Title: GENETICS OF SHEEP TRANSFERRINS AS DETERMINED BY DISC ELECTROPHORESIS

approved: Ralph/Bogart Redacted for Privacy A total of 902 plasma samples from the Rambouillet, Targhee, Columbia, Lincoln, and Suffolk breeds of sheep were analyzed for transferrin type by disc electrophoresis. Six transferrin types, TfA, TfB, TfC, Tfp, TfE, and TfP, were found in the Rambouillet, Targhee, and Columbia breeds while five, A, B, C, D, E, and four, A, B, C, D, types were observed in the Suffolk and Lincolns respectively. Mating data involving five of the six alleles confirmed previous reports that the transferrins are inherited as co-dominant autosomal allelic genes. No evidence was found to support a previous suggestion of maternal-fetal incompatibility expressed as a disturbed segregation ratio. Gene frequencies were calculated for breeds and strains within breeds. It was shown that there were characteristic breed frequencies but they could not be used to predict the degree of relationship between breeds. An excess of homozygotes was observed in the Rambouillet, Targhee, and Columbia breeds which was probably due to inbreeding and subdivision of the population. Characteristic frequencies were observed for inbreds, linecrosses, and control lines within breeds. The frequency of the B allele was much lower in the Rambouillet, Targhee, and Columbia breeds of the U. S. Sheep Experiment Station at Dubois, Idaho, than in the Suffolk and Lincoln breeds of western Oregon. Since the Dubois Station differs considerably from western Oregon in severity of climate, altitude, management, plane of nutrition, and incidence of various diseases, it was suggested that the B allele might be at a disadvantage in higher altitudes with a more severe climate and a higher incidence of disease such as that present at the Dubois Station. The effect of transferrin type on some pre-weaning and yearling performance traits was found to be significant for birth weight and average daily gain from birth to weaning. The effect of transferrin type on weaning weight and grease fleece weight, although not statistically significant, closely approached significance. Neither weaning nor yearling indices were significantly different among alleles. Since selection is by the index method in the sheep population at the Dubois Station, it was suggested that artificial selection has little or no effect on frequency of transferrin alleles in these particular populations.