On the use of commercial quails as study organisms: lessons about food intake from individual variation in body mass

We analysed inter-individual body mass variation of Japanese quail (Coturnix coturnix japonica) in an examination of the effectiveness of regulations governing daily food requirements. We measured the daily food intake of 26 adult female quail during a feeding trial over four consecutive days. Non-ingested food was weighed every morning and 70 g of food was provided to each bird for every day of the trial. This represented more than three times the theoretical recommended daily amount of food required by Japanese quail, as described in the literature. We then calculated a female-specific mean daily food requirement and found highly significant variation among individuals. Daily food intake was significantly repeatable within-female over the trial and mean food intake was highly correlated with female body mass. We suggest that using daily requirements for individuals based upon 'population' means, whilst ignoring differences in body mass among individuals might have severe consequences for the welfare of birds. Furthermore, these results have significant implications for studies where the aim is to perform identical experimental manipulations (as some studies intend and suggest), resulting in the drawing of unsubstantiated conclusions.