Effect of Eimeria acervulina infections on plasma L-arginine

As part of a program to study the pathological effects of coccidia infectio ns on growth, we have examined the relationship of plasma L-arginine (ARG) levels to infective doses of Eimeria acervulina and infection-associated ch anges in weight gain, plasma carotenoids, and plasma NO2- + NO3-. Chickens consuming a Starter ration containing 1.68% ARG were infected with a range of doses of E. acervulina. At 6 d postinoculation (PI), weight gains were s ignificantly reduced by infections with 5 x 10(5) and 1 x 10(6) oocysts per chick (OPC). Gross lesion-scores of chickens infected with 5 x 10(4) throu gh 1 x 10(6) OPC were significantly greater than scores of chicks infected, with 1 x 10(3) OPC. Compared with levels from uninfected controls, plasma NO2- + NO3- concentrations were significantly increased by infection with 5 x 10(5) and 1 x 10(6) OPC, plasma concentrations of ARG were significantly decreased by infection with 5 x 10(4) through 1 x 10(6) OPC, and plasma ca rotenoids were significantly decreased by all infection doses. Plasma argin ine was significantly correlated with plasma carotenoids (P > 0.0187), but not with infection dose or weight gain; plasma NO2- + NO3- was positively c orrelated (P > 0.0043) with infection dose and negatively correlated (P > 0 .0158) with weight gain. Regression analysis of the measured variables indi cated that the strongest relationship existed between plasma ARG and carote noids. This finding suggests that in this infection model, reduction in pla sma ARG is most likely associated with nutrient malabsorption that accompan ies infection and is likely not significantly impacted by synthesis of nitr ic oxide that is associated with the immune response.