Hernandez, F., Megias, M. D., Orengo, J., Martinez, S., Lopez, M. J. and Madrid, J. (2013) “Effect of dietary protein level on retention of nutrients, growth performance, litter composition and NH3 emission using a multi-phase feeding programme in broilers”, Spanish Journal of Agricultural Research, 11(3), pp. 736-746. doi: 10.5424/sjar/2013113-3597.