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dc.contributor.advisorSmith, A.
dc.contributor.authorMentz, Andreas Hercules
dc.date.accessioned2017-04-11T10:39:20Z
dc.date.available2017-04-11T10:39:20Z
dc.date.issued1977-11
dc.identifier.urihttp://hdl.handle.net/11660/6068
dc.description.abstractEnglish: In the development of crossbreeding systems in beef production under South African conditions, more information on the combination ability of various types of exotic beef breeds with the indigenous Africander is of primary importance. For this reason four breeds of bulls namely Brahman, Charolais, Hereford and Simmentaler were used on purebred Africander cows in this study. These breeds represented a Zebu type, large frame lean meat type, small frame fat meat type and a large frame dual purpose type of cattle respectively. Simultaneously purebred Africanders were produced as controls. The progeny of the five bull breeds (838 in total) were evaluated in respect of duration of gestation, birth and weaning mass. Postweaning growth and development of steers as slaughter animals were studied under two production systems while the female progeny were evaluated as breeding animals. Special attention was given to the occurrence of interactiombetween sire breed and production system as well as sire breed and production function. It is apparent that the choice of a breed/type of bull for the production of Africander F1-calves is of utmost importance due to the effect thereof on birth mass. and dystocia. As a result of the extreme size of the Charolais-Africander calves at birth and the extent of dystocia, the production of this cross seemed not to be of any merit. Furthermore, although this combination of breeds performed very well in a semi-intensive production system, it was found that the female progeny lack in mothering ability and cannot be recommended as replacements in herds. The crosses of Brahman, Hereford and Simmentaler bulls, however, proved to be of excellent potential for exploitation under specific conditions. The Brahman progeny has a dual purpose production potential in an extensive production situation as a store animal as well as a replacement heifer. Likewise the Simmentaler cross has a multi-purpose production function in terms of replacement heifer and slaughter animal. For the latter purpose it became apparent that this cross is equally efficient as a fodder animal or store, keeping in mind that it only becomes marketable at an advanced mass especially under extensive grazing conditions. Hereford crosses proved to be extremely suitable as Slaughter animals, regardless of the production system, although it performed especially well under intensive management.en_ZA
dc.description.abstractAfrikaans: Vir die beplanning van kruisteelstelsels by beesvleisproduksie vir Suid-Afrikaanse toestande, is dit van primêre belang dat meer inligting bekom word oor die kombinasievermoë van verskillende tipes uitheemse vleisbeesrasse met die Afrikaner wat as die basis van beesvleisproduksie in die Republiek van Suid-Afrika beskou kan word. Vir hierdie rede is vier rasse van bulle naamlik Brahman, Charolais, Hereford en Simmentaler, verteenwoordigend van 'n uitheemse Seboetipe, grootraam-maervleistipe, kleinraam-vetvleistipe en grootraam-dubbeldoeltipe, respektiewelik, in dié studie op suiwer Afrikanerkoeie gebruik. Suiwer Afrikaners is tegelykertyd as kontrolediere geproduseer. Die nageslag van die vyf bulrasse (838 in totaal) is geëvalueer ten opsigte van draagduurte, geboortemassa, voorkoms van distokie, speenmassa, naspeengroei en -ontwikkeling van die tollies as slagbeeste onder twee produksiestelsels en die naspeengroei, -ontwikkeling en produksie van die vroulike nageslag as teeldiere. Spesiale aan: dag is gegee aan moontlike interaksiesvan vaarras met produksie: stelsel en produksiefunksie. Dit is duidelik dat die keuse van 'n ras/tipe van bul. vir die produksie van Afrikaner F1-kalwers van deurslaggewende belang is weens die invloed van bulras/tipe op geboortemassa en distokie. As gevolg van uitermatige groot kalwers by geboorte en die omvang van distokie wat dit tot gevolg gehad het, blyk die produksie van Charolais-Afrikanerkruise geen meriete te hê nie. Hoewel hierdie raskombinasie as slagbees in 'n semi-intensiewe produksiestelsel uitstekend presteer het, is verder gevind dat sodanige vroulike nageslag swak moedereienskappe het en nie aan te beveel is vir vervangingsdoeleindes in koeikuddes nie. Brahman-, Simmentaler- en Herefordkruise het egter 'n baie goeie potensiaal vir eksploitering onder bepaalde omstandighede. Die Brahmannageslag het 'n dubbeldoelige produksiepotensiaal en wel om onder ekstensiewe toestande as stooros sowel as vervangingsvers hoogs doeltreffend te funksioneer. Die Simmentalerkruise het insgelyks 'n meerdoelige produksiefunksie in terme van 'n vervangingsvers en slagbees. Vir laasgenoemde doel is aangetoon dat hierdie kruising ewe geskik as 'n voerbees of stooros is. Dit moet egter in berekening gebring word dat hierdie kruistipe eers op 'n groot massa markklaarheid bereik. Die Herefordkruise blyk liefs slegs as slagbees aangewend te word, ongeag die produksiestelsel, hoewel dit veralonder intensiewe toestande by uitstek goed presteer het.af
dc.description.sponsorshipNoordkaap Lewende Hawe Koöperasieen_ZA
dc.language.isoafaf
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectThesis (Ph.D. (Animal Science))--University of the Free State, 1977en_ZA
dc.subjectAfrikanerbeesteen_ZA
dc.subjectCattle -- Productivityen_ZA
dc.titleProduksiepotensiaal van verskillende eerstekruising Afrikanerbeesteaf
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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