Dietary Management of Prepartum Cow for Prevention of Milk Fever: A Review
Basic biochemical defect in milk fever include reduction in the levels of ionized calcium in tissue fluids. It occurs most commonly in high producing adult lactating dairy cow within the first 48 h after calving. Almost in all cases of milk fever cows become recumbent and are unable to rise even after great efforts (Goff 1999). Presently there are number of methods available for the control of milk fever in ruminants which include dietary management before and after calving, oral administration of calcium gels during parturition and administration of vitamin D and its analogs just before parturition etc. A specific control program should follow when incidence of milk fever is more than 10% but it may not be economical during low incidence of milk fever in such cases careful monitoring of cow during and 48 hours after calving and treatment of affected cow is the only effective and economical way to control milk fever in herd. Besides these, composition of prepartum diet has a significance role in the incidence of milk fever in dairy cow. Level of calcium, phosphorus, acidifiers, dietary cation anion difference plays crucial role in prevention of milk fever in dairy cow.
Common observable symptoms in milk fever
- Depression and unwillingness to move and eat.
- The body temperature goes below normal and the extremities becomes cold.
- The muzzle and nose become dry.
- The eyes become dull and expressionless and the membrane covering the eye turn reddened.
- The animal lies with its head turned to one side for which the neck assumes an S shape.
- The pulse and breathing become accelerated and very often breathing becomes laboured and accompanied by groaning.
- There may be bloating i.e. accumulation of excessive gases in the rumen as the gut becomes paralysed.
- The animal goes to coma and death may occur within a few hours.
Level of calcium and phosphorous in diet
High calcium diet during prepartum period increases the incidence of milk fever and diets low in calcium will reduce the incidence of milk fever in dairy cows. During dry period if daily calcium intake is more than 100 gram then it will leads to increased incidence of milk fever. If animal is fed to low calcium diet (20g/day) during last 15 days before calving then it will leads to decrease incidence of milk fever. Low level of calcium in prepartum diet activate the calcium homeostatic mechanisms before calving, making the cow able to mobilize the large quantities of calcium for the colostrum production. Negative calcium balance is created when dietary calcium availability is below calcium requirements which lead to secretion of parathyroid hormone which in turn increases renal reabsorption of calcium (Goff, 2008). stimulates calcium resorption from bone and stimulates production of 1, 25-dihydroxyvitamin D (Calcitriol) in kidney. Calcitriol stimulates the active transport of calcium across the intestinal epithelial cells. Use of intestinal calcium binder such as sodium aluminum silicate or zinc oxide is also another common practice for prevention of milk fever. Addition of sodium aluminium silicate in dry cow ration at the rate of 1.4 kg of pellets per day for the last 15 days of pregnancy results in an increase in plasma calcium during calving. Feeding soya bean oil to pregnant dairy cow during the transition period is another effective in preventing milk fever and increases milk solids production in early lactation. Dietary phosphorus >80 g/head per day increase the incidence of milk fever because of inhibitory effect of increase level of phosphorous on renal enzymes which catalyze the production of 1, 25- (OH)2 D, which is responsible for intestinal calcium absorption. So in case of increased level of phosphorous intestinal calcium absorption becomes inefficient during colostrum production which leads to increased chances of milk fever.
Calcium and phosphorus ratio in diet
Maintenance of proper ratio of calcium and phosphorous in prepartum diet is also a prime requirement for prevention of milk fever. Low Ca:P ratio result into negative calcium balances which stimulate activity of the parathyroid gland so that calcium is maintained to normal level during colostrum production.
