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Feeding the dairy herd

Table 16-17 Table of Contents  

TABLE 18. DESCRIPTION AND PREVENTION OF DAIRY COW DISEASES AND DISORDERS
Name Description Prevention
Acidosis - acute
(indigestion, engorgement toxemia)
The rumen may develop an acid condition (pH of 4.0 to 4.5) that impairs rumen function and digestion. The animal has a poor appetite and a dull appearance. Later, faster pulse rates may be observed together with sunken eyes and a dehydrated appearance. Avoid accidental access or rapid changes to a high-energy feed, such as grain mixture, or too much high moisture corn. Early diagnosis and treatment are very important in severe cases to maintain life of animals.
Acidosis - chronic
(off-feed, founder)
The rumen develops an acid condition below pH 6 for several hours per day. DM intake may drop, fat test varies, and sore feet can develop. Feed balanced rations with adequate fiber form and length. Limit grain intake to 5 to 7 lb per meal. Ration moisture should not exceed 50 percent. Add a buffer.
Bloat An excessive accumulation of gases in the rumen. Severe bloat occurs on legume pastures. Breathing becomes labored and excessive salivation is common. Left side of the cow balloons. Feed at least 10 lb dry hay before permitting grazing or recommended levels of bloat-preventing drugs.
Chemicals
   - Insecticides
   - Parasiticides
   - Herbicides
   - Pesticides
Occasionally cattle have been contaminated with chlorinated hydrocarbon compounds such as DDT, dieldrin, heptachlor, PCB, PBB or plasticizers. These compounds are fat soluble, collect in the body fat deposits, and eventually are excreted in milk. Dairy farmers must be cautious about feeds that could be contaminated by direct application or drift from aerial application. Always follow directions on label of insecticides, herbicides, wormers, and chemical products. Consult with veterinarian, extension agent, or sales personnel before using a product if there are any questions about its use.
Displaced abomasum
(twisted stomach)
The fourth compartment of the cow's stomach moves in the body cavity after calving; it may twist, preventing passage of feedstuffs. Occurs most frequently at calving time in cows fed a high level of grain or low forage (ensiled) rations. Limited passage of "putty-like" feces. Veterinarian's diagnosis is by detecting a "pinging" sound using a stethoscope. Feed a minimum of 5 lb of long hay; avoid finely ground or chopped feeds; avoid abrupt ration changes; rations must contain adequate fiber quantity and quality for good rumination. Control other diseases (mastitis and metritis are examples).
Ergot Fungus which infects the flower of cereal grain, causing the seed to develop a large purplish-black growth. Ergot toxicity is due to alkaloids that can cause restricted blood flow, abortions, and reduced milk flow. Avoid grains that contain over .06 percent (6 kernels in 10,000). Dilute ergot-infected feed with wholesome feed, avoid feeding to pregnant animals, and watch animals for symptoms (lameness, muscle tremors, or lower milk yield).
Fatty liver syndrome Cows have lowered level of liver function due to enlarged liver infiltrated with fat. Symptoms include a reduced appetite; secondary conditions may occur, such as ketosis, off-feed, and impaired immune system. Feed a balanced ration (protein, minerals, and vitamins) to meet requirements. Prevent excessive weight gain during the dry period, to avoid fat cow syndrome, and prevent metabolic disorders.
Foot rot A break in the skin or hoof, usually between the toes, allowing bacteria to enter. Symptoms are a rapid, progressive lameness; swollen foot; characteristic foul odor. Infection often gets into joints, spreads up the leg, and may kill the cow. Clean yards and facilities of foreign materials that might cause a break in the skin or hoof. Soft, non-callused feet on stubble or wire grass pastures are highly susceptible. Small stones lodging between the toes can also be a problem. Feed recommended iodine and zinc levels. Use a foot bath with copper sulfate (2%).
Grass tetany
(hypomagnesemia)
May be observed in cows on lush grass pasture high in nitrogen, resulting in low absorption of magnesium. They will suddenly develop tetany, walk with a stiff gait, fall, go into convulsions, and die. Watch cattle closely when pasturing grass field fertilized heavily with nitrogen. Supplement 2 oz. of magnesium oxide daily during the danger period.
Hardware disease Results from a puncturing of reticulum by a sharp object. The animal will have a sudden lack of appetite, a reluctance to move, and a careful gait. Respiration is frequently rapid, pulse rate is fast, and rectal temperature is 100 F or higher. Avoid making hay or silage from fields containing old fences or recently abandoned buildings. Avoid using baling wire. Give magnets to cows when a herd problem exists.
Ketosis
(acetonemia)
Most frequently observed in well-conditioned cows 2 to 6 weeks after calving, resulting from rapid utilization of body reserves and impaired carbohydrate metabolism. Cows refuse to eat grain, then silage and finally hay. They gaunt up and milk production drops rapidly within a few days. Gradually increase grain intake after calving to avoid indigestion and subsequent disease. Some hay is preferred to high silage rations. Avoid fat cows. Use propylene glycol or sodium propionate if ketosis becomes a herd problem. Early detection possible by using "kits" to test milk or urine. Adding 6 g of niacin can be beneficial. Supplemental fat feeding may also help.
