Incidence and risk factors of milk fever among cross-bred dairy cows in Khartoum state, Sudan
The study was conducted on 206 cross-bred dairy cows in different dairy herds in Khartoum State, Sudan, during the period from March 2003 to June 2004 to determine the prevalence and incidence rate of milk fever (MF) based on clinical and laboratory diagnosis, and to recognize the risk factors associated with the disease in Khartoum State. The incidence rate was 5.3% among the examined dairy cows. Using Ch-Square cross-tabulation statistics, herd and parity did not represent risk factors for the occurrence of MF. The incidence ranged between 2.2 and 8.0% among the examined herds. The incidence was 2.5%, 4.0% and 9.1% among dairy cows of 1-2, 3-4, and > 5 parities respectively. Milk yield, age and previous history represented high risk factors for the occurrence of MF in this study. Among age groups of 3-4, 5-6 and > 5 years the incidence rates were 3.3%, 2.0% and 10.5% respectively. Cows elder than 6 years constituted 72.7% of the positive cases. Among the milk yield groups, the incidence was significantly higher (19.5%) among dairy cow producing 12-25 liters per day, whereas no milk fever case was reported in dairy cows producing 10 liters or less per day. The disease was studied based on clinical signs and laboratory examinations of serum calcium, phosphorus and magnesium. In all positive cases, body temperature, heart rate and rumen motility were examined. Rectal temperature and rumen motility were significantly low (37.0+ 0.5C˚ and 0.25+ 0.2 per minute respectively). Heart rate was significantly increased (103.5+ 6.9 beat per minute). Blood calcium and Phosphorus levels were significantly lower (4.6+ 0.5 mg/dl and 2.3+0.4 mg/dl respectively) than the levels measured after treatment and recovery, but magnesium levels remained unaffected before and after treatment. The increased blood calcium levels were followed by immediate recovery of 81.8% of the diseased cows. The recovery delayed in 9.1% of cases. 9.1% of the affected cows died. This study is the first, of its kind, was based on laboratory diagnosis in Sudan with featured results indicating that the parity did not affect the incidence of the disease as the disease occurred in one primi-parous cow (9.1%), and magnesium has no role on the pathogenesis of the disease as the levels remained unchanged before and after treatment.