Abstract

Liveweight, milk yield and feed intake were measured in two experiments, the first with 30 cows grazing on pasture and the second with 16 cows fed indoors on fresh pasture. Feed intakes by the grazing cows were estimated from faecal outputs, using chronic oxide as the indigestible marker. The relation between daily metabolisable energy intake (MEI), daily milk energy output, liveweight 0.75 (LW0.75) and daily change in liveweight were examined by multiple regression analysis. Milk energy was significantly related to MEI, and therefore (at a common milk energy output) on feed conversion efficiency. An "index of efficiency" is proposed which will enable cows which differ in milk yield, weight and breed to be ranked accordingly to their predicted "gross feed conversion efficiency".

CB, Glassey, and JR McPherson

Proceedings of the New Zealand Society of Animal Production, Volume 53, , 47-50, 1993