Endocrine Changes Associated with a Dietary-Induced Increase in Ovulation Rate (Flushing) in Gilts

Abstract

Effects of an increased level of dietary energy (flushing) on plasma concentrations of FSH, LH, insulin, progesterone and estradiol-17 beta and ovulation rate were studied in 16 gilts. Gilts received 5,400 kcal ME/d for one estrous cycle and the first 7 d of a second. On d 8 of the second estrous cycle, gilts received either 5,400 kcal ME/d (control [C], n = 8) or 11,000 kcal ME/d (flushed [F], n = 8) for the remainder of the estrous cycle. Blood was collected daily at 15-min intervals for 6 h from d 8 through estrus. Gilts were examined by laparotomy 6 d after estrus. Ovulation rate was greater (P less than .05) in F than C gilts (16.0 vs 9.4). Mean daily concentrations of FSH were greater (P less than .05) in F gilts at 5 d, 4 d and 3 d prior to estrus compared with C females. In both C and F gilts, FSH decreased (P less than .05) prior to estrus. Mean daily concentrations of LH and LH pulse amplitude were not different (P greater than .05) between treatments. Mean number of LH pulses/6 h at 4 d, 3 d and 2 d prior to estrus were greater (P less than .05) in F than in C gilts. In both treatments, LH pulse amplitude decreased (P less than .05) and pulse frequency increased (P less than .07) prior to estrus. Mean plasma concentrations of insulin tended to be higher (P less than .07) in F than in C females during the 7-d period before estrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Feeding lactating primiparous sows to establish three divergent metabolic states: I. Associated endocrine changes and postweaning reproductive performance.

“…Indeed, LH has the ability to affect ovarian development directly (Cox and Britt, 1982;Rojanasthien et al, 1988;De Rensis et al, 1991). Local effects of insulin (Cox et al, 1987;Meurer et al, 1991) and nutrition (Flowers et al, 1988) on the number of follicles selected to ovulate have been established in gilts. However, the results of this experiment clearly indicate that the availability of additional nutrients during lactation did not increase ovulation rate or decrease the time to return to estrus.…”

Effect of different dietary energy levels on the reproductive performance of Kivircik sheep under a semi-intensive system in the South-Marmara region of Turkey

“…Realimentation or flushing is associated with significant increases in systemic luteinizing hormone secretion (Flowers et al, 1988;Booth, 1990) that ultimately restores the ovulation rate. In this study, ewes fed the moderate and high energy diets were receiving adequate or excess dietary requirements, respectively; therefore, their reproductive performance was not compromised, as shown by the high litter size.…”

Endocrinology of nutritional flushing in gilts

“…Since chronic, severe feed restriction impairs the hypothalamic gonadorropin-releasing hormone (GnRH) pulse generator (Armstrong and Britt 1987) and a significant and rapid increase in luteinizing hormone (pLH) secretion occurs after realimentation (Flowers et al 1988;Booth 1990), it appears that gonadotropins mediate the restoration of ovulation rate. Whether a comparable hypothalamic-hypophyseal response occurs during realimentation after mild restriction (i.e., flushing), however, needs clarification.…”