Trouble- shooting Milk Fever and Downer Cow Problems — Dairy Cattle Nutrition — Penn State Extension. Possible Causes. In the time period shortly before calving, large amounts of calcium are removed from the blood and are utilized in the mammary gland to be part of the colostrum. Calcium in colostrum may be eight to ten times greater than in the blood supply. The rapid drop and the decreased mass of the calcium pool prior to parturition, and the failure of calcium absorption to increase fast enough after the onset of lactation, can predispose animals to milk fever or hypocalcemia. There are other probable causes that have been associated with inducing milk fever. They include excessive bone formation due to elevated levels of gonadal hormones and rations containing excessive dietary levels of cations, especially potassium. In addition, other metabolic disorders can lead to clinical and subclinical hypocalcemia (i. Table 1 lists additional factors and situations. Table 1. Conditions associated with milk fever. Factors. Situations. Low calcium intake, especially for dry cows (< 0. TRDM))Heavy corn silage feeding; high moisture corn feeding; inadequate supplementation; low grain intake (dry cows); low forage – high grain feeding. Low phosphorus intake (< 0. TRDM)Inadequate supplementation; high forage – low grain (i. Stage I milk fever often goes unobserved because of its short duration (< 1 hour). ![]() Signs observed during this stage include loss of appetite, excitability, nervousness, hypersensitivity, weakness, weight shifting, and shuffling of the hind feet. The clinical signs of stage II milk fever can last from 1 to 1. The affected animal may turn its head into its flank or may extend its head. The animal appears dull and listless; she has cold ears and a dry nose; she exhibits incoordination when walking; and muscles trembling and quivering are evident. ![]() Other signs observed during stage II are an inactive digestive tract and constipation. A decrease in body temperature is common, usually ranging from 9. The heart rate will be rapid exceeding 1. Stage III milk fever is characterized by the animal's inability to stand and a progressive loss of consciousness leading to a coma. Heart sounds become nearly inaudible and the heart rate increases to 1. Cows in stage III will not survive for more than a few hours without treatment. Problem situations. Milk fever is considered a herd problem when over 1. The higher value may apply to herds where many cows are freshening that have a history of getting milk fever, i. An example of this would be when five out of the last eight freshening cows are diagnosed with milk fever. Forms of Milk Fever. Typical milk fever. An acute form affecting cows usually within a few days after parturition, but it sometimes occurs in late lactation or the dry period. Typical milk fevers respond well to treatment. Refractory or atypical milk fever. An acute form with little or no response to treatment. ![]() Milk fever (or hypcalcaemia) is the result of a reduction of blood calcium in the early stages of lactation. This is due to the cow having a sudden, dramatically. Salt is essential for successful dairy production. Champion’s Choice® Salt, as cow salt licks or blocks or bricks, can meet a variety of nutritional needs. Animal First. Productivity Always. For the most important jobs you need to get done, Arm & Hammer Animal Nutrition can help keep you on the road to success. Symptoms and Problem Situations Stages of milk fever. Milk fever is divided into three stages based on clinical signs. Stage I milk fever often goes unobserved. Milk Fever (Hypocalcaemia, Parturient Paresis) The average annual incidence of milk fever in UK dairy herds is estimated to be approximately 7-8 per cent but. The cow may remain alert, eat, and milk but cannot regain her feet. She may become a creeping downer cow with flexed pasterns and posterior paralysis. Rupture of the large muscle or group of muscles in one or both hind legs may complicate the problem. Similar fracture or dislocation of a hind joint may have occurred when the cow went down initially or in struggling to rise. Tremors or sub- acute. Cows are easily excited with muscle twitching and tremors occurring. Usually, several cows are involved. Many of these animals may be in late lactation, dry, or recently fresh. Often, there is a magnesium deficiency involved as well. Blood Parameters. The most notable changes occurring in the blood are a decrease in blood calcium and blood phosphorus levels and an increase in blood magnesium levels. In cases of milk fever complicated by a lack of magnesium, the blood magnesium level may remain normal or even be depressed. Table 2 illustrates the blood mineral levels for animals in various stages of milk fever. Table 2. Blood serum concentration of dairy cows in various metabolic states. State. Blood serum (mg/dl)Calcium. Blood serum (mg/dl)Phosphorus. Blood serum (mg/dl)Magnesium. Sources: Compiled from The Ruminant Animal: Digestive Physiology and Nutrition. Prentice Hall, Englewood, NJ. Chapter 2. 