cows in field

Recent Odairy Discussion, November, 2018

November 2018. A sudden flurry of third trimester abortions on one farm caused the farmer to send out blood samples to a lab. The animals were in a group of dry cows and bred heifers, all receiving a diet of 100% pasture in fields of predominantly fescue. The herd on this farm had not been vaccinated for over 20 years, so the farmer suspected they were having an outbreak of Lepto. Surprisingly, the blood tests came back negative for both Lepto and BVD. The farmer asked the group for insight on what may be causing the abortions. One farmer suggested that the wet weather may have brought on an outbreak of Salmonella. Another producer felt that the cause may be an endophyte infected fescue problem. He felt that endophytes improve the “livability” of the stand, and wet weather after drought can cause increased levels of toxins in the fescue. This can cause outbreaks that hadn’t been seen before because the levels vary year to year and within season depending on the stage of growth. Another farmer believes endophyte-free grasses can be re-infected with the endophyte by feeding hay in the paddock. He thinks the toxic parts are concentrated in the seed head and stalk, so mowing the paddock may help reduce the toxin load. Two vets suggested other causes: one reported that these symptoms are classic for Neospora caninum. “It will usually hit the dry cows for a few months, and then disappear.” He also stated that in the case of toxic fescue, there would generally be peripheral circulation symptoms present like a tail dropping off, quarter dying back, or ear tip shortening. Another vet disagreed with the lab results for the Lepto test. He pointed out that the titers were low, but “what you might expect …in an unvaccinated cow early in infection.” He suggested taking another set of samples, two weeks after the first, and submitting them together. To rule out other possible causes, he recommended that samples be sent from the fetus and placenta, in addition to blood samples to get the best diagnosis. A third vet suggested that if the diagnosis is confirmed to be Lepto, there is a very effective homeopathic nosode as a protection from future outbreaks.

There was a long discussion on the control of horse nettles in pastures. Two farmers shared their frustration with trying to battle the weed through grazing management and mowing. Another farmer suggested that we take a step back to understand why they were growing there in the first place: he informed us that horse nettles (along with field mustard, penny cress, morning glory, quackgrass, wild chamomile, and pineapple plant) are indicators of soil crust formation and/ or soil hardpan. A soil crust is formed when soil is too wet when it is worked, or when a soil dries up after having been cultivated before it has settled, or as a consequence of too deep plowing when the soil is saturated. “A hard crust also forms when fields are too frequently put into grain crops with insufficient root and green manure crops rotating in between the grains.…A hard pan is formed when wet soil is plowed, or standing water dries up in the surface layers.” He went on to explain, “Early and late pasturing have a soil crusting effect equivalent to cultipacking wet soils. Hard pan formation can result from too many years of pasturing when soils are somewhat or mostly saturated causing standing water to dry in soil surface layers. Animal hooves are, in soil effect, cultivation tools.” “A grain crop densely sown when the soil is in moist, not wet, condition, and then followed with a cultivated crop is often the best remedy for reducing horse nettle and the above-mentioned weeds. As the farm’s economics allow, the grain crop can be mown, grazed, or interseeded with a legume that is incorporated when the grain is in tender flower stage. Cultivated root crops other than potatoes will help break up hardpan. Frequent mowing, grazing, and incorporating green manure crops must be done only when the soil is not wet.” And on the positive side, this farmer noted that your poultry will enjoy very young nettles, and nettles stimulate humus formation. “They are endeavoring to heal the soil.” Another farmer suggested regular applications of limestone and gypsum will help to open tight soils, increase soil flocculation, decrease “weed” pressure, and increase forage quality and animal performance.

The alarm went up from a central New York farmer that both grain corn and corn silage are testing positive for mycotoxins because of the unusual weather this year. Specifically, vomitoxin, which can affect dairy cows by reducing feed intake, reducing nutrient utilization, suppressing immunity, and cause reproduction problems. She recommended that famers may want to include toxin binders in their feed ration as a preventative this year. Three different types of toxin binders were identified:

  1. Clay/silicate-based products (Desert Dynamin, Redmond Conditioner, bentonite, calcium aluminosilicate) are effective against aflatoxin, but with little effect on vomitoxin.
  2. Yeast cell wall extract products (Fuse 207, Check M, Immunowall, FloMatrix, Mycotex, UltraSorb etc) are reasonably effective against vomitoxin.
  3. Hydrolyzed yeast product (Alltech’s Integral A+) is a relatively new product, but is showing promise in better protecting an animal’s gut on a routine basis.