Effect of age of castration, oestradiol treatment and genotype on the fat colour of beef cattle raised at pasture

Abstract

It is hypothesized that the fat colour of steers raised at pasture can be manipulated by altering animal growth patterns using the effects of post-pubertal surgical castration and oestradiol treatment. The fat colour of 151 steers of three genotypes of beef cattle, castrated at approximately 9 months or 18 months of age and treated, or not treated, with oestradiol after castration, was studied.

Surgical castration of beef cattle at both 9 months of age or 18 months of age caused no readily apparent animal welfare problems. The combined effects of early or late castration and oestradiol treatment produced varying growth patterns with early castrates exposed to two post-castration episodes of growth associated with carotene-rich forage and late castrates only one such episode of growth.

Late castrates and early castrates treated with oestradiol had a less yellow fat than early castrates not treated with oestradiol. The proportion of carcasses with commercially significant yellowness in the fat was decreased by either late castration or by oestradiol treatment. There was no effect of genotype on fat colour.