Incremental levels of sun-dried and coarsely ground cactus pear (Opuntia ficus-indica var.
Algerian) cladodes were used to substitute part of the lucerne hay in balanced diets and fed to
28 Dorper wethers. The extent to which sun-dried and coarsely ground Opuntia cladodes can
be incorporated in balanced sheep diets without effecting sheep performance was investigated
over a period of 70 days. The three treatment diets (T0, T24 and T36) used in this study
comprised respectively (air-dry basis) 0, 240 and 360 g/kg sun-dried, coarsely ground
Opuntia; 660, 410 and 285 g/kg coarsely ground lucerne hay; 300 g/kg yellow maize meal; 0,
10 and 15 g/kg feed grade urea; and 40 g/kg molasses meal. The dry matter intake (DMI)
varied little between diets but the apparent digestibility increased [P<0.05; 71.4% (T0) vs.
75.6% (T36)]. The average daily gain (ADG) of the wethers decreased slightly as Opuntia
inclusion increased. This suggests that the overall effects of the diets on the performance of
the wethers were small. As the inclusion level of Opuntia increased in the diets, the water
intake of the wethers also increased (P<0.05; T0 vs. T36), while urine excretion showed little
increase (P>0.05). The faeces DM excreted remained the same for all diets, but with the
higher levels of Opuntia inclusion the DM content of the faeces excreted visibly decreased
considerably. It is suggested that the mucilage ingested via the Opuntia and present in the
digestive tract of the wethers may have interacted with the water fraction in the digesta,
rendering some of the water unavailable for absorption. Hence, the wethers were compelled
to drink more water to compensate for this extra water loss via the faeces. The wetter faeces
were assumed to be the result of diarrhoea by some researchers, but the wet faeces lacked the
customary foul smell associated with diarrhoea. Opuntia inclusion in the diets had no effect
on carcass characteristics of the wethers (weight, fat thickness, surface area of musculus
longissimus dorsi and relative tissue coefficients). This suggests that the effect of Opuntia in
the treatment diets on the carcass weight and quality of the wethers were small. From these
results, it seems that, irrespective of the dietary treatment, adequate nutrients for sheep
maintenance and production was supplied by the diets. Sun-dried and ground Opuntia
cladodes can be seen as an alternative feed supplement in semi-arid and arid regions of most
countries that can be included in sheep maintenance or production diets without any
detrimental effects on animal performance or carcass quality. It is recommended that research
should focus on the formulation of Opuntia-based production diets with a high energy
content, to be used in feedlots. The effect of mucilage on the wetter faeces excreted by sheep on Opuntia-based diets and what happens in the alimentary canal also needs further
investigation.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-03192009-103609 |
| Date | 19 March 2009 |
| Creators | Einkamerer, Ockert Bernard |
| Contributors | Prof HO de Waal |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-03192009-103609/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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