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Describes the cognitive steps a student should go through to be able to answer a chemical equilibrium question and investigates student responses to identifying particular symbols and words. (YDS)

English: A laboratory study was under taken to investigate the nutritional value of different Opuntia varieties from chemical analysis. One year old cladodes from six different varieties of Opuntia ficus-indica namely Castello, Chicco, Fusicaulis, Montery, Morado and Rubasta were randomly harvested in five replicates. The highest (P<0.05) average dry matter (DM) content was observed for the Chicco variety and was the average for all varieties generally low (9.13%). There were no significant difference (P>0.05) in ash content. Significant (P<0.05)differences among varieties were recorded for crude protein (CP) (3.7 to 8.1%), acid detergent fibre (ADF) (13.6 to 17.4%), neutral detergent fibre (NDF) (19.9 to 38.5%), cellulose (2.4 to 14.8%), hemicellulose (4.5 to 12.7%), lignin (2.51 to 21.5%), non fibre carbohydrates (NFC) (33.4 to 48.6%), ether extract (EE) (1.9 to 2.4%). The average mineral composition were as follows, phosphorus (P) 0.18%, potassium (K) 3.02%, calcium (Ca) 2.3%, magnesium (Mg) 3.6% and sodium (Na) 0.04%. It was concluded that in general cladodes could be classified as a high moisture energy source with an energy level between that of roughages and concentrates with a low CP and high Mg, K and Ca content. In a second study the influence of dry matter (7.12 to 27.6 %) and molasses (0 to 24%) content on the fermentation characteristics of Fusicaulis cladode silage was investigated. One year old cladodes was ensiled in three litre square plastic bottles (six replicates). A higher DM content were characterized with a lower (P<0.05) ADF, NDF, CP and EE content. The inclusion of molasses resulted in a lower (P<0.05) ADF, NDF and EE content. An increased (P<0.05) acetic acid (AA) content in Fusicaulis silage was observed as the level of DM and molasses increased. A higher silage DM content resulted in a lower (P<0.05) propionic acid (PA) and butyric acid (BA) content. No significant (P>0.05) influence of molasses on PA and BA occurred. Lactic acid (LA) con, Afrikaans: ’n Laboratoriumstudie is uitgevoer om die voedingswaarde van verskillende Opuntia variëteite vanaf chemiese ontledings te ondersoek. Eenjaar-oud turksvyblare vanaf ses verskillende variëteite van Opuntia ficus-indica naamlik Castello, Chicco, Fucicaulis, Montery, Maroda en Rubasta is ewekansig in vyf replikasies geoes. Die hoogste (P<0.05) gemiddelde droëmateriaalinhoud (DM) is vir die Chicco variëteit waargeneem en was die gemiddeld vir al die variëteite oor die algemeen laag (9.13%). Geen betekenisvolle (P<0.05) verskille in asinhoud het voorgekom nie. Betekenisvolle (P<0.05) verskille tussen variëteite is vir ruproteïen (RP) (3.7 tot 8.1%), suurbestande vessel (SBV) (13.6 tot 17.4%), neutraalbestande vessel (NBV) (19.9 tot 38.5%), sellulose(2.4 tot 14.8%), hemisellulose (4.5 tot 12.7%), lignien (2.5 tot 21.5%), nie-veselkoolhidrate (33.4 tot 48.6%), eterekstrak (EE) (1.9 tot 2.4%) waargeneem. Die gemiddelde mineraalsamestelling was as volg: fosfaat (P) 0.18%, kalium (K) 3.02%, kalsium (Ca) 2.3%, magnesium (Mg) 3.6% en natrium (Na) 0.04%. Daar is tot die slotsom gekom dat turksvyblare in die algemeen as ’n hoë energiebron met ’n energiepeil tussen die van ’n ruvoer en kragvoer, met ’n lae ruproteïen en hoë Mg, K en Ca- inhoud geklassifiseer kan word. In ’n tweede studie is die invloed van DM-(7.12 tot 27.6%) en melasse-inhoud (0-24%) op die fermentasie-eienskappe van Fusicaulis turksvyblaarkuilvoer ondersoek. Eenjaar-oud turksvyblare is in drie liter vierkantige plastiese bottels (ses replikasies) ingekuil. ’n Hoër DM- inhoud is gekenmerk met ’n laer (P<0.05) SBV-, NBV-, RP- en EE- inhoud. Die insluiting van melasse het ’n laer (P<0.05) SBV-, NBV- en EE- inhoud tot gevolg gehad. ’n Hoër (P<0.05) asynsuurinhoud (AA) in Fusicaulis kuilvoer is waargeneem soos die DM en melassepeile toegeneem het. ’n Hoër kuilvoer DM- inhoud het met ’n hoer (P<0.05) propioonsuur (PA) en bottersuurinhoud gepaardgegaan. Geen betekenisvolle (P<0.05) invloed van melasse op PA e, Agricultural Research Council (ARC)

Appartient à l’ensemble documentaire : BNormand1, Contient une table des matières, Avec mode texte

The mineralogical, geological and metallurgical characteristics aof each orebody have a controlling influence on the flotation process to be used. Scaling up of laboratory tests, the broad aspects of plant design, the separation process itself, process control and manpower requirements are considered. Examples from the copper-zinc concentrator of the Anglovaal mine, Prieska Copper Mines (Pty) Ltd, South Africa, are detailed., The mineralogical, geological and metallurgical characteristics aof each orebody have a controlling influence on the flotation process to be used. Scaling up of laboratory tests, the broad aspects of plant design, the separation process itself, process control and manpower requirements are considered. Examples from the copper-zinc concentrator of the Anglovaal mine, Prieska Copper Mines (Pty) Ltd, South Africa, are detailed.

Appartient à l’ensemble documentaire : BNormand1, Contient une table des matières, Avec mode texte