Dietary protein content and ventilation rate affects litter quality, pododermatitis and water/feed ratio in broilers

Two identical experimental houses, each divided in two units allowing separate ventilation schedules were used. A ventilation scheme with a setpoint at 1.0 m³/hour/kg live weight was compared with 1.7 m³/hour/kg live weight. Each of the units was subdivided in four large pens with 1,500 broilers. From day 10 off, half of the pens were phase fed with diets containing a commercially used crude protein (C-CP) content (21.0%, 20.5% and 20.0%, respectively during the 3 consecutive phases) while the other pens received a diet with a 7%; 10% and 13% reduced protein content (R-CP), respectively. Apart from the protein content, the two diets were formulated to have the same energy and nutrient content. The trial was repeated during three consecutive batches with each time 24,000 one-day-old Ross 308 chicks. The C-CP diet resulted in significant (P<0.01) higher pododermatitis, hockburn and breast soiling scores. Slaughter weight (on average 2,345 g at 36 days) did not differ significantly but a significant worse feed conversion ratio was obtained with the R-CP diet. Water/feed ratio was 1.84 (C-CP) and 1.74 (R-CP) (P<0.01). No influence of the ventilation curve was found during the summer batch but in winter time the higher ventilation schedule resulted in a heavier (3.4%; P<0.05) slaughter weight, less pododermatitis and better litter quality. However, effects of dietary protein content or ventilation rate on gut health (dysbacteriosis) were not pronounced.