Toxic planets can cause acute poisonings, but they are also well known for adversely affecting reproduction.
They can trigger early embryonic death and abortion and produce fetal anomalies.
The outcome of the poisoning depends on the specific toxin involved and at what stage pregnancy is the first trimester. This is when the fetus is most susceptible to teratogens, the chemicals that cause deformities. It’s also the time the cow is most likely to lose the calf.
Milk vetches, also called locoweeds, are the most toxic plant and have the most economic impact. There are more than 370 species of this plant but few are actually toxic.
Each subspecies can contain one or more of several toxins, which can be confusing. The main toxin in locoweed is an indolizidine alkaloid. It affects energy metabolism and contributes to widespread organ damage.
Chronic ingestion of this alkaloid can affect the mother and fetus at any time during gestation. The toxin adversely affects hormones, the ones needed to maintain and control pregnancy. It can cause abortion and infertility and affect placental circulation to such a degree that there is a massive accumulation of fluid in the uterus, a condition called hydrops.
Animals that have aborted because of locoweed do not suffer from uterine damage and tend to resume cycling. They can conceive again if they are prevented from eating more locoweed.
Locoweed can also cause deformities, such as twisted and deformed limbs due to contracted tendons and abnormal development of bones and joints. Identical syndromes can be seen in cows eating lupins, poison hemlock and tobacco plants, so it is important to determine the cause.
Sheep suffer an interesting effect from locoweed. If ewes eat the plant between day 60 and day 90 of pregnancy, their lambs can develop enlarge hearts and thyroid glands. Often, the heart stops, causing fetal death followed by abortion.
If locoweed is growing on a farm, locoweed poisoning should always be considered as a cause for reproductive failure. Blood test can detect the toxin in the bloodstream, but testing is only valid with two days of consumption.
It is normally difficult to pin down this specific poisoning because the defects are encountered long after the plants are eaten.
Lupins are perennial herbs that grow about a metre tall. Some species are not toxic and are used as a high0protein food sources for human and animal consumption. However, some are poisonous, containing quinolizidine and piperidine alkaloids.
Lupins can cause crooked calf disease, which occurs in cows that eat one-half to one kilogram of lupins per day between 40 and 70 days gestation. Calves may have limb and spine deformities called arthrogryposis as well as cleft palates. The same syndrome is mimicked by an inherited genetic disorder seen in Charolais cattle.
Lupins have also been linked to a fatal neurological condition. Animals develop muscle tremors, laboured breathing, convulsions, coma and die.
Lupins can also cause lupinosis if they are infested with a fungus. The fungus produces a mycotoxin that can cause severe kidney, liver and muscle disease.
Poison hemlock is a widespread weed. It produces a toxin called coniine that poisons cattle and pigs; horses and sheep are immune. Cattle that eat it between 50 and 70 days gestation can give birth to crooked calves. These cows sometimes have trouble calving because the deformity prevents the calf from passing through the birth canal.
Many other plants can cause reproductive loss, such as pine needle abortion that occurs in cattle grazing in forested areas. Cows can die from this poisoning.
Cattle eat the pine needles when they are stressed or there is a lack of forage because of snowstorms.
It is also possible to see poisonings from nitrates, because some plants accumulate this chemical, especially after frost. Problems also occur with phyto-estrogens, which are seen in alfalfa and some clovers.
In these cases, diluting the feed with non-toxic forage can help avoid symptoms if the tainted forage must be fed.
Animal Health
Jeff Grognet, DVM, BSc (Agr)
Jeff Grognet is president of the British Columbia Veterinary Medical Assoc. and is practicing in Qualicum Beach, B.C.
Published in the Western Producer
The 2007 Memorial Award was presented to Chris Hepfner by the Association President Ron Walker. This award is given to the person or business that helps promote and support the Texas Longhorn cattle. Before his passing, Robert not only owned longhorn cattle, but proudly supported the A.T.L.A. in promoting the Texas Longhorn cattle.
July 4 – 13th, the Association was once again at the Calgary Stampede promoting the Texas Longhorn cattle. The week was very busy answering questions and selling promotional items. Numerous visitors from all over the world stopped by to take pictures of the Longhorn cattle that were proudly on display. Thank you to Ken & Charlotte Beler for bring their steer and to Ron Walker for bring his cow & calf. The Association would like to say thank you to Chris Hepfner, Charlie & Val Gordon, Mark & Tina Stewart and Lee & Bonnie Stringer for also donating their time during stampede week. With the help of members, we can continue to promote the Texas Longhorn cattle at agricultural events.
In September, Mark and Sheri Johnson became proud parents of a beautiful baby girl.
Pictured:
Charlotte Beler, Lee & Bonnie Stringer, Ken Beler, Ron Walker
