Influence of Short-term Fasting during the Luteal Phase on Ovarian Follicular Diameter and Number, Corpus Luteum Size, Steroid Hormones some Metabolic Hormones in Holstein Dairy Heifers

The aim of this study was to evaluate the short-term fasting in the luteal phase on follicular diameter, the size of corpus luteum (CL), steroid hormones and some metabolic hormones in Holstein dairy heifers. In this study 60 heifers were allocated randomly to 2 groups, control and treatment, that contained 30 heifers with the same age and weight. After estrous synchronization, heifers entered the luteal phase; diet was used in control group based on NRC at one meal, and the treatment group at two meals during 12 days (for short-term fasting during the luteal phase). Number and size of follicles were evaluated by ultrasonography at observation of heat, and CL diameter was estimated by ultrasonography as every other day at 30 h after heat. Also, estrogen hormone was measured at follicular phase and progesterone hormone at luteal phase as every other day. Two glucose samples were estimated within 5 days during short-term fasting. Also, GH hormone and IGF1 was measured at the end of follicular phase and mid-luteal phase, respectively. Results of study showed that number of follicles, CL diameter on left ovary, and the level of progesterone and IGF1 were significantly different (P