Effect of glycerol supplementation across the transition period on energy balance and inflammation in multiparous dairy cows milked with automated systems

Abstract

The objective of this study was to quantify the effect supplementing transition dairy cows with dry glycerol in the prepartum and postpartum periods has on markers of energy balance and inflammation. Multiparous Holstein dairy cows (n = 60) were enrolled in a 2x2 factorial design study. From d 21 to calving, cows individually received (in automated bins) a dry cow diet with either: 1) 250 g/d glycerol supplementation (66% pure glycerol; n = 30), or 2) no supplementation (n = 30). After calving, cows were individually assigned to: 1) 250 g/d glycerol product (66% pure glycerol; n = 30), or 2) no supplementation (n = 30) to their partial mixed ration (PMR) for the first 21 DIM. All cows were milked and offered a target of 5.4 kg/d pellet (23% of target total DMI) by an automated milking system (AMS) and followed for 21 d. Blood samples were collected 7 d before calving and 3, 7, 10, and 14 DIM for analysis of glucose and BHB, as well as 3 and 7 DIM for NEFA and haptoglobin (HAP). Initial dry cow BW, initial lactation BW, calf BW, as well as the −7 DIM blood sample measure were tested as covariates. Treatment factors and their interaction were analyzed using mixed-effect linear regression models. Postpartum NEFA was reduced in cows that received glycerol prepartum (0.54 vs 0.70, ± 0.05 mmol/L; P = 0.03) and postpartum (0.54 vs 0.71 ± 0.05 mmol/L; P = 0.01), such that those cows with supplementation pre- and postpartum had the lowest NEFA (0.44 ± 0.07 mmol/L) and those not supplemented had the highest (0.77 ± 0.07 mmol/L). No difference (P > 0.24) in blood glucose levels were detected due to supplementation during prepartum (2.74 ± 0.05 mmol/L) or postpartum (2.74 ± 0.05 mmol/L). Cows supplemented with glycerol prepartum tended to have reduced blood BHB levels compared with those without (0.67 vs 0.81 ± 0.05 mmol/L; P = 0.08). Postpartum glycerol supplementation tended to decrease BHB levels at 7 DIM (0.70 vs 0.87 ± 0.07 mmol/L; P = 0.09). No differences in postpartum HAP were detected (P > 0.25); cows supplemented with glycerol pre- and postpartum had the lowest concentration (0.62 ± 0.26 g/L), while those not supplemented at all had the highest (1.08 ± 0.23 g/L). These results suggest glycerol supplementation during the transition period can improve indicators of energy balance postpartum in multiparous AMS cows.