Associations of serum haptoglobin in newborn dairy calves with 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 growth, morbidity, and mortality in calves <4 mo of age were investigated. A total of 1,365 Holstein heifer calves from 15 dairy farms were enrolled in this study from January to December, 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 d, 15 to 21 d, 36 to 42 d, and 90 to 120 d of age. At these sampling times, each calf was assessed using a standardized clinical score for general health, and height and weight were measured. At 1 to 8 d of age, a blood sample was collected to measure serum total protein and Hp concentrations. Treatment events and death loss were recorded throughout the study by the farm staff. 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 time. Furthermore, the association between serum Hp and the severity of nasal discharge varied by age at first sampling time. Calves with higher Hp in their first week of life had significantly higher total health scores throughout the entire sampling period. Haptoglobin was not significantly associated with average daily gain or treatment for bovine respiratory disease. 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. Treatment for bovine respiratory disease, diarrhea, or any other disease resulted in increased odds of calf mortality. In addition, Hp concentration in the first week of life was associated with mortality in calves <4 mo 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 alone as a diagnostic test for individual calves was low.