A study of food intake and production in grazing ewes Part I. The measurement of food intake

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Abstract
The problems involved in estimating the food intake of the grazing animal are considered and an account is given of studies made on eighteen Clun ewes and six Hampshire × Clun wethers. Results are given from sixty-eight observations on the relationship between food intake and a fraction dissolved in the faeces when a milled sample is left to stand in 0·2N-HCl for 18 hr. Using, in addition, data from grazing ewes subjected to total faeces collection during winter and spring 1959–60 it is concluded that 4 consecutive days of collection give a reasonable estimate of faecal output, and that where similar groups of sheep are grazing on the same pasture at the same time it is unnecessary to convert faeces output data to intake figures in order to compare intake-production relationships between individuals within a group. Where, however, comparisons are to be made between individuals or groups of sheep grazing different pastures at different times then it becomes necessary to allow for differences in food-faeces ratios; for this purpose the dissolved fraction discussed here is likely to prove a useful faecal indicator eliminating many disadvantages of earlier methods and some of the seasonal bias inherent in other indicators at present in use.