IMMUNOMODULATION OF FAT DEPOSITION

Consumer concern about health together with resistance to the use of exogenous substances in meat production has increased the importance of developing 'friendly' methods to increase the lean content of meat. Immunological methods may be more consumer acceptable. One such approach is to directly lyse adipocytes by administration or production of antibodies to adipose tissue plasma membrane proteins. To date, antibodies have been raised to rat, rabbit, chicken, ovine and porcine adipose tissue by active immunisation of other species and their effect on adipose tissue accretion examined in the target species. Such treatment decreased body fat in rats by up to 30%, in rabbits by 17% and in sheep by up to 15%, and decreased backfat thickness by 30% and loin fat by 25% in pigs. There was no effect on fat deposition in poultry. The effects appear to be adipose tissue site specific, to reflect decreases in cell size and number and to be influenced by the age of the animal when immunised and the interval between immunisation and slaughter. Antibodies have been successfully raised by active immunisation with homologous adipose tissue preparations but the effects on fat deposition were less than those observed for the passive approach. Future developments of this technology require the identification of specific antigenic determinants from individual adipose tissue sites. Their use as antigens, when coupled to an immunogenic protein and/or the use of polyclonal or monoclonal antibodies derived from these antigens could lead to commercially important improvements in the efficiency of lean meat production without adverse effects on animal welfare or meat quality.