|Morgan, B. - OK STATE UNIVERSITY|
|Nelson, J - OK STATE UNIVERSITY|
|Olson, T - UNIVERSITY OF FL|
Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2002
Publication Date: July 1, 2002
Citation: Coleman, S.W., Phillips, W.A., Chase, C.C., Jr., Riley, D.G., Morgan, B., Nelson, J., Olson, T.A. 2002. Organ weights and internal fat of Angus or Romosinuano steers finished in the feedlot or with grain-on-pasture. Journal of Animal Science. 80(Suppl. 1):147. Technical Abstract: Tropical adaptation is a desired trait for cows located in the sub-tropical regions of the U.S.A., including the Gulf Coast and most of the Southeast. Zebu breeds have traditionally been used for this area, but have some limitations such as reproduction and carcass quality. Criollo cattle from South America, such as the Romosinuano, have been reported to have good reproduction under tropical and sub-tropical conditions. The objective of this study was to characterize organ weights and fat depots in Romosinuano steers as compared to Angus. At weaning, 12 Romosinuano and 12 Angus steers from contemporary USDA-ARS STARS herds were shipped in Oct. to El Reno, OK, and grown for 224 d . The steers were then finished under two regimens; either 1) total confinement feedlot or 2) by grazing grass pastures with ad libitum access to a finishing diet. Romosinuano steers produced heavier (P < 0.05) empty body weight than Angus when finished with hgrain on pasture, but breed types were similar when finished in the feedlot. When adjusted to a constant empty body weight, there were no differences (P > 0.10) due to breed or finishing treatment for weight of heart or kidney. Romosinuano steers had heavier (P < 0.05) hide, spleen, and internal fat than Angus, but lighter liver, and empty rumen tissue. Steers finished in the feedlot had more (P < 0.05) internal fat, and lighter (P < 0.05) head and lung weights than those finished on pasture. An interaction (P < 0.05) was observed for weight of empty GI tract (minus rumen) weight. These data may explain the observation that Romosinuano cattle appear to carry less finish than conventional breeds and may have implications on how tropically adapted cattle adjust to feast or famine conditions of the wet-dry tropics by storing and mobilizing internal fat.