Ruminal biohydrogenation of linoleoyl methionine and calcium linoleate in sheep

Four ruminally and duodenally cannulated Hampshire wethers were used in a 4 x 4 Latin square experiment to determine whether linoleoyl methionine and calcium linoleate would increase duodenal flow of unsaturated fatty acids (C18:2 + cis C18:1). All animals received the same basal diet plus a treatment enclosed in gelatin capsules that were placed directly in the rumen. Of the four experimental treatments, one was a control (empty capsules) and three were 5 g of fatty acid equivalent as either free linoleic acid, calcium linoleate, or linoleoyl methionine. Linoleoyl methionine had the lowest ruminal disappearance of C18:2 + cis C18:1. Ruminal loss of unsaturated fatty acids from each supplement exclusive of feed unsaturated fatty acids was 69.8, 92.9, and 94.6% for linoleoyl methionine, free linoleic acid, and calcium linoleate, respectively. Duodenal flow of methionine also was higher for linoleoyl methionine than for control, free linoleic acid, or calcium linoleate (2.5, 1.7, 2.0, and 2.5 g/d, respectively). Plasma linoleic acid was higher for linoleoyl methionine than for control or free linoleic acid but was not different from calcium linoleate (22.0, 17.8, 18.9, and 20.2% of total fatty acids, respectively). Plasma methionine levels were not different among treatments. Intestinal disappearance of unsaturated fatty acids did not differ among treatments. Linoleoyl methionine resisted ruminal biohydrogenation and was digested normally in the intestine. Calcium linoleate did not escape biohydrogenation by ruminal bacteria.