With breeding season underway and plans to move cattle to summer pastures on your mind, keep a lookout for lupines and other plants that can cause pregnancy problems.
Native pastures in the West often contain several types of lupine. This hardy plant blooms in early spring. Several types have blue flowers, but some are yellow, white, blue and white, or pink. Blooms stay on for many weeks, dotting the hillsides with color.
Some lupine species are harmless to livestock, according to Robert Cope, DVM, of Salmon, ID, but others require caution.
“Cows eating lupine in early gestation are at risk for deformed calves; alkaloids in lupine will affect a fetus if eaten between the 40th and 70th day of pregnancy,” says Cope.
These alkaloids affect the brain and act as a sedative, and the sedated fetus isn’t moving. Legs and joints become stiff or fixed in abnormal positions. A fetus may have one or more joints or limbs affected, or the spine. Affected calves may be born with front legs cocked forward at the knee, with deformed knee and ankle joints, or cleft palate where there is a hole between nose and mouth.
Some calves are so seriously deformed (with twisted spine and legs) they cannot be born, and must be delivered surgically by C-section, or by cutting the fetus into pieces to bring out through the birth canal.
Dr. David Steffen, diagnostic pathologist and professor at the University of Nebraska, explained that most of the body structures are formed during early gestation, so this is when they can be adversely affected by alkaloids in lupines and other plants ingested by the cow.
“We see similar defects in geographic regions where there isn’t any lupine; these defects can be caused by other plant toxins such as hemlock. Any kind of plant alkaloid or toxin can affect the nervous system of the developing calf, and even some viruses can cause these abnormalities.”
When a calf is born with crooked legs or fused joints, we don’t always know why, but in many cases, we can suspect plant toxins, especially if the cows were grazing pastures containing lupine during early pregnancy, Steffen explained.
[inline_image file=”c4ceea43eb7480791bf6664b42988f32.jpg” caption=”An example of a lupine calf with affected forelimbs. This is a milder form of what commonly gets called “crooked calf syndrome.” Some lupine-caused deformities can be so severe the calf cannot be born alive.”]
Real-world impacts
Lupine-related deformities are usually pretty rare. For example, 1-3 percent of calves born on Adams County, WA rangelands suffer from “crooked calf syndrome” due to lupine in most years, according to livestock specialists with the Washington State University Extension Service.
But some years can bring an “epidemic” of lupine deformities. In 1997, Adams County saw cool, wet weather the preceding summer, which increased the amount of lupine on rangelands. About 20 percent of calves born that year were so seriously affected they had to be humanely destroyed.
Lupine deformities can also occur because of a late spring; the lupine greens up ahead of the grass and cows eat more of it. Many ranchers in Lemhi County, ID had crooked calves during the 2003 calving season, due to a late spring the preceding year, for example.
Michael and Carolyn Thomas’ herd of 180 cows had sporadic incidence of crooked calves over the preceding 25 years—and all were functional enough to grow big enough to sell or butcher—but during the 2003 calving season, four of their cows had calves so twisted that their veterinarian had to cut them up or take them out by C-section.
“A few years ago, we changed our calving season until later; our cows are not yet pregnant during spring when lupine is blooming,” said Michael Thomas.
“This stopped the problem in our herd. But most Western ranchers have to use BLM and forest ranges and their cows are often bred by the time the lupine is blooming. It can be a dilemma.”
Lupine details
Lupine grows in every Western state and western Canada. Plant specialists at the USDA Poisonous Plant Research Laboratory at Logan, UT say some are annuals, but most (including the toxic types) are perennials. The perennials start growing early in the spring, flowering in May or June, with blooms staying on until seeds are formed in July or August.
The poisonous species are dangerous to livestock from the time they start growing in early spring until they dry up in the fall. Young plants in spring are more dangerous than mature plants in summer, though the plants are also dangerous again in late summer because of the high alkaloid content in the seeds.
Livestock poisoning and instances of crooked calves can be reduced by keeping hungry animals out of lupine patches in early growth stage in spring, and also in late summer when the plant has highly toxic seeds. Lupine may be safely grazed by cattle in the fall after the pods have released their seeds. — Heather Smith Thomas, WLJ correspondent
