Research Information related to your Herd Health Program.
Animals need time to adapt to changes in feed. Ruminants especially need to gradually switch from high roughage rations to high grain rations. Rapid changes may cause acidosis, or other digestive upsets in cattle or sheep. Feeding hay to cattle and sheep before allowing them to graze green crops or lush pastures can prevent some of the digestive problems. Or, you might allow the animals to graze only a few hours a day until they have adapted to the new feed. Some animals may develop allergic reactions to substances in fresh, lush, green feeds.
Mold and Ergot
Mold toxins or ergot can cause poisoning in animals. Swine and pregnant animals are most susceptible to these toxins. These toxins, if consumed at high levels, may cause abortion, vaginal or rectal prolapse, internal bleeding or dry gangrene-like symptoms and, even, death. Weak and starving animals are less able to detoxify these toxins. Addition of vitamin, A,D, and E may help the animals tolerate theses toxins. Diluting the moldy feed with clean feed may bring the toxin concentration down to a safe level. Dilute ergoty feeds to less than one ergot body per 1000 kernels.
Feeding excessive levels of low quality hay or straw to cattle without adequate grain supplementation to provide energy and protein can leave the forage undigested and cause rumen impaction. Lack of water may also contribute. Hammering low quality forage can increase the amount of forage eaten but may also lead to impaction if the ration is low in energy and protein content. You must be particularly watchful to ensure adequate energy intake during periods of sever cold.
Problems due to water
While producers have successfully used clean snow as the winter water source for beef cows and sheep, this practice must be used with extreme care as lack of water can lead to rumen impaction or reduced feed intake. If you are concerned about the quality of water for your livestock or have noticed your animals are eating less or drinking less or your animals have scours, you should have a water analysis carried out to determine the level of minerals present in it.
Pesticides and Herbicides
If you intend to salvage cereal crops for feed, ask about pesticide and herbicide applications to make sure restrictions listed have been compiled with. Never feed seed grain treated with chemicals. Awns from wild barley or “foxtail” can lodge in an animal’s mouth, sometimes causing an abscess. Hay with a lot of “foxtail” is unpalatable and should be avoided.
Dicoumarol poisoning or “Sweetclover Disease”
Moldy sweetclover hay or silage may contain dicoumarol. This agent prevents blood from clotting, so animals may bleed to death internally or from external wounds. One rule of thumb for safe feeding is: 3 weeks on sweetclover and 3 weeks on another feed. New low-coumarin varieties of sweetclover such as Polara do not become toxic with molding.
Frost, drought and weed sprays may be factors in high nitrate accumulation by plants. Oat straw and oat hay are most affected. Green oats should be cut either immediately after a frost before nitrates build up or after 14 days with no frost to allow the nitrate built up to be cleared by the plant’s system. Green feed cut after a frost should be tested for nitrates. Agricultural representatives can do a quick spot test for presence of nitrates. If nitrates are present, the amount should be determined. The rule of thumb for feeding is to dilute the nitrate-containing roughage with nitrate-free roughage so the total feed contains no more than 0.5 percent nitrate. For example if green oats has 1.0 percent nitrate it should be diluted half and half with nitrate free roughage. This should be done with each feeding to prevent over consumption by any individual animal. It does not work if high-nitrate feed is fed one day and nitrate free feed the next. Forages containing nitrates may cause death to cattle and sheep by interfering with oxygen transport by the blood. Symptoms of nitrate poisoning include rapid breathing and pulse as the animal strives for oxygen, frothing from the mouth, blue color of the mucous membranes, muzzle and udder and brown colored blood. Treatment requires early intravenous injection of a 40 percent solution of methylene blue.
Prussic acid (Hydrocyanic Acid) Poisoning
Flax that has been frozen or severely affected by drought may contain toxic quantities of prussic acid (0.03 – 0.04 per cent). Symptoms of prussic acid poisoning are similar to nitrate poisoning except blood remains bright red. Death usually occurs before treatment is possible, although early intravenous injection of sodium nitrate and sodium thiosulfate by a veterinarian may be beneficial. Where prussic acid may be a problem, feed should be analyzed and suitable precautions taken. Prussic acid in cured forage gradually disappears and is seldom a problem in the winter.
Nutritional deficiency diseases
Poor quality feeds supply fiber to the animals, but are low in energy, protein, minerals and vitamins. Inadequate amounts of nutrients may lower conception rate, disease and parasite resistance, and may result in weak calves and lambs and sometimes still-born off-spring. When low quality forages are fed, you must provide mineral and vitamin supplements. Pay particular attention to supplying adequate vitamin A and supplying minerals free-choice or force feeding. It bears repeating, know the quality of your feeds and your animals requirements. Avoid wasting feed or underfeeding by having your feed analyzed. Talk to your Ag Rep, Livestock Specialist or feed company nutritionist about the best rations for your cattle.
The following disease conditions pose higher risks during very dry periods:
Severe blowing dust can irritate the respiratory tract of cattle and cause an increase in cases of pneumonia.
Poor pasture conditions increase the risk of plant poisoning. A good many poisonous plants are rather unpalatable but when grass is short cattle will eat such things as choke-cherry leaves, marsh arrow grass, etc. which can result in poisoning.
Soil borne diseases such as Blackleg present a higher risk because cattle are grazing close to ground level.
Severe drought followed by heavy rain may result in rapid, lush growth of cereals and/or seeded pasture. This has the potential of causing grass tetany, a disease somewhat similar to milk fever and a form of pneumonia variously called AIP (atypical interstitial pneumonia) pulmonary emphysema, fog forever, etc. The major symptom of this form of pneumonia is labored breathing. The local practicing veterinarian can provide additional information regarding these and other potential disease conditions. Hungry cattle should be fed before being turned into new pasture. They may eat poisonous plants because they won’t selective graze at first. They should be watched carefully the first few days for digestive upsets or AIP (change of pasture pneumonia).