Effects of GRF in early gestation on foetal development in Large White and Genex-Meishan gilts

Abstract

. 2003. Effects of GRF in early gestation on foetal development in Large White and Genex-Meishan gilts. Can. J. Anim. Sci. 83: 469-477. The effects of growth hormone-releasing factor (GRF), given in early gestation, on reproductive traits, foetal development and pre-weaning growth of piglets from two breeds were studied. Large White (LW, n = 26) and Genex-Meishan (GM, containing 50% Meishan genes, n = 37) pregnant gilts were divided in two groups: (1) saline injections (n = 33) and, (2) injections of 6.66 µg kg -1 of a GRF analogue (n = 30), given thrice daily from days 18 to 33 of gestation. Jugular blood samples were collected on days 17, 34 and 109 of gestation and were assayed for various hormones and metabolites. Thirty-six gilts were slaughtered on day 110 of gestation and uterine, foetal and placental measurements were obtained. The other 27 gilts farrowed. There was a day × treatment interaction (P < 0.001) for glucose, insulin, free fatty acids (FFA) and insulin-like growth factor I (IGF-I), with values being greater on day 34 in gilts receiving GRF. The increase in insulin concentration was greater in LW-than in GM-treated gilts (P = 0.02). Exogenous GRF increased foetal weight in LW litters only (1.13 ± 0.04 vs. 1.05 ± 0.03 kg; P = 0.04) whereas fat content of carcasses tended to be lower only in foetuses of treated GM gilts (5.3 ± 0.2 vs. 5.8 ± 0.2%; P = 0.1). Weight of the longissimus muscle and its fibre number were not influenced by GRF. Furthermore, growth of piglets to 28 d was not affected by GRF treatment (P > 0.1). In conclusion, GRF given in early gestation seems to have different effects in LW and GM litters, yet it does not alter pre-weaning growth rate.Key words: Porcine, gestation, growth hormone-releasing factor, insulin-like growth factor I, foetus, MeishanLewis, E., Laforest, J-P., Gariépy, C. et Farmer, C. 2003. Effets d'un apport de GRF en début de gestation sur le développe-ment foetal chez des cochettes Large White et Genex-Meishan. Can. J. Anim. Sci. 83: 469-477. Les effets d'un apport de GRF en début de gestation sur des paramètres de reproduction, le développement foetal et la croissance pré-sevrage de porcelets de deux races ont été étudiés. Des cochettes gravides Large White (LW, n = 26) et Genex-Meishan (GM, avec 50% de gènes Meishan, n = 37) ont été divisées en deux groupes: (1) injections de saline (n = 33) et, (2) injections de 6.66 µg kg -1 d'un analogue de GRF, données 3 fois par jour des jours 18 à 33 de gestation. Des échantillons sanguins ont été obtenus au niveau de la veine jugulaire aux jours 17, 34 et 109 pour mesures hormonales et métaboliques. Trente-six cochettes ont été abattues au jour 110 de gestation afin de prendre des mesures au niveau de l'utérus, des foetus et des placentas. Les autres 27 cochettes ont mis bas. Il y avait une interaction jour × traitement (P < 0.001) sur les concentrations de glucose, d'insuline, d'acides gras libres et d'IGF-I indiquant que les valeurs au jour 34 étaient plus élevées chez les cochettes ayant reçu du GRF. L'augmentatio...

Glucose and hormonal profiles of Meishan-derived and Large White gilts in early and late gestation

“…Yet, data in early gestation were not obtained in the earlier trial. Interestingly, GM foetuses were shown to have greater circulating concentrations of IGF-I than LW foetuses on day 110 of gestation (Lewis et al 2003). Even if circulating IGF-I concentrations in gilts were similar between breeds at the end of gestation, the IGF system could still be involved in the different metabolism of the two genotypes.…”

“…size in GM, yet it is not likely, since concentrations of glucose were found to be similar in GM and LW foetuses (Lewis et al 2003). It is evident that more research is needed to clearly establish the differences in metabolic and endocrine status of Meishan-derived pigs compared to pigs from European breeds.…”

Growth-hormone-releasing factor given to early-pregnant Genex-Meishan and Large White gilts: Effects on growth, carcass, meat quality and histochemical traits of the progeny

“…This effect was more pronounced (P < 0.05) over the finishing phase (from 120 d postpartum until slaughter) in LW pigs. In the prenatal phase of this study, at 110 d of gestation, LW foetuses from GRF-treated sows were heavier than those from control sows, yet this effect was not present at 28 d post-partum (Lewis et al 2003) and was not apparent in the present trial over the growing phase (56 to 120 d postpartum). Likewise, a number of studies did not report any influence of either maternal pGH or GRF treatment on postnatal growth rate of the progeny (Etienne et al 1992;Kelley et al 1995;Gatford et al 2003;Kuhn et al 2004).…”

“…Gilts were randomly allocated to one of the two following groups: (1) saline injections (control; LW, n = 5; GM, n = 5) or, (2) injections of 6.6 µg kg -1 BW of a potent GRF analog (Hoffmann-La Roche, NJ, USA) (LW, n = 5; GM, n = 5), which were given s.c. (just above the vulva) at 0730, 1530 and 2300 daily from days 18 to 33 of gestation. Details on the preparation of the GRF solutions, management of sows during gestation and lactation and management of piglets from birth to weaning can be found in Lewis et al (2003). At 56 d of age, four piglets (two barrows and two gilts) each from the resulting 20 litters were selected, allotted into individual pens and grown to slaughter weight.…”

1. The neonatal pig: developmental influences on vitality

“…Circulating concentrations of triiodothyronine were also greater in feral piglets, which is important because of the role of this hormone in oxidative metabolism. Differences in carcass composition and organ weights in piglets at birth were also noted between Large White and Chinese-derived breeds (Lewis et al, 2003), with the latter having more dry matter and ash.…”