Surto de intexicação espontânea por cianeto em bovinos leiteiros alimentados com tifton 68 (Cynodon Nlemfuensis Vanderyst) no estado da Paraiba

Abstract

Tifton 68 (Cynodon nlemfuensis Vanderyst) is a forage of high nutritional value adapted to the conditions of the Brazilian Northeast. However, its potential to accumulate cyanogenic glycosides represents a significant risk, which can lead to hydrocyanic acid (HCN) poisoning. This compound blocks cellular respiration, resulting in tissue anoxia and an acute clinical picture with neurological signs and death. The objective of this study is to report an outbreak of Tifton 68 poisoning in dairy cattle in Paraíba, describing its epidemiological, clinical, and pathological aspects. The case occurred in the municipality of Galante, Paraíba, on a dairy farm with a herd of 32 animals, raised intensively and fed corn silage, capiaçu grass (Pennisetum purpureum Schum), cactus pear (Opuntia stricta (Haw) Haw), soybean and corn meal (at a 1:1 ratio, with 1 kg of meal provided for every 3 kg of milk produced), supplemented with mineral salt and ad libitum access to dam water. The owner contacted a technician at the University Veterinary Hospital of the Federal University of Paraíba (HV-UFPB), reporting tympanism and motor incoordination in two animals, at which point a team was mobilized to provide care at the property. The attended animals were a three-year-old Girolando female, weighing approximately 450 kg, and a five-month-old heifer, weighing 120 kg. During the anamnesis, the owner reported that five days prior, a change had been made to the roughage provided to the animals without a prior adaptation period. Hydroponic corn, at a quantity of 10 kg/animal twice a day, and Tifton 68 grass (C. nlemfuensis Vanderyst), harvested from the property's paddocks, began to be supplied in the trough. The introduction of hydroponic corn was the main change, in addition to the provision of very tender and recently fertilized Tifton grass. The clinical findings identified in the heifer were permanent recumbency, tympanism, 12% dehydration, hypothermia, bradypnea, bradycardia, pollakiuria, and sialorrhea. The cow was standing, with 8% dehydration, sialorrhea, a capricious appetite, bradycardia, and ruminal hypomotility. Dysmetria and muscle tremors were also identified. A therapeutic protocol of rehydration and anti-inflammatory drugs was established to stabilize the clinical condition, but the animals died the following day, along with a third young animal. The owner, suspecting that the ingestion of hydroponic corn was the cause of the deaths, suspended its supply, keeping only Tifton grass as the roughage. However, five other animals presented similar symptomatology and were referred to the HV-UFPB. One animal, which showed generalized and intense muscle tremors and permanent recumbency, did not survive and also died, being sent for necropsy. In the histological study, pseudolaminar cortical necrosis compatible with hydrocyanic acid poisoning was identified. The picrosodic paper test confirmed the plant's toxicity. It is concluded that the lack of knowledge regarding the toxicity of Tifton 68 is a primary cause of sudden death in herds, making the dissemination of this case an essential tool to raise awareness among producers, veterinarians, and agricultural science students about the risks associated with this forage.