FORT STOCKTON – As the record-setting drought strengthens its sinewy grip across Texas, one may wonder what the remaining livestock and wildlife are eating.
Across the western half of the state, mesquite beans most likely are a big part of the answer, according to a pair of Texas AgriLife Extension Service experts at Fort Stockton.
A heifer grazes on mesquite beans. (Texas AgriLife Extension Service photo by Steve Byrns)
Dr. Bruce Carpenter, AgriLife Extension livestock specialist, and Dr. Alyson McDonald, AgriLife Extension range specialist, said while mesquite beans do have good feed value, it takes an awful lot of them to really make much of a difference to a hungry cow.
“I recently raked up all the beans from a 10 foot mesquite; total weight was just over five pounds,” McDonald said. “Those dry beans had a moisture content of one percent. I also picked some green beans from a tree and they jumped to 50 percent moisture.
Carpenter said problems can arise when cattle eat mesquite beans for more than 60 percent of their diet continuously for two months or more. He said this usually happens when other forages become limited due to drought or when drought-stricken forage lacks enough protein to meet the animal’s needs.
“The protein content of mesquite beans drops from 28 percent in young beans to about 12 percent at maturity while fat increases from about two to three percent and fiber increases from 17 to 30 percent,” Carpenter said. “Many parts of Texas have seen a bumper bean crop this year and some areas even got a second crop, so mesquite beans are definitely on the menu.”
As with anything else, Carpenter said too much of a good thing can be bad. The beans have a high sugar content of 65 percent to 80 percent. Too much sugar can cause increased acidity in the cow’s rumen, killing the micro flora needed to digest course fibrous plant material. This causes a digestive slowdown, leading to an impaction of the digestive tract that can be fatal.
“Under normal circumstances this high fiber would be broken down and digested or passed out as undigested material,” he said. “Impacted animals essentially begin to starve. Severe weight loss is the most obvious sign, but other symptoms include swelling under the jaw, partial tongue or jaw paralysis, excessive salivation and constant chewing.”
Carpenter said affected animals can recover if placed on a high-quality ration. Inoculation of the rumen with fluid from a healthy animal is also reported to help.
“Watch your saddle horses too,” Carpenter warned. “Although horses aren’t ruminants, they are susceptible to mesquite bean impaction problems. Colic may result causing horses to hump-up and kick at their abdomens or roll violently. Death is a real possibility in severe cases.”
Goats are fairly resistant to over-consumption problems, and sheep seem to be the most resistant of all common livestock, Carpenter said.
Most ranchers want less mesquite, so how much mesquite is actually spread through bean-eating animals? Not as much as many may think, McDonald said.
“It’s true that ingestion is an important dispersal mechanism and that exposure to digestion does increase germination, because the seed is able to more quickly absorb moisture,” McDonald said. “However, seedling establishment is dependent on the seed being in contact with the soil and covered slightly. That soil must also receive adequate moisture within days of germination for the plant to live, which hasn’t been much of a factor this year. Even in a good year, many seeds may germinate, but only a fraction, 20 percent or less, will become established. And if after one year the seeds haven’t germinated, as few as five percent will even be viable.”
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