Anyone driving through the foothills will notice extremely dry rangelands that are still brown and dry from summer and the obvious shortage of water in the lakes and reservoirs. The extremely dry winter we’re experiencing is having a critical impact on Calaveras County cattle ranchers. Many have turned to buying hay, lots of hay, as they wait anxiously for green grass to grow.

“Everybody who I know has been buying quite a bit of hay, and it’s pretty expensive,” said Rex Whittle, a lifelong Calaveras resident who raises cattle on property around Angels Camp and in the Salt Springs Valley. “They are buying it to try to hang on to the number of cows they have. There is a lot of uncertainty right now. Ranchers just can’t keep buying hay forever. It’s a pretty bad deal.”

Whittle said hay prices have gone up steadily and he’s had to buy twice as much as normal this year.

“We buy it by the ton and truckload,” he said. “A guy will buy 25 tons at a time. That’s a truck and trailer. That costs about $7,000 every time that truck comes through the barn. For myself, I’ve probably bought three or four truckloads of hay more than I normally do in the year.”

Without winter rains, the new grass won’t grow, which means the cattle are hungry. They end up eating dry grass from the prior year, which can stall the growth of new grass.

“There’s not a lot of old cover on a lot of these ranches,” Whittle said. “All fall, the cows ate dry grass. Usually, we try to leave a lot of dry cover on the ground so the new grass has protection when it’s growing. Old, dry feed insulates it to help it grow. It germinates real well. But with no rain, the cows eat the dry grass right up. There is a lot of bare ground out there. It’s really observable. It’s nobody’s fault, the normal number of cows. Even when we feed them hay, the cows still go out and eat the dry grass.”

Ranchers are hoping to get rains in the spring, because without that, it could be a very difficult summer.

“If it rains in February and March and we get some grass growth, then people will be ecstatic. If it doesn’t rain at all then, there will be a big, big problem.”

Oak toxicity

In addition to the lack of winter feed, another concern ranchers have is the potential for oak toxicity.

Whittle said this hasn’t been a huge problem in Calaveras County to his knowledge, however it’s something on rancher’s radar.

“You’ll have a few cows that can only think about eating acorns,” Whittle said. “We call them acorn cows. It does screw them up. But anyone who starves them down that far, they have problems. If you’re feeding hay, like a smart guy would be doing, you’re not going to have to too many problems.”

But with no grass and budgets tight, oak toxicity could become a serious problem for Calaveras ranchers.

There are more than 50 common species of oak trees in California and all contain some levels of the toxic tannins and phenols that can cause problems in cattle. The buds, young leaves, and fresh acorns have the highest level of toxins. There is considerable variation in the concentration of toxins in the plant tissues and is dependent on: the species of oak trees, the season of the year and the climate of the year in question.

Most California beef cattle spend at least part of the year in areas where oak trees abound. The problem with oaks is that they can be toxic to cattle. Disease problems due to ingestion of acorns or oak leaves are not an everyday problem, however when problems do occur, they can be catastrophic. Several years ago, in a few Northern California counties, about 2,700 cattle died due to oak toxicity.

Why are we concerned this year?

In a normal year, fall rains typically coincide with oak trees shedding their nuts. As the acorns fall, winter grasses begin to grow and quickly camouflage the nuts lying on the ground. In drought years, the lack of green grass makes the acorns easily accessible to foraging animals. In addition the lack of available feed makes the nuts and trees more enticing.

How do the toxins affect the cattle?

The oak toxins (tannins and phenols) cause damage to the gastrointestinal tract (mouth, esophagus, rumen and intestines) resulting in ulcers, bleeding and perforation. In some cases the toxins can travel to the kidneys where they cause severe damage resulting in renal failure and death. Younger cattle (fewer than 400 pounds) are usually affected more severely than older cattle.

What do the affected cattle look like?

Symptoms usually appear shortly after cattle eat 50 percent or more of their diet as oak (leaves, buds, acorns). Some animals may simply be found dead. A day or two after eating oak leaves or buds, bloody or dark diarrhea may be noticed. Throughout the course of clinical disease, the cattle appear weak, listless and have no appetite.

What are the most important risk factors that can lead to oak toxicity?

The presence of large numbers of acorns when forage is scarce is one of the main risks. Wind, hail or snowstorms can cause large numbers of acorns or limbs with leaves and buds to drop so that cattle can gain easy access to these potentially toxic materials. California outbreaks have been worse in the late winter and early spring when oak buds and small leaves are present in large numbers and a wet snowstorm occurs. The wet snow breaks branches and limbs which fall to the ground. The snow also covers the available grass and this leaves the cattle very hungry. This leads to consumption of these very toxic buds and young leaves because it is the only feed available. Likewise, this year with the large acorn crop and dry conditions with very little grass, the consumption of acorns has been very high in some herds.

How do you treat cattle with oak toxicity?

Successful treatment of affected animals usually requires fluid therapy, antibiotics and supportive care. A veterinarian should be consulted and a treatment protocol set up to increase the odds of success and to provide the most relief for the cattle. The antibiotics help prevent secondary pneumonia and abscessation of the bowel. Fluid therapy will be necessary for many cattle to survive and must be planned with a veterinarian. Ready access to water and good quality grass hay will be very important parts of providing adequate nursing care.

How can oak toxicity be prevented?

Oak toxicity can be prevented by supplementing the cattle with hay or other feed when forage conditions are poor and acorns are abundant. Likewise, when late snowstorms cover the grass and knock down oak limbs with large amounts of buds and young leaves, be sure to start hay supplementation immediately. Do not wait until cattle get sick or die. A delay of only a day or two can easily result in many more deaths and ill cattle. If cattle are in conditions where toxicity is a longer term possibility the use of calcium hydroxide in a supplement can prevent sickness. The addition of 10 percent calcium hydroxide (hydrated lime) to a supplement will still be palatable to cattle. Then if the cattle will consume about 2 pounds of this supplement per day it will prevent many cases of oak toxicity. This supplemental calcium hydroxide has to be consumed before exposure to be effective.

Scott Oneto is the farm adviser for El Dorado, Amador, Calaveras and Tuolumne counties. Contact him at sroneto@ucanr.edu, call the University of California Cooperative Extension at 754-6477 or visit cecentralsierra.ucanr.edu. Joel Metzger contributed to this story.