Pooled serum sample metabolic profiling as a screening tool in dairy herds with a history of ketosis or milk fever

Abstract

The present study was designed to compare blood analyte concentrations, measured in pooled serum samples and collected at different periods relative to calving, in herds with no problems (NP) and those with a history of ketosis (K) or milk fever (MF) to determine if patterns of analyte changes can provide diagnostic value in herd-based assessment of dairy cow problems. Furthermore, as potential predictors for K and MF, body condition score (BCS) and ultrasound measurements of back fat thickness (BFT) were also investigated. Based on the problems experienced by herd history, herds were classified into health group (HG) of no problem (n = 6), ketosis (n = 8), and milk fever (n = 7). In each herd, 40 multiparous cows were sampled and classified according to their lactation stages into four different groups as close-up stage (3–1 week antepartum), fresh lactation stage (0–1 week postpartum), early lactation stage (3–5 weeks postpartum), and mid-lactation stage (15–18 weeks postpartum). To make a pooled sample for each time period, serum was harvested from each individual sample of equivalent time period and an equal aliquot (1 ml) from each individual was transferred to a new collection tube. In the close-up period, BCS and BFT were higher in herds with a history of ketosis than other herds (P 3 and >23 as critical thresholds for BCS and BFT, respectively, for the early detection of ketosis in dairy herds. In all time periods, except in the mid-lactation period, pooled serum levels of non-esterified fatty acids were significantly higher in herds with a history of ketosis than herds with no problems or those with a history of milk fever (P < 0.05). In the fresh and early lactation periods, pooled serum concentrations of β-hydroxybutyric acid were higher in herds with a history of ketosis than herds without problems or those with a history of milk fever (P < 0.05). In the fresh lactation period, pooled profile of serum total bilirubin was significantly higher in herds experiencing ketosis than herds without problems or those with a history of milk fever (P < 0.05). In the fresh lactation period, pooled serum profiles of aspartate aminotransferase, creatinine kinase, and glutamate dehydrogenase were higher in herds with a history of ketosis or those experiencing milk fever than herds without problems (P < 0.05). In the close-up, fresh lactation, and early lactation periods, pooled serum calcium profile was significantly lower in herds with a history of milk fever than herds without problems or those experiencing clinical ketosis (P < 0.05). Data in the present study suggest that pooled samples can provide herd-based diagnostic information for the detection of some metabolic health problems as analyte concentrations showed significant differences between herds without problems compared to those with a history of ketosis or milk fever. Variation in health group effect on blood analytes over different times relative to calving suggests the presence of potential analyte patterns that could be used as specific disease diagnostic criteria. Further research is required for the application of pooled sample interpretation criteria in determining herd disease problems. In addition, prepartum BCS and BFT could be used as potential predictors for subsequent postpartum ketosis.