A simple model to predict the herbage intake of grazing dairy ewes in semi-extensive mediterranean systems

The objective of this study was to develop a model to predict herbage intake of dairy lactating ewes during grazing in semi-extensive Mediterranean systems. For this purpose a total of 670 individual intakes from 210 Comisana and Pinzirita lactating ewes were collected in Sicily over 8 years of trials. The relationships between herbage intake and characteristics of the pasture (biomass availability, DM, CP and NDF content, herbage height), the animal (live weight, milk production) and the supplement(grams of DM and CP supplied daily to each animal) were investigated. Processing of data resulted in the formulation of two linear equations diversified for two qualitative levels of the pasture recognizable from the CP content of the herbage (CP > 16% DM and CP < 16% DM). Of the variables analysed, biomass, herbage height, herbage DM content, milk production and feed supplement, expressed as grams of CP individually offered each day, were those significantly correlated with ingestion. Inclusion of these variables in the model provides good reliability in predicting ingestion. The r2 values were 0.45 for CP < 16% and 0.54 for CP > 16%.