Breed differences and genetic parameters for melting point, marbling scoreand fatty acid composition of lot-fed cattle

Fatty acid composition, marbling score and melting point data collected bet ween 1994 and 1996 were analysed. The data were from the adipose tissue of 764 Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu crossbred cattle slaughtered after lot-feeding at 500 days of age. The aim was to investigate sire-breed differences and to estimate heritability and genetic and phenotypic correlations. Significant breed differences were fou nd: Jersey crosses had the highest marbling score and Belgian Blue crosses had the lowest. Limousin crosses had the highest melting point and Jersey c rosses the lowest. South Devon crosses bad the highest proportion of steara te and Jersey crosses the lowest. Desaturation indices in C16 and C18 fatty acids were highest in Jersey crosses and lowest in Limousin and South Devo n crosses. In contrast, there were no breed differences in the proportions of palmitate, oleate, total saturated, total mono-unsaturated fatty acids a nd elongation index. Heritability estimates of individual fatty acids and t heir summations, melting point and marbling were low to moderately low (0.0 5-0.27). Strong genetic correlations of melting point and desaturation inde x in C16 fatty acids (-0.93), melting point and stearate (0.62), marbling a nd stearate (-0.71) and marbling and desaturation index in C18 fatty acids (0.62) were observed. Phenotypic correlation were generally low. The result s imply that fatty acids in the adipose tissue of lot-fed cattle have a mod erately low heritability, hence genetic progress might be slow.