POISONINGS OF LIVESTOCK

New Zealand Journal of Agriculture, Volume 64, Issue 2, 16 February 1942, Page 99

POISONINGS OF LIVESTOCK

Continuing his article on poisonings of livestock from the January issue, the author goes on to deal with a luniiiiiuiiiih number of other common plants which may cause stock > i

mortality. It is probable that these two lists include most plants likely to cause losses of importance in this country.

By

D. MARSHALL,

District Superintendent, Livestock Division, Wellington. iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiinaiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii

RAGWORT has probably been the cause of greater stock loss in New Zealand than all other forms of poisoning put together. The work of Gilruth about 40 • years ago first established its poisonous nature. The toxic principle is in greatest amount in the flowering stage, and remains active even though the plant may be cut and dried, as in hay. There is evidently much less in the low rosette stage, as attempts to produce poisoning with this stage in sheep have failed. Cattle, sheep, and horses are liable to poisoning. In cattle, there is believed to be a type of acute poisoning where animals are compelled to eat large amounts of the weed over a short period, deaths occurring within six or eight weeks. Typical ragwort poisoning is a chronic,. slowly-developing condition. The final symptoms and death appear to be due not so much to the poison as to the state of the liver which it has produced. The chronic irritation of the toxin causes such an increase in fibrous tissue that the specialised liver tissue is largely destroyed and its function lost. A feature is the occasional appearance of symtoms two to six months after the animals have been removed from ragwort areas. It is pleasing to note that, with the reduction in rank ragwort growth due to systematic clearing campaigns or to the greater use of sheep for control, there has been a marked reduction in cattle losses from this cause.

Symptoms

Symptoms in cattle are indefinite'unthriftiness and loss of condition, and later, diarrhoea, nervous disturbance, and irritability, and frequent heaving

and straining. These symptoms may be observed over periods of three to six weeks. On post-mortem examination the carcass is found emaciated, the fat is watery and jelly-like, and dropsical fluid is found in the belly cavity, even distending the folds in the lining of the fourth stomach. The liver is characteristic, being slatey bluish in colour, and tough and rubbery to handle or cut due to, excess, fibrous tissue. In horses, the observed duration is shorter. There is dullness, Unsteadi-

mess, and paddling of hind limbs, and a tendency to wander aimlessly or blunder into fences, etc. Sheep appear to be more resistant. Old ewes acquire a taste for the weed, and in a fresh paddock may be seen eating the flowering ragwort before anything else. Mortality may occur in animals exposed to ragwort feeding over periods of 12 months or more where much of it is . in a rank or flowering state, but there is ' considerable z evidence that, once the rough has been cleared up, they can graze the rosette stage with little risk’. , Deaths in cattle appear to be most common in the late spring, when the flush of feed appears, probably because of the greater strain on the already damaged liver.

No form of treatment appears to have much influence on ragwort poisoning once symptoms appear,> and when one considers the state of - the liver, this is not surprising.

Tutu

Tutu causes a spectacular type of poisoning, and at one time it was not uncommon -for comparatively large numbers of cattle on “trek” to be lost either through being put hungry into paddocks containing the plant or through eating it on the .roadside. Poisoning usually occurs where animals are put into strange pastures. The alkaloid of tutu is, in effect, something like strychnine, and the symptoms observed are usually excitement and increased response to any stimulus, bellowing, a tendency to fits or spasms, and bloating. Bleeding was the stockman’s remedy, and heroic feats were performed in ensuring this from the roof of the mouth, the ears, or the tail. Kerosene was also given internally.. Sedatives in full doses,

such as chloral hydrate, together with tapping, if required, to relieve bloat, may be useful in otherwise quiet animals. With run cattle, such treatment may be impracticable, and beyond removing them from the tutu-infested area, they are probably better left quietly alone. '

Hemlock

The spotted hemlock has a leaf slightly resembling a carrot, a stem speckled, with brown, and heads of small white flowers. It may reach a height of five feet, and has an unpleasant smell, so that stock are unlikely to eat it unless compelled to, as in bare runs and paddocks. In one observed instance the symptoms resembled those of milk fever, the cows showing dullness, sleepy expression, semi-paralysis, and lowered temperature. Treatment is by free use of stimulants. Poisoning in pigs has been noted where the plant was plentiful in runs.

