The influence of moisture content on the dry matter intake of American aloe (Agave americana)
B.R. King and J.H. Hoon
Grootfontein Agricultural Development Institute, Middelburg CP, 5900
The potential of Agave americana (American aloe) as a feedstuff has been investigated and promising results regarding the use of the plant in a maintenance diet for sheep have been obtained (Hoon & King, 1993). The research revealed two disadvantages connected with the plant, namely its harvesting which is labour intensive, and its high moisture content (approximately 880/11) resulting in the insufficient intake of dry matter by animals. Terblanche, Mulder & Rossouw (1971) report that dry matter intake of spineless cactus can be increased by feeding the dried plants. They report dry matter intakes of 345,7, 396,1 and 507,1 g/sheep/day of fresh, wilted and dried cactus respectively. This represents a 47-% increase in dry matter intake from the fresh to the dried form. If the dry matter intake of American aloe can be increased in the same way, it will result in better utilisation, less labour and reduced harvesting costs. The aim of the experiment was to investigate the possibility of increasing intake by decreasing moisture content.
Materials and method
This experiment was carried out at Grootfontein with 21 adult Dorper ewes which were adapted to American aloe. The sheep were divided on a stratified mass base into three groups of seven sheep each and were allowed to consume the following diets ad lib.:
- Freshly chopped American aloe with an average moisture content of 86,21 %.
- Wilted American aloe with an average moisture content of 80,06 % (chopped and dried on shade cloth in the sun for 24 hours).
- Dried American aloe with a dry matter content of approximately 91 % (chopped and dried on shade cloth for 4 to 5 days, followed by grinding through a hammermill with a 25-mm screen).
The required amount of calcium hydroxide (0,5 %) was added to all three forms of American aloe to prevent the occurrence of acidosis. Sheep were kept in individual pens. Moisture content of the fresh. wilted and refused aloe was determined daily. Clean, fresh water was available at all times and water intake was recorded daily. Live body mass of the sheep was recorded weekly.
Results and discussion
The chemical composition of American aloe is illustrated in Table 1. The effect of the different forms of American aloe on dry matter intake, water intake and animal performance is shown in Table 2. Contrary to results published by Terblance et al (1971) on spineless cactus, the moisture content of American aloe in this study did not significantly (P<O,O5) influence dry matter intake. Sheep receiving the dried American aloe drank more water (P<O,05) (1,27 l/sheep/day) than sheep on the fresh and wilted diets which consumed 0,108 and 0,255 l of water/sheep/day respectively. This can be attributed to the fact that succulence of feed is negatively related to water consumption (Groenewald & Boyazoglu, 1980). Animal performance was not significantly (P<0,05) influenced by the different forms of American aloe as reflected by the changes in body mass taking place during the experimental period. However, it is evident that American aloe alone supplies insufficient nutrients to satisfy maintenance requirements, irrespective of moisture content.
According to the results there is no improvement in dry matter intake and animal performance when the moisture content of American aloe is reduced by wilting or drying the aloe.
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SASAT Congress 1994 / Grootfontein Agric, Vol. 1, No 1,1995 (18-19)