Rumen-Protected Methionine Fed to Dairy Cows: Bioavailability and Effects on Plasma Amino Acid Pattern and Plasma Metabolite and Insulin Concentrations

Abstract

An experiment was performed to compare the bioavailability of D,L-methionine (Met) of two rumen (polymer and fat)-protected Met forms (Smartamine; Rhône-Poulenc, Animal Nutrition, Antony, France and Mepron; Degussa AG, Hanau, Germany, respectively) fed once daily (at 0730 h) in amounts of 50 g per cow for 5 d. Six dairy cows were used in the crossover design. Blood samples were obtained from jugular veins 3 d before and 5 d after the start of Met supplementation at 1000, 1400, and 1800 h, and the three blood samples were pooled for analyses. Smartamine M feeding caused elevations of sulfur-containing amino acids (Met, Cys, and taurine) and reductions of Val and Ile and the total of branched-chain amino acids (Val + Leu + Ile). Mepron M85 feeding caused only a rise of Met concentrations. Concentrations of Met, taurine, and Gln were higher when Smartamine M than when Mepron M85 was fed. Concentrations of nonesterified fatty acids were reduced, and those of insulin were increased only by Mepron M85 feeding. Milk urea concentrations were lower in cows fed Mepron M85 than in controls, but milk yields; concentrations of fat, protein, and lactose; and somatic cell counts did not significantly change during the experiment and were not different between groups. Food intake, body weight, and body condition scores were not affected. In conclusion, only Mepron M85 supplementation influenced nonesterified fatty acids and insulin concentrations. However, the bioavailability of Met from Smartamine M was greater than of Mepron M85 and effects on other plasma-free amino acids were more marked. Whether less Met in the form of Smartamine M as Mepron M is needed to have the same effects on milk yield and composition needs to be investigated with doses used in practice.

Effect of rumen-protected methionine, lysine or both on milk production and plasma amino acids of high-yielding dairy cows

“…This is in agreement with findings of other studies that also described an elevated plasma concentration of AA when they were supplied in a RP form (e.g. Blum et al, 1999;Kröber et al, 2001) but not in all instances (e.g. Xu et al, 1998).…”

“…This is in accordance with the other studies (e.g. Blum et al, 1999;Weekes et al, 2006). As expected, plasma Met concentrations were increased (P < 0.05) in the M and ML group.…”

“…In the present experiment, in M none of the other AA in plasma except Met and Lys was affected by the treatment. The same findings were reported by Rogers et al (1987) or Blum et al (1999). In L, no effect of RP Lys on the concentrations of other AA was observed.…”

“…Schwab et al, 1992). In contrast, Blum et al (1999) or Robinson et al (1999) did not find any effect of RP Met and Lys supplementation on the intake of dry matter and its components. a,b means in the same row followed by different superscripts differ (P < 0.05) 1 treatments were as follows: C -control; L -control + supplemental Lys (11.7 g/day); M -control + supplemental Met (18.2 g/day); ML -control + supplemental Met and Lys (18.2 and 11.7 g/day, respectively) 2 Lys determined as LysHCl…”

“…This is in agreement with the study of Donkin et al (1989), who reported that the addition of RP Met + RP Lys did not alter milk production or 4% FCM yield. Similarly, Blum et al (1999) or Kröber et al (2001) found only minor effects of additional Met on milk yield. This contradicts findings of an elevated milk yield with supplementary Met (e.g.…”