Estimation of genetic parameters for growth traits in South African Brahman cattle
| dc.contributor.advisor | Neser, F. W. C. | |
| dc.contributor.advisor | Van Wyk, J. B. | |
| dc.contributor.author | Pico, Boipuso Alpheus | |
| dc.date.accessioned | 2015-11-23T12:23:45Z | |
| dc.date.available | 2015-11-23T12:23:45Z | |
| dc.date.copyright | 2004-12 | |
| dc.date.issued | 2004-12 | |
| dc.date.submitted | 2004-12 | |
| dc.description.abstract | English: The present study was carried out to estimate genetic, phenotypic and environmental parameters for growth traits, genetic trends as well as the level of inbreeding in the South African Brahman breed. The data used were obtained from the South African Brahman Breeders’ Society and consisted of pedigree information of 181 508 animals and 221 015 performance records, ranging from birth to 18-months weight /final weight collected between 1955 and 2002. Performance records available before editing as classified according to age ranges were birth weight (BWT) = 67 336, weaning weight (WWT) (80–300 days) = 62 159, yearling weight (YWT) (301-500 days) = 41 313 and final weight (FWT) (501-900 days) = 32 602. The linear animal model used included the fixed effects of contemporary group (herd-year-season), sex, management group, age of the calf, age of the dam. Direct genetic, maternal genetic and permanent maternal environmental as random effects as well as sire x herd-year-season interaction as an additional random effect. Preliminary analyses showed that all fixed effects had a significant (P<0.0001) effect on all traits studied. Genetic parameters for growth traits were estimated using ASREML software by fitting univariate and bivariate animal models. Production traits considered after editing were BWT = 41 509, WWT = 37 705, YWT = 22 682 and FWT = 13 055 records collected between 1985 and 2002. The reason for using the data only from 1985 is that only a small number of records were recorded up to 1984. The direct heritability estimates of BWT, WWT, YWT and FWT were 0.28, 0.14, 0.14 and 0.18 respectively. The corresponding maternal heritability estimates were 0.11, 0.06, 0.05 and 0.03 respectively. The maternal permanent environmental component due to the dam contributed 3 - 7 % of the total phenotypic variance of the traits under consideration. The corresponding contribution of sire x herd-year-season interaction ranges from 5 - 6%. The genetic correlation between animal effects was -0.36 for BWT, other traits studied did not show an antagonism between animal effects. The prospects of improvements of these traits by selection seem possible and the contributions of permanent maternal environmental effect are not equally important as maternal effects though the effects are small. Estimates of phenotypic correlations were low to moderate (0.22 to 0.64), whereas genetic correlations were moderate to high (0.47 to 0.91). Genetic correlations between BWT and WWT, YWT and FWT were 0.62, 0.47, and 0.52 respectively. The corresponding genetic correlations between direct and maternal effects of the same trait (ram, rma) were (-0.4204, -0.014), (-0.4241, 0.0567) and (0.05170, 0.0879) respectively. Genetic correlations between WWT and postweaning weights were 0.88 and 0.91 for YWT and FWT respectively. The corresponding maternal correlation was at unity. Lastly, the genetic and maternal correlation between YWT and FWT were 0.83 and unity, respectively. Positive genetic trends were observed for all traits except for the maternal genetic trend for BWT, which had a slightly negative slope. Direct genetic progress for BWT was 0.0207 kg/year (1987-2002), whereas progress for WWT was 0.1kg/year (1985-1995) and 0.4 kg /year (1996-2001). Progression in direct genetic effect for YWT was 0.1kg/year (1985- 1995) and 0.3 kg/year (1996-2001) whereas progress for FWT was 0.13 kg/year (1985-2001). The maternal genetic trends were -0.003, 0.04, 0.008 and 0.003 kg/year for BWT, WWT, YWT and FWT, respectively. Genetic progress was in general low over the years for all traits. Therefore, estimation based on BLUP of breeding values may be more important in the future and should be considered to maximise opportunities for genetic change. Inbreeding level and its possible influence on growth traits of the South African Brahman cattle were investigated. Inbreeding coefficients were calculated by inverting the diagonal of the inverse relationship matrix using the MTDFNRM program of the MTDFREML package. Inbreeding depression was estimated as the regression of performance on individual and dam inbreeding coefficients using an animal model. The mean inbreeding of the population was very low (0.01) with an average of (0.03) for inbred animals. Although regression coefficients of BWT, WWT, YWT and FWT on inbreeding of animal and dam were significant for all traits, the results showed that inbreeding at present is not a serious problem in the South African Brahman breed. | en_ZA |
