Through the use of these two items, animals that deviate from the expected feed intake, either by eating more than or less than what's expected of them, can be identified and managed as the farmer sees fit. Because feed intake is heritable, knowing the RFI index of an animal is also useful when breeding.[2] By selecting animals with the aim to reduce RFI, farmers can breed animals that eat less but continue at the same rate of production.[1]
There is no phenotype link between RFI and the characteristics used to calculate expected feed intake, which allows for the comparison of animals who function at differing production numbers. This has led some authors to believe that RFI is representative of individual differences in the metabolic processes of the animals. For example, one study shows that the amount of feed a Hereford bull requires to maintain a kilogram of body weight is closely related to genetic variation in its RFI. Similarly, in laying hens, variation in RFI is directly linked to variations in maintenance energy expenditure.