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Nitrate‐nitrite toxicity in cattle and sheep grazing Dactyloctenium radulans (button grass) in stockyards
Author(s) -
McKENZIE RA,
RAYNER AC,
THOMPSON GK,
PIDGEON GF,
BURREN BR
Publication year - 2004
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/j.1751-0813.2004.tb12612.x
Subject(s) - nitrate , nitrite , grazing , dry matter , agronomy , toxicity , zoology , potassium nitrate , feces , chemistry , biology , potassium , ecology , organic chemistry
Hungry cattle and sheep introduced to stockyards containing a dominant or pure growth of Dactyloctenium radulans (button grass) suffered acute nitrate‐nitrite toxicity in four incidents in inland Queensland between 1993 and 2001. Deaths ranged from 16 to 44%. Methaemoglobinaemia was noted at necropsies in all incidents. An aqueous humour sample from one dead steer contained 75 mg nitrate/L and from one dead sheep contained 100 mg nitrate and 50 mg nitrite/L (normal = ca 5 mg nitrate/L). Both lush and dry button grass were toxic. The nitrate content of button grass from within the stockyards ranged from 4.0 to 12.9% as potassium nitrate equivalent in dry matter and from outside the stockyards ranged from <0.2 to 0.4%. These data suggest that urine and faeces in stockyard soil may boost the nitrate content of button grass to a concentration hazardous to hungry ruminants.