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Evaluating plasma methionine in response to feeding three rumen-protected methionine products.

M. S. Smith

Evaluating plasma methionine in response to feeding three rumen-protected methionine products.
M. S. Smith*1, S. K. Cronin1, J. Mateos2, D. Martinez del Olmo2, F. Valdez3, T. F. Gressley1. 1University of Delaware, Department of Animal and Food Sciences Newark, DE, 2Kemin Animal Nutrition and Health, Herentals, Belgium Herentals, Belgium, 3Kemin Industries Inc DesMoines, IA.

Rumen protected amino acids offer the opportunity for precise feeding of limiting amino acids to ruminants. Plasma methionine (Met) is a strong indicator of bioavailability of rumen protected Met products and is directly influenced by intestinal absorption of Met. This study examined the comparability of a new rumen protected Met product, KESSENT M, to 2 currently marketed products. Ten multiparous Holstein cows, 280 ± 73 DIM, were used in a replicated 3x3 Latin square design, with 7 d experimental periods. Treatments consisted of a control diet plus 12 g/d of either KESSENT M (Kemin Animal Nutrition and Health, Herentals, Belgium), Smartamine M (Adisseo Inc., Antony, France), or Mepron (Evonik Nutrition & Care GmbH, Hanau-Wolfgang, Germany). Cows were fed ad libitum with 33% of their daily feed allotment provided every 8 h. Milking occurred at 4:30 a.m. and 3:30 p.m. daily with milk samples collected on d 5—7 of each period. During d 5—7 of each experimental period, blood samples were collected from jugular catheters at 2, 4, 6, and 8 h after the morning feeding. At the end of the experiment, samples were sent to Missouri Agriculture Experiment Station Chemical Laboratories for amino acid analysis by cation-exchange chromatography with an amino acid analyzer. There was no significant effect of treatment on DMI or production parameters. Plasma Met as a % of total amino acids minus Met was 1.5085, 1.5267, and 1.3622% for KESSENT M, Smartamine M, and Mepron, respectively. KESSENT M and Smartamine M were not found to be significantly different (P = 0.3420), however KESSENT M and Mepron were significantly different (P < 0.0001), with KESSENT M yielding greater plasma Met Levels. There was a significant effect of time of sampling on plasma Met as a percentage of amino acids minus Met (P = 0.002), due to higher Met at 2 h (1.508%) than 4, 6, and 8 h (1.439, 1.447, and 1.469% respectively). Similarities in plasma Met levels between KESSENT M and Smartamine M treatments would suggest comparative bioavailabilities and bioavailability greater than that of Mepron.

Keywords: rumen-protected methionine, dairy cow.