High Nitrate Poisoning?

Press, Volume CVI, Issue 31107, 9 July 1966, Page 9

High Nitrate Poisoning?

About 150 mainly Friesian dairy cows due to start calving from the end of July were gradually recovering early this week from poisoning apparently caused by a high level of nitrate in the greenfeed oats on which they were feeding.

The cows were on a butterfat farm in the ClarkvilleOhoka area. They had been

on Winter Grey oats and then last Saturday they were given a fresh break of two acres of what were Black Gartons Supremes. These oats sown last March with lewt of superphosphate following a dressing of a ton of lime were about 12in high. They are a strong robust looking oat with a very broad leaf. The cows went on about 11 a.m. and about an hour and a half later it was noticed that they had all gone off the feed and were assembled around a creek at one end of the paddock. It is believed that they probably grazed the oats for no more than about half an hour. When a visit was made to the herd on Sunday morning to feed out hay all was not welt. A good many of the cows were then finding it difficult to get to their feet and a handful could not get up at all. Their eyes were frequently sunken, coats were rough and they were also scouring quite badly. In fact one observer said he saw only one Jersey cow which did not seem to have been affected. It was estimated that as many as 50 or more cows were in a state of senrifounder—they had difficulty in getting up. Some cows did not move any distance in the course of about two days. Excluded When the trouble was noticed the herd was immediately excluded from the new greenfeed break and by Monday afternoon they were starting to brighten up again. At this stage only four were still down and they were given an injection by a veterinarian and they were all up by the next morning. A veterinarian who attended the herd said that the situation had looked pretty frightening initially but it had not turned out to be so serious after all. Quite a few of the cows had looked as if they could slip their calves. This sort of condition is

apparently not uncommon on oats. Mr H. W. Mclntosh, consulting officer for the New Zealand Dairy Board in this area, said this week that he had been coming across it for a number of years and the main offender seemed to be oats of the Gartons family. It had also been seen frequently where green oats and chou moellier were fed at the same time.

Possibly an unusual feature of last week-end’s trouble was the number of cattle affected. Normally it seems that the numbers affected are smaller and Mr Mclntosh said usually the trouble developed more gradually with animals getting progressively thinner and scouring badly. Other Crops The veterinarian said that it was a condition likely to be temporary. It was also encountered on turnip tops, rape and mangolds. It was likely to be associated with immature plants and a possible answer was therefore to see that such a crop was sown early and reached maturity before the winter. Heavy breathing, scouring and a brown colouration of the mucous membranes were some of the symptoms of the condition. Where cattle had been treated he said that an oxidising agent had been used. While most common in cattle, it could also occur in sheep and in some degree in pigs. Dr. J. W. McLean, head of the veterinary department at Lincoln College, suggested this week that the unusually mild conditions experienced at times this winter could possibly give rise to high nitrate levels in such crops. Such a condition might also apply to regrowth of chou moellier, thousand headed kale and rape, and it might possibly even be a problem in autumn saved pasture if it continued to grow under mild conditions. It might be desirable for farmers to watch their stock very carefully for a few hours when they were, say, introduced to a new greenfeed area. Where the trouble cropped up last week-end the offending oats were disced in early this week. The farmers concerned were taking no chances but from all accounts the poisonous condition of the plants may well have only been shortlived. On this particular property oats had been fed for years previously without any trouble.