The use of prilled fat to coat and protect amino acids from ruminal degradation

A series of trials was conducted to determine the effectiveness and limitations associated with the use of partially hydrogenated triglycerides as a protective coating to enhance amino acid escape from the rumen. Commercially prepared prills and laboratory‐synthesized prills containing either lysine or methionine were incubated from 0–24 h in situ, in a fistula Ted cow fed hay and grain (1:1, w/w DM). Multiple factors were found to affect the ability of fat to protect amino acids. Examination of prill size where prills were separated by sieves into sizes ranging from 703 μm to 2.5 mm indicated that, overall, larger prills provided greater protection than smaller prills. Differences in protection exist between amino acid source, as methionine recovery was consistently greater than lysine. Reduction of lysine particle size improved its protection, but was still not protected as well as methionine. Prills with iodine values (IV) of < 1, 17 and 40 were also examined. Differences in protection between IV levels was not great, however, IV < 1 and 17 provided greater protection than IV 40. Utilizing results from the various trials, maximal protection level was achieved (approximately 90%) for methionine in prills made from IV 17 which ranged in size from 2 to 2.5 mm.