Evaluation of Forage Sorghum Cultivars
The development of a fodder flow is very important for livestock farmers, but can also be very difficult in some cases. Dairy farmers, in particular, battle with the autumn quality gap, a gap in the fodder flow that can be successfully filled by the forage sorghums. The forage sorghums are also a useful supplement to veld grazing, to give animals a boost, especially for steaming up animals in preparation for the mating season.
However, there are a number of questions to be answered before proper recommendations can be made to farmers :
Which cultivar is best suited to your area.?
What length rotation should be used for best results?
What about the dangers of prussic acid poisoning?
An evaluation trial is currently being conducted which includes 16 cultivars, some of which are hybrid forage millets (Pennisetum) which are said to be free of prussic acid. The trial is repeated at several sites : Cedara, Dundee, Empangeni, Kokstad, and Makhathini. This spread of sites should enable fairly reliable cultivar recommendations for most of KZN. The trial also includes different defoliation frequencies of : 4, 6 and 8 weeks. This should allow for cultivar specific recommendations on the grazing rotation to be used.
Prussic acid poisoning is an important consideration, but dangers involved can be managed. Prussic acid levels are only high in plants that have been stressed, either by water shortages or by frost. Grazing animals must be removed from the pasture when signs of wilting are observed to prevent poisoning. Dairy farmers, in particular, can simply feed a preventative dose of sulphur to their cows for the duration of their stay on the pasture - a tablespoonful of sulphur per cow per day will prevent prussic acid poisoning.
Results form these trials will be available in due course, and will be forwarded to extension officers.
C F Luthuli & G M Peddie
P O BOx 626
Telephone: (034) 212 2479
Facsimile: (034) 212 2476