Effects of Conjugated Linoleic Acid on Finishing Holstein Beef
-Lance Baumgard, Glenn Duff, Ron Allen and Darrel Goll
Department of Animal Sciences, The University of Arizona
One hundred forty four Holstein feeder cattle were housed at the University of Arizona and grouped into 18 pens (6 animals/pen). Approximately 150 days prior to expected slaughter, treatments were initiated. Four pens were utilized as positive controls (no calcium salts), 4 pens served as negative controls (calcium salts of palm oil), 4 pens received 7 ounce conjugated linoleic acid (CLA, tallow)/head/day (calcium salts, Bioproducts Inc. Fairlawn OH) and 4 pens received 14 oz. CLA/hd/d. All animals were weighed every 28 d until harvested. All animals were harvested at Sun Land Beef Co at similar body weights (1318 lb).
Two days after slaughter carcass measurements were obtained and fat tissues collected from different areas. Animals fed the calcium salts ate less feed per day, gained less weight and were on feed longer compared to tallow fed steers. At harvest, hot carcass weight, loin eye area, and marbling score did not differ (P > 0.09) among treatments. However, 12th rib fat (P < 0.001), yield grade (P < 0.001), and kidney, pelvic and heart fat (KPH) (P < 0.001) were increased for tallow vs. calcium salts. In addition, 12th rib fat (P < 0.001), yield grade (P < 0.001), and KPH (P < 0.001) were decreased for CLA treatments vs. controls.
The 2 CLA treatments increased the content of both cis-9, trans-11 CLA, trans-10, cis-12 CLA and unidentifiable CLA isomers in heart, liver, muscle, abdominal, intramuscular, and subcutaneous lipids (fats). The highest CLA treatment increased the content of total CLA isomers by 4.7, 5.4, 4.0, 4.8, 4.9 and 2.8 fold for heart, liver, muscle, abdominal, intramuscular and subcutaneous lipids, respectively.
The CLA group (trt 4) also had increased C18:1 trans isomers, in all tissues, suggesting some of the CLA was partially metabolized in the rumen. Results indicate that CLA can markedly increase the CLA content in edible beef tissues and slightly reduces carcass fat parameters but decreases live performance.