Assessment of faecal nitrogen as an index for estimating digestibility and intake of food by sheep on Pennisetum clandestinum based pastures

Abstract

A simple and a multiple regression model was used to relate digestibility and intake parameters to the percentage and total amount of nitrogen in the faeces of sheep consuming kikuyu (Pennisetum clandestinum) based pastures. A total of 144 individual 'sheep periods'' were analysed. The results indicated large differences exist in the relationships between pasture types and, unless these effects are considered, large biases may result. Significant differences between the relations found with kikuyu and nitrogen-fertilized kikuyu were established. Further, the value of these relationships in predicting digestibility and intake appears to be small because of large errors of prediction. Coefficients of variation of about 6 and 13 per cent were associated with the regressions predicting digestibility and intake respectively.