Animal Feed Science and Technology 123–124 (2005) 703–715 Bioavailability of organic manganese sources in broilers fed high dietary calcium S.F. Li 1 , X.G. Luo ∗ , L. Lu, T.D. Crenshaw 2 , Y.Q. Bu, B. Liu, X. Kuang, G.Z. Shao, S.X. Yu Mineral Nutrition Research Division, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), No. 2 Yuanmingyuan West Road, Haidian, Beijing 100094, PR China Received 24 November 2004; received in revised form 20 February 2005; accepted 13 April 2005 Abstract A total of 624-day-old Arbor Acres male broilers were used to investigate the relative bioavail- abilities of supplemental organic manganese sources for broilers fed high calcium diets. The broilers were randomly allotted to six replicate cages (eight chicks per cage) for each of 13 treatments in a completely randomized design involving a 4×3 factorial arrangement of treatments (four sources of Mn×three levels of added Mn, plus the control with no added Mn). Dietary treatments included the high calcium basal diet (the Control, containing 18.5 g Ca/kg and 20 mg Mn/kg) and the basal diet supplemented with 60, 120, or 180 mg Mn/kg as Mn sulphate (MnSO 4 ·H 2 O) or Mn methionine E (Mn Met E) with weak chelation strength [formation quotient (Q f ) = 3.2, containing 82.7 g Mn/kg], Mn amino acid B (Mn AA B) with moderate chelation strength (Q f = 45.3, containing 64.8 g Mn/kg), or Mn amino acid C (Mn AA C) with strong chelation strength (Q f = 115.4, containing 78.6 g Mn/kg). Heart manganese-containing superoxide dismutase (MnSOD) mRNA level and heart Mn concentration in- creased as supplemental dietary Mn increased (P<0.001). Heart MnSOD mRNA level (P=0.020) was a more sensitive criterion than heart Mn concentration (P=0.037) for detecting differences among Mn sources. Relative to Mn sulphate (assigned 1), bioavailability of the three organic Mn sources Abbreviations: Mn AA, manganese amino acid; MnSOD, manganese-containing superoxide dismutase; NU, nitrite formation unit; Q f , formation quotient; RT-PCR, reverse transcription polymerase chain reaction ∗ Corresponding author. Tel.: +86 10 62816012; fax: +86 10 62810184. E-mail address: wlysz@263.net (X.G. Luo). 1 Present address: Department of Animal Sciences, Hebei Science and Technology Normal College, Changli 066600, China. 2 Present address: Department of Animal Sciences, University of Wisconsin, Madison, WI 53706-1284, USA. 0377-8401/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.anifeedsci.2005.04.052