α-Tocopherol Concentrations in Milk and Plasma During Clinical Escherichia coli Mastitis

Abstract

Eighteen cows were challenged by intramammary infusion with Escherichia coli 727 to determine the effects of acute clinical mastitis on α-tocopherol concentrations in plasma and milk. Cows were fed diets supplemented with 1000 IU of vitamin E/d from calving through the experimental period. At challenge, geometric mean DIM was 33 d. Each mammary quarter was diagnosed with an IMI and clinical mastitis at 24 and 48h after challenge. The α-tocopherol concentrations in milk from challenged quarters were approximately 60% greater by 24 and 48h after challenge than concentrations at prechallenge and 168h postchallenge. Plasma α-tocopherol concentrations did not change after intramammary challenge. The α-tocopherol in plasma and milk was correlated at 48 and 168h postchallenge but at prechallenge or 24h postchallenge. Milk α-tocopherol and SCC were correlated positively across all sample periods. Milk fat and milk α-tocopherol concentrations were correlated at each sample period except 24h postchallenge. Increases in milk α-tocopherol during clinical mastitis were not correlated to milk production, DMI, or BSA concentration in milk. Changes in milk α-tocopherol concentration during clinical mastitis were similar to the dynamics of milk SCC.