Last update: August 18, 2011 07:44:17 AM E-mail Print

 

The Alkalinization of American Aloe for the Feeding of Small Stock

D Wentzel

 

The occurrence of lameness in ruminants fed with American aloe (garingboom) was reported early this century. During droughts American aloe has proved to be a useful drought fodder crop – the succulent leaves merely being chopped and fed to both small and large stock. Obviously, the frequent incidence of lameness in some animals receiving a diet containing American aloe - presumably those ingesting too much of it - presents a serious problem to farmers in the semi-arid areas where American aloe is commonly used for drought feeding.

Investigation of this lameness problem revealed that the primary cause of the condition is an acid-overload resulting from large intakes of American aloe, which has a relatively low pH (approximately 4,3). In an experiment, young Dorper sheep, accustomed to American aloe and fed this fodder only, developed the typical signs of lameness reported earlier. Observations of these affected animals suggested some resemblance to the "stiffness" syndrome seen in ruminants suffering from a grain-overload.

Therefore a similar approach to that used to overcome the problem of grain-overload and subsequent acidosis, and which led to the "alkali-ionophore" treatment of grain (chocolate grain), was basically followed in this case. In laboratory trials, it was ascertained that the addition of 0.5 % of calcium hydroxide (slaked lime) to the homogenized contents of American aloe leaves increases the pH thereof from its relatively low level to a neutral pH of 7. Thereafter chopped American aloe was treated similarly by adding half a percent of slaked lime to it, while mixing it in a concrete mixer. This treated American aloe was then fed to Dorpers and, although similar intakes to those reported earlier were recorded, no signs of lameness occurred during the following two months when they received this fodder alone, on an ad. lib. basis.

The findings of this trial indicate firstly that the lameness resulting from feeding American aloe to ruminants is caused by large intakes of fodder with a too low pH. Secondly, these results indicate that this condition can be prevented by alkalinization of the fodder with slaked lime to increase the pH to an acceptable level for the ruminant. Further trials, however, need to be undertaken to ascertain the optimum level of inclusion of slaked lime to prevent lameness, while retaining the maximum level of animal production.

 

Published

Karoo Region Newsletter 1