CHAKWAL: Two weeks ago, Mahar Ehsan, a resident of Matan Kalan village located at Chakwal-Khushab border in Salt Range, was left shocked when he found one of his cows missing as the herd returned home after daylong grazing in the hills. When the following day the villagers stepped into the jungle, they found the cow sitting haplessly as she was not able to stand up. The villagers took the cow home and called veterinary practitioners. But after two days, the cow expired.

“She delivered a calf a month ago,” Ehsan told Dawn. The sudden death of the cow was the result of a mysterious disease which has not been clearly identified yet though vets termed it nitrate toxicity. As many as 20 cows have died so far in the village,” said Mohammad Fiyaz, a progressive farmer from Matan Kalan.

It is not the first outbreak of the disease rather it targeted cattle last year when 70 cows died.

As many as 15 cows died in Lakhwal village while animals in small number have died in Sar Kalan, Rawal Bala, Dhakku, Watli, Dullah, Bharpur and Thoha Bahadur villages as well.

Although symptoms of the disease are same in Matan Kalan, Sar Kalan, Watli, Lakhwal, Ballo Kassar and Uthwal, three cows died in Dhakku recently without showing prior signs of any disease.

A team of vets visited Matan Kalan and Lakhwal and examined animals suffering from the disease and treated them.

“We took samples of blood, faeces and feed and sent them to a laboratory in Lahore. The report issued by the laboratory showed that the cows had died due to nitrate toxicity occurred because of parthenium, a deadly weed,” said Altaf Mahmood, a disease investigation officer at Chakwal Livestock and Dairy Development Department.

He said though all type of fodder contained a certain level of nitrate, they were two time high in parthenium. He said parthenium had spread across the district.

“Cows who died in Matan Kalan are left unattended in the jungle by their owners and they return home in the evening. In the jungle, parthenium grows on a largescale and cattle eat it along with grass,” Dr Altaf said, adding that in Lakhwal only those cows died which had grazed along the village dam where this deadly weed is grown heavily.

According to a website related to cattle, nitrate-poisoning is a rare but main cause of poisoning in cattle.

It can occur as a result of eating crops such as brassicas, green cereals or sweet clover that contain high levels of nitrate. However, the most common source is inorganic nitrate fertiliser, either directly (straight from an open bag), via grazing an over-fertilised field, or via water run-off from heavily fertilised fields. Spring is the most common season for nitrate poisoning.

Nitrate poisoning occurs because the nitrate is broken down to nitrite in the rumen. In normal circumstances, this nitrite is further broken down to ammonia in the rumen and is then used by the rumen microbes to make protein.

However, when large amounts of nitrate are eaten over a short period of time, the nitrite accumulates in the rumen and is absorbed. Once in the bloodstream it reacts with iron in the red blood cells so that they can no longer bind oxygen.

The animal caught in nitrate-toxicity shows signs as abdominal pain, scour, weakness, muscle tremors, drooling of saliva and blue discolouration of mouth.

“Cattle which once contract nitrate toxicity hardly survive,” said a senior official in Punjab Livestock Department said.

But villagers are not ready to accept the version of vets as they claim that cattle belonging to other villages also graze in the jungles.

“If our cows are dying due to nitrate toxicity when this disease has not emerged in the surrounding villages as their cows also graze in the hilly areas where this weed is grown as it is grown in the area of our village,” asked Mohammad Fiyaz.

Published in Dawn, July 10th, 2019