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 metab olism (PCS): together with supplements of protected sunflower seed mea l (PSM), on the performance and fatty acid profile of adipose tissue i n feedlot steers was examined. Sixty-two Hereford cross steers, averag e weight 470 kg, were assigned to 4 groups and fed rations based on ba rley-corn silage for 150 days. The diets offered contained 10% untreat ed 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% t ogether with 10% PSM resulted in an increase (P < 0.01) in dressing pe rcentage 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 suppl ement. A significant reduction occurred in the proportion of oleic aci d (C18:1 cis), but the percentage of palmitic acid (C16:0) was not aff ected; the proportion of stearic acid (C18:0) in subcutaneous fat incr eased with PCS supplementation.