DISEASES OF SHEEP

Press, Volume LXVIII, Issue 20729, 14 December 1932, Page 7

DISEASES OF SHEEP

——» ROOT FEEDING AND ANTEPARTUM PARALYSIS. INVESTIGATIONS AT LINCOLN COLLEGE. Highly interesting results were disclosed in the report, wliicli was made public at yesterday's meeting of the Canterbury Agricultural College Board, of the work of the College Veterinary Department, under Mr A. Leslie, M.R.C.V.S., on roots and their relation to disease in ewes and lambs in Canterbury. The report is the result of experiments following field observations which seemed to show that a high incidence of ante-partum paralysis among highproducing ewes was associated with loss of body weight due either to undernutrition or mal-nutrition. During the past two seasons these observations have been strengthened both experimentally and under natural conditions. The demonstration of the influence of checking the food supply before lambing and the production of the disease under controlled dietary conditions have increased considerably knowledge of the disease. The report, states, inter alia: "In previous College publications on connexion between die!, and antepartum paralysis of ewes, it has been indicated that the effects of! undernutrition (under-feeding) and malnutrition (unbalanced feeding) are cumulative and that the onset of this disease is not necessarily associated with the feeding conditions prevailing at the time of development. On those grounds it is possible to explain the occurrence of the disease under widely diverse conditions. "In Canterbury, pools—turnips, swedes, or mangels—form the main winter diet of breeding ewes. Tho < basic principle of grassland farming, viz., an all grass ration (as pasture, hay or as silage) the year round is not strictly applicable to our conditions. 'I he teed requirements of breeding ewes more closely parallel the seasonal production from pasture than do those of dairy cows With sheep, slock numbers arc doubled (by when pasture growth is beginning. When it is most rapid, the lambs are increasing m size as are also the total feed requirements. After December, -weaning, and the sale of fats both reduce the quantity ot feed required. Simultaneously pasture production is declining. Tins parallelism between feed requirements anil pasture production is only approximate, but it, is for this season that the sheepfanner saves proportionately less hay or silage than the dairyman. The latter s i feed requirements are more nearly cojv ! stant. During the early summer • uush he is, relatively, less highly stocked than the sheepfarmer, and can therefore i save a larger proportion for winter use. Thus in Canterbury root-growing enables a high winter carrying capacity than if grass alone is depended on. It possesses further the advantages ot lit tin" in .veil with the maintenance ot a team tor cropping and for pasture renewal. "It is common knowledge that roeis are low in protein (flesh-formers) and mineral matter (lime, phosphate, etc.). In Ihe light of what has been stated above, it is not surprising that their incorrect use is associated with disease. Prolonged root feeding, which may constitute either malnutrition or undernutrition, seems to bo conducive to mineral and endocrine alterations that predispose to disease, the nature of which is influenced by age, breed, sex, prolificacy, and other factors. The advantages of supplementing tho root portion of the diet with balancing foodstuffs, although well understood, are not yet generally appreciated by many Canterbury sheepf armors, who still rely upon roots as the sole winter diet lor breeding ewes. Ante-Partuiu Paralysis. '•College data show that dietary conditions capable of producing endocrine, mineral, and other metabolic disturbances predispose high-producing ewqs to dopiness or sleepy sitkness. "When roots constitute the major portion ot the ration, when no attempt is made to supplement them with balancing in gredients, and when they are fed for long periods, a high incidence of antepartum paralysis may be anticipated. The exact influence that improper feeding produces on the various body functions of ewes developing the above condition still remains obscure, although veterinary investigational work during tho last "season indicates, in a limited number of cases, that an endocrino disturbance may be responsible for the various clinical forms of the disease which are encountered in the field. If these observations are correct, the use of biological products should relieve the condition. Promising results along these lines have been obtained. Roots m& Dietetic Abortions. "The College holds the view that dietetic abortions and weak and dead lambs at birth are closely allied in their etiology to ante-partum paralysis. Field work during the past three years has shown that prolonged and heavy root feeding without balancing feeds is a common cause of premature births of lambs. Blood tests and microscopic examination of suitable material rule out the possibility of organismal infection as a cause. " Susceptibility is greatest in young ewes, decreases with age, but may also be high in aid toothless individuals. The increased susceptibility of two and four-tooth ewes depends in a large measure upon the demands of growtli as well as those of reproduction. According to our field work the feeding of roots alone for more than eight to ten weeks favours the development of endocrine and metabolic disturbances that result in premature births of lambs. Ewes in low condition before turnipfeeding starts will show the harmful effects even more rapidly —as this season has shown. In areas experiencing losses from abortions the ewes had not recovered from the effects of last season's drought before going on to turnips. Pulpy Kidney in Offspring. "The work of Gill, of the New Zealand Department of Agriculture, and others in Australia, has resulted iri the isolation of a powerful bacterial toxin as the final cause of losses from pulpy kidney of lambs, Sq far, however, considerable difficulty has been experienced in denning the dietary conditions pf the ewe and lanib under whieb the organ-, ism becomes virulent. In our field ,of: work we have been able to correlate big losses of lambs from alimentary disturbances, including pulpy kidney, with excessive and prolonged root feeding of the dam during the winter months. If this correlation is correct, the -nutrition of the lamb birth becomes at least one factor of predisposition to pulpy kidney. "In those areas of Canterbury where losses from ante-partym paralysis, associated with the excessive use of roots,, w,as common, it was not unusual to experience heavy losses of lambs. During the past two seasons Canterbury Agricultural College veterinary work has taken into consideration the influence of better feeding of the ewe before lambing and its relation to lamb mortality from digestive disturbances as. well as pulpy kidney. To date i* is 3

