Evaluation of calcium and canola oil in the diet of feedlot steers

Abstract

An experiment was conducted to determine whether the addition of 5.6% canola oil to a barley-based feedlot ration would improve the efficiency of conversion of feed into weight gain and increase the deposition of intramuscular fat. A second aim was to determine what further benefits might accrue from the addition of calcium ions to the rumen.Five groups of 30 steers representing 4 breed crosses were fed in a feedlot for 122 days. The control diet was a standard barley-based ration containing 1.6% calcium carbonate. In a second diet (calcium), calcium carbonate was replaced with 1.2% calcium hydroxide to increase the availability of calcium ions in the rumen. In a third diet (oil), 5.3% canola oil replaced a corresponding weight of barley. The fourth diet comprised oil + calcium and in the fifth, the same weight of oil protected against rumen fermentation was given as Rumentek, replacing 19.5% barley.There was no significant benefit in feed conversion or carcass composition to the substitution of oil for barley in the ration. Supplementary calcium hydroxide reduced the intake of the control diet with little reduction in growth rate. No benefits were observed from the provision of calcium ions in the rumen with either the control or oil diets. The Rumentek diet conferred no benefits in growth rate or feed conversion efficiency, but substantially increased the proportion of unsaturated to saturated long-chain fatty acids in subcutaneous fat, chiefly as polyunsaturates.