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Few studies have investigated the effects of nutrition during the periconception and early gestation periods on fetal and placental development in cattle. In this study, nulliparous yearling heifers (n = 360) were individually fed a diet high or low in protein (HPeri and LPeri) beginning 60 days before conception. From 24 to 98 days after conception, half of each treatment group was changed to the alternative high- or low-protein diet (HPost and LPost) yielding four groups in a 2 × 2 factorial design. A subset of heifers (n = 46) was necropsied at 98 days after conception and fetoplacental development assessed. Placentome number and volume decreased in response to LPeri and LPost diets respectively. Absolute lung, pancreas, septum and ventricle weights decreased in LPost versus HPost fetuses, whereas the post-conception diet altered absolute and relative liver and brain weights depending on sex. Similarly, changes in fetal hepatic gene expression of factors regulating growth, glucose output and lipid metabolism were induced by protein restriction in a sex-specific manner. At term, neonatal calf and placental measures were not different. Protein restriction of heifers during the periconception and early gestation periods alters fetoplacental development and hepatic gene expression. These changes may contribute to functional consequences for progeny, but this may not be apparent from gross morphometry at birth. This study is the first to show that moderate protein restriction in yearling heifers during the periconception and early-gestation periods is concomitant with sex-specific asymmetric restriction of fetoplacental development. Sex-specific programming effects were observed on genes regulating growth, hepatic glucose output and lipid metabolism in the 98 dpc fetus. These findings provide insights into the underlying molecular pathways that promote susceptibility to increased postnatal fat deposition. [ABSTRACT FROM AUTHOR]

During ovarian development stroma from the mesonephros penetrates and expands into the ovarian primordium and thus appears to be involved, at least physically, in the formation of ovigerous cords, follicles and surface epithelium. Cortical stromal development during gestation in bovine fetal ovaries (n = 27) was characterised by immunohistochemistry and by mRNA analyses. Stroma was identified by immunostaining of stromal matrix collagen type I and proliferating cells were identified by Ki67 expression. The cortical and medullar volume expanded across gestation, with the rate of cortical expansion slowing over time. During gestation, the proportion of stroma in the cortex and total volume in the cortex significantly increased (P < 0.05). The proliferation index and numerical density of proliferating cells in the stroma significantly decreased (P < 0.05), whereas the numerical density of cells in the stroma did not change (P > 0.05). The expression levels of 12 genes out of 18 examined, including osteoglycin (OGN) and lumican (LUM), were significantly increased later in development (P < 0.05) and the expression of many genes was positively correlated with other genes and with gestational age. Thus, the rate of cortical stromal expansion peaked in early gestation due to cell proliferation, whilst late in development expression of extracellular matrix genes increased. During ovarian development the movement and behaviour of cortical stroma derived from the mesonephros appears to be critical for the formation of ovigerous cords, follicles and surface epithelium, but little is known about ovarian stroma. We found that the greatest rate of stromal expansion occurred early in development with high expression of many extracellular matrix genes late in development. Thus, ovarian cortical stroma is very dynamic during the development of the ovary. [ABSTRACT FROM AUTHOR]