Abstract

Protein and fat percent as content of milk are high-priority criteria for financial aims and selection of programs in dairy cattle. In order to incorporate information on marker- quantitative trait locus (QTL) associations, QTL detection and parameter estimation should also be performed. Microsatellite markers are most valuable markers in association studies between different loci with the production traits. With the aim of analysis markers previously identified by other researchers in QTLs of milk fat and protein percent traits in Iranian Holstein dairy cattle sample population, we use ten microsatellite markers on chromosomes 1, 6, 7 and 20. All microsatellite markers were genotype in 156 dairy cattle which have at least one year data of milk fat and protein record using 6 to 8% polyacrylamide gel electrophoreses determined with silver nitrate staining. We find 7, 5 and 8 out of 10 markers showing significant effect on milk fat percent in 1 to 120, 120 to 240 and 240 to 360 milking days, respectively. Our results show 6, 8 and 9 out of 10 markers have significant effect on protein percent in 1 to 120, 120 to 240 and 240 to 360 milking days respectively.

Key words: Fat percent, Iranian Holstein cattle, microsatellites, milking days, protein percent, quantitative trait locus (QTL).

Abbreviation

Abbrviations: QTL, Quantitative trait locus; PCR, polymerase chain reaction