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Associations of Serum Haptoglobin in Newborn Dairy Calves with Future Health, Growth and Mortality up to 4 Months of Age
The objective of this research was to investigate factors associated with serum haptoglobin (Hp) levels in newborn calves. In addition, the associations between serum Hp levels in newborn calves with future growth, morbidity and mortality in calves up to 4 months of age were investigated. A total of 1,365 Holstein heifer calves from 15 dairy farms were enrolled in this study during 2008. Following calving, a birth record was completed, including information on the calving event, colostrum administration and other details. During weekly farm visits, each calf was assessed at 1 to 8, 15 to 21, 36 to 42, and 90 to 120 days of age. At these times, each calf was assessed using a standardized clinical score for general health, and height and weight were measured. At the first sampling event, a blood sample was collected for the determination of serum total protein and Hp. Treatment events and death loss were recorded by the farm staff throughout the study. Data analysis was conducted using a multivariable linear regression model to evaluate associations of explanatory variables with serum Hp. Separate multivariable logistic models were used to determine associations of various factors with treatment for disease and mortality. Serum Hp concentration in the first week of life was not significantly associated with the degree of calving difficulty. However, serum Hp was higher in calves with a higher rectal temperature and depressed attitude at the first sampling event. Calves with higher Hp in their first week of life had a significantly higher total health score throughout the entire sampling period. Haptoglobin was not significantly associated with average daily gain or treatment for bovine respiratory disease (BRD). Yet, for every 1 g/L increase in serum Hp in the first week of life, the odds of being treated for any other disease during the study period increased by 7.6 times. In addition, Hp concentration in the first week of life was associated with mortality in calves up to 4 months of age. The optimal cut-point for Hp was determined to be 0.13 g/L for the prediction of disease and death, although the sensitivity of Hp concentration as a diagnostic test for individual calves was low. Monitoring serum Hp in the first week of life shows considerable promise at the group level for overall assessment of calving management and the impact of calving events on future health and mortality.
Keywords: haptoglobin, health, mortality