Project Objectives
- Quantify the physiological and welfare effects of pre-operative fasting in sheep.
- Compare outcomes between fasting vs. non-fasting and water-restricted vs. unrestricted conditions.
- Assess rumen fill, content, and gastrointestinal physiology.
- Measure stress and metabolic markers (e.g. cortisol, blood gases, electrolytes, haematology).
- Determine whether fasting reduces rumen volume sufficiently to justify its use.
- Evaluate an improved fasting method (muzzling within the group) if fasting benefits are demonstrated.
- Produce evidence-based fasting recommendations for sheep.
How This Advances 3Rs Implementation
- Provides the first systematic dataset on fasting effects in sheep.
- Enables refined, welfare-optimised fasting guidelines.
- Harmonises fasting practices across institutions.
- Supports future reduction or elimination of fasting where appropriate.
Background
Sheep scheduled for anaesthesia are commonly fasted for 16 to 18 hours, and sometimes subjected to water restriction. These practices aim to reduce rumen fill and prevent complications such as gastro-oesophageal reflux. However, fasting recommendations vary widely across institutions, from 12 to 48 hours for solids and 0 to 12 hours for water, and are not backed by robust evidence. This lack of standardisation introduces unnecessary animal welfare concerns as well as variability in physiological readouts during research procedures.
This project addresses this gap by comparing several fasting and water-restriction strategies in adult sheep already undergoing anaesthesia. By assessing stress markers, rumen physiology, metabolic status, and welfare indicators, the study aims to establish evidence-based recommendations that improve both animal wellbeing and scientific rigour.
