LAMB MORTALITY

Otago Daily Times, Issue 23517, 3 June 1938, Page 24

LAMB MORTALITY

WINTER SHOW AND RACING CARNIVAL

HEAVY LOSSES THIS YEAR EXPERIMENTS IN CAUSE AND TREATMENT LINCOLN COLLEGE RESEARCH For some time now Dr M. C. Franklin, of the staff of Canterbury Agricultural College, has been conducting certain experiments in connection with the mortality among lambs, and he has now issued a progress report in view of the fact of recent heavy losses which have been reported. This states that many theories have been put forward during the last two years to explain the heavy losses which have occurred, and are still occurring, among lambs in Canterbury It is our opinion, however, that no obscure cause for the trouble need be sought "for. The three main factors responsible for the losses are. in their order of importance:— 1. Climate, 2. Nutritional, 3. Parasitic, and of these three the second and third are intimately associated with, or dependent upon, the first. CLIMATIC FACTORS Rainfall, sunshine, temperature, and other meteorological data have been collected daily by Lincoln College since it was first opened in 1880 Several years ago a 46-year average of this information was compiled, and it is being used as the basis for comparisons with the weather records of the last few months. • RAINFALL—LINCOLN COLLEGE RECORDS

No attempt has been made to recall, with figures, the very heavy rainfall of 1936. Memories of it will still be present in the minds of all Canterbury farmers. The total rainfall for that year was 38.80 in, whereas the college average for 46 years has been 25.34 in. February of that year was 9.18 in, the wettest month ever recorded and March and November of 1936 were wetter than any previous March or November since the college started recording in 1880.

Many farmers will agree that we can date our troubles back to 1936, and the persistence with which the weather conditions have been against farmers since that time. Last year rainfall figures for December. 1936. to April, 1937, period were fairly normal, but the heavy carry-over of moisture from the previous year, with abundance of succulent feed and heavy parasitic infestation in many cases, can be linked up with many of last year’s losses. Had conditions returned to normal this year, or had we experienced ,an abnormally dry year losses would probably have been negligible. December of 1937 and January of this year were wet months, particularly the former. The history of some of this year’s losses probably dates from December, if not earlier. Several cases are known where farmers shore their ewes in December, and unfortunately had a week of cold southerly weather immediately following on the shearing. The ewes’ milk supply dropped off, or ceased completely, with the result that the lambs must have received a check, a cheek which was often sufficient to allow other factors, such as internal parasites, to get the upper hand. Losses in late December, January, and early February were widespread and on many farms heavy. Conditions improved during March, and although the lambs were not doing as well as could be desired, losses had certainly eased off. and on some farms had ceased altogether. April has been another black month, and heavy losses are occurring over a large area. In the above table it will be seen that the rainfall for April of this year is more than twice the 46-year average, and distribution has been over the greater part of the month. The lambs have been wet during practically the whole of the month, a state of affairs which must pull them down in condition even il everything else —food, parasites, and shelter— it satisfactory. On one farm where the college is carrying out an experiment on about 100 lambs, only three lambs had died in the experimental groups from February 26 until April 9—just over a six-week period. The rest of the lambs were showing a very definite improvement in condition. With the recurrence of wet conditions in April 16 deaths took place in the fortnight ending on April 23. SUNSHINE When the rainfall figures are considered along with the hours of bright sunshine, the weather factor, as a cause of losses, becomes even more striking. The following is the record for April of this year: — # Honrs. First week of April .. .. 15-5 Second week of April .. .. 27.7 Third week of April .. .. 12.0 Fourth week of April .. .. H. 5 Total M .... »• 69.? /

