Genetic changes in a New Zealand pedigree Jersey herd : being a thesis presented in partial fulfilment of the requirements for the degree of M. Agri. Sc., Massey Agricultural College, University of New Zealand

Abstract

The majority of sires used in New Zealand herds are obtained from pedigree breeders and in consequence, the genetic merit of the national herd depends largely upon the quality of the pedigree section of the cattle breeding industry. The continued use of pedigree sires by many commercial farms has probably resulted in a narrowing of the genetic margin between registered and non-registered dairy cattle. Upon this genetic margin the present elite status of pedigree cattle depends and if it were possible to demonstrate that this margin was negligible then the present rigid distinction between pedigree and non-pedigree stock would not be justified. This would have far reaching implications the most important of which would be that there would be little justification in restricting sires used in the industry to those bred in pedigree herds. On the other hand if it were possible to demonstrate that pedigree herds were improving genetically and preserving a genetic margin over commercial herds then the present policy of attempting to effect national herd improvement through the pedigree section of the industry would be vindicated.