03550naa a2200325 a 450000100080000000500110000800800410001902200140006002400360007410000150011024501680012526000090029350005760030252019620087865300170284065300260285765300560288365300120293970000180295170000210296970000200299070000160301070000170302670000160304370000160305970000160307570000160309170000200310777300970312710642572023-07-19       2023    bl uuuu     u00u1 u    #d  a1090-02337 a10.1016/j.tvjl.2023.1060132DOI1 aSCHILD, C.  aResponse of cows with osteomalacia grazing sub-tropical native pastures to phosphorus supplementation with loose mineral mix or feed blocks.h[electronic resource]  c2023  aArticle history: Accepted 20 June 2023; Available online 22 June 2023. -- Correspondence author: Riet-Correa, F.; Programa de pós-graduação em Ciência Animal nos Trópicos, Escola de Medicina Veterinária e Zootecnia, Universidade Federal da Bahia, Salvador, Brazil; email:franklinrietcorrea@gmail.com  -- FUNDING: This work was supported by Agencia Nacional de Investigación e Innovación . [grant FMV_1_2017_1_136347 ]. A postgraduate scholarship was provided to Carlos Schild by INIA and the Comisión Académica de Posgrado de la Universidad de la República. --  aOsteomalacia outbreaks often occur in cattle grazing native pastures in regions with endemic phosphorous (P) deficiency. This study evaluated the responses of two groups of cows, initially with clinical signs of chronic P deficiency, to P supplements (100 g P/kg) offered ad libitum for 13 weeks as a loose mineral mix (LMM group) or the same mineral mix offered as blocks (BMM group). Half of the cows in each group were categorized as ?with? or ?without? severe osteopenia according to a test that depended on the resistance to penetration of a needle through the left lateral process of the L4-L5 lumbar vertebra. The groups grazed two paddocks that were switched each 3 weeks. The liveweight, supplement intakes, and the P-concentrations in soil, forage, blood, and external cortical bone (ECB) of the ribs were measured. The bicarbonate-extractable P in soil was 3.5 mg/kg. The mean of total P in forage (0.95 g/kg/DM), inorganic P in serum (iP, 0.96 mmol/L), and total P in the ECB of the ribs (85 mg/mL) at the beginning of the experiment were all low and consistent with severe chronic P deficiency. The P supplementation allowed clinical recovery in 18/20 cows with their serum and ECB P and calcium approaching normal values and in the two remaining cows the only sign was abnormal gait. Cows consumed more of the LMM than BMM supplement (means 8.3 and 6.6 g P/day, respectively). After 13 weeks cows initially classified as ?with severe osteopenia? and supplemented with LMM had higher (P < 0.05) final liveweight (difference = 21.6 kg), iP (difference = 0.74 mmol/L), bone Ca (difference = 65.7 mg/mL) and bone P (difference = 26.5 mg/mL) concentrations and lower (P < 0.01) final serum Ca/iP ratio (difference = -0.65) than cows with severe osteopenia but supplemented with BMM. The treatment of severe P deficiency cows grazing P deficient sub-tropical grasslands by P supplementation for 13 weeks was more effective with LMM than BMM. © 2023  aOsteomalacia  aPhosphorus deficiency  aPLATAFORMA DE INVESTIGACIÓN EN SALUD ANIMAL - INIA  aUruguay1 aBOABAID, F.M.1 aOLIVEIRA, L.G.S.1 aARMENDANO, J.I.1 aSARAVIA, A.1 aCUSTODIO, A.1 aALGORTA, J.1 aALVAREZ, C.1 aJAURENA, M.1 aDIXON, R.M.1 aRIET-CORREA, F.  tVeterinary Journal. 2023, Volume 298-299, 106013. https://doi.org/10.1016/j.tvjl.2023.106013