Ngaio

The ngaio is a common tree in coastal regions, and frequent instances of poisoning in cattle are on record, particularly following storms where branches or whole trees have been blown down. Symptoms noted have been staggering, constipation, and evidence of severe pain. :

Buttercup

■; Definite confirmation of poisoning by buttercups, by experiment or in the field, appears difficult to obtain, although certain species have long been considered dangerous. Aston reviews the subject in the “Journal” (June, 1918). v . Two common species, R. repens, the creeping buttercup, and R. Sardous, are believed to be only slightly, if at all, poisonous, which is fortunate, as particularly the latter—a low-growing, somewhat hairy plant is extremely common in many damp areas, notably in parts of the Hauraki Plains, so that stock can hardly avoid'

eating it. R. Acris, the tall crowsfoot, an erect plant about two or three feet high, with much divided leaves, has been frequently blamed for deaths of cattle in other lands, but does not appear common in New Zealand. Plants have been observed in the Woodville district. R. Scleratus, the celery-leaved buttercup, is a succulent, shiny-leaved plant which is found commonly in ditches or wet. areas growing at water-level. It has been associated with deaths in cows, although the feeding of sheep with the plant from the same area produced no harm-

ful effects. R. rivularis (Waoriki) has also a bad reputation. The reputedly poisonous varieties are , stated to be most dangerous at the flowering stage. They contain an acrid juice, which has a blistering, irritant effect on the lining of the mouth and alimentary tract, and the symptoms are colicky pains, salivation, depression, slow, weak pulse, and slow, snoring breathing.

Nightshade

The black nightshade is a common annual weed up to two feet high, bear-

ing. little white flowers, followed ' by green berries, which later turn black. It is a weed of cultivated land. Poisoning (by black nightshade is described by Bonner in the “Journal” (August, .1938). The symptoms were staggering, delirium, and later, coma, 1 with occasional convulsions. The poison is in largest amount in the berries. The extent to which the plant is poisonous may. vary in different seasons, and probably a considerable amount is required to cause symptoms.

Privet

Poisoning , of yearling heifers by privet was described in the “Journal” for November, 1939. ■ Intense inflammation of the lining of the fourth stomach and part of intestine was . found in two affected animals on ■ postmortem examination. The berries aye believed to be the most poisonous part of the plant, and poisoning would be most likely to occur from untrimmed

privet hedges. Horses have also been poisoned.

Mangolds

Deaths following the feeding of mangolds have been recorded from time to time. In each case, . the roots had apparently not been stored long enough. Aston in the “Journal” for September and October, 1911, discusses the matter, and suggests that poisoning may result from nitrites formed from the nitrates in the root, which, in certain conditions, are present in abnor-

mal amount. In . one observed case eight cows were found dead on the morning following the feeding out of a load of mangolds. In two other cases pigs .died rather suddenly after mangold feeding. Analysis of mangolds in two of these cases showed an above normal amount of nitrites. Mangolds are a useful feed, and any risk is largely avoided by lifting and storing for two months before use. This list, together with the notes published in the January issue of the

“Journal,” probably includes most plants i likely to cause losses ! of importance in this country.

The Breeding of Horses

PRICES for draught horses are still reported to be low, and it appears that the scarcity of labour makes it necessary to use tractors as much as possible, states the Director of , the Livestock Division in his annual report. This, position will probably remain, so long as fuel is available for the mechanical power, but, on the other hand, one would expect an increased demand for horses to enable owners to dispense with mechanised traction under the present conditions. The operation of the Stallions Act should assist in the eventual elimination of the unsound stallion. So far, the Act applies only to the compulsory examination of the younger stallions—two- and three-year-old stallionsalthough many of the older stallions were examined for certificates of soundness the previous year. In regard to the breeding of light horses, subsidies were again provided under the Remounts Encouragement Act. These subsidies enable the owners of approved mares to obtain the services of selected and approved stallions at reduced fees. The stallions were stationed at convenient centres in both islands, and 40 stallions were subsidised during the year 1940-41, compared with 39 in the previous year: The number of mares approved for service was 1381, compared with 1339 in the previous year. This service is still being well patronised. Although some good reports . have been received concerning foals produced under the subsidy scheme, some criticism has been raised in other districts. Favourable comment has been made in regard to many of . the stallions used, but so far it has not been possible to exercise a close scrutiny or selection of the mares. A uniform type is not likely to be produced until Committees are able to exercise a more rigid selection of the breeding-mares. The use of old mares should be discouraged, as in this class the foaling percentage is low and the death rate at foaling-time comparatively high. Unfortunately, the number of mares offering does not allow of a strict selection in regard to type and other aspects. The assistance given by the New Zealand Racing Conference, the New Zealand Trotting Conference, and other kindred bodies is much appreciated. The work of the District Remount Committees has been made more difficult.during the year through the necessity for restriction of motor travelling.