Environmental Factors Associated with Nitrate Poisoning in Livestock in Botswana

Abstract

Some cases of sudden deaths in cattle, sheep and goats reported to the National Veterinary Laboratory, Gaborone were investigated. The clinical signs included: stupor, weakness, staggering, trembling, dyspnoea (difficulty in breathing), salivation, diarrhoea, and convulsions for those in extremis. The most consistent sign was the muddy coloured mucous membranes. Necropsy findings included: marked gastroenteritis and generalized congestion and petichiation in all internal body organs and chocolate brown coloured blood that clotted poorly. The presence of nitrate/nitrite in the blood of live animals, amniotic fluid, urine, ocular fluid, urine, drinking water and consumed forage were demonstrated by the diphenylamine test and subsequently confirmed by Gries test. Further confirmation of nitrate/ nitrite poisoning was by response to therapeutic intervention with methylene blue using the intravenous route of inoculation.Environmental factors that may have contributed to the poisoning episodes included, drought, high ambient temperatures, low cloud cover, soil leaching after flooding, soil moisture content and forage nitrogen content and natural geoformations associated with high nitrate content in the water. This is the first account of confirmed cases of nitrate/ nitrite poisoning in livestock in Botswana.

Silage review: Animal and human health risks from silage

“…However, in situations of high NO 3 − intake, NO 2 − can accumulate in the rumen and be absorbed into blood, where it reacts with hemoglobin to produce methemo-globin, which cannot carry oxygen from lungs to tissues. Methemoglobinemia is the term used to describe the condition, which can present in a range of severities including reduced feed intake, abortion, respiratory distress, coma, and even sudden death (Bolan and Kemp, 2003;Binta and Mushi, 2012;Lee and Beauchemin, 2014;Rasby et al, 2014). Stored forages with NO 3 − concentrations in excess of 1,700 mg of NO 3 − -N/kg of DM may cause acute toxicity and should be given to livestock in a ration balanced with other feeds (Adams et al, 2016) to dilute the toxicity.…”

A Vulnerability Assessment in Scant Data Context: The Case of North Horr Sub-County

“…This work evaluates the vulnerability of nitrate (NO 3 − ) contamination in open shallow water sources for human and livestock consumption in a scant data context. Understanding the vulnerability to nitrate contamination is pivotal since the consumption of contaminated water can have severe outcomes in humans, such as methemoglobinemia, hypertension, increased infant mortality, central nervous system birth defects, diabetes, spontaneous abortions, respiratory tract infections and changes to the immune system [15][16][17][18][19], as well as methemoglobinemia, spontaneous abortion and even death in livestock [20][21][22]. River and groundwater contamination is generally caused by chemical fertilizer, manure and nitrogenous waste products, all containing nitrogen, used for both agricultural and industrial purposes [23].…”