PERIPARTUM LIVER TRIGLYCERIDE AND PLASMA METABOLITES IN DAIRY-COWS

Nine pregnant, nonlactating cows were used to monitor liver triglyceri des before and after parturition. Estimates were made of the contribut ion of depressed feed intake and parturition to plasma NEFA concentrat ions and development of fatty liver. Liver biopsies and plasma samples were obtained on d 19, 10, 5, 3, and 1 prior to calving and on d 1, 7 , 14, and 21 after calving. Depression of DMI started on d 2 prior to calving and was 40% of DMI on d 3 prior to depression of feed intake. Elevation of plasma NEFA concentrations started prior to DMI depressio n, on d 5 before parturition. Liver triglyceride infiltration did not occur until the concentration of plasma NEFA was maximized on d 1 afte r calving. This result implicated the acute rise in NEFA at calving as a contributing factor to triglyceride accumulation in the liver. The increasing plasma glucose and decreasing plasma BHBA prior to calving may have reflected metabolic changes toward gluconeogenesis. Liver gly cogen decreased 70% during the final 19 d prior to calving. Hepatic tr iglyceride infiltration (7.7% DM basis) on d 1 postpartum and duration of DMI depression prepartum were less severe than those observed in p revious studies. Frequent liver biopsies did not affect DMI.