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Hypovitaminosis A in extensively grazed beef cattle
Author(s) -
Parker EM,
Gardiner CP,
Kessell AE,
Parker AJ
Publication year - 2017
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/avj.12560
Subject(s) - vitamin , zoology , herd , dry matter , outbreak , vitamin a deficiency , beef cattle , veterinary medicine , retinol , biology , medicine , virology
Case report Vitamin A deficiency was diagnosed in a herd of 97 19‐month‐old Braford heifers in the Mitchell Grass Downs (Astrebla spp.) bioregion of Hughenden in north‐western Queensland during November 2015. Two heifers died after a 48‐h history of sternal recumbency and of the 19 that had neurological signs, 7 were blind. Histological changes in the optic nerves of the two necropsied cattle were consistent with vitamin A deficiency. This diagnosis was supported by vitamin A concentrations in fresh liver samples of 5 and 6 mg/kg wet tissue (reference range, 100–175 mg/kg) despite treatment of the cattle with twice the recommended dose of parenteral vitamin A 3 weeks prior to sampling. Rainfall on the property during the 2 years before the outbreak was less than the annual rainfall average of 464 mm, with a total of 281 mm in 2014 and 117 mm from January to November in 2015, most of this falling in January. Conclusion Plant assays for both β‐carotene and crude protein concentrations in dry matter ( DM ) were less than the recommended dietary requirements for beef cattle (0.30 mg/kg DM and 56 g/kg, respectively).