Nutrition During the Dry Period and Hepatic Lipid Metabolism of Periparturient Dairy Cows

Abstract

From dry-off until 7 d before expected parturition date, 30 Holstein cows were fed a low energy diet (control) to maintain body condition or high energy diets (high fat or isocaloric high grain) to attempt to increase body condition. After parturition, all cows were fed a common lactation diet. Body condition was unchanged for cows fed control or high grain diets, but was decreased for cows fed the high fat diet because DMI was decreased. Cows fed the high fat diet during the dry period had decreased triglyceride accumulation in the liver at 1 d postpartum, which was accompanied by lowered plasma NEFA, increased peroxisomal β-oxidation of palmitate by liver homogenates, and decreased esterification of palmitate by liver slices. During the last 3 wk prepartum, cows fed the high fat diet had lower glycogen and higher acid-soluble carnitine in liver, higher concentrations of NEFA and bST in plasma, higher ratio of triiodothyronine to thyroxine in plasma, and lower concentrations of insulin and thyroxine in plasma than did cows fed the high grain diet. After parturition, cows fed the high fat diet during the dry period had decreased percentage and production of milk fat; differences among treatments were not significant for DMI, body condition, milk production, or milk protein. Periparturient lipid metabolism was altered significantly in cows fed a high fat diet during the dry period, although diet composition and nutrient intakes were confounded.