4, Metabolic problems related to nutrition. The Dairy Reference Manual, Northeast Agricultural Engineering Service, Ithaca, NY. Chapter 6, pg. 7. It is recommended to include the WBC differential as this can indicate stress or infection. Other blood parameters that can denote toxemia are sodium, potassium, chloride, and fibrinogen. Fibrinogen levels can signal that inflammation and infection is present. If toxemia is a factor and is not overcome, treatment for milk fever may not be successful. For downer cow problems, consider creatine phosphokinase (CPK) and aspartate aminotransferase (AST) in the blood test. CPK normally ranges between 1. IU/L. A value greater than 1. IU/L indicates severe muscle damage from being down. AST levels over 2. IU/L flag a guarded prognosis and levels over 5. IU/L can indicate severe muscle damage. Control Suggestions. Make certain that mineral tests on forages are available. Minerals to test should include calcium, phosphorus, magnesium, potassium, sodium, sulfur, and chloride. Consult with a nutritionist to evaluate the present ration program and the feeding management practices. Include all pertinent information including incidence and severity of milk fever cases. Collect a blood sample from the animal before administering treatment for hypocalcemia. If the animal does not respond to treatment, submit blood sample for blood counts and clinical chemistry. Include in the profile serum minerals, PCV, WBC with differential, and BUN. Some situations may warrant checking CPK and AST. Pending results of feed and blood testing and ration evaluations. Check feeding management practices. For example: Are dry cows consuming free- choice forages or mineral premixes? Is there selective consumption by cows for forages? Discontinue any free- choice mineral feeding. Force feed all minerals. Check that dry cows are receiving supplemental vitamin D at 1. A maximum intake of 5. Check dry cow rations, especially during. This is particularly appropriate if high rumen p. H is suspected. Check urine p. H promptly. Most cows should have a urine p. H of 7. 0- 8. 6. Inject intramuscularly 1. D3 in a water- soluble, highly crystalline form within 2. Do not repeat dose for at least 1. Use three million units in a repeat dose. Before giving up on downer cows, give a drench of two pounds of Epsom salts in one gallon of water. This will sometimes remove toxins in the lower gastrointestinal tract and enable cows to stand within two to four hours. Administer high calcium boluses (about 7. Dietary Cation — Anion Balance. Another method of preventing and controlling milk fever is balancing dry cow rations for anions (negatively charged molecules) and cations (positively charged molecules). Sodium and potassium are the cations and chloride and sulfur are the anions of interest in formulating anionic diets. The dietary cation- anion balance (DCAB) equation most often used to determine milliequivalents per 1. Eq/1. 00g = m. Eq (Na + K) - m. Eq (Cl + S). Based on current research, the range that achieves the lowest incidence of milk fever is a DCAB of –1. Eq/1. 00g dry matter (DM) or –1. Eq/kilogram. Achieving a DCAB of –1. Eq/1. 00g requires adjustments in the major mineral levels that are quite different than what is normally programmed for regular close- up dry cow rations (no anionic salts). Table 3 lists recommended mineral levels for both regular and anionic rations. Table 3. Guide to mineral composition (dry matter basis) for close- up dry cows. Mineral. Regular. Anionicaa. DCAB may be calculated from the percent element in diet dry matter. The equation is as follows: m. Eq/1. 00g DM = . Urine acidity is affected by these changes in the cow's acid- base status, Table 4. Checking urine p. H can help producers and veterinarians monitor the effectiveness of an anionic ration. Table 4. Urine p. H predicts calcium status of cows at calving. Ration DCABPre- fresh cow. Urine p. HPre- fresh cow. Acid- base status. Fresh cow. Calcium status. Source: Davidson J. Hoard's Dairyman, pp. Positive (> 0 m. Eq/1. 00g)8. 0 to 7. Alkalosis. Low blood calcium. Negative (< 0 m. Eq/1. 00g)6. 5 to 5. Mild metabolic acidosis. Normal blood calcium. Negative (< 0 m. Eq/1. 00g)Below 5. Kidney overload, crisis. Normal blood calcium. Feeding a combination of different anionic salts is necessary for achieving the desired DCAB, Table 5. The most commonly fed salts are ammonium sulfate, calcium sulfate, magnesium sulfate, ammonium chloride, calcium chloride, and magnesium chloride. Pay special attention to the degree of hydration of specific salts in formulating rations as well as their costs and availability. Table 5. Chemical composition of commonly available anionic macromineral salts. Mineral salt. Chemical formula. Percent as- fed. NPercent as- fed. Ca. Percent as- fed. Mg. Percent as- fed. SPercent as- fed. Cl. DM%Ammonium sulfate(NH4)2. SO4. 21. 2- -2. 4. Calcium sulfate. Ca. SO4*2. H2. O- 2. 3. Magnesium sulfate. Mg. SO4*7. H2. O- -9. Ammonium chloride. NH4. Cl. 26. 2- -- 6. Calcium chloride. Ca. Cl. 2*H2. O- 2. Magnesium chloride. Mg. Cl. 2*6. H2. O- -1. Before incorporating DCAB into a dry cow program, there are several factors to consider. Some of the anionic salts are very unpalatable which can depress intakes significantly in conventional feeding programs. In particular, ammonium salts may result in more intake and palatability problems, especially when a silage based ration is not being fed. Reduced dry matter intakes as a result of feeding anionic salts can lead to the development of other metabolic disorders. Much of the success with anionic salts has been in herds feeding a total mixed ration. The use of an anionic diet is appropriate when high calcium forages are fed at relatively high levels during the close- up dry period.
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