Die teeltstruktuur van die Suid-Afrikaanse merino
| dc.contributor.advisor | De Lange, A. O. | |
| dc.contributor.author | Erasmus, Gert Johannes | |
| dc.date.accessioned | 2018-02-09T09:10:09Z | |
| dc.date.available | 2018-02-09T09:10:09Z | |
| dc.date.issued | 1977-12 | |
| dc.description.abstract | English: 1. An analysis of the flock records kept by the Merino Stud Breeders' Association of South Africa is made. A qualitative classification of studs according to definition is made in an effort to determine the breed structure of the Merino. 2. The number of registered breeders as well as the total number of stud ewes shows. a sharp increase to 1967 with an equally sharp decline between 1970 and 1973. 3. The abovementioned changes are largely to be found in the ranks of the smaller studs. 4. The average number of stud ewes per breeder has stabilised at approximately 230 since 1966. 5. It is found that smaller studs have a smaller chance of survival. 6. The 773 active studs. in 1974 are classified as follows by definition: 15 “parent” studs, 258 “daughter studs”, 431 “general” studs, 69 “isolated” studs. 7. The "parent" studs are dominated by three studs and their "daughters" as far as supplying rams is concerned. Large differences in number of stud ewes and number of stud and and flock rams sold exist between parent studs. 8. The "family groups" ("parents" plus "daughters") are the largest vendors of stud rams (76,3 per cent of 'total) while the "general" studs and family groups sell approximately the same number of flock rams. 9. It is estimated that the registered Merino breeders supply only approximately 54 per cent of the total number of Merino rams required in the Republic. 10. Although the average number of stud ewes per breeder is small, it is estimated that registered breeders each possess on the average approximately 2 000 commercial ewes. The recommendation is made that the size of the present stud flocks be in: creased by making use of these ewes. 11. It is calculated that the registered breeders sell on the average approximately 37 per cent of their available rams but that this proportion varies considerably. The proportion of rams sold has no connection with stud size. Many registered studs sell no rams. 12. It is concluded that the breed structure of the Merino rather tends towards a two-tier structure than a classical three tier pyramid. Most of the studs are relatively more dependant on within-flock selection of rams for breeding improvement than on rams purchased. It can, however, be concluded that a more precise description of breed structure is necessary. 13. Evidence pertaining to the existence of a selection plateau in fleece weight in many cases is discussed. It is concluded that effective selection on measured performance is a necessity. 14. The implications of the present breed structure on the strategy of extension efforts with regard to the National performance Testing Scheme is discussed. It is concluded that an extension program directed at the whole Merino industry is needed and that a fleece analysis service cannot be restricted to certain "elite" flocks. 15. It is found that Merino stud flocks are largely centered in the Eastern Karoo area. The implications of this situation is discussed. 16. The necessity of inter-flock comparisons of actual genetic merit is stressed. | en_ZA |
| dc.description.abstract | Afrikaans: 1. 'n Ontleding van die kudderekords gehou deur die Merinostoettelersvereniging van Suid-Afrika is gemaak. 'n Kwalitatiewe indeling van stoetkuddes volgens definisie is gedoen in 'n poging om die teeltstruktuur van die Merino vas te stel. 2. Die getal geregistreerde telers sowel as die totale getal stoetooie toon 'n skerp styging tot 1967 met ‘n ewe skerp daling tussen 1970 en 1973. 3. Bogenoemde veranderings het hoofsaaklik in die geledere van die kleiner stoeterye voorgekom. 4. Die gemiddelde getalooie per teler het vanaf 1966 op ongeveer 230 gestabiliseer. 5. Dit is gevind dat hoe kleiner 'n stoetery, hoe skraler word sy oorlewingskanse. 6. Die 773 aktiewe stoeterye in 1974 is volgens definisie as volg ingedeel: 15 "ouer"-stoeterye, 258 "dogter"-stoeterye, 431 "algemene"-stoeterye, 69 "geisoleerde"-stoeterye. 7. Die "ouer"-stoeterye word deur drie stoeterye en hul "dogters" wat die verskaffing van ramme betref, oorheers. Groot verskille irigetal stoetooie en getal stoet- en kudderamme verkoop kom onder die "ouer"-stoeterye voor. 8. Die familie-groepe ("ouers" en "dogters") is die belangrikste verkopers van stoetramme (76,2% van totaal) te;rwyl die "algemene"-stoeterye en die familie-groepe nagenoeg dieselfde hoeveelheid kudderamme verkoop. 9. Dit is beraam dat die geregistreerde Merinotelers slegs ongeveer 54 persent van die getal Merinoramme in die Republiek benodig, verskaf. 10. Hoewel die gemiddelde getal stoetooie per teler klein is, is beraam dat geregistreerde telers elk gemiddeld ongeveer 2 000 kommersiële ooie besit. Die aanbeveling word gemaak dat die bestaande stoetkuddes met hierdie ooie vergroot moet word. 11. Daar is beraam dat die geregistreerde telers gemiddeld ongeveer 37 persent van hul beskikbare ramme verkoop maar dat hierdie proporsie aansienlik varieer. Die proporsie ramme verkoop hou nie verband met stoetgrootte nie. Heelwat geregistreerde telers verkoop geen ramme nie. 12. Dit is gevind dat die teeltstruktuur van die Merino meer na 'n twee-laag struktuur neig as 'n klassieke drie-laag pirimidale hierargie. Die meeste stoeterye is relatief meer afhanklik van binne-kudde ramseleksie as van ramaankope vir Teeltvordering. Die gevolgtrekking word egter gemaak dat 'n meer presiese beskrywing van die teeltstruktuur nodig is. 13. Getuienis wat daarop dui dat 'n seleksie-plato in vaggewig in baie gevalle reeds bereik isp word bespreek. Die gevolgtrekking word gemaak dat doeltreffende seleksie op gemete prestasies noodsaaklik is. 14. Die implikasies van die huidige teeltstruktuur op die strategie van uitbreidingspogings van die Nasionale Prestasie: toetsskema is bespreek. Die gevolgtrekking word gemaak dat 'n voorligtingsprograrn tot-·die hele Merinobedryf gerig moet word en dat vagontledingsdienste nie tot sekere "elite"- kuddes beperk kan word nie. 15. Dit is gevind dat Merino stoetkuddes hoofsaaklik in die Oostelike Karoo gebied gesentreer is. Die implikasies hiervan word bespreek. 16. Die noodsaaklikheid van inter-kudde vergelykings van werklike genetiese meriete word beklemtoon. | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11660/7796 | |
| dc.language.iso | af | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Merino sheep -- Breeding -- South Africa | en_ZA |
| dc.subject | Dissertation (M.Sc.Agric (Genetics))--University of the Free State, 1977 | en_ZA |
| dc.title | Die teeltstruktuur van die Suid-Afrikaanse merino | en_ZA |
| dc.type | Dissertation | en_ZA |