Effect of Short-Term Fasting on Hepatic Steroid Hormone Metabolism in Cows

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In the present study, effect of 4-day fasting on steroid hormone metabolism in the liver and secretion of LH was examined in cows. Six non-pregnant, dry Holstein cows were used. All cows were synchronized the estrous cycle using CIDR-Ovsynch. Cows were allocated to a control group (n=3) and a fasting group (n=3). In the fasting group, cows were fasted for four days from day –4 to day –1 (day 0=day of 2nd GnRH injection) but otherwise were fed ad libitum. The experiment was repeated in a crossover design after an interval of about one month. The peripheral progesterone (P4) concentration in the fasting group was significantly higher than in the control group on day –1 and 0. The peripheral estradiol-17β concentration in the fasting group was also significantly higher than in the control group on day –1 and 0. The portal vein P4 concentration in the fasting group was significantly higher than in the control group. On day 0, LH secretion was no difference between groups. The mean percentages of lipid droplets in liver cells in the fasting group were significantly higher than the control group on day 0. These results suggest that short-term fasting leads to reduced hepatic steroid hormone metabolism by accumulation of fat in the liver, which causes a high peripheral steroid hormone concentrations.