Die teeltstruktuur van die Suid-Afrikaanse merino

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.