Dietary cation anion difference (DCAD)
Maintenance of proper dietary cation anion difference in prepartum diet is another method for controlling milk fever in dairy cow. High content of cation like Sodium and potassium increases the chances of milk fever while the diet, containing high amount of anion like chloride and sulfur make the animal less prone to milk fever (DeGaris and Lean 2009). Since most of the prepartum diets are rich in cation they cause metabolic alkalosis which causes hindrance in bone resorption of calcium making the cow more prone to milk fever. Addition of anion in prepartum diet induces metabolic acidosis which enhances renal synthesis of 1,25-dihydroxyvitarnin D and facilitates bone resorption and intestinal calcium absorption during colostrum production hence cow become more resistant to milk fever and hypocalcaemia. The DCAD is expressed in mEq/kg DM using the equation DCAD= (Na +K) – (CI + S). Previous studies indicate that a DCAD of – 50 to 100 mEq/kg DM is optimal for the prevention of milk fever. Addition of anionic salt in prepartum diet during last three week before parturition upto a level sufficient to reduce DCAD upto -15 mEq/kg DM is another method of choice to prevent milk fever in dairy cow. Main problem with addition of anion is reduced palatability which affects appetite of cow thus decreasing dry matter intake. Most common anions which are commonly added in prepartum diet are chloride and sulfate. The incidence of milk fever was reduced by the addition of chloride and sulfur in excess relative to sodium and potassium in the diet. Maximum limit of adding anionic salt in prepartum diet is 300 mEq of anions/kg diet DM without affecting dry matter intake.
Now a day number of anionic salts are available in market for addition in prepartum diet but the most common salts are ammonium chloride and ammonium sulfates. Out of these two, ammonium chloride is preferred because it is more potent acidifier than ammonium sulfate. Recommended quantity of supplementation of ammonium chloride in prepartum diet is 100 g/head per day 21 days prior to parturition .
Table-1: Nutritional factors responsible for milk fever
No. ———-Factor——————————————————— Effect
1 General Nutritional status at Prepartum period Increase K – pasture, Over fat cow and very thin cows
2 Reduce feed intake on day of calving ———–Reduce Ca intake and absorption
3 Increase Ca intake prepartum ———–Increase passive absorption and quiescence of Parathyroid gland
4 Increase P intake prepartum (>80 g P/d)———— Inhibits Vit-D metabolism
5 Reduce Mg concentration at prepartum ————-Reduce production and secretion of PTH
- Dietary Cation Anion Differences ————Increase DCAD balance
Vitamin D and its metabolites
1,25-dihydroxyvitamin D, which is produced in the kidney with the help of parathyroid hormone, regulate Intestinal Ca absorption and bone Ca resorption (Horst et al. 1994) thus involve in calcium homeostasis (Goff et al. 2004). When blood Ca is within the normal range, parathyroid hormone secretion is decreased (Taylor et al. 2008). So, oral administration of vitamin D (20 million IU) continuous for five days prior to calving is an advantageous for controlling milk fever in dairy cow.
Nutritional strategies to prevent milk fever
Occurrence of Milk fever has direct relationship with the feeding strategies followed during the pregnancy and immediately after calving. Thus, it is possible to prevent milk fever by adopting appropriate feeding strategies during the above mentioned periods. The following feeding strategies are suggested to prevent milk fever occurrence in high milk producing dairy cows.
Restriction of calcium in the prepartum (before calving) period
Calcium is an essential mineral required for a number of functions to sustain life of animals. As a preventive measure of milk fever, calcium should never be supplemented before calving. Dietary calcium level should also be low (intake should be around 20 g/day). Vitamin D helps in absorption of calcium from the digestive tract and significantly helps to prevent milk fever when given a week or so before calving. However, as the commonly fed forages and concentrates provide significant quantities of calcium, manipulation of ration to low calcium level is sometimes difficult practically to ensure low calcium intake. In such situation supplementation of zeolite and vegetable oils can be done as both are known to reduce the absorption of calcium sufficiently.
Magnesium supplementation
Magnesium is another important body element and 70% of body magnesium is found in bones. Magnesium is responsible for membrane stability and thus related with cardiac and skeletal muscle functions and nervous tissue function. It is also related with several enzymes required for body metabolism and most importantly plays very important role in calcium metabolism. Magnesium is essential for maintaining blood calcium level in animals thus indirectly responsible for occurrence of milk fever. Magnesium supplementation at the rate of 15 to 20 g/day along with a source of easily digestible carbohydrate helps in preventing milk fever in dairy animals. During pregnancy magnesium should be supplemented at the rate of 0.4% of dry matter of ration.
Supplementation of calcium to susceptible animal after calving
It is not advisable to use this method as a first line of prevention. Supplementation should be done depending on the quality of ration provided and level of calcium in it, as there are chances of negative effects for breaking of calcium homeostatic pathways in the body.
