Ondersoek na linieêre klassifikasie in die Suid-Afrikaanse Jerseyras - Van Niekerk, Daniel Jacobus (University of the Free State, 1999)
A total of 36000 records that were obtained from INTERGIS were used in this study to determine genetic parameters for the South African Jersey breed. After editing 9447 records qualified for the analysis. The data set consisted of animals with official first lactation records and linearly scored during their first lactation. The individual animal record contained the following information: identification number, sire, dam, birth date, owner, classification date, classifier, 13 linear type-traits (wither height, strength, dairy form, rump angle, thurl width, rear legs, hoof inclination, fore-udder attachment, rear-udder height, rear-udder width, udder cleft, udder depth and teat placement), final udder class, final class, age at first calving, milk-, butterfat- and protein production, butterfat percentage, protein percentage as well as length of lactation. A variance analysis on 9447 records was conducted by means of the SAS OLM (1988) procedures. The following effects were tested: herd, year of birth, year and season of calving, classifier, classification year, classification month, region, age at first calving and stage of lactation. Effects that were significant at the 1% level were included in the model. Nine models were specified and the resulting heritability estimates were obtained by DFREML procedures (Not all the non-genetical effects were significant for all the traits). Bivariate REML-procedures were done to determine the genetic parameters for the South African Jersey breed. The heritability estimates obtained varied between 0.05 for hoof inclination to 0.32 for wither height. The heritability estimates are in agreement with results reported in the literature. The genetic and phenotypic correlations obtained between the 13 linear type-traits and the three production traits (milk, butterfat, protein) are in agreement with results reported in the literature. The highest positive genetic correlation was found between rear udder height and rear udder width (0.99). The highest positive genetic correlation with protein production was found with rear udder width (0.83). The highest negative correlation was found between rear legs side view and hoof inclination (-0.96). These results could be used to the benefit of the breed, for example in determining estimates breeding values for linear type traits.

36000 Rekords is vanaf INTERGIS verkry vir die bepaling van genetiese parameters in die Suid- Afrikaanse Jerseyras. Slegs 9447 rekords het gekwalifiseer vir insluiting in die ontledings. Die rekords het bestaan uit alle diere met amptelike eerste laktasie rekords, sowel as 'n klassifikasierekord wat gedurende die dier se eerste laktasie gedoen is. Die diererekord het die volgende inligting bevat: identiteitsnommer, vader, moeder, geboortedatum, eienaar, klassifikasiedatum, klassifiseerder, 13 linieêre tipe-eienskappe (skofhoogte, sterkte, suiwelvorm, kruishelling, draaibeenwydte, agterbenesykant, hoefinklinasie, vooruieraanhegting, agteruierhoogte, agteruierbreedte, uierspleet, uierdiepte, voorspeenplasing), finale uierklas, finale klas, eerste kalwingsdatum, melk-, bottervet-en proteïenproduksie, bottervet- en proteïenpersentasie en laktasielengte. ~ 'n Variansie-analise is met behulp van SAS GLM (1991) gedoen om die niegenetiese faktore wat die linieêre tipe-eienskappe beïnvloed, te bepaal. Die volgende niegenetiese faktore is getoets: kudde, geboortejaar, kalwingsjaar, seisoen van kalwing, klassifiseerder, klassifikasiejaar, klassifikasiemaand, streek, klassifikasie-ouderdom en stadium van laktasie. Effekte wat op die 1% peil betekenisvol was, is in die model ingesluit. Nie al die niegenetiese effekte was vir al die eienskappe betekenisvol nie. Nege modelle is gespesifiseer. Voortvloeiende oorerflikhede is deur middel van DFREML prosedures verkry. Twee-Eienskap-REML-ontledings is uitgevoer om die genetiese parameters vir die Suid-Afrikaanse Jerseyras te bereken. Die oorerflikhede wat beraam is, het gevarieer tussen 0.05 vir hoefinklinasie en 0.32 vir skofhoogte. Oorerflikhede waaargeneem in ander studies, het grootliks ooreengekom met die oorerflikheidsberamings in die studie. Die genetiese en fenotipiese korrelasies wat verkry is tussen die 13 linieêre tipe-eienskappe en die drie produksie-eienskappe (melk-, bottervet- en proteïenproduksie) het tot 'n groot mate ooreengestem met die korrelasies wat in ander studies verkry is. Die hoogste positiewe genetiese korrelasie bestaan tussen agteruierhoogte en agteruierbreedte (0.99). Die hoogste positiewe genetiese korrelasie met proteïenproduksie is agteruierbreedte (0.83). Die hoogste negatiewe genetiese korrelasie bestaan tussen agterbene sykant en hoefinklinasie (-0.96). Hierdie resultate sal tot voordeel van die Jerseyras gebruik kan word deur byvoorbeeld teelwaardes vir die linieêre tipe-eienskappe te beraam.
Dissertation (M.Sc.Agric. (Animal Science))--University of the Free State, 1999
Keywords: Dairy cattle -- Breeding -- Statistical methods; Jersey cattle; Dairy cattle breeds