The 46-year average for April is 159 hours. We have bad only a little more than two-fifths of the sunshine which we may normally expect during April. It is not surprising that lambs have failed to do well. It is probably a tribute to the powers of resistance of the animal body that they have not fared worse. NUTRITIONAL FACTORS During the last week several analyses of pasture samples-have boon made at the college. The following table sets out the pounds of dry matter in every 1001 bof the samples collected the balance is water: — Dry matter per 1001 b lb Italian rye sown early February, 15)38 ........ 10 Permanent pasture, sown February, 1937 .. , .. H-5 Permanent pasture, sown February, 1937 12.3 Permanent pasture not. grazed for four weeks .. .. 8.9 Permanent pasture not grazed for four weeks .. 8.8 Voung cocksfoot 3-4 weeks' growth • 6.4 Those figures are surprisingly low Good pasture should contain from 151 bto 201 bof dry matter per 1001 b. It will be seen how far the above figures fail to do this, The above information becomes even more striking il we consider how much of the above pasture would have to be eaten by a lamb of, say. 701 b live-weight, if it is to get sufficient food for maintenance and in addition put on 21b of live-weight a week It will be sufficient to consider the two extremes- -namely the grass containing 6.41 b of dry matter per 1001 b. and that containing 12.31 b. In the case of the former 2181 b a week would have to be eaten; in the case of the - latter 1121 b a week. On many Canterbury farms the figure would range between these two. If a lamb could eat the above quantities it would be consuming with the food more than 20 gallons of water on the more watery food, and nearly 10 gallons on the less watery Both these figures are considerably above the quantity which is regarded as adequate for lambs. American experiments have shown that lambs on dry feed will drink up to two quarts a day. This is thi’ee and a-half gallons a week, a figure much below the above data. It has been a common experience that ewe lambs, which have been turned on to rough pasture containing a fair proportion of roughage, and therefore material with a smaller percentage of water, have done satisfactorily, and losses have been negligible, whereas wether lambs turned out on to succulent rape, green feed, watery pasture, and so on have slipped badly. , PARASITIC FACTORS The two factors discussed above, climatic aud nutritional, are s sufficient explanation in themselves for the poor condition of many of the lambs this year. Coupled with these, however, has been the heavy parasitic infestation on many, Canterbury farms. The .two wet years, 1936 and 1937, saw the commencement of the trouble which has reached a climax this year, or. at all events, has shown very little diminution in losses or in difficulty in getting the lambs away as fats. Recently the Department of Agriculture ha« made parasitic counts on some of the lambs in one of our experimental mobs. Six typical lambs were taken prior to the commencement of drenching experiments, and the total number of parasites in the fourth stomach and the first 30ft of the small intestine counted. The number of parasites! (several varieties) present ranged from 8000 to 64.000. These figures are typical of the degree of infestation on many farms, and can be reckoned as the third contributing factor in this year’s losses. ; Research work has established that lambs heavily infested with parasites are not able to digest their food as efficiently as lambs which are comparatively free from heavy worm infestation. Hence a badly infested animal would have to consume even more food than given in the figures above if it was to maintain its live-weight or put on a few pounds of increase each week. Very heavy infestation can reduce the digestibility of the food by 25 per cent., or even more in the worst cases. DRENCHING EXPERIMENTS Drenching experiments are being carried out on severrl farms with different drenches. A detailed report of this work will be published later. To date the copper sulphate and nicotine sulphate drench in the following proportions—llb copper sulphate, lib nicotine sulphate (40 per cent.) in five gallons of water, and given as loz doses a lamb—has given the best results. Drenching? have been carried out at weekly intervals for five weeks and at two-weekly intervals since. On one farm 64 lambs which had slipped badly were selected from the main mob early in February. These were divided into four groups of 16. One lot served as controls, and the other groups were given three different drenches at the intervals stated above. On April 23, when they were last weighed and drenched, 13 out of the 16 were alive in the Milestone plus nicotine sulphate group, while seven, seven, and six, respectively, were still alive in the other groups. CONCLUSION. So long as the present weather lasts losses will continue, and may even be expected to become worse. Losses can be checked, however, by:— (1) Providing good shelter where possible. (2) Feeding dry feed, such as oat-sheaf chaff, good hay, or, better still, oats, either whole or crushed. When dry feed is used good results cannot be expected, unless adequate quantities are fed. In many cases, of course, the difficulty is to get the lambs used to dry feed at this stage. Quiet perseverance over a week or two will, however, soon accustom the majority of a lamb flock to taking dry feed. (3) When it is not possible to feed extra dry feed the lambs should be provided with grazing containing a fair quantity of roughage. One only has to consider how ewe lambs have done compared with wether lambs in order to appreciate this point. (4) Lambs should be kept from water as rar as possible. It possible to do so, races or other supplies of water should be fenced off or the lambs confined in paddocks free from water. It is appreciated, however, that it has been impossible to prevent lambs getting an excess of water during the last week or two Where heavy losses have occurred the *' diers ’ will generally be found haunting the water-races or other supplies of water. (5) Keep the lambs off second-growth rape. This will be oversucculent and probably heavily infested with parasites from earlier grazing. (6) Drench regularly at weekly or ten-day intervals with loz doses of a 2 per cent solution of copper sulphate and nicotine sulphate

46-year 1937 Days 1936 Aver. Days ins. ina. ins. December .. 5.49 13 2.32 2.12 10.0 1938 1937 January .. 3.36 7 2.34 2.23 9.4 February 3 2.70 1.66 7.7 March .. 1.50 13 1.64 2.27 10.0 April (to 28th) ., 4.17 15 1.92 1.98 9.4