Variability in individual animal's intake of minerals offered free-choice to grazing ruminants

A review of the literature indicates that there is very little published information on the variation in intake of minerals and other supplements offered free-choice to grazing animals. Most of the studies have been conducted with molasses feedblocks and liquid licks and the data indicate large day to day and among animal variation. A computer recording system has been developed and tested which allows for more information to be collected with regard to frequency of consumption of free-choice supplements by grazing animals. Studies have been conducted with molasses blocks and loose mineral supplements provided to grazing cattle. Results indicate that the supplements were consumed by almost all animals on a regular basis. However, there was considerable variation among animals in the quantity of supplement consumed. For the molasses blocks daily intake averaged 1.2 +/- 0.6 kg per head within a range of 0.72-1.65 kg. For the mineral supplement the average daily consumption was 135 +/- 55 g per head within a range of 50-300 g. The supplement feeders were visited every hour of the day but approximately 40% of the visits occurred in the late evening. Information on the behavioural pattern of consumption may enable strategies to be developed which could reduce the variation in consumption.