TROUBLES OF STOCK.

New Zealand Herald, Volume LXVII, Issue 20744, 11 December 1930, Page 25

TROUBLES OF STOCK.

WORM INFESTATION.

LOSSES AMONG SHEEP.

GUARDING LAMBS AND HOGGETS. The treatment of lambs and hoggets for the prevention and cure of worm infestation is the subject of the latest bulletin issued by the Canterbury Chamber of Commerce in collaboration with Canterbury Agricultural College. Coinciding with the period of greatest susceptibility in the life of the young lamb, the bulletin makes its appearance at an additionally appropriate moment in that the present season, with its abundant/rainfall, has been particularly favourable for the spread of worm trouble. It is pointed out that the period immediately before and after weaning is often attended with a number of losses of lambs, and although many factors may

be responsible, yet the three chief causes which influence the mortality are shortage of food, the loss of the mother's milk, and the presence of worms in the stomach and bowels and lungs. The development in a flock of lambs or hoggets of gradual or rapid loss of condition, persistent diarrhoea, toughing, etc., and deaths invariably suggests the presence of worm infestation of the flock, if th» trouble is

widespread. If wonn-infested sheep are present to begin/ with, then heavier stockinrr will probably cause an increased infestation. Before the best results can bo obtained from intensive agriculture, efficient drainage and ample reserve of food are essential, and significance in the control of worm parasites. Old, low-lying, damp pastures favour parasites.

11l Effects of the Pests. The,presence in the stomach and bowels of many blood-sucking parasites entails the consumption of large quantities of food materials,which would otherwise be available for the needs of the host. Furthermore, irritation of the lining membrane of the alimentary canal predisposes to lowered vitality, bacterial infection, and disease.

The incidence of losses by deaths and by reduction in wool and carcases bears a close relationship to the available feed, the less the food supply, the greater being the effects of parasites; and although regular iuedicinal treatment for worms with reliable drugs is usually followed by marked improvement in health and condition, thq significance of an ample fqod supply for stock reared on worm-infested pasturage must always be considered along with treatment.

Although some of the phases of the life histories of the different worm parasites of sheep remain somewhat obscure, nevertheless it has been definitely established that a. period of about 24-28 days is necessary under favourable conditions of temperature and moisture for the completion of their life cycles. Hence the necessity fur repeating any treatment given ouco a month. Heavily-infested lambs may show symptoms of debility and severe scouring as early as 20 days following the ingestion of badly-Conlaminated pastures. Lambs, therefore, reared on worm-contaminated pastures are often infested long before weaning time. Control ol Lung Worms. The lung worms that affect sheep, and produce coughing, when once established in the substance of the lungs, are so situated that medicines capable of destroying them would likewise destroy the lung tissue and the animal. It is believed, however/ that the immature worms on their way to the lungs pursue a tortuous course via the alimentary canal of the host. These larvae arc somewhat susceptible to the action of bluestone solution, and herein lies a factor of considerable practical importance in the' prevention and control of lungworm disease. Sheep are often infested with stomach and lung worms at the same time, but it haS been shown that if the stomach worms are regularly treated, death seldom follows lungworm infestation. But if the sheep are subjected to hard conditions, such as, for example, over-driving on a long jodrney, or unfavourable conditions on a sea voyage, then death may occur through this lung worm infestation, intensifying the danger from pneumonia. Occasionally certain worms confine their activities to/the bronchial tubes, and in that situation they are amenable to injections into the 'windpipe, a treatment which would be of undoubted value in the treatincut of highly-prized animals. Result of Investigations.

Recent investigations carried out at Cambridge by the Institute of Animal Pathology sliowed tliat no treatment lias been discovered that will kill every kind of worm, although certain treatments will kill certain worms. This is a very important finding, and serves to explain the unsatisfactory results so frequently met with following the use of many proprietary medicine/i'. Experiments show that . htcmonchus contortus, one of the commonest parasitic worms, can be killed with copper sulphate, and that this substance is very suitable for general use, since it is cheap and safe, and can be given either dry in capsules or in solution, ilfcmonchus contortus is one of the commonest of parasitic worms in New Zealand, and the fact that it can be killed by so simple and cheap a drug as bluestone is of great practical importance. Other remedies tested consisted of carbon tetracholride, tetrachlorethylcne (nema) arsenic tabloids, a combination of copper sulphate and sodium arsenite, and, among others, a mixture of turpentine, chloroform and linseed oil. The results showed that these remedies were either ineffective, expensive, dangerous, or possesssd no advantage over bluestone. Drenching of Sheep. Although the drenching of sheep is quite a simple operation, the beginner often succeeds in choking several animals. ]f the sheep is allowed to throw back its head during the operation, the chances of the drench entering the windpipe are greatly increased. Jhe simplest method of preventing this happening is to place the left thumb in the animal's mouth or the left hand over the animal's face while adininisterir'lg the drench with the right. The best drencher to use is a self-filling metal one .such as is comrn< on the market to-day. All sheep to be dosed for internal parasites should be fasted for 12 to 15 hours prior to treatment; nevertheless, each sheepfarmei l should be guided by the condition of his flock as to whether they will stand the full fasting period or full dose of medicine. A full dose of worm medicine should not bo given to weak animals, as better results can be obtained by halving the dose and repeating in a fortnight. It would bo foolish to suggest the monthly mustering of hundreds of sheep scattered over thousands of acres carrying one. sheep per so many acres. That is licyond practical consideration, and seldom is parasitism common on 6uch pastures.