Associations of prepartum plasma cortisol, haptoglobin, fecal cortisol metabolites, and nonesterified fatty acids with postpartum health status in Holstein dairy cows

The association between negative energy balance and health has led to the testing of blood analytes such as nonesterified fatty acids (NEFA) to identify opportunities for improving the management of transition dairy cows. The objective of this study was to evaluate whether prepartum analytes associated with stress (cortisol) or inflammation (haptoglobin) could also identify dairy cattle at increased risk for health complications after calving. Prepartum blood and fecal samples were collected once weekly from 412 Holstein dairy cows on 2 commercial dairy farms (at wk −3, −2, and −1 relative to calving) and analyzed for concentrations of NEFA, haptoglobin (Hp), and cortisol in plasma and cortisol metabolites in feces. Retained placenta (RP), displaced abomasum (DA), subclinical ketosis (SCK), high Hp concentration (HiHp), and death were recorded up to 30 d in milk (DIM), and animals were subsequently categorized into 3 health categories: (1) no disorder of interest (NDI); (2) one disorder (RP, DA, SCK, or HiHp); or (3) more than one disorder (RP, DA, SCK, HiHp) or death. With the exception of prepartum NEFA, no associations were detected between prepartum concentrations of our analytes of interest and the occurrence of one disorder (RP, DA, SCK, or HiHP) by 30 DIM. Haptoglobin concentration tended to be greater during wk −2 and −1 in cows that developed more than one disorder or that died by 30 DIM; however, when calving assistance was included as a covariate in the analysis prepartum, Hp was no longer a significant risk factor for this postpartum health outcome. Primiparous cows with plasma cortisol concentrations >22.2 nmol/L during wk −2 had reduced odds [odds ratio (OR) 0.41; 95% confidence interval (CI) 0.17-0.98] of developing more than one disorder or death by 30 DIM, whereas multiparous cows with plasma cortisol >34.1 nmol/L during wk −2 tended to have greater odds (OR 2.53; 95% CI 0.87-7.37) of developing more than one disorder or death by 30 DIM. Individual variation in daily cortisol secretion patterns and stress responses to the restraint and handling associated with sample collection make prepartum plasma cortisol data and its relationship to postpartum health difficult to interpret. Among multiparous cows, for every 500-unit (ng/g of fecal dry matter) increase in fecal cortisol metabolite concentration during wk −2, cows had increased odds (OR 1.41; 95% CI 1.12-1.79) of developing more than one disorder or dying after calving. For multiparous cows, every 0.15 mmol/L increase in plasma NEFA concentration during any of the 3 wk before calving was associated with an approximately 2-fold increase in the odds of developing more than one disorder or dying by 30 DIM. Fecal cortisol metabolite concentration during the prepartum period did not predict which cows would go on to develop more than one disorder or die within 30 DIM as accurately as prepartum NEFA concentration; therefore, this analyte is not a suitable substitute for NEFA for assessing opportunities to improve herd health.