Bioavailability comparison between herbal methionine and DL-methionine on growth performance and immunocompetence basis in broiler chickens

Herbal methionine can be compared relative to Dl-methionine with evaluation of bioavailability of this source of methionine. An experiment was carried out to determine the relative bioefficacy of herbal methionine [H-Met][registered sign] relative to DL-methionine [DL-Met] on performance criteria and immunocompetence of Met sources in male broilers. Atotal of 160 male broilers were fed a Met-deficient basal diet or the basal diet supplemented with three or four concentrations of each Met sources. Multiexponential and multilinear regressions were used to determined bioavailability of herbal methionine [HMet] [registered sign]relative to DL-Met on performance and immunocompetence of broilers. Body weight gain and feed intake of the broilers fed H-Met or DL Met improved in the experiment, regardless of Met sources, relative to those broilers that were fed the basal diet. Immunocompetence of broilers were not significant at 28 day of age [p>0.05], whereas the broilers were significantly affected by the additional levels of Met sources at 42 day of age. The bioefficacy estimates for H-Met[registered sign] relative to DL-Met on a product basis were 55% for weight gain, 71% for feed intake, 78% for feed conversion ratio, 70% for dilution 1-choloro 2- 3-dinitrobenzene [DNCB], 67% for sheep red blood cell [SRBC], and 68% for phytohemagglutinine [PHA-P]. The relative effectiveness of H-Met[registered sign] compared to that of DL-Met is 68% on average across performance criteria and all immune criteria tested. H-Met[registered sign]can be supplemented as a new and natural source of Met for the poultry industry

Effect of Walker 256 tumor growth on intestinal absorption of leucine, methionine and glucose in newly weaned and mature rats

In tumor-bearing rats, most of the serum amino acids are used for synthesis and oxidation processes by the neoplastic tissue. In the present study, the effect of Walker 256 carcinoma growth on the intestinal absorption of leucine, methionine and glucose was investigated in newly weaned and mature rats. Food intake and carcass weight were decreased in newly weaned (NT) and mature (MT) rats bearing Walker 256 tumor in comparison with control animals (NC and MC). The tumor/carcass weight ratio was higher in NT than in MT rats, whereas nitrogen balance was significantly decreased in both as compared to control animals. Glucose absorption was significantly reduced in MT rats (MT = 47.3 ñ 4.9 vs MC = 99.8 ñ 5.3 nmol min-1 cm-1, Kruskal-Wallis test, P<0.05) but this fact did not hamper the evolution of cancer. There was a significant increase in methionine absorption in both groups (NT = 4.2 ñ 0.3 and MT = 2.0 ñ 0.1 vs NC = 3.7 ñ 0.1 and MC = 1.2 ñ 0.2 nmol min-1 cm-1, Kruskal-Wallis test, P<0.05), whereas leucine absorption was increased only in young tumor-bearing rats (NT = 8.6 ñ 0.2 vs NC = 7.7 ñ 0.4 nmol min-1 cm-1, Kruskal-Wallis test, P<0.05), suggesting that these metabolites are being used for synthesis and oxidation processes by the neoplastic cells, which might ensure their rapid proliferation especially in NT rats.

Characterisation of the routes of methionine transport in mouse mammary glands.

The sites of methionine uptake by mammary glands from late pregnant and lactating mice were studied in vitro. Using the specific A system inhibitor, N-(methylamino) isobutyric acid (MeAIB) and the specific L system inhibitor, 2-amino-bicyclo (2.2.1) heptane 2-carboxylic acid (BCH), we have defined four modes of methionine entry into these tissues. (i) A sodium-dependent A system with a Vmax of 13.4 and 18.8 n mol/g cells/min in pregnant and lactating mice, respectively. This mode of entry was completely inhibited by MeAIB and its Km value was similar (0.45 mM) in both groups. (ii) A sodium-dependent mode with a Vmax of 6.7 and 12.4 n mol/g cells/min and a Km of 0.24 and 0.46 mM in pregnant and lactating mice, respectively. This mode of entry was insensitive to inhibition by MeAIB, and was similar to the ASC (alanine, serine, cysteine) system in other tissues. (iii) A sodium-independent L system with a Vmax of 13.8 and 30.0 n mol/g cells/min and a Km of 0.27 and 0.46 mM in pregnant and lactating mice, respectively. This mode of entry was completely inhibited by BCH. (iv) A sodium-independent non-specific entry amounting to 25 per cent of the total entry at 0.1 mM external methionine which was not inhibited by high concentration of BCH. The results of our studies show an increase in the number of active carriers of the A, ASC and L systems of methionine uptake in mammary glands of mouse during lactation.