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Can ε-polylysine provide metabolizable lysine to cattle?

E. A. Petzel



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Can ε-polylysine provide metabolizable lysine to cattle?
E. A. Petzel*, S. Acharya, E. A. Bailey, D. W. Brake. Division of Animal Sciences, University of Missouri Columbia, MO.

Metabolizable Lys can limit growth or lactation in cattle fed corn-based diets. Addition of crystalline Lys to diets does not provide large increases in metabolizable Lys because it is ruminally fermented, and efforts to increase metabolizable Lys with lipid coatings seem to provide only slight increases in metabolizable Lys flows to cattle. ε-Polylysine (εPL) is a peptide comprised of Lys residues with antimicrobial activity and is commonly used to preserve foods and cosmetics. Thus, εPL may be an effective ingredient to increase metabolizable Lys in diets fed to cattle. Our objective in this experiment was to determine if εPL was able to provide metabolizable Lys to cattle. We used 6 Holstein bull calves (initial BW = 52 � 2.2 kg) to evaluate the bioavailability of εPL compared with Lys-HCl. Each calf was provided 0, 4.8, or 9.6 g of Lys by addition of Lys-HCl or εPL to a milk replacer (403.11 � 0.58 g DM / d) formulated to meet or exceed the ME and metabolizable Lys requirements of a 68 kg calf gaining 0.45 kg daily. Each calf was provided each combination of treatments in a manner balanced for carryover effect. Calves were adapted to treatments for 6 d and samples of jugular blood were collected each 4 h on d 7 to determine AA bioavailability. Data were analyzed using the MIXED procedure of SAS and differences in Lys bioavailability were determined from the ratio of the slopes between Lys-HCl and εPL. Plasma Lys concentrations increased linearly in response to greater Lys intake from Lys-HCl (slope = 13.51 �M/g Lys, P < 0.01), but plasma Lys concentrations did not respond to increased intake from εPL (P = 0.29). Nonetheless, increases in plasma Lys in response to greater εPL intake resulted in a 15% numerical increase in Lys bioavailability from εPL. Plasma concentrations of Thr, Met, Glu, and Gln decreased (P ≤ 0.03) with increased εPL intake while concentrations of His, Val, Leu and Ile increased (P ≤ 0.01) with increased εPL intake. Apparently, εPL is not a good source of metabolizable Lys to calves. Concentrations of other AA were affected by εPL; perhaps as a result of altered luminal transport of AA in response to the strong cationic characteristics of εPL.

Keywords: cattle, lysine.