Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2001
Publication Date: 6/1/2001
Citation: GEARY, T.W., MCFADIN-BUFF, E.L., MACNEIL, M.D., FUNSTON, R.N., SHORT, R., GRINGS, E.E., KEISLER, D.H. A POSSIBLE ROLE OF LEPTIN ASSAY IN ASSESSING CARCASS FAT AND COMPOSITION IN BEEF CATTLE. WESTERN SECTION OF ANIMAL SCIENCE PROCEEDINGS. 2001. Interpretive Summary: The opportunity to modify body composition through selection or management can help cattle producers and feeders produce beef that more consistently meets the expectations of consumers. Circulating levels of leptin provide an indicator of adiposity in live animals and thus may facilitate more appropriate feeding and marketing management strategies. Further research is needed to discern predictors of carcass value than can be applied before harvest.
Technical Abstract: The hormone leptin is produced by adipocytes and is positively correlated with body fatness. In cattle, fat makes up approximately 36% of an animal's empty body weight. Approximately 70% of this fat is stored as either intermuscular, intramuscular, or kidney fat, which are all difficult to accurately estimate in the live animal. Our objective was to determine if a newly developed leptin radioimmunoassay (RIA) could be used to predict carcass merit in fed cattle. Two different groups of crossbred Bos taurus steers and heifers were managed under feedlot conditions in Miles City, MT. The first group (CGC) consisted of 88 1/2Red Angus, 1/4Charolais, and 1/4Tarentaise composite steers harvested at the Con Agra processing facility in Greeley, CO. The second group (LB) consisted of Limousin, Hereford, or Piedmontese crossbred steers and heifers harvested at a local processing facility in Miles City. Blood samples were collected 24 h before harvest (CGC) or 3-5 d before and at harvest (LB). Circulating leptin concentrations were positively correlated (P<0.01) to fat depth in both CGC (r=0.34) and LB cattle (r=0.38). Leptin concentrations were also positively correlated (P<0.01) to marbling score (r=0.35 and 0.37) and KPH (r=0.42 and 0.46) in CGC and LB cattle, respectively. Ribeye area was not correlated to leptin in CGC steers (r=0.12, P=0.3), but was negatively correlated to leptin in LB cattle (r=-0.25, P=0.02). Leptin concentration was correlated to yield grade in both CGC and LB groups (r=0.23, P<0.05 and r=0.36, P<0.01, resp.). Leptin has a significant association with fat deposition in feedlot cattle and may prove to be a powerful and accurate tool in assessing fat content in feedlot cattle.