Low fat test Severe fat test depression (i.e., 3.8% to 2.8% or less) is associated with high levels of grain feeding and/or small feed particle size. Cows usually drop in milk production and gain weight. Increase amount and length of fiber in ration. Add bentonite at 5%, or sodium bicarbonate or sodium sesquicarbonate at 1% (or 0.4 lb daily) to the grain ration.
Mastitis Infection of the mammary gland caused by any one of several bacterial organisms. Staphylococcus or streptococcus organisms are most frequently involved. Symptoms vary with degree of inflammation. Acute cases show a swollen and painful udder and frequently cause the cow to go off-feed. Chronic cases have slightly swollen quarters and small flakes in milk. No feed is known to cause or cure mastitis. However, a sudden addition of nutrients may result in a marked increase in production and cause more stress. This, in turn, might cause subclinical cases. For prevention of mastitis, consult a veterinarian. Feeding recommended levels of selenium and vitamin E may be helpful.
Milk fever
(parturient paresis)
Occurs at calving; caused by a sudden shortage of blood calcium. First sign is staggering, then difficulty in rising, and finally down and not able to rise. Cows are usually down with head turned back towards the flank. Delayed treatment results in death of cow or slow response to treatment. Feed low calcium (less than 100 g) - phosphorus (30 to 40 g) ration during the dry period. Feed milk fever-prone cows a specific calcium deficient ration 10 to 14 days before calving, or add anionic salts to the ration.
Moldy feed toxicity
(aflatoxins)
The fungus, Aspergillus flavus, and certain other molds, may produce toxic substances when feed grains are stored under conditions of high moisture and poor ventilation. They develop fatty liver degeneration, large adrenal glands and oversized bile ducts, reduce feed intake, have a lowered milk production, and may have a poor reproductive performance. Death in adult animals is rare. Suspected feeds should be laboratory tested to determine if dose levels exceed 0.45 mg aflatoxin per 100 lb of body weight. Limit aflatoxin to 20 ppm in the total ration DM to avoid milk residue problems.
Nitrite poisoning
(nitrate poisoning)
Toxicity is due to an excessive intake of nitrates or nitrites. Blood hemoglobin cannot carry oxygen to the body cells resulting in labored breathing, frothing at the mouth and a brownish color of the nonpigmented skin within a few hours after feeding. Abortions can occur. Death can occur within an hour in extreme cases. Stressed plants (frost or drought) and weeds can be dangerous. Does not accumulate in grain portion of plants. Levels below 1000 ppm nitrate nitrogen are safe. Dilute the problem feed with wholesome feed based on feed test results.
Poisonous plants Several hundred plants are known to be toxic to livestock under certain conditions. Bracken fern, algae, and nightshade are common poisonous plants. Cattle will eat whatever is available when feed is scarce, consuming enough of a toxic plant to produce toxic or even fatal effects. Fortunately, cattle that consume adequate amounts of other feeds will seldom eat enough of a poisonous plant to do any harm.
Polioencephalomalacia or PEM
(cerebrocortical necrosis)
Central nervous system condition characterized by circling, head pressing, blindness, convulsions, and death. An enzyme that destroys thiamine contributes to the problem. Feed 150 mg of thiamine, control lactic acid acidosis, and avoid plants and molds that contain thiaminases.
Prussic acid poisoning Drought or frost-stressed hybrid sorghums or sudan grass produce toxic hydrocyanic acid. Symptoms are rapid breathing, depression, stupor, convulsions, paralysis, and cherry red blood. Death may follow. Avoid feeding young plants or secondary growth below 24 inches tall. Silage or dry hay reduces the risk. If an animal shows symptoms, call a veterinarian immediately and remove all animals from the pasture.
Sweet clover poisoning Animals hemorrhage (failure of blood to clot) resulting from sweet clover hay that has developed a white mold producing dicoumarol. Stiffness or lameness first appears 2 to 4 weeks after introduction of damaged sweet clover. Patches of blood under the skin may appear later. Death may occur early without warning. Avoid feeding moldy sweet clover hay or silage. A preliminary feeding trial with only a few animals is suggested if the feed is questionable. If symptoms suggest sweet clover poisoning, call a veterinarian immediately.
Udder edema Edema is an excessive accumulation of fluid in the udder under the skin. Usually occurs at calving and is more severe in first lactation cows. Limiting access to either sodium or potassium salts during the dry period. Avoid excess grain. Treatment includes stimulating circulation by massaging the udder. Diuretics should be used with care and direction of a veterinarian.
Urea toxicity
(ammonia toxicity)
Too much urea at one time or insufficient carbohydrate intake results in excessive ammonia in the rumen. Animals show an uneasiness, muscle and skin tremors, excessive salivation, labored breathing, incoordination, and bloat. Animal urinates excessively. No more than 0.4 lb of urea should be fed per cow per day.

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