Associations of peripartum markers of stress and inflammation with milk yield and reproductive performance in Holstein dairy cows.

The objective was to evaluate the association of peripartum concentrations of fecal cortisol metabolites (11,17-dioxoandrostane; 11,17-DOA), plasma cortisol and haptoglobin (Hp), as well as two markers of negative energy balance, non-esterified fatty acid (NEFA) and postpartum β-hydroxybutyrate (BHBA), with milk yield and reproductive performance. Blood and fecal samples were collected weekly from 412 Holstein dairy cows from wk -3 through wk +1 relative to calving. Pregnancies by 150 days in milk (DIM) and projected 305-d mature equivalent (305ME) milk yield based on the 3rd Dairy Herd Improvement (DHI) test day (mean±SD; 102±17 DIM) were measured. Multivariable linear regression models were used to describe the associations of metabolites with 305ME milk yield. Semiparametric proportional hazards models were used to describe associations of the same metabolites with risk of conception by 150 DIM. Negative associations with milk yield were found for prepartum Hp in wk -2, -1, and +1 relative to calving (estimate±SE: 490±251, 564±259, and 464±136kg lower yield for every increase in Hp concentration by 1g/L, respectively) as well as with NEFA concentration in wk -2 (estimate±SE: 1465±541kg lower milk yield for an increase in NEFA concentration by 1mEq/L). Postpartum associations of NEFA with milk yield depended on parity; NEFA was associated with an increase in milk yield in primiparous animals only (estimate±SE: 1548±510kg increase for an increase in NEFA concentration by 1mEq/L). An increase in plasma cortisol concentration by 1μg/dL in wk +1 relative to calving was associated with an increase in milk yield (estimate±SE: 580±176kg). Prepartum 11,17-DOA was associated in all three prepartum sampling weeks with a reduced hazard ratio (HR) of conception (HR [95% CI]: 0.81 [0.67-0.97], 0.85 [0.72-0.99], and 0.85 [0.75-0.97] for every increase in concentration by 1mg/g fecal dry matter (DM) in wk -3, -2, and -1 relative to calving, respectively). Increased cortisol concentrations in wk -3 and -1 relative to calving were associated with decreased hazard of conception in primiparous animals only (HR [95% CI]: 0.54 [0.32-0.92] and 0.59 [0.35-0.99], respectively. Increases in postpartum metabolites Hp and BHBA had a negative association with hazard of conception (HR [95% CI]: 0.81 [0.70-0.97], 0.74 [0.56-0.98], respectively). Biomarkers of inflammation and stress around calving may be useful to assess opportunities for improved milk yield and reproduction.