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Short-term maternal psychological stress in the post-conception period in ewes affects fetal growth and gestation length

CSIRO Livestock Industries, FD McMaster Laboratory, Armidale, New South Wales 2350, Australia¹ Goyaike SAACI y F Biotecnología Animal, Carmen de Areco, CP 6725, Buenos Aires, Argentina² CSIRO Livestock Industries Queensland Biotechnology Precinct, St Lucia, Queensland 4067, Australia

Correspondence should be addressed to J R Hill who is now at the University of Queensland, St Lucia, 4072 Queensland, Australia; Email: jonathan.hill{at}uq.edu.au

Fetal development can be influenced by maternal environment in the peri-conceptional period. This study investigated the effect of maternal feed intake and psychological stress within the first 6 days after conception on embryo development and fetal growth. Superovulated ewes (n=40) were artificially inseminated with semen from one ram. Ewes were then divided into four groups (n=10): group 1 (control) was fed at maintenance level, group 2 (high) at 2x maintenance, and group 3 (low) at 0.5x maintenance on days 2–6 after conception. Group 4 (stress) was fed at maintenance level and then an intense physical and psychological stress challenge was applied for 1 h only on days 2 and 3 after conception. Embryos were recovered at day 6. A total of 113 transferable grade embryos were transferred singly into synchronized untreated recipients, while the remaining embryos (n=165) were fixed and stained for cell counts. Post-conception maternal stress or feed intake did not alter the cell count or grade of day 6 embryos. Fetuses from the stress group had longer crown-rump lengths at day 30 and longer femur length at day 58. Fetuses from the stressed and high feed groups had greater abdominal circumferences at day 85. Subsequent birth weights were not significantly different. Ewes carrying lambs from the stress treatment had shorter gestation lengths. These results show that short-term perturbations of the post-conception maternal environment have measurable effects on fetal development and gestation length.