| dc.description.abstract | Afrikaans: Die doel van hierdie studie wa s om genetiese, fenotipiese en omgewingsparameters vir groei - eienskappe vir die Suid - Afrikaanse Brahmanras te beraam, asook genetiese tendense en die vlak van inteling by dié ras. Data met stamboominligting van 181 508 diere en 221 015 prestasie - rekords w at wissel van geboorte - tot 18 - maandegewig / finale gewig, versamel tussen 1955 en 2002, is van die Suid - Afrikaanse Brahmaantelersvereniging verkry. Onverwerkte prestasie data wat beskikbaar is, word geklassifisser volgens die verskillende ouderdoms groepe . Hierdie prestasie data is as volg: geboortegewig (BWT) = 67 336, speengewig (WWT) (80 - 300 dae) = 62 159, jaar - oudgewig (YWT) (301 - 500 dae) = 41 313 e n finale gewig (FWT) = 32 602. Die lineêre dieremodel wat gebruik is het die volgend vaste effekte ingesl uit , kontemporêre groep (kudde - jaar - seisoen), asook geslag, bestuursgroe p, ouderdom van die kalf, ouder dom van die moeder . D irekte genetiese , maternale genetiese en permanent maternale omgewing as toevallige effekte , so wel as vaar x kudde - jaar - seisoen int eraksie as ‘n addisionele toevallige effek . Voorlopige ontledings het getoon dat alle vaste effekte ‘n hoogs betekenisvolle (P< 0.0001) effek op alle eienskappe wat bestudeer is gehad het. Genetiese parameters vir groei - eienskappe is beraam deur gebruik te maak van die ASREML - sagteware deur enkel - en twee - eienskapdieremodelle te pas. Na verwerking was die volgende aantal rekords beskibaar , BWT = 41 509, WWT = 37 705, Y WT = 22 682 en FWT = 13 055. Hierdie rekords is tussen 1985 en 2002 ingesamel is. Die r ede waarom dat slegs vanaf 1985 af gebruik word is, dat daar min record was tot en met 1984. Die direkte oorerflikheidsberamings van BWT, WWT, YWT en FWT was 0.28, 0.14, 0.14 en 0.18, onderskeidelik. Die maternale permanente omgewingskomponent te wyte aan die moeder het 3 – 7 % van die totale fenotipiese variansie van die eiensk appe wat oorweeg is, bygedra. Die ooreenstemmende bydrae van vaar x kudde - jaar - seisoen interaksie wissel van 5 – 6 %. Die genetiese korrelasie tussen diere - effekte was – 0.36 vir BWT, terwyl ander eienskappe wat bestudeer is nie ‘n antagonisme tussen diere - effekte getoon het nie. Die verbetering van hierdie eienskappe deur seleksie blyk moontlik te 62 wees en die bydrae van permanente maternale omgewingseffek is nie van gelykstaande bela ng as maternale effekte nie, alhoewel die effekte klein is. Beramings van fenotipiese korrelasies was laag tot middelmatig (0.22 tot 0.64), terwyl genetiese korrelasie middelmatig tot hoog was (0.47 tot 0.91). Genetiese korrelasies tussen BWT, WWT, YWT e n FWT was 0.62, 0.47 en 0.52, onderskeidelik. Die ooreenstemmende genetiese korrelasie tussen direkte en maternale effekte van dieselfde eienskap (r am , r ma ) was ( - 0 - 4204, - 0.014), ( - 0.4241, 0.0567) en (0.05170, 0.0879), onderskeidelik. Genetiese korrelas ies tussen WWT en na - speengewigte was 0.88 en 0.91 vir YWT en FWT, onderskeidelik. Die ooreenstemmende maternale korrelasie was een. Ten laaste was die genetiese en maternale korrelasie tussen YWT en FWT 0.83 en een, onderskeidelik. Positiewe genetiese tendense is waargeneem vir alle eienskappe, behalwe vir die maternale genetiese tendens vir BWT, wat ‘n effense negatiewe helling gehad het. Direkte genetiese vordering vir BWT was 0.0207 kg/jaar vir die jare 1987 - 2002, terwy l die vordering vir WWT vir di e jare 1985 - 1995 was 0.1 kg/jaar en 0.4 kg/jaar vir die jare tussen 1996 – 2001 . Vordering in direkte genet iese effekte vir YWT vir die jare 1985 - 1995 was 0.1 kg /jaar en 0.3 kg/ja a r vir die jare tussen 1996 - 2001, terwyl d ie vordering vir FWT was 0.13 kg /jaar vir die jare tussen 1985 - 2001 . Die maternale genetiese tendense was – 0.003, 0.04, 0.008 en 0 .003 kg/ jaar vir BWT, WWT, YWT en FWT, onderskeidelik. Genetiese vordering oor die jare was oor die alge meen laag vir alle eienskappe. Daarom mag beraming gebaseer op BLUP van teelwardes belangriker in die toekoms word en behoort dit oorweeg te word om geleenthede vir genetiese verandering te maksimeer. Die intelingsvlak en die moontlike invloed daarvan op groei - eienskappe van die Suid - Afrikaanse B rahmanbeeste is ondersoek. Intelingskoëffisiënte is bereken deur die diagonaal van die inverse verhoudingsmatriks om te keer deur gebruik van die MTDFNRM - program van die MTDFREML - pakket. Inteeltverval was beraam as die regressie van prestasie op individuele en moeder - int elingkoëffisiënte deur gebruik van ‘n 63 dieremodel. Die gemiddelde inteelt van die populasie was baie laag (0.01), met ‘n gemiddelde va n (0.03) vir ingeteelde diere. Alhoewel regressie - koëffisiënte van BWT, WWT, YWT en FWT op inteling van dier en moeder bete kenisvol vir alle eienskappe was, het die resultate getoon dat inteling op hierdie stadium nie ‘n ernstige probleem in die Suid - Afrikaanse Brahmanras is nie. | af |
| dc.description.sponsorship | Mellon Foundation | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11660/1721 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Dissertation (M.Sc.Agric. (Animal, Wildlife and Grassland Sciences))--University of the Free State, 2004 | en_ZA |
| dc.subject | Zebus -- South Africa | en_ZA |
| dc.subject | Beef cattle -- Breeding -- South Africa | en_ZA |
| dc.subject | Cattle -- Growth | en_ZA |
| dc.subject | Inbreeding | en_ZA |
| dc.subject | Genetic and phenotypic parameters | en_ZA |
| dc.subject | Genetic trends | en_ZA |
| dc.subject | Brahman | en_ZA |
| dc.subject | Growth traits | en_ZA |
| dc.title | Estimation of genetic parameters for growth traits in South African Brahman cattle | en_ZA |
| dc.type | Dissertation | en_ZA |