The influence of pre-slaughter nutrition on the potency of foetal serum in cell culture was studied. Ewes carrying late-gestation foetuses (120-day gestation) were either fasted for 66 h (F), fasted for 66 h but drenched with Ketol, a propylene glycol preparation, (5 × 120 ml doses; FK), given food ad libitum (A), or given food ad libitum and drenched with Ketol (5 × 120 ml doses; AK). Following slaughter foetal blood was collected for the determination of potency in cell culture using industry-standard cell culture bioassays: cloning efficiency, plating efficiency and a 96 h cell proliferation assay. Foetal serum insulin-like growth factor (IGF) concentrations were also measured. Pre-slaughter fasting or drenching with Ketol had no effect on the potency of foetal serum in any of the cell culture bioassays. Fasting significantly lowered foetal plasma IGF-1 levels (F < 0·01). Foetal IGF-2 levels were unaffected by fasting or drenching with Ketol.