significant that improved nutrition of the ewe before lambing reduced the Josses of lambg up to about eight weeks of age. This is contrary to the view that good feed favours pulpy kidney development. ''There is evidence to suggest that i the offspring of ewes wintered on natural herbage of low nutritive value are more susceptible to digestive disturb- | anees and pulpy kidney than those ! whose natural diet has been suitably ; supplemented. A discussion on the ante-paTtum and post-partum nutrition of the ewe and its association with increased susceptibility of certain lambs to disease of the alimentary canal is outside the scope of this article. Lamb Mortality at Birth. •'lt can now ba said without much fear of contradiction that the prejudices against lambing on roots aro more imaginary than real. The harmful results which do occur are contrary to the experiences in other countries where an endeavour is made to supplement the root ration with concentrates, hay, etc. Even prolonged periods of such feeding do not leave the body of the individual in a precarious mineral and endocrine state. "In this connexion it is significant that heaviJy turniped breeding ewes are very susceptible to sudden checks in the food suppjy as well as to unfavourable climatic conditions. A high mortality following and during unfa v. ourable cold weather ia all too often a measure of the poorness of the feeding system practised before the storm. Fatness of condition does not necessarily indicate fitness, minerally and endocrinologically. On these grounds alone losses under diverse dietary conditions are explicable. "In experimental aheep work here and elsewhere it has been noted that there are various stages and degrees of malnutrition in the same fipek in which only a few cases of fully established disease occur. This latter statement is applicable to root feeding. The therapeutic value of additional suitable feed for ewes about to lamb is now beyond dispute. Not only does this evtra dieting improve the health and vitality of the datn but in a similar manner is reflected in the fitness of the new-born. Such lambs are far less susceptible to unfavourable environmental conditions, including cold, shortage of milk, etc. In well wintered flocks there appears to be significantly leas trouble in lambing. In one particular instance where prolonged root foodiuc had been practised for years, whore difficult lambin«s were the rule and not the exception, an alteration in tho feeding system, gave a marked reduction in the number of cases of difficult lambing. Bearing Trouble. "it is realised that bearing trouble of iii-lamb ewes occurs amongst stock ■which have never fed on turnips. The fact, however, that a high incidence of bearing trouble is often associated with prolonged and heavy root feeding is of some fundamental importance in arriving at a conclusion regarding the dietary factors predisposing to this disease. Our field work docs not support the popular view that roots predispose to excessive fatness of condition. This may be true to some extent if supplementary feeds are given aloug with roots. In our experience heavily turniped cues approach lambing in a poor condition if roots alone have been j fed and no other feed allowed. I Numerous post-mortems conducted duFiug the past three seasons on ewes | affected with bearing trouble indicate that malnutrition and undernutrition, together with excessive distention of the stomach, predispose ewes to this trouble. The rate of passage of roots through the alimentary canal will therefore be of some importance. Examination of the various tissues of the bodies of the ewes which died from bearing trouble shows that during life there has been a lack of tone (tonus) iu the structures involved. That this may be due to improper or inadequate nutrition cannot be denied, although it is realised that excessive distention of the rumen or first stomach appears to be an important factor in producing the condition in animals suffering from muscular and other tissue weakness. Mortality and Spring Feed. "It has previously been stated that the nature of the dietary conditions prevailing at the onset of a disease of : nutritional origin need not necessarily ! be the exciting cause of the trouble, i It. has been freely stated that tho high \ protein content of ihe luscious spring! growth is an important predisposing j factor in lamb mortality. Tn our field j work on lamb mortality, the irrational I use of roots seems to be a more important factor than an abundance of spring j feed. To our knowledge no attempt ; has been made so far to correlate lamb j mortality from digestive disturbances j with the nature of the diet of the dam i prior to lambing. It is realised that i improved maternal nutrition may bene- ', fit in many ways the well-being of tho i offspring. Isolated cases of lamb mortality v»ill always be experienced. Our data" refer to the dietary conditions associated with large outbreaks of digestive derangements in lamb?. "If those observations have been properly interpreted, a solution capable of practical application is placed at the disposal of the farmer who experiences heavy mortality in lambs. It is pleasing to record here that the data arc substantially in agreement with the views expressed by this College in 1930 —that if feeding systems were altered to prevent ante-partum paralysis, or a high incidence of weak and dead lambs at birth in non-susceptible paralysis flocks, lamb losses from digestive disturbances, including pulpy kidney, would also be reduced. Balancing tjjo Root Ration. "As with other foods that are unbalanced in themselves, roots may fall into disrepute if an insufficiency or excess is fed. It is admitted that excess of roots may bo fed without apparent harmful effects. This depends upon (a) the condition of the ewes before going on to turnips, (b) the length of the root feeding period, (c) the size of the break, (d) the age of sheep, (e) prolificacy, (f) state of teeth of owes, (g) the nutritive value of the turnips at various stages (loss of leaf, withering, etc.), (h) the amount and nutritive value of herbage in the run out, and {i) the amount of balancing supplementary feed consumed. "In order to provide a better balanced ration towards the end of the winter, it is a good practice to drill in 12-15 or more pounds of Italian rye. per acre along with the roots. Tho object is not to make a pasture, merely to balance the ration. Turnips can then be grubbed in the ordinary way. "If tho turnip crop should perchance be a bumper one it is not advisable to: increase the 4aiJy amounts. It is generally more profitable to sell the excess. If the turnips are unsaleable even ploughing under might be preferable to feeding them to sheep which arc already receiving a sufficient quantity of them. "When the dry feed does not supply sufficient mineral material a lick containing lime, phosphate, and salt' should be made available."