The effects of altered maternal nutrition on development of the fetal and postnatal calf are substantively different than in the offspring of rodent species commonly used as models for the human. The bovine model has critical advantages including the similarity to humans in relation to their long gestational period, placental growth trajectory, rate of singleton pregnancies and ability to identify fetal gender early in pregnancy (~60 days) together with the gender specific patterns of growth during both pre and postnatal development[1]. In addition, the fetal growth trajectory can be measured through ultrasonography and the bovine model facilitates the investigation of the effects of stringent nutritional treatments. Organogenesis, myogenesis and adipogenesis are complete before birth in cattle, as in the human, and the pattern and timing of gene expression in the developing embryo and fetal gonads, including expression of steroidogenic enzymes are very similar[2]
We report early results from a current study investigating the effects of high (12%CP) or low (7%CP) maternal dietary protein pre and post-conception on foetal development(n=354) . Different preconception diets resulted in significant differences in fetal crown rump length (CRL) (p=0.0274) and biparietal diameter (BPD) (p=0.0091) as early as 36dpc. Interestingly by 60dpc BPD was also affected by diet post conception (p=0.0469). As reported in our previous studies these effects upon fetal growth are sex dependent. These results suggest that preconception diet influence upon oocyte and embryo development may have long term effects. Assessment of fetal organ and placental development as well as hormone levels will be available at 90dpc and at term. Postnatal development in surviving offspring will also be assessed.

Acknowledgements: We are indebted to S.Kidman and Co., Ridley Agriproducts and ARC for funding the research and Maddie Jonas, Wendy Bonner, Peter Atkinson for technical expertise.