There are a few diseases/disorders in dairy cattle and buffaloes which occur for improper feeding and/ or nutritional management. Milk fever is one of such disorders which occurs due to faulty feeding practices during the pregnancy period and immediately after calving of dairy animals.
Milk fever is a disease of high producing dairy animals occurring within one or two days after calving. It is because of low calcium supply through feeds and hence the animal is unable to meet the demand of the body’s requirement for heavy drainage of calcium through milk. On an average, there is drainage of about 23 g of calcium for every 10 litres of colostrum produced just after calving. If this amount is added to the daily requirement during this period the need is about 10 times higher than the supply of calcium through feed. When feed-stuffs provided to the cows are unable to meet this requirement of needed calcium, milk fever develops. Milk fever develops when serum calcium drops below 6.5 mg/dl of blood from normal 8-10 mg/ dl of blood.
Milk fever can also be called the ‘gateway disease’ as it increases the risk of other diseases manifold such as mastitis, ketosis, retained placenta, displaced abomasum and uterine prolapsed.
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.
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 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.
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.
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.
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.
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.