NUTRITION DURING THE DRY PERIOD AND HEPATIC LIPID-METABOLISM OF PERIPARTURIENT DAIRY-COWS

From dry-off until 7 d before expected parturition date, 30 Holstein c ows were fed a low energy diet (control) to maintain body condition or high energy diets (high fat or isocaloric high grain) to attempt to i ncrease body condition. After parturition, all cows were fed a common lactation diet, Body condition was unchanged for cows fed control or h igh grain diets, but was decreased for cows fed the high fat diet beca use DMI was decreased. Cows fed the high fat diet during the dry perio d had decreased triglyceride accumulation in the liver at 1 d postpart um, which was accompanied by lowered plasma NEFA, increased peroxisoma l beta-oxidation of palmitate by liver homogenates, and decreased este rification of palmitate by liver slices. During the last 3 wk prepartu m, cows fed the high fat diet had lower glycogen and higher acid-solub le carnitine in liver, higher concentrations of NEFA and bST in plasma , higher ratio of triiodothyronine to thyroxine in plasma, and lower c oncentrations 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; d ifferences among treatments were not significant for DMI, body conditi on, milk production, or milk protein. Periparturient lipid metabolism was altered significantly in cows fed a high fat diet during the dry p eriod, although diet composition and nutrient intakes were confounded.