By DOUG WARNOCK
For the Capital Press
Crooked Calf Syndrome (CCS) is a malformation of calves resulting from cows grazing certain species of lupine during early pregnancy.
Typical skeletal deformities in these crooked calves include twisted or bowed limbs, spinal column deviations and cleft palate. These deformities can either reduce calf viability or cause death and at certain times have resulted in major economic loss to individual ranchers.
This erratically occurring condition has been experienced most seriously in the Channeled Scablands of east-central Washington and on some rangelands near Pendleton, Ore. However, CCS has occurred on ranches throughout the Pacific Northwest in lesser degrees.
Researchers and ranchers working together have studied the syndrome and developed management strategies to help cattle producers minimize the incidence of CCS. A report in the April, 2013, issue of Rangelands, a publication of the Society for Range Management, reviews management practices, which can help producers reduce the effects of CCS.
Lupines are legumes and can provide a good source of protein in the diets of grazing animals, but when certain species are consumed during early gestation of cows, they can cause this serious condition. While there are 150 species of lupines found in the intermountain western United States and Canada, most CCS is caused by a very few lupine species, mainly Velvet lupine (Lupinus leucophyllus) in the Channeled Scablands region of eastern-central Washington and Sulphur lupine (Lupinus sulphurus) in the rangelands near Pendleton.
Research done at the Poisonous Plant Research Laboratory over the last 20 years found that the skeletal malformations and cleft palate conditions are the result of reduced fetal movement in the womb caused by alkaloids in these specific lupine species when consumed in early pregnancy.
The severity of the malformation depends upon the amount of lupine eaten, the alkaloid content of the lupine, the number of continuous days it is ingested and the stage of pregnancy in which it is ingested. For cleft palate to occur, the pregnant cow must graze lupine consistently for 5 to 10 days during the gestation period of 40 to 50 days. For skeletal malformations to occur, the cow must graze lupine continuously for at least 10 days during the period of 50 to 100 days of pregnancy.
Multiple practices can be employed to reduce losses from CCS, but the simplest approach is to avoid grazing in pastures with known toxic lupine species during the susceptible time periods. It is especially important for producers to identify lupine species in their pastures and know which are present and may be toxic.
It may be possible for some producers to adjust breeding schedules to avoid exposing pregnant cows to lupines when they are at highest risk. Another approach is to move cows to non-lupine pastures when lupine grazing is observed or pull "lupine eaters" out when they start to graze lupines. Lupine containing-pastures can be grazed by stocker cattle, open heifers or other livestock species, while putting pregnant cows in lupine-free pastures during the critical time period.
The risk of lupine-induced CCS depends on many factors, including which lupine species are present and their numbers, the availability of high quality forage plants, weather and climate factors, stage of pregnancy and grazing management strategies. Ranchers have found that with the proper management they can reduce the impact of CCS.
Doug Warnock, retired from Washington State University Extension, lives on a ranch in the Touchet River Valley where he consults and writes on ranch management.