Pastures Infested

Franklin Times, Volume XXVII, Issue 110, 19 September 1938, Page 8 (Supplement)

Pastures Infested

LAMB AND HOGGET MORTALITY ENGLISH EXPERIENCES (Contributed by Canterbury Agricultural College). In view of the widespread losses of lambs and hoggets during recent years the experiences of workers confronted with similar problems overseas should be of interest to New Zealand farmers. Recent publications from the Wye Agricultural College, in Kent, have drawn attention to the similarity of many of the problems of stock losses which have occurred in the Romney Marsh area in the South of England, with those which have been occurring in New Zealand. Apparently 70 per cent of the flock owners sell their lambs at the autumn sales, the lambs being weaned on tlie morning of the sale. Those lambs which are not sold are wintered on tlie higher ground of Kent, Surrey and Sussex, where they remain for about seven months, and are returned to . the Marsh the following April (spring). Writing in 1035, Dr. A. D. McEwen, of the staff of Wye College, slates that lambs wintered on tlie Romney Marsh areas will not thrive and a high mortality can be expected. He has found that the smaller stomach and intestinal worms are primarily responsible for the trouble. Bluestone-Nicotine With the object of investigating the efficacy of the bluestone-nicotine sulphate drenching treatment in controlling parasitic infestation, McEwen placed 80 lambs under experiment in June, 1934. These were divided into two groups, 40 in each group, and one of I lie groups was treated regularly with a solution containing a per cent of bluestone mid u per cent of nicotine sulphate. This is a stronger solution than that which lias been recommended under New Zealand conditions but correspondingly smaller quantities were used at each drenching. The other group served as controls. It is not possible to give full details of MeEwen’s results in this article, but the following table summarises the value of the animals at the end of the experiment on April lb. when the surviving animals were sold at public auction:- £ s. d. 10 best treated animals .. 23 10 0 1 o second best treated animals 22 10 0 12 remaining animals .... 24 12 0 Totals 70 12 0 10 best original controls .. 18 5 0 10 remaining controls ... 13 lb bi Total 31 la <> ! Comment on Results ! Commenting on the experimental

animals McEwen says : “From the symptoms shown by the original control animals and the postmortem examinations it is evident that the sheep suffered from a parasitic gastritis (inflammation of the stomach) and enteritis (inflammation of the intestines), but that the enteritis was the more severe, this being indicated not only by the greater number of worms found in the small intestine, but also by the greater number of the control lambs which had diarrhoea and survived. To what extent diarrhoea may be symptomatic is uncertain, but it has not been observed in certain flocks even when the animals were emaciated and dying from heavy infestation of stomach worms, either Haemonchus contortus or Ostertagii species, or both, and when insignificant numbers of worms were present in the small intestine. Profuse diarrhoea is, therefore, regarded as a symptom indicative of parasitic enteritis rather than parasitic gastritis. The success achieved by McEwen in his earlier experiments has been continued for writing in the January, 1938, issue of the Wye College Journal, McEwen states: — “The majority of inquiries and investigations concerned with sheep diseases were connected with parasitic gastero-enteritis, and excellent results continue to be obtained with the copper sulphate and nicotine sulphate mixture when administered as recommended in a previous report. This treatment fortunately appears to be increasingly used by sheep farmers, but it is considered regrettable that much more dilute solutions of the mixture are occasionally used under the impression that the treatment is the one which gave such dramatic and excellent results when tested in experimental 'sheep on the Romney Marsh two years ago, as it is unlikely that the full benefit will be obtained by reduced doses.” Lincoln College Experiments This year Lincoln College has carried out a series of experiments under the auspices of the Canterbury Sheep Survey Committee’s investigations, and the findings substantiate those of McEwen in England. The college has also stressed repeatedly the importance of proper management in the control of parasitic • infestation. The value of suitable stock and crop rotation, the necessity for feeding adequate quantities §f good quality dry feed, such as lucerne hay or high quality clover and grass hay, oatsheaf chaff, and grain, are all methods whereby losses through parasitic infestation in abnormal seasons, such as those we have been experiencing recently, can be reduced or completely eliminated. Confirmatory English Opinion In this connection an article in the most recent issue of Agricultural Progress (published in England) makes interesting reading. The article is entitled “Management in Relation to Internal Parasites of Sheep,” and is written by Mr W. H. Tomlinson. assistant agricultural organiser for the Wiltshire County. Writing of English conditions the author says: — “That abnormal growth in sheep attributed to sheep sickness is at least DU per cent due to worms is considered a safe statement: possibly 99 per cent would be correct" for all enclosed areas with a normal herbage. | “Semi-starvation from grossly overstocking and actual shortage of food is unlikely to occur on pastures of normal productivity, as the animals wilt become interesting veterinary specimens before that stage is leached unless correctly treated. This refers to sheep farms with permanent flocks, not individual’ fields and badly managed flocks.

“Lambs showing signs of acute malnutrition due to sheep sickness have been seen on excellent pasture

land in the West Midlands. The only ; deficiency was knowledge of the sub;jects. | “The losses from worms may be direct and result in deaths from ' worm infestation, and frequently ] from complications due to lowered. constitution, but a far greater loss | occurs from lowered fertility of ewe flocks, weaker lambs at birth, lowered. | milk production of the ewes, and thus j further losses in severe weather, in addition to subnormal growth of the lambs from direct attack. The more severe the infestation the greater the proportion of cull or small weak, lambs that are not saleable at the-

normal time.” j The author of the article estimates that the loss on the 7,000,000 ewes in. England is at least two million sterling, and may well be more than, three million sterling.

I Causes of Infestation I Dealing with causes of infestation,. Mr Tomlinson says:— J “It is obvious that infestation is J from the larvae on food or possibly in ponds with surface drainage. Thus preventative, measures aim at either j starving out the larvae by intermittent stocking, or by lengthening the ■>' life cycle by limited stocking; the- v* former is the most suitable for in - tensive sheep farming, the latter for extensive methods.” Infestation of Pastures The number of eggs laid by parasites varies for different species. The' female Triehostrongylus apparently example, will usually lay about 8000 eggs every 24 hours, whilst thefemale Tricostrongylus apparently lays only about 200 eggs in the same time period. '

A sheep heavily infested with Haemonchus contortus frequently passes 10,000,000 eggs every 24 hours. In infestations with Triehostrongylus the number pased may not exceed one million. In both cases, however, the piling up of infestation on the pastures would be rapid. It was assumed that a paddock was stocked at the rate of five lambs an acre with animals heavily infested with Haemonchus contortus, so that • t he number of eggs excreted an animal s,as similar to that mentioned above, this would represent a daily return to the pasture of 10,600 eggs a square yard. With an equally heavy infestation of Triehostrongylus the egg excretion a day might be 1060 a square yard. This may have been the position on many Canterbury farms last year.