An estimation of the genetic distance between Polish Red and other Red Cattle breeds on the basis of selected milk protein loci

The material for the study were six populations of Red Cattle, including three samples of the Polish Red cattle population (PC’69, n = 203, PC’82, n = 261 and PC’96, n = 313) and one each of the Danish Red (DC, n = 169), German Red (NC, n = 510) and Czech Red (CC, n = 14). DNA was isolated from blood, according to the method by Gemmell and Akiyama (1996). All individuals were genotyping for the following proteins: a S1-casein, b-casein, k-casein and b-lactoglobulin. The frequency of alleles was estimate and was used for the estimation of the genetic distance between populations. Using the PHYLIP ver. 3.5c software the genetic distance was determined according to 1) Nei, 2) Cavali-Sforza and 3) Reynolds. All the populations demonstrated a similar distribution of allele frequencies at individual loci. Only the Czech Red showed different tendencies as regards b- and k-casein and b -lactoglobulin. This may have been the effect of the smaller population size as compared to the remaining breeds. Genetic distances estimated by these three using methods were similar. The smallest genetic distance was observed between populations PC’96 and NC (0.0007). In turn, the highest value was obtained between population DC and CC (0.0776). In the case of the genetic distance calculated according to the formulas by Cavalli-Sforza and Reynolds, the values obtained were higher then value of genetic distance estimated by Nei. The comparatively low values for the genetic distance obtained in the present studies may indicate that the breeds analysed originate from a common ancestor or lived on neighbouring geographical regions, what could lead to a frequent exchange of genes. The considerable similarity between those breeds could also be caused by a similarly conducted selection, based on similar assumptions (similar type of production). Those populations demonstrate similar gene pools what may be used for common preserve breeding programmes, which would decrease the danger of inbreeding. An analysis of the data collected over 30 years for the three populations of the Polish Red cattle, renders it possible to conclude that the frequency of individual alleles of the proteins examined are subjected to a small but continuous change.