The Influence of Exogenous Growth Hormone on Ovulation Rate in Gilts

Abstract

Although it has been demonstrated in the rat that the local ovarian IGF-l concentration is elevated after growth hormone administration in vivo , the influence of growth hormone treatment and elevated serum IGF-I concentrations on ovulation rate has not been determined.Therefore, an experiment was undertaken to test the hypothesis that exogenous growth hormone would increase the ovulation rate in post-pubertal gilts.MATERIALS AND METHODS Thirty-two prepubertal gilts tYorkshire x Landrace) were selected at 78.0 + 1.5 kg body weightand 138.0 + 3.5 dofage, andtransported from the finishing to the breeding barn on a daily basis. The gilts were exposed to a mature boar for 30 min d I and observed for signs of estrus.Fourteen days after the onset of puberty the gilts were assigned to one of two treatment groups involving the daily injection (i.m.) of either porcine growth hormone (1.0 mg ml--r of 1.7 IU mg -' pGH in carbonate-buffered saline, pH 9.4, administered at 9O p.g kg-' bodyweight; GH, n :20) or vehicle buffer (CT, n = l2). The growth hormone dose employed was similar to that considered to give an optimal improvement in growth rate (Etherton et al. 1987) and which, from a pilot study conducted in our laboratory, also resulted in a marked increase in serum IGF-I concentrations (Kirkwood, unpublished data

Endocrine bases of lactational anoestrus in the sow

“…This may be explained by the fact that the opioids released at suckling inhibit both GnRH and dopamine secretions and that dopamine itself inhibits prolactin release (Kraeling etal, 1982 In prepubertal gilts, daily injection of GH (90 pg/kg body weight) reduces the oestradiol-induced release of LH (Kirkwood et al, 1988). Data are lacking in lactating sows.…”

“…In underfed prepubertal gilts, refeeding increases follicular fluid IGF-I concentrations (Charlton et al, 1993). In cyclic gilts, insulin treatment increases ovulation rate even without a concomitant rise in LH secretion (Cox et al, 1987b (Kirkwood et al, 1988). In cultured porcine granulosa cells, GH enhances the stimulatory effects of oestradiol-17P and FSH on progesterone secretion (Hsu and Hammond, 1987).…”

The Effect of Exogenous Growth Hormone on the Endocrine Status and the Occurrence of Estrus in Gilts

“…(43%) ont laiss6 voir un cycle oestral normal (P<0,001). Chez ies truies qui ont connu un deuxibme oestrus, le traitement i la pGH, n'a eu aucun effet sur la dur6e du cycle oestral (20,4, 20,9 et 20,5 (Kirkwood et al 1988a). …”

Endocrinology of nutritional flushing in gilts

“…Plasma samples ( 1 rnl-) were extracted twice using 7 mL of glassdistilled diethyl ether, and extraction efTiciency, as determined by the recovery of (2,4,6,7-'H(N))- Kirkwood et al (1988), lbllowing the method of Furlanetto et al (1977) hormones, insulin concentrations were assessed Cannulas from two gilts (LH, n : 1; HH, using the daily sampling times as main effect of n : l) were lost due to blockage, and plasma (Fig. 1 bottom).…”