The development of stocking rate models for three veld types in Natal.

Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1990.

The overall objective was to develop stocking rate models for three veld types. namely the Lowveld. the Southern Tall Grassveld and the Natal Sour Sandveld. in Natal. Sub-objectives were to determine the 1) residual herbage mass at the end of the summer, 2) residual herbage mass at the end of winter and 3) individual animal performance under grazing conditions, and the effect of stocking rate on these three variables. Multiple linear regression component models were successfully developed to meet all three of the sub-objectives for each of the three veld types. Results show that veld condition is an extremely important factor determining animal production from veld, and that stocking rate on veld in good condition could possibly be double that on veld in poor condition. Stocking rate did not have the expected impact on individual animal performance in the summer. although it did have an important moderating influence under any particular set of environmental conditions. Stocking rate did. however. have a marked effect on herbage production and therefore on herbage availability in winter and so also on the ability to overwinter cattle without having to supply additional supplementary feed. Stocking rate in summer therefore had a major indirect effect on animal production in the winter. Carryover of residual herbage from one year to the next is probably not as important in these veld types as in some other parts of the country.