The relationship between feed intake and liveweight in domestic animals

Ronald M. Lewis, Gerry C. Emmans

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Feed intake changes as animals age and grow. A constraint of most functional forms used to describe this relationship is that intake is maximum only once an animal reaches its mature weight. Often such is not the case and maximum intake is achieved earlier. Our aim was to describe a form unburdened by such a constraint and to determine its utility to describe the relationship between feed intake and liveweight across multiple species. Twelve data sets representing seven domestic animal species (cattle, chicken, dog, pig, rat, sheep, and turkey) with a wide range of mature weights were used. Average daily ad libitum feed intakes and liveweights were available on either a weekly or fortnightly basis. Rates of intake were scaled to mature intake. Within each set, the quadratic regression of scaled intake on the degree of maturity in weight was fitted. This form provided a very good description of the relationship between these variables (R2 > 0.86) and, for all but one case, a realistic prediction of mature intake. With one exception, intake reached its maximum value at a liveweight below its mature value. Furthermore, by appropriately scaling the relationship between intake and liveweight, the data could be described by a function with a single parameter with general relevance across species. By expressing the rate of intake as a function of its value at maturity, a quadratic form provides a robust and general description of the relationship between feed intake scaled to mature intake and degree of maturity in weight.

Original languageEnglish
Article numberskaa087
JournalJournal of Animal Science
Issue number4
Early online date20 Mar 2020
Publication statusPrint publication - 11 Apr 2020


  • degree of maturity
  • describing feed intake
  • domestic animals
  • predicting feed intake
  • quadratic regression


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