GnRH‐agonist deslorelin implant alters the progesterone release pattern during early pregnancy in gilts

Abstract

Contents The aim of this study was to investigate the relationship of progesterone (P) and luteinizing hormone (LH) during recognition and establishment of pregnancy in the gilt. Therefore, the effects of eliminating episodic LH pulses on P patterns were determined during early pregnancy. To this end, a slow‐release GnRH implant deslorelin was used for GnRH down‐regulation. A group of gilts (GnRHa, n = 8) was implanted with the GnRH‐agonist on Day 11 of pregnancy, while a control group (C, n = 5) was treated with a non‐impregnated placebo implant. Blood was collected via a vena cava caudalis catheter at 10‐min intervals for 8 hr on Day 16 and 21 of pregnancy. As expected, the GnRH implant reduced LH secretion (p < 0.01) and abolished LH pulses completely at Day 16 and Day 21 of pregnancy. On Day 16, there was no difference in P levels between the treatments. However, on Day 21, the GnRH‐agonist treatment led to significantly increased P concentrations (p < 0.01) compared with the control gilts. Progesterone was secreted in a pulsatile manner in both treatment groups and no relationship between LH pulsatility and P pulsatility was observed. In conclusion, abolishment of LH pulsatility did not affect the pulsatile pattern of P secretion but led to an unexpected overall increase in P on Day 21 of pregnancy; this effect was delayed and occurred 10 days after commencing treatment with the GnRH depot agonist. The elevation of P on Day 21 of pregnancy in the GnRHa group suggests either a reduced negative feedback effect or an increased autocrine response by the corpora lutea.

Coping with large litters: the management of neonatal piglets and sow reproduction

“…Further, there is a positive relationship between follicle diameter at ovulation and corpus luteum (CL) diameter after ovulation [76,82]. Good CL development is necessary for embryo development during early pregnancy [2,83,84], as CL has been shown to positively relate with progesterone level and pulse [85][86][87][88]. Smaller follicles at ovulation may therefore be A C C E T E D detrimental for early embryo development.…”

Effect of dietary l-carnitine supplementation to sows during gestation and/or lactation on sow productivity, muscle maturation and lifetime growth in progeny from large litters

“…Previous work by our group, in which supplemental CAR was fed to highly prolific gilts from day 38 of gestation (average total litter size of 14•8 piglets), observed no increase in litter size at birth (30) . The present findings therefore suggest that the effect of CAR functioned primarily during embryo implantation, which occurs during the first 35 d of gestation (41) . This supports the hypothesis that CAR promotes embryo viability and this beneficial effect is mediated through an improvement in in utero nutrition (14) .…”

Application of Exogenous GnRH in Food Animal Production

“…Exogenous GnRH agonists in non-injection form, such as intravaginal implants of goserelin acetate or deslorelin [ 58 , 59 ] or a gel containing triptorelin acetate [ 22 , 28 , 60 , 61 , 62 , 63 , 64 ], have been used to control ovulation and so improve the management of artificial insemination in swine. Knox et al [ 65 ] used mature gilts following estrus synchronization using the orally active progestogen, altrenogest, to perform a dose–response study with the vaginal deposition of different doses of triptorelin gel administered at different times after the last altrenogest feeding.…”