Fatty acid profile of adipose tissue and performance of feedlot steers supplemented with dehulled cottonseed and sunflower seed meal protected from ruminal metabolism

The effect of feeding dehulled cottonseed protected from ruminal metabolism (PCS): together with supplements of protected sunflower seed meal (PSM), on the performance and fatty acid profile of adipose tissue in feedlot steers was examined. Sixty-two Hereford cross steers, average weight 470 kg, were assigned to 4 groups and fed rations based on barley-corn silage for 150 days. The diets offered contained 10% untreated whole cottonseed + 6% untreated sunflower seed meal (Group I), 10% PCS + 10% PSM (Group II): 15% PCS + 10% PSM (Group III), or 20% PCS + 10% PSM (Group IV). Inclusion of PCS at the level of 10, 15, and 20% together with 10% PSM resulted in an increase (P < 0.01) in dressing percentage together with an improvement in feed conversion ratio. There was a 5-8-fold increase in the proportion of linoleic acid (C18:2) in omental, perirenal, and subcutaneous fat from cattle fed the PCS supplement. A significant reduction occurred in the proportion of oleic acid (C18:1 cis), but the percentage of palmitic acid (C16:0) was not affected; the proportion of stearic acid (C18:0) in subcutaneous fat increased with PCS supplementation.