Manipulating the DCAD of ration
The DCAD i.e. dietary cation-anion difference of ration is directly related with incidence of milk fever. The DCAD of ration can easily be calculated if percentages of concentrations of sodium, potassium, chlorine and sulphur ions of the ration are known [DCAD = (Na + K) – (Cl + S)]. Cattle fed ration with a high DCAD tends to cause milk fever, whereas negative DCAD tends to prevent milk fever. Reduction of DCAD rather than calcium content of ration during prepartum (before calving) is considered as the method of choice for preventing milk fever. It is because feeding more concentrates or cereal silages to dry cows to lower calcium intake may be expensive and may predispose cows to other complications like fatty liver syndrome, ketosis, abomasal displacement for high energy density. The DCAD can be reduced by addition of anionic salts (i.e. salts of chloride, sulphur or phosphorus) to the ration of pre-calving cows. Usually typical ration of dairy cows has DCAD ranging from +100 to +200 meq/ kg dry matter (meq= milliequivalent i.e. one meq is equal to 1/1000th of equivalent weight). Addition of anionic salts (minerals high in Cl and S relative to Na and K) or mineral acids to the ration lowers DCAD and reduces the incidence of milk fever. Addition of three equivalents of anions to 12 kg ration dry matter lowers DCAD by 250 meq/kg.
Other feeding suggestions
- Just after calving, cow should not be milked completely for about 2-3 days. However, to avoid associated complication like mastitis, the calf should be allowed to suck milk for about 36 hours during this period.
- Forages rich in calcium should not be fed before calving particularly during the last trimester of pregnancy period.
- The following formulation can be suggested as a lick on feed: 1 cup molasses + 4 tablespoons linseed oil or meal + 2 tablespoons salt + 2 tablespoons causmag or dolomite.
- It is important to restrict potassium (K) intake for dry cows to prevent milk fever.
How to treat milk fever
It is always advisable to call a Veterinarian when the animal is sick. Treatment by farmers based on the observable symptoms are not at all advisable. Remarkable success can always be expected if treatment is carried out properly. The following treatment strategies can be followed.
- Intravenous injection of calcium borogluconate (20% solution) or other calcium salts. Special care is required while injecting calcium borogluconate so that it is not made under the skin or the solution does not enter the tissues surrounding the vein since this causes irritation which may result restraining of the animal difficult.
- No commercial oral preparation is available. But, for suffering cows which are still on their feet or have only just sat down and can still hold their heads up, an oral preparation can be suggested. The recipes of that oral preparation are as follows:
- Dissolve calcium chloride (around 150g, but not more than 200 g) in 200 ml of warm cider vinegar.
- After properly dissolving the calcium chloride, add around 150 ml of fish or vegetable oil.
- Then 50 g of causmag or dolomite should be added and the volume of the solution should be made up to 500-600 ml with molasses.
- The solution should be shaken thoroughly before feeding to the animal so that the vegetable oil is suspended well. Vegetable oil helps to protect intestinal mucosa from irritation due to calcium chloride.
- It is advisable not to give more than three treatments with this preparation as calcium chloride may cause stomach ulcers. If at all required calcium chloride should be replaced with lime flour.
CONCLUSION
Thus we can conclude from above discussion that prepartum diet play an important role in prevention and control of milk fever in dairy cow. Proper quantity of calcium, magnesium, phosphorous and vitamin D, maintenance of optimum Ca: P ratio, addition of dietary acidifiers and proper maintenance of dietary cation anion difference in prepartum diet are some of the common feeding practices for prevention of milk fever in dairy cow. The milk fever is not only economically important, but also it causes loss of animals as it occurs at the most productive period of a lactating cow. Economic loss due to milk fever happens because of reduction in quantity of milk as well as expenditure on treatment of disease-affected animal. As milk fever is a metabolic disease directly related with feeding management, adopting appropriate feeding strategy during the pregnancy period and immediately after calving can prevent the occurrence of milk fever. Feeding of proper balanced ration considering the factors predisposing milk fever will help the farmers to avoid this menace successfully.
Compiled & Shared by- This paper is a compilation of groupwork provided by the Team, LITD (Livestock Institute of Training & Development)
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