<P> As a rule of thumb, the daily FCR is low for young animals (when relative growth is large) and increases for older animals (when relative growth tends to level out). However FCR is a poor basis to use for selecting animals to improve genetics, as that results in larger animals that costs more to feed; instead Residual Feed Intake (RFI) is used which is independent of size . RFI uses for output the difference between actual intake and predicted intake based on an animal's body weight, weight gain, and composition . </P> <P> The outputs portion may be calculated based on weight gained, on the whole animal at sale, or on the dressed product; with milk it may be normalized for fat and protein content . </P> <P> As for the inputs portion, although FCR is commonly calculated using feed dry mass, it is sometimes calculated on an as - fed wet mass basis, (or in the case of grains and oilseeds, sometimes on a wet mass basis at standard moisture content), with feed moisture resulting in higher ratios . </P> <P> Animals that have a low FCR are considered efficient users of feed . However, comparisons of FCR among different species may be of little significance unless the feeds involved are of similar quality and suitability . </P>

The ratio of the chicken to pigs to horses