Effect of L-arginine supplementation on Salmonella organ invasion in neonatal chicks.

摘要

L-arginine (L-ARG) is the precursor to nitric oxide (NO) synthesis and NO has been shown to exhibit bactericidal properties. The effect of oral gavage with various doses of L-ARG was evaluated to determine the effect on Salmonella enteritidis (SE) organ invasion in one-day-old chicks. Chicks were administered either 12.5, 25.0, 50.0, or 100.0 mg L-ARG followed by challenge with SE eight h later. Treatment with either 50.0 or 100.0 mg led to significant reductions in SE organ invasion in three experiments. In a subsequent experiment, SE was incubated in the presence of L-ARG at 37 C for four h to determine any direct effects on viability. Results indicated no adverse effect on viability when compared to controls incubated in water. D-arginine (D-ARG) administration was then compared to L-ARG administration at a dose of 100.0 mg. In three experiments, both L-ARG and D-ARG resulted in significant reductions in SE organ invasion. D-ARG was approximately half as efficacious at reducing invasion relative to L-ARG. The reduction in SE organ invasion was associated with a significant increase in serum concentration of nitrate (NO₃) and nitrite (NO₂) following treatment with L-ARG or D-ARG. In three experiments, the protective effect of L-ARG was blocked by administration of nitro-L-arginine methyl ester (L-NAME) at a dose two-fold higher than that of L-ARG. Additionally, the significant increase in NO₃/NO₂ serum concentrations was blocked by L-NAME treatment. Administration of either 50.0 or 75.0 mg L-ARG led to significant reductions in Salmonella gallinarum (SG) organ invasion in one-day-old broiler chicks. Treatment with 50.0 mg L-ARG led to a significant reduction in SG related mortality over a ten day period post challenge. The results indicated that L-ARG administration significantly decreases the ability of SE and SG to invade the organs in one-day-old chicks. The mechanism involved remains to be elucidated but may involve increased synthesis of NO since D-ARG did not provide equal protection and protection was blocked by L-NAME. The results indicated that L-ARG may hold potential as an alternative to feeding of antibiotics for the control of these and other potential enteric pathogens of commercial poultry.