Dietary choline affects field performance and broiler leg deviations

•Growth performance was improved when broiler chickens were fed maize-soy diets with increasing levels of choline chloride.•Broiler chickens receiving the diet without choline chloride supplementation exhibited the greatest varus (5.7%) and rotated tibia (19.3%) scores.•The average of total choline requirement estimates were 2,516 ppm for body weight gain and 2,533 ppm for feed conversion. An experiment was conducted to evaluate responses of broiler chickens fed a corn-soy (soy protein isolate) choline-deficient diet that was gradually supplemented with choline chloride to a content expected to exceed usual choline concentrations. A total of 525 one-day-old slow feathering male chicks were randomly distributed to 5 treatments and 15 replicates of 7 broiler chickens each. Broilers were fed diets having dietary choline supplementations at 0, 700, 1,400, 2,100 and 2,800 ppm from choline chloride, totalizing formulated concentrations at 727, 1,427, 2,127, 2,827 and 3,527 ppm, respectively. The non-supplemented diet had 736 ppm analyzed choline. Growth performance was weekly evaluated until d 21 when leg deviations were evaluated and liver and tibia were collected. Broiler chicken responses were fitted to quadratic polynomial (QP) and quadratic broken-line (QBL) models. Broilers fed the diet without choline supplementation had the lowest BWG and FI, greaterr FCR as well as greater varus and rotated tibia frequency (P < 0.05) compared to broiler chickens fed diets at any supplemental concentration of choline. Estimations of maximum responses for choline requirements from d 1 to 21 using the QP and QBL regressions were of 2,936 and 2,077 ppm for BWG and 2,827 and 1,627 ppm for FCR, respectively. Broiler chickens fed the diet without choline chloride supplementation had the greatest varus (5.7%) and rotated tibia scores (19.3%) (P < 0.01). The average of total choline requirement estimates obtained were 2,516 ppm for BWG and 2,533 ppm for FCR, whereas 2,202 ppm was needed to minimize the locomotor disorders.