Effects of Charcoal-Extracted, Bovine Follicular Fluid on Gonadotropin Concentrations, the Onset of Estrus and Luteal Function in Heifers

Abstract

A study was conducted to determine the effect of charcoal-extracted, bovine follicular fluid (CFF) on plasma follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations, the interval from luteolysis to estrus, and subsequent luteal function in heifers. Fifteen Angus, Simmental and Hereford heifers were allotted by age, weight and breed to a control (C, n = 8) or a CFF (n = 7) group. Heifers received injections of saline or CFF (iv, 8 ml/injection) every 12 h from d 1 (d 0 estrus) through d 5 of the estrous cycle. On d 6, each heifer was injected (im) with 25 mg of prostaglandin F₂α (PGF₂α). Blood samples were collected every 12 h by venipuncture starting just before the first saline or CFF injection and continuing until estrus. Thereafter, blood samples were collected every other day during the subsequent estrous cycle and assayed for FSH, LH, estradiol-17β and progesterone by radioimmunoassay. Injections of CFF had no effect (P>.05) on circulating FSH or LH concentrations from d 1 to 5 relative to the C group; however, there was a transient rise (P<.05) in FSH concentrations 24 h following cessation of CFF injections. This transient rise in FSH was not immediately followed by an increase in plasma estradiol-17β concentrations. Although CFF injections did not interfere with PGF₂ α-induced luteolysis, the interval from PGF₂α injection to estrus was delayed (P<.05) by 5 d in the CFF group compared with the C group. Furthermore, the rise in estradiol-17β following PGF₂α injection was delayed in the CFF group. The length of the subsequent estrous cycle and the plasma concentrations of progesterone were similar (P>.05) in the C and CFF groups. In summary, cessation of CFF injections resulted in a selective, transient increase in FSH concentrations. Furthermore, CFF injections preceding PGF₂α-induced luteolysis delayed the onset of estrus but did not alter subsequent luteal lifespan. Copyright © 1985. American Society of Animal Science . Copyright 1985 by American Society of Animal Science