2012 Annual Report 1a.Objectives (from AD-416): Develop feeding strategies to grow yearling cattle to slaughter readiness in the fall on high quality forage diets (hay or silage) with limited amounts of supplemental concentrate (flaxseed), and determine the effects on resulting of omega-3 fatty acids in the beef. 1b.Approach (from AD-416): The USDA-ARS, Northern Great Plains Research Laboratory (NGPRL) will cooperate with North Dakota State University (NDSU) through its Hettinger Research and Extension Center (HREC) to conduct collaborative livestock feeding trials comparing different levels of flaxseed supplementation. Cattle growth rate and feed efficiency will be determined along with the levels of omega-3 fatty acids in the beef. 3.Progress Report: Feedlot pens were modified to facilitate feeding baled hay ad libitum at one end of each pen and silage, ground hay and/or concentrates at the other end of the pen in concrete feed bunks. When they were fed only high quality alfalfa hay and sudangrass silage the bull calves grew slower than expected (average daily gain of 0.58 lbs) from weaning in early November until January 24th. However, their average daily gain improved to 1.92 lbs per day when fed high quality forage plus a small amount of concentrate each day from January 25th until April 5th. Calves were judged to be too small at weaning (average body weight 438 lbs) and at the end of winter (average body weight 618 lbs) to have reasonable potential to finish as yearlings by the end of fall while grazing high quality forage with supplemental flaxseed, so the growing and finishing trial was postponed until 2013 when faster growing calves are expected to be available.