Microbial phytase improves performance and bone traits in broilers fed diets based on soybean meal and containing lupin meal

A completely randomised design study with a 3 x 2 factorial arrangement was conducted. A total of 480 male broiler chickens were used to determine the influence of phytase addition, plant protein source [soybean meal, soybean meal + 200 g/kg of blue lupin meal (Lupinus angustifolius L.) or soybean meal + 200 g/kg yellow lupin meal (Lupinus luteus L.)] on performance of broiler chickens, ileal calcium (Ca), phosphorus (P) and protein digestibility, tibia bone characteristics and nitrogen-corrected apparent metabolisable energy. All diets were deficient in Ca, available P as well as lysine and total sulfur amino acids. Birds fed different protein sources were characterised by similar bodyweight gain and feed intake during the whole trial but feed conversion ratio was higher when birds were fed supplemented with yellow lupin meal (P < 0.05). Phytase improved bodyweight gain and feed conversion ratio regardless of protein source (P < 0.05). Diets supplemented with 200 g/kg blue or yellow lupin meal were found to be lower in nitrogen-corrected apparent metabolisable energy than soybean meal diets (P < 0.05). Birds fed diets supplemented with phytase were characterised by higher utilisation of Ca and P than birds whose feed was not supplemented with phytase (P < 0.05). Tibia bone ash as well as Ca content was similar across protein sources (P > 0.05), whereas tibia P content was lower when soybean meal or blue lupin meal was used (P < 0.05). Birds fed diets supplemented with blue lupin meal were characterised by the highest tibia P content (P < 0.05). Birds fed phytase-supplemented diets were characterised by higher tibia Ca and P content irrespective of protein source.