There is disclosed a method for the management of animals grazing in a pasture, comprising feeding a marker labelled supplement to grazing animals. Monitoring consumption of said marker labelled supplement by said animals to generate supplement consumption data tor said animals. Measuring physical characteristics of said animals to generate physical characteristic data for said animals. Collecting faecal samples from said animals. Analysing said faecal samples, samples of said pasture and said supplement to generate faecal data, pasture data and supplement data and processing Said supplement consumption data, said physical characteristic data and said fecal data, pasture data and supplement data to determine individual animal diet and nutritional information for animal management purposes.