Research was conducted to evaluate the effect of increasing dietary linoleic acid through corn oil supplementation fed to grazing steers and feedlot steers on beef conjugated linoleic acid (CLA) cis-9, trans-11 isomer content and on animal performance and carcass traits. Sixteen Angus crossed steers grazing ryegrass were supplemented with ground corn (1%BW) without and with corn oil (0.075% BW). Oil supplementation decreased DMI but neither performance nor carcass traits were affected. Corn oil supplementation increased cis 9, trans 11 in the s.c. tissue of steers grazing ryegrass. Twenty commercial steers were finished in drylot fed corn silage without and with corn oil supplementation (7% DMI). The longissimis dorsi (LD) of steers finished in drylot had significantly decreased palmitic (C16:0) and myristic (C14:0) acids. Oil supplementation decreased cis 9, trans 11 and had no effect on trans 10, cis 12 in LD samples. A trend was observed in subcutaneous (s.c.) lipids for increased cis 9, trans 11 and trans 10, cis 12 with corn oil supplementation. Performance of finishing steers fed corn silage or low grain forage sorghum silage with corn oil supplementation was determined along with the effect of diet on the concentration of CLA in beef. Steers supplemented with corn oil had higher concentrations of cis-9 trans-11 in LD and s.c. samples. Steers fed corn silage with oil supplemented diets had higher concentrations of trans-10, cis-12. The effect of supplemental pigeon peas on the performance of lactating dairy cows fed diets based on corn silage was determined along with the concentration of CLA in milk. The cis 9, trans 11 and trans 10, cis 12 isomers in rumen fluid exhibited a time by treatment interaction. The highest peak of fatty acids occurred 2 hours prior to feeding and then again 4-6 hours post feeding. The two main CLA isomers (c9, t1l and t10, c12) were not significantly different among treatments in milk samples (P < 0.77). The isomer c9t11 was numerically higher for cows fed the control diet, and t10c12 was numerically higher for the 10% pigeon pea treatment. Results from the first three studies demonstrate that beef nutraceutical properties could be enhanced by increasing its CLA cis-9, trans-11 isomer content through supplementation of grazing steers, drylot steers or finishing steers on low grain forage sorghum with corn oil. Results from the fourth study demonstrate that pigeon peas may be used as a protein supplement in dairy diets affecting neither milk production, DM intake nor the rumen environment but milk CLA content was not altered.
