Genetic Characterisation of Mafriwal Dairy Cattle of Malaysia Using Quantitative and Molecular Methods
Palani, Kalaiselvi (2004) Genetic Characterisation of Mafriwal Dairy Cattle of Malaysia Using Quantitative and Molecular Methods. PhD thesis, Universiti Putra Malaysia.
In Malaysia, there is an increasing demand for milk and other dairy products. The total milk consumption has almost doubled in the last decade, but self-sufficiency has decreased. Among the government’s effort to stimulate the dairy industry was the development of the tropicalised synthetic breed named “Mafriwal” by crossbreeding of Sahiwal and Friesian breeds. The Mafriwal, being a new breed, is still subjected to selection and improvement. Therefore, it is essential that its performance and genetic structure be monitored. This study was carried out to characterise the Mafriwal dairy cattle of Malaysia, using quantitative methods and microsatellite markers, and to investigate possible association between microsatellite markers and quantitative trait loci for milk production and reproduction traits. This study focused on the Mafriwal herd at Institut Haiwan Kluang, Johor. Evaluation of four breed groups, namely M50, M56, M63 and M75 with 50%, 56%, 63% and 75% Friesian gene, respectively, based on retrospective data 1058 cows born between 1982-1996, showed breed group effect to be non-significant for LTM, P305, DPM, LL, DM and DP but significant (P<0.05) for NSC, CFS and CBW. P305M, DPM and DM was significantly (P<0.05) low in the first lactation. First parity had significantly (P<0.01) longer CFH, CFS and lower CBW than subsequent parities. The phenotypic correlations between the milk production traits were high (0.78 to 0.86), and that between reproduction traits ranged from 0.23 to 0.96. Repeatability estimates for the four breed groups were 0.14 - 0.68 for milk production traits and low for reproduction traits. The modified gamma function used to fit lactation curves of 144 cows revealed initial milk yield was higher (P<0.05) in M56 and M63 compared to M50 and M75, but their rise to peak production and rate of decline were lower. The lactation curve parameters were higher for cows that calved after 1996 and were significantly (P<0.01) lower for first lactation. Microsatellite analysis of a random sample of 40 cows using 55 established marker primers detected 90.9% polymorphism. The polymorphic loci showed 4 to 10 alleles, with 8 to 20 genotypes per locus. The allele frequencies ranged from 0.01 to 0.45 and genotypic frequencies ranged from 0.03 to 0.38. Observed heterozygosity was 0.20 - 0.75, with mean 0.520.12. Significant (P<0.05) deviations from Hardy-Weinberg equilibrium were observed for all the polymorphic loci, except RM209. The 30 high producers (HP) and 30 low producers (LP) in the herd, analysed for the 50 polymorphic microsatellite loci, could not be distinguished by any particular marker and were quite similar in terms of genetic variability. Among HP, three alleles showed significant (P<0.05) association with milk production traits and nine alleles with reproduction traits. Among LP, absence of allele SPS115:D/150 showed significant (P<0.05) increase in LL and two alleles showed significant (P<0.05) association with reproduction traits. For the pooled data (HP, LP and random sample), presence of following alleles was significantly (P<0.05) associated with higher means for performance traits: AGLA29:E/146, BM143:A/100, BM4208:G/190, BM678:H/175, CSSM5:C/125 and TGLA170:C/95 with LTM, BM143:A/100 and RM372:G/170 with LL and BM143:A/100, BM4208:G/190, BM678:H/175, CSSM5:C/125 and HUJV174:E/150 with DM. Animals with alleles AGLA29:E/176, BMS678:H/175 and CSSM5:D/133 showed significantly (P<0.05) shorter CFH and CFS and with alleles BMS4028:F/120 and BMS678:H/175 had shorter CCo and CI.
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