- Nutritive value of Karoo Veld : the influence of nutrition and climate on the wool of Merino sheep on divergent veld types
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THE NUTRITIVE VALUE OF KAROO VELD: THE INFLUENCE OF NUTRITION AND CLIMATE ON THE WOOL OF MERINO SHEEP ON DIVERGENT VELD TYPES
J. J. VENTER, J. G. CLOETE and W. K. EDWARDS, Agricultural Research Institute of the Karoo Region, Middelburg, Cape Province
A comparative study was undertaken of the productivity of Merino sheep kept under different climatic and nutritional conditions on a mountain plateau (Danthonia veld), a lower mountain plateau (mixed veld) and on Karoo flats (Pentzia veld). One group utilized natural veld grazing whereas the control group received a standard diet of lucerne hay ad lib. in pens. Thus the influence of nutrition and climate could be separately assessed.
No marked differences were observed in environmental temperature and rainfall, while large differences were recorded in relative humidity. During the growing season the protein and crude fibre content of the grass components were respectively higher and lower than during dry season grazing. Body weights and wool growth of penned groups were significantly (P < 0.01) higher than those of veld groups. Total raw and clean wool production of sheep on the Pentzia veld was significantly higher than those of sheep on mixed or Danthonia veld. The sheep on Pentzia veld compared with the other veld groups, had a longer staple and showed an increase in fibre thickness. No significant differences were found between penned groups on the different sites. Climatic and environmental factors, in terms of the penned groups had no influence on staple length, changes in crimps per inch, fibre thickness, compressibility, wool wax, fluidity (iodine number) of the wool wax, suint content and the degree of photochemical decomposition. .
In comparison with the veld groups the wool of the penned groups in general had a longer staple length, larger increase in fibre thickness, a slighter decrease in compressibility, higher suint content, higher pH, higher moisture content and less photo-chemical decomposition (weathering). These differences, consequently, may entirely be ascribed to differences in the nutritive value of the grazing.
Agroanimalia 1 (3)