As we discussed last month, if there is a super grass, it is fescue. Exceptionally drought tolerant, it grows under a wider temperature range than just about any other grass. If that weren't enough, it is also exceedingly productive under that broad temperature range. For areas with mild winters, it will provide abundant amounts of forage almost year-round.
There are, however, two drawbacks. One is forage quality. While fescue out-produces many other grasses, it is somewhat coarser. As a result, cattle will not gain on fescue as well as less fibrous grasses. However, for cow-calf production, fescue can almost be considered ideal. Cows do not need to gain appreciable weight, and a grass that provides large amounts of forage most of the year is just what is needed.
The real drawback to fescue is toxicity. To anyone in a technical capacity, fescue toxicity is one of the most frustrating aspects of beef production. We know what causes it, and we know what the effect on the animal is. But we cannot directly prevent it and absolutely we cannot treat it. All we can do is manage around it.
The primary cause of toxicity is the same fungus that causes ergot in cereal grains. In humans, ergot is a potentially life threatening toxicant. In cattle, death loss is rare, but there are serious physiological problems that typically translate into impaired performance.
The primary action on cattle is a constricting of blood vessels. During periods of extreme cold, this can restrict the flow of blood (and warmth) to the extremities, causing gangrene to occur in the foot and/or tail switch. Indeed, during winter fescue toxicosis is often referred to as fescue foot.
Summer Stress But the majority of problems occur during the summer. Constricted blood flow to the surface of the body greatly interferes with the ability of the animal to regulate its temperature (cool itself). This translates into heat stress.
The endophyte is totally contained within the plant, and can be transmitted only through the seed. Endophyte-free varieties are available, but reportedly are not quite as productive in some climates. Ironically, the endophyte gives the plant insect and disease resistance and may be one reason why fescue is so productive.
The importance of fescue and the frustration with toxicity can be seen in the enormous amount of research effort to find a cure or preventive agent. At almost any given time, one or more of the land-grant universities have some sort of trial examining various potential cures. To date, I am not aware of any compound widely recognized as effective.
Having said that, I must point out that anthelmintics are important. The stress of a worm load is exacerbated by fescue toxicosis and the performance of "wormed" cattle over parasitized cattle is typically much better than would otherwise be predicted.
I should also mention that there is at least one university Extension specialist who believes a particular anthelmintic has a function independent of its efficacy on parasites. To date, however, that theory is not widely accepted, nor to the best of my knowledge is the product manufacturer seeking a label claim. For the time being, then, I would simply say that for cattle grazing fescue, added emphasis should be placed on monitoring and/or treating for parasites regularly.
Manage With Clover Other than planting endophyte-free fescue, probably the best agronomic practice is to interseed clover (a good idea even with endophyte-free varieties). Aside from the nitrogen fixing/fertilizer sparing function, clover is beneficial as it dilutes the consumption of fescue during the most critical period: summer.
That is, during the hottest of weather, clover grows most vigorously. Cattle will preferentially root around the fescue to graze the clover, which reduces the consumption of fescue during the most critical period.
Of course, there can be problems. Bloat is always a potential problem with legumes. Beyond that, during breeding season the excess protein contained in clover can affect conception. But these are problems that can be managed through supplemental feeding. Something else to keep in mind is that endophyte levels are the highest in fescue seed. So, cattle should not be allowed to graze mature fescue. Ideally, grazing management should not allow fescue to reach maturity.
As a practical matter this means rotational grazing is required. If you do not rotationally graze, at some point mature fescue will emerge. Under continuous grazing cattle do not graze uniformly. They graze and regraze lush regrowth - while ignoring rank, mature growth. At some point, however, when no lush growth is available, they will be forced to the mature growth. If that is the case, then the pasture must be mowed or clipped.
Producers in drought-stricken areas should watch for nitrate and prussic acid poisoning of cattle grazing or eating hay or silage. Both types of poisoning are often associated with drought conditions and can cause death within minutes. Other symptoms are staggering, gasping, salivation and rapid pulse, says Clay Wright, livestock specialist with the Noble Foundation.
Sorghums are most noted for causing nitrate and prussic acid poisoning, but small grains, millet, fescue and many weeds (pigweed, dock, Russian thistle) can also cause problems.
To prevent poisonings Wright says to avoid grazing forages with potentially toxic levels. When in doubt, have forages analyzed for nitrate or prussic acid before grazing them.