Effect of maternal body condition on placental and fetal growth and the insulin-like growth factor axis in Dorset ewes

Abstract

This study investigated the effects of maternal body condition on fetal growth. Fetal and placental parameters from Dorset ewes of body condition score 2.0 (lean, n = 5), 3.5 (moderate, n = 7) and 5.0 (fat, n = 4) at mating were studied on day 65 of gestation. The fetal weight and fetal weight:crown-rump length ratio were greater in fat ewes than in ewes of moderate condition. The raised total and mean placentome weight in fat ewes compared with ewes of moderate condition may have contributed to their increased fetal growth. However, the fetal crown-rump length was not affected. With in situ hybridization, insulinlike growth factor II (IGF-II) mRNA and insulin-like growth factor binding protein 2 (IGFBP-2), -3 and -6 were all detected in the placentome capsule; IGF-II mRNA was also found in the mesoderm of the fetal villi and IGFBP-3 and IGFBP-6 were present in the caruncular stroma of the maternal villi. Ewes of moderate condition, which had the smallest placentae, had the greatest placental expression of IGF-II, IGFBP-2 and IGFBP-3. In the intercotyledonary endometrium, IGFBP-3, IGFBP-5 and uterine milk protein (UTMP) mRNA were all expressed in the glandular epithelium. IGFBP-3 and IGFBP-5 absorbance values were lowest in the lean ewes, whereas UTMP values were highest. Maternal insulin concentrations were greater in fat ewes, whereas plasma glucose and IGF-I concentrations in the fetal compartment were lowest in fat ewes. Therefore, in obese ewes, fetal and placental growth is increased in mid-gestation in association with higher maternal insulin concentrations and lower expression of IGFBPs in the maternal placentomes. Placental and fetal development in lean ewes may be promoted by reduced IGFBP expression in the placentomes and enhanced UTMP production by the endometrial glands. The ewes of moderate condition had the smallest fetuses and placentae coupled with the highest placental expression of IGF-II and IGFBPs.

The effect of maternal undernutrition on the placental growth trajectory and the uterine insulin-like growth factor axis in the pregnant ewe

“…Therefore, there were opposite trends in closely adjacent maternal uterine tissues, which were presumably exposed to similar circulating hormone concentrations. In the Dorset ewe in mid gestation we have previously reported reduced expression of both IGFBPs-3 and -5 mRNA in the glandular epithelium of ewes of fat compared with thin body condition (Osgerby et al 2003a). Surprisingly little is known about local factors regulating IGFBP expression in different tissues.…”

“…Earlier studies have demonstrated that placentome proliferation reaches a maximum rate between days 50 and 60 of gestation, with placentomes attaining a maximum weight by days 75 to 80 (Ehrhardt & Bell 1995). Nutritional insults during this period have thus been associated with changes in placental growth (McCrabb et al 1992), with maternal factors including weight, age and body condition influencing this interaction (DeBarro et al 1992, Wallace et al 1997, Osgerby et al 2003a. In this study, placentome weight was not, at this early stage, influenced by nutrition although we have previously reported that the 70% reduction in ration did result in altered fetal growth by day 90, with more obvious signs of fetal growth retardation apparent by day 135 of gestation (Osgerby et al 2002).…”

Effects of Administering Exogenous Bovine Somatotropin During the First Trimester of Pregnancy Altered Uterine Hemodynamics in Suckled Beef Cows

“…Maternal plasma IGFs play a role in maternal tissue growth and metabolism, resulting in the modulation of nutrient availability for adequate conceptus growth and have been positively correlated with fetal growth in several livestock species (Sferruzzi-Perri et al, 2011). As a result, maternal plasma IGF-1 could potentially affect fetal growth indirectly and is itself altered by both BCS and diet during gestation (Osgerby et al, 2002(Osgerby et al, , 2003a.…”