Rumen inert fat (RIF) is a type of fat supplement that is used in the diets of beef cattle as early as 6 mo of age in calves and continues through the finishing period to improve the dietary energy density which can be used by the animal to deposit more lipid in the muscle tissue. However, for Hanwoo beef cattle, the precise time of RIF supplementation has not yet been determined. This study hypothesized that supplementing RIF at the growing phase (9 to 13 mo of age) would have a positive influence on the marbling characteristics of meat at slaughter. The growth rate and performance of steers were not improved by RIF supplementation, however, an increase in intramuscular fatty acid content was noted that was accompanied by the increased number of intramuscular adipocytes and decreased intramuscular adipocyte diameter. Supportively, upregulation of the genes associated with fatty acid uptake and esterification during the fattening phase of RIF-fed animals was noted. Overall, supplementing RIF at the growing stage could improve the lipid content of the meat which is supported by the increased lipid hydrolysis during the growing phase and followed by increased lipid accumulation during the fattening phases.

Read the full article in the Journal of Animal Science.