Plasma progesterone and lipid profiles in superovulated heifers

Abstract

Estrous cycles of 22 Holstein-Friesian and Hereford crossbred heifers were synchronized by a IO-day treatment with progestagen releasing ear implants (Crestar, Intervet). Heifers were superovulated with 2,000 IU eCG i.m. (Folligon, Inter-vet) on Day 10 of the synchronized cycle followed by 30 mg PGF,, (Enzaprost, Chinoin) 2 days later. Heifers were inseminated at estrus (Day 0 = Day of Al), flushed on Day 7 and injected with 30 mg PGF,, (PG) on Day 13. Number of corpora lutea (CL) were estimated by real time ultrasonography and rectal palpation on the day of non-surgical embryo collection. Plasma samples for progesterone RIA were collected by jugular venipuncture after withdrawal of the ear implants, at estrus and on days 7, 10 (eCG treatment), 12 (PG treatment), then daily between 2 d before and 2 d after Al, thereafter on Day 5, 7 (flushing), 10 and 13 (PG administration). Plasma samples for total cholesterol (TCh), HDL cholesterol (HDL-Ch), total carotene (TCar), triglyceride (TG) and non-esterified fatty acids (NEFA) were collected on the following days: 0, 2, 5, 7, 10, 13 and 16 after Al. Based on the number of CL counted on the day of embryo recovery, the animals were allotted into low (~2 CL, n=7) or high (~3 CL, n=15) response categories. Blood parameters before and after the superovulatory cycle were compared within the groups as well as between the groups after the superovulatory treatment. Progesterone concentrations were significantly higher during the superovulatory treatment than during the previous non-stimulated cycle in both groups.