Growth, Blood Parameters and Tissue Lipids of Finishing Cattle Fed a Formaldehyde Treated Casein-Safflower Oil Complex

Formaldehyde treated casein-safflower oil (1/1) was fed for 56 days at levels of 0, 10, 20 and 30% of the diet to eight finishing beef heifers (354 kg) and eight finishing steers (413 kg) to determine animal performance, response of blood cholesterol and amino acids, and changes in tissue lipid composition. Feed intake and weight gain decreased linearly as the percentage of dietary casein-oil increased, intake decreasing such that there was no difference in casein-oil consumption among the three treatments with the complex. At 56 days blood plasma cholesterol had increased 75% in cattle fed the casein-oil complex compared to control animals. There was no difference (P >.10) in blood plasma total essential amino acid concentration between cattle fed control and casein-oil diets.Half the cattle were fed 650 USP units of supplemental vitamin E daily, but this had no effect on tissue tocopherol concentration. Stearic and oleic acids in tailhead adipose tissue as a percentage of total long-chain fatty acids changed little during this study. Linoleic acid in tailhead fat of cattle fed casein-oil increased from 3.7% at the start of the experiment to 5.8% at 56 days. After the feeding trial was completed, the cattle were slaughtered and tissue lipid was analyzed. There were no differences (P <.05) among treatments in linoleic acid percentage in omental and kidney fat, but all cattle in the casein-oil treatments had higher percentages of linoleic in subcutaneous rib fat and in intramuscular loin than cattle fed no casein-oil. Changes in tissue fatty acid composition of these finishing cattle were not as pronounced as with lighter-weight cattle in prior studies.