poor cow nutrition. Muscle color can indicate vitamin E deficiency. Broken ribs can indicate the cow stepped on the calf.
A thumb rule for doing necropsies is when deaths exceed a 1 to 3 percent loss.
“Because many issues can lead to death, necropsying every calf can be enlightening,” Hoppe says.