Last update: August 15, 2011 03:26:25 PM E-mail Print

 

MODELLING DIET SELECTION, INTAKE AND PERFORMANCE OF STEERS GRAZING CENCHRUS CILIARIS L. cv MOLOPO

 

L G du Pisani, W L J van Rensburg & J M de Jager

 

 

The STEER model was developed to simulate diet selection, intake and growth of steers grazing Cenchrus ciliaris at various stocking rates.

Available forage (computed by another model) is parameterized by STEER into 3 quality sub-pools on the basis of plant structure and age, each with a specified digestibility. Diet selection and intake of OM from each sub-pool is calculated on the basis of herbage availability, age and frame type of the animal, selective grazing and the rate of passage through the digestive tract. The energy equivalent of the diet is calculated, maintenance requirements subtracted and the remaining energy expressed as ADG and change in carcass grading.

Output was calibrated and validated with data from a 6-year grazing trial. Evaluation statistics included analysis of variance, Pearson's product moment correlation coefficient, Willmot's similarity index, mean bias error, mean absolute error and root mean square error. The statistical analyses confirmed that STEER is able to accurately simulate the plant: animal interaction and animal performance.

 

Published

Proceedings 32st SASAS congress