Abstract

Chromium may regulate dairy cow metabolism; a chelated formation of chromium methionine (Cr-Met) is available to the feed industry. The objective of this study was to investigate the effect of Cr-Met supplementation on lactation performance, hepatic respiratory rate and anti-oxidative capacity in early-lactating Holstein dairy cows. 64 multiparous cows were assigned to 16 blocks based on parity and milk yield and then the four cows in a block were randomly allocated to four treatment groups with 0, 4, 8 or 16 g/d of Cr-Met per cow supplemented to a basal diet. Cows were moved from an open dry lot to a naturally ventilated tie stall barn 2 weeks before treatment to adapt to this facility, fed and milked at 0630, 1400, and 1930 h every day. The experiment lasted for 12 weeks. Milk yield and composition were recorded weekly. Dry matter intake was measured every 2 weeks for a total of six times throughout the trial. The plasma variables were measured in weeks 4, 8 and 12 of the experiment. Supplementation of Cr-Met did not affect DM intake of cows. As the supplementation of Cr-Met increased, yields of milk, fat, energy corrected milk (P < 0.01) and lactose (P = 0.01) increased in a linear manner. In terms of plasma variables, insulin concentration decreased in a linear manner with Cr-Met supplementation. As for variables relating to hepatic respiration rate, concentrations of pyruvate and NAD in the plasma were increased in quadratic manners, and lactic dehydrogenase activity was linearly increased as Cr-Met feeding levels increased. Moreover, plasma glutathione peroxidase and superoxide dismutase activity were increased in a linear manner. In conclusion, our study suggested that Cr-Met supplementation improved lactation performance of early-lactating dairy cows through enhancing antioxidant capacity and hepatic cellular respiration.

Highlights

  • During the early-lactation period, dairy cows are subject to metabolic diseases including fatty liver, ketosis, and immunosuppression [1]

  • The results suggest that chromium methionine (Cr-Met) supplementation improved lactation performance of earlylactating dairy cows through enhancing antioxidant capacity and hepatic cellular respiration

  • One of the key issues for metabolic homeostasis disruption during this stage is that feed intake and glucose supply to the dairy cows does not meet their need for maintainace and milk production [2]

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Summary

Introduction

During the early-lactation period, dairy cows are subject to metabolic diseases including fatty liver, ketosis, and immunosuppression [1]. The insufficient glucose supply leads to body reserve mobilization and severe oxidative stress of early-lactating dairy cows [3, 4]. Improved respiration rate and reduced oxidative stress would be beneficial to metabolic glucose supply in early-lactating dairy cows. Previous study showed that chromium supplementation can improve milk production of early-lactating cows via different mechanisms including increased blood glucose clearance, improved insulin sensitivity of liver and mammary gland [6], and reduced immune response [7]. Zhang et al [9] suggested that Cr supplementation failed to improve antioxidant capacity of mid-lactating cows with heat stress. As a stressed physiological stage, the role of Cr supplementation in antioxidant capacity and respiratory status in early-lactating cows has not been evaluated yet

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