In dié studie is sekere aspekte van voedingswaarde van droogtebestandegewasse, tussen twee seisoene en op drie verskillende lokaliteite nl Hatfield, Mier en Lovedale, geondersoek. Die spesies wat met mekaar vergelyk is, was: C. sturtii, A. nummularia, A. halimus A. canescens(Santa Rita), A. canescens (Veldreservaat 1), en A. canescens(Rincon). Die twee seisoene was herfs en winter. Uit dié resultate kan die volgende afleiding gemaak word:betekenisvolle(P < 0.05) laer blaar-totstamverhouding gedurende die winter as die herfs kon by die onderskeie proefpersele van, C. sturtii en A. canescens (Veld 1)(Hatfield); A. canescens(Veld 1) en A. canescens(Rincon)(Mier); A. canescens(Veld 1) en A. canescens(Santa Rita)(Lovedale), waargeneem word. In teenstelling met die bogenoemde bevindinge het A. nummularia(Lovedale) betekenisvol (P < 0.05) hoër blaar-totstamverhouding in die winter as die herfs gehad. Vir A. canescens (Santa Rita) het die Mier proefperseel betekenisvolle (P < 0.05) hoër blaar-tot-stamverhouding as die ander twee lokaliteite getoon. By al drie proefpersele, vir alle spesies, is die blaar RP % sowel as die IVDMV % van die blare betekenisvol (P < 0.05) hoër as dié van stamme. Vir al die spesies geoes by Mier, was die NBV % in die winter betekenisvol (P < 0.05) hoër as in die herfs. C. sturtii (Lovedale) het geen betekenisvolle (P > 0.05) verskille in die chemiese samestelling tussen seisoene getoon nie, terwyl die ander spesies wel betekenisvolle (P < 0.05) verskille getoon het. Slegs in die geval van A. nummularia kon betekenisvolle (P < 0.05) verskille in IVDMV % tussen lokaliteite waargeneem word. Indien die tempo van degradasie (c) gedurende die herfs by Hatfield geoes, tussen spesies vergelyk word, het A. canescens (Veld 1)betekenisvolle (P < 0.05) hoër c-waarde as dié vanaf A. nummularia en A.canescens (Santa Rita) gehad. Slegs monsters op Hatfield gedurende die herfs geoes kon betekenisvolle (P < 0.05) verskille in PD tussen A. canescens (Veld1) en A. nummularia waargeneem word. Slegs by Mier, in die herfs, het A. nummularia betekenisvol(P < 0.05) hoër ED as A. canescens (Veld 1) gehad. Vir wintermonsters kon geen betekenisvolle (P > 0.05) verskille in die c-waarde tussen spesies en lokaliteite waargeneem word nie. Wintermonsters, geneem te Mier, het A. canescens (Veld 1) betekenisvol (P < 0.05) laer PD as die ander spesies gehad, terwyl by Lovedale het A. canescens(Santa Rita) betekenisvol (P < 0.05) laer PD as die ander spesies gehad. A. nummularia het betekenisvol (P < 0.05) hoër ED as die ander spesies, by Mier en Lovedale, vir monsters wat gedurende winter geoes is, gehad. Wanneer gasproduksiewaardes tussen spesies vergelyk word, het A. canescens (Veld 1) betekenisvol (P < 0.05) minder gas as die ander spesies, vir inkubasie tye 20,30 en 44 ure, geproduseer. Betekenisvolle (P < 0.05) verskille in die a-waarde kon tussen die hoë C. sturtii en die lae A. canescens. (Santa Rita), maar nie tussen die ander spesies, waargeneem word. Betekenisvollen (P < 0.05) verskille in die b-waarde kon tussen: C. sturtii (145.1 ml/g DM), A. canescens (Veld 1)(127.9 ml/g DM)en A. canescens (Rincon)(164.9 ml/g DM) waargeneem word. Betekenisvolle verskille (P < 0.05) in die tempo van gasproduksie kon net tussen die hoë C. sturtii (0.086/h) en die lae A. canescens (Santa Rita)(0.065/h) waargeneem word. Betekenisvolle (P < 0.05) verskille in die potensiële gasproduksie (a + b) kon tussen: C. sturtii, A. canescens. (Veld 1) en A. canescens (Rincon) waargeneem word. Droogtebestande gewasse kan as medium tot lae kwaliteit voerbronne beskou word,wat op strategiese tye(droogte tye) benut kan word. ENGLISH : The nutritive value of four drought tolerant crops were investigated at three localities during two seasons. The species which have been compared, were C. sturtii, A. nummularia, A. halimus, A. canescens (Santa Rita), A. canescens (Field reserve 1), and (Rincon). The two seasons were autumn and winter. A significantly (P < 0.05) lower leaf-to-stem ratio was recorded for the species <i<C. sturtii and A. canescens (Field 1) at Hatfield, while at Mier A. canescens (Field 1) and A. canescens (Rincon) were found to have significant (P < 0.05)lower values in the winter than in the autumn. At Lovedale, the winter leaf-to-stem ratios were significantly (P < 0.05) lower than in the autumn for A. canescens (Field 1) and A. canescens (Santa Rita). In contrast to the above, A. nummularia had a significantly (P < 0.05) higher leaf-to-stem ratio in winter than in autumn at Lovedale. Overall, A. canescens (Santa Rita) harvested at Mier had a significantly (P < 0.05) higher leaf-to-stem ratio than material from the other two sites. At all the sampling sites and for all accessions the CP % and the IVDMD % of the leaves were significantly (P < 0.05) higher than those of the stems. The NDF % in most of the species harvested during winter, was significantly (P < 0.05) higher than those harvested during autumn. C. sturtii was the only species for which no significant (P > 0.05) differences in the chemical composition could be found between the two seasons. Only in the case of A. nummularia could significant (P < 0.05) differences in the IVDMD % be found between localities. A. canescens (Field 1) harvested during autumn at Hatfield, had a significantly higher rate of passage(c) than A. nummularia and A. canescens (Santa Rita). Samples harvested at Hatfield in autumn also produced significant (P < 0.05) differences in PD between A. canescens (Field 1) and A .nummularia. Mier was the only sampling site where significantly (P < 0.05) higher (A. nummualaria) and lower (A. canescens(Field1)) ED were observed for samples taken during autumn. No significant (P > 0.05) differences in the rate of passage (c) were observed between species or sampling sites for samples taken during the winter. Winter samples taken from A. canescens (Field 1) at Mier and A. canescens (Santa Rita) taken from Lovedale, showed significantly (P < 0.05) lower PD than the other species. A. nummularia had significantly (P < 0.05) higher ED than the other species harvested at Mier and Lovedale, during winter. When gas production values between species were compared it was clear that A. canescens (Field1) produced significantly (P < 0.05) less gas compared to the other species at incubation times of 20, 30 and 44 hours. Significant (P < 0.05) differences in the a-values were also observed between the high C. sturtii and the low A. canescens (Santa Rita) values. Significant (P < 0.05) differences in the b-value were observed between C. sturtii (145.1ml/g DM), A. canescens (Field 1)(127.9 ml/g DM) and A. canescens (Rincon)(164ml/g DM). C. sturtii (0.086/h) and A. canescens (Santa Rita)(0.065/h) were the only species that differed significantly (P < 0.05) in terms of the rate of passage(c). Significant (P < 0.05) differences in the potential gas production (a + b) were observed between C.sturtii, A. canescens (Field 1) and A. canescens (Rincon). Drought resistant crops can be considered as a medium to low quality source of fodder which can be used at strategic times, especially during periods of drought. Copyright / Dissertation (MScAgric)--University of Pretoria, 2010. / Animal and Wildlife Sciences / unrestricted
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:up/oai:repository.up.ac.za:2263/27389 |
| Date | 19 August 2010 |
| Creators | Vermaak, Pieter Johannes |
| Contributors | Prof W A Van Niekerk, Prof N F G Rethman, middelburgcvo@telkomsa.net |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Dissertation |
| Rights | © 2009, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
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