Effect of varying dietary crude protein and metabolizable energy levels on leg abnormalities and performance in broiler chickens

Background: Nutrient restriction is a common strategy to prevent metabolic disorders in fast growing broiler chickens, but limited information available regarding the impact of diets with low protein and energy on leg abnormalities. Objective: Two experiments were conducted evaluate effect varying crude (CP) metabolizable (ME) levels gastrocnemius tendon (GTeBS) tibia breaking strength (TiBS), gait score (GS) valgus/varus angulation (VAng). Methods: In Experiment 1, eight-d-old Ross 308 broilers (n=90) randomly assigned into three treatments: 13/2,900 (13% CP 2,900 kcal ME kg-1 diet), 17/3,000 (17% 3,000 21/3,025 or control (21% 3,025 diet). 2, six-d-old chickens (n=192) distributed two 16/3,000; 16% diet 21/3,000 control; 21% diet. both data analyzed as one-way ANOVA. Results: treatments had similar (p>0.05) GTeBS (202 224 N, respectively), TiBS (338 332 respectively). Birds treatment showed higher GS (lower walking ability; 80% birds >3), greater VAng (53% >2) than (0% >3 0% >2). 16/3,000 VAng, treatment. However, lower (-26%) (p<0.05). Conclusions: Feeding did not affect strength, angulation. A containing less 2,900-3,000 reduces strength.