Last update: August 12, 2011 02:48:57 PM E-mail Print




J.H. Hoon, P.R. King & G. Jordaan

Grootfontein Agricultural Development Institute, Middelburg 5900


Mainly two of the six Prosopis species that are found in South Africa, are responsible for the invasion of agricultural land. The Prosopis pods, which are a valuable feedsource for livestock, are normally utilized under natural grazing conditions. The excretion of large quantities of indigestible seed in the faeces leads to Prosopis invasion. Several methods are used by farmers to minimize the spreading of Prosopis trees. The objective of this study was to evaluate the efficiency of these methods by determining the rate of passage of seed through the digestive tract and the germination potential following excretion. Dorper wethers received Prosopis pods for three successive periods (one, three and five days). After each period, the animals were randomly divided into two groups, namely a Feed (lucerne ad libitum + water) and a Water Group (water only). Seed in the faeces of all animals was counted and the germination potential after different periods of exposure to rumen action, was determined. The results indicated that the first seed appeared in the faeces between 24 and 30 hours after ingesting the first pods. After the intake of pods ended, it took between 11 and 13 days in the Feed Group for all the pods to be excreted. Treatment of the Water Groups were stopped after seven days, due to the poor condition of the sheep. At that stage an average of 50 to 80 seeds/animal/day were still being excreted. The germination percentage of the seed from the Feed Group was consistently lower than that of the Water Group, and no germination, occurred at the Feed Group after five days in the rumen. The results indicate that the methods currently pursued by farmers to prevent the spreading of seed, are inadequate due to the long period that is required for complete excretion of seed.



Proceedings 34the SASAS congress