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Threonine requirement of broiler chickens during subclinical intestinal Clostridium infection

Star, L., Rovers, M., Corrent, E., van der Klis, J. D.
Poultry science 2012 v.91 no.3 pp. 643-652
Clostridium intestinale, Clostridium perfringens, Eimeria maxima, amino acid requirements, bacterial infections, broiler chickens, coccidiosis, diet, digestive system diseases, dose response, feed intake, liveweight gain, mortality, threonine
The aim of this study was to determine the threonine requirement of broilers during a subclinical Clostridium infection. Three experiments were performed: experiments 1 and 2 to investigate the dose-response of threonine supplementation during infection and experiment 3 to validate the threonine requirement during infection. In each experiment, 1-d-old Ross 308 male broilers were used. An infection model was used with inoculation of Eimeria maxima and Clostridium perfringens at d 9 and 14 of age, respectively. Control birds were inoculated with saline and liver broth at d 9 and 14 of age, respectively. From d 9 of age, infected birds were fed diets differing in the standardized digestible threonine-to-lysine ratio (realized ratios experiment 1: 0.55, 0.58, 0.63, 0.69, and 0.72; realized ratios experiment 2: 0.64, 0.65, 0.67, 0.69, and 0.72; and realized ratios experiment 3: 0.63 and 0.67). Uninfected birds were fed diets with a realized Thr:Lys ratio of 0.63 in experiments 1 and 2 and of 0.63 or 0.67 in experiment 3. The incidence of lesions, lesion severity, and mortality rate of infected birds was not affected by the Thr:Lys ratio. Experiments 1 and 2 showed that the decrease in BW gain and feed intake was less severe in infected birds fed a diet with a Thr:Lys ratio of 0.69 and 0.67, respectively (not significant). Validation of the Thr:Lys ratio in experiment 3 showed that the BW gain and feed intake were higher for infected birds with a Thr:Lys ratio of 0.67 compared with infected birds with a Thr:Lys ratio of 0.63. This resulted in an increased BW gain and feed intake of 129 and 148 g, respectively, with a higher Thr:Lys ratio over a production period of 37 d. This indicates that a higher Thr:Lys ratio in infected birds improved production performance during infection with C. perfringens, although intestinal damage (incidence and lesion severity) was not affected.