Development of a method for measuring lysine and methionine bioavailability in rumen-protected product for cattle
2003
Rulquin, H. (Institut National de la Recherche Agronomique, Saint-Gilles (France). Unite Mixte de Recherches Production du Lait) | Kowalczyk, J. (Polish Academy of Sciences, Jablonna (Poland). Kielanowski Institute of Animal Physiology and Nutrition)
The objective of the experiment was to find a quantitative test to determine the lysine or methionine bioavailability of rumen-protected amino acids. For these purposes was elaborated a blood test including an in vivo calibration phase and this test was used on two commercial products whose bioavailability is known. Three ruminally and duedenally fistulated low-yielding Holstein cows were used. The calibration phase consisted of relating blood plasma methionine and lysine concentrations to duodenal infusion of graded amounts of methionine and lysine. The blood plasma responses of methionine and lysine to graded amounts infused duodenally were linear. The methionine response was the same for all cows, but the lysine response varied with the cows. The proposed blood test is valuable for the determination of the bioavailability estimation, but not lysine, of rumen-protected products
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