Animal performance and utilization of opuntia-based diets by sheep

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Date
2008-05
Authors
Einkamerer, Ockert Bernard
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University of the Free State
Abstract
English: 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 61 on Opuntia-based diets and what happens in the alimentary canal also needs further investigation.
Afrikaans: Toenemende vlakke van son-gedroogde en grof gemaalde turksvyblaaie (Opuntia ficusindica var. Algerian) is gebruik om ‘n deel van lusernhooi in gebalanseerde diëte te vervang en is an 28 jong Dorperhamels gevoer. Tydens ‘n totale proefperiode van 70 dae is ondersoek ngestel tot watter mate son-gedroogde en grof gemaalde Opuntia blaaie in gebalanseerde skaapdiëte ingesluit kan word sonder noemenswaardige invloed op die prestasie van die skape. Die drie behandelingsdiëte (T0, T24 en T36) het onderskeidelik (lugdroë basis) 0, 240 en 360 g/kg son-gedroogde, grof gemaalde Opuntia; 660, 410 en 285g/kg grof gemaalde lusern hooi; 300 g/kg geel mieliemeel; 0, 10 en 15 g/kg voergraad ureum;en 40 g/kg molasse meel bevat. Die inname van droë materiaal (DM) het min tussen diëte verskil, maar die skynbare verteerbaarheid het toegeneem [P<0.05; 71.4% (T0) vs. 75.6% (T36)]. Die gemiddelde daaglikse toename (GDT) van die hamels het effens afgeneem soos Opuntia insluiting vermeerder het. Dit dui daarop dat die algemene effekte van die diëte op die prestasie van die hamels klein was. Soos die insluitingsvlak van Opuntia in die diëte verhoog het, het die waterinname van die hamels dienooreenkomstig verhoog (P<0.05; T0 vs. T36), terwyl uitskeiding van urine min toename getoon het (P>0.05). Uitskeiding van die mis DM was onveranderd vir alle diëte, maar met die hoër vlakke van Opuntia insluiting het die DM-inhoud van die mis uitgeskei sigbaar aansienlik afgeneem. Daar word vermoed dat die slymgom-inname via Opuntia in die verteringskanaal van die hamels op ’n onbekende wyse met water inmeng en ’n deel van die water nie vir absorpsie beskikbaar stel nie. Gevolglik het die hamels meer water gedrink om te kompenseer vir hierdie ekstra water wat in die mis uitgeskei is. Meeste navorsers skryf die nat mis toe aan diarree, maar die kenmerkende stank wat met diarree geassosieer word het in die nat mis ontbreek. Insluiting van Opuntia in die diëte het geen effek op karkaseienskappe van die hamels (massa, vetdikte, oppervlak van musculus longissimus dorsi en relatiewe weefselkoëffisiënte) gehad nie. Dit dui daarop dat die effek van Opuntia in die behandelingsdiëte op die karkasmassa en karkaskwaliteit van die hamels klein was. Hierdie resultate dui daarop dat, ongeag die dieet wat in die studie gebruik is, voldoende voedingstowwe vir onderhoud en produksie van skape deur die diëte voorsien is. Son-gedroogde en gemaalde Opuntia blaaie kan as ‘n alternatiewe voerbron in semi-ariede en ariede omgewings van meeste lande benut word as diëte vir die onderhoud en produksie van skape sonder noemenswaardige nadelige effek op diereprestasie of karkaskwaliteit. Dit word aanbeveel dat navorsing behoort te fokus op die formulering van Opuntia-gebaseerde 63 produksiediëte met ‘n hoë energie-inhoud vir gebruik in voerkrale. Die effek van slymgom op die natter mis wat deur skape op Opuntia-gebaseerde diëte uitgeskei word en veral wat in die verteringskanaal gebeur benodig verdere navorsing.
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Keywords
Water intake, Urine, Mucilage, Faeces, Digestibility, Carcass characteristics, Sheep -- Feeding and feeds, Sheep -- Feed utilization efficiency, Prickly pears -- South Africa, Dissertation (M.Sc.Agric. (Animal Wildlife and Grassland Sciences))--University of the Free State, 2008
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