Sodium sesquicarbonate toxicity in broiler chickens

A case of feed misformulation resulted in the addition of sodium sesquicarbonate (SSC) into broiler chicken feed. SSC is a buffering agent used in the manufacture of high urea ruminant feeds that were also produced in this feed mill. Within 2 days of receipt of the tainted broiler feed on the farm, chickens were exhibiting polydypsia and wet droppings and had increased levels of mortality. The postmortem lesions were dehydration, fluid-filled intestines, swollen, pale kidneys, and visceral urate deposits. Histopathology of the kidneys revealed dilated tubules with a giant cell response, loss of tubular epithelium, and a few needlelike crystals. The mortality within 4 days of exposure in three severely affected houses reached 17%. An analysis of the feed revealed sodium levels ranging from 2.59% to 4.88%, with chloride levels of 0.24%-0.40%. Ten percent of the ration was thought to be SSC that contains 36% sodium. To determine if the presence of the SSC caused the problems observed, a controlled study was undertaken. One hundred fifty 3-wk-old broilers were evenly distributed into three floor pens. One group was fed a normal grower ration, a second group was fed a ration containing 5% SSC, and a third group received a ration with 10% SSC. Mortality, packed cell volumes (PCV), total serum proteins, and histopathology of the kidneys were determined. The 10% SSC group had a 6% mortality. Dehydration was evident by elevated PCV within 1 day of ingestion of either ration containing SSC. Microscopic lesions in the kidney were more severe in chickens ingesting SSC when compared with control groups.