A system for all seasons (1973)

[Music] don't gamble with your sheep much unthriftiness and loss of livestock can be prevented by good husbandry grassland Management in its widest sense hygiene housing eing and attention to the general condition of the animal there are times when good husbandry far from helping can increase the chance of disease for instance it's well known that the husbandry required to produce early fat Lambs increases the risk of pulpy kidney disease pulpy kidney disease is caused by a germ of the clostridia family A group of related bacteria responsible for disease in man all farm animals and many other species sheep are unfortunately prone to a larger number of these lethal diseases than most other animals the clostridial diseases of British sheep are black leg black disease brai tetanus lamb dentry struck and pulpy kidney disease these are caused by clostridium chovi clostridium edaan types B and D clostridium septicum clostridium tetani clostridium weli types b c and d struck and pulpy kidney disease are often known as enterotoxemia struck affect sheep only in certain localities but most of the diseases are fairly widespread occurring in most parts of the British Isles in particular the risk of black leg tetanus and pulpy kidney disease is ever present as clustal bacteria are common inhabitants of the soil sheep are in constant contact with them they lie amongst them they eat them and the bacteria can enter any small wound or scratch consequently a large number of sheep Harbor these bacteria in their gut or other parts of the body where they cause no ill effects unless other factors trigger off disease unlike animals plants and most other bacteria clostridia do not need oxygen for life or growth therefore they can grow readily in such places as the bottom of a deep puncture wound they mainly act by producing poisonous toxins which are carried by the bloodstream throughout the body and kill the animal there is little that can be done by husbandry to prevent the diseases since they're all produced by bacteria from the soil therefore the only Safeguard is immunization protection by the use of vaccines or anti-era a review of the basic principles of immunization against clostridial diseases will show how the vaccines or antisera work when bacteria enter the body the animals built-in defense mechanism attempts to neutralize and eradicate them the neutralizing substances or antibodies are stimulated by the Invaders or antigens very severe infections can cause death but if the animal survives the anti body is produced May render it immune to that particular disease for a time however as a general rule animals do not survive clustal infections sheep can be safely protected against clostridial diseases by injecting killed bacteria or killed toxins because the defenses cannot distinguish the difference and will still produce antibodies this is the principle of a vaccine the type of immunization which makes the Sheep actively produce its own protection is is therefore known as active immunization produced by the injection of vaccines readymade antibodies can also be injected into Sheep by using an anti-serum because they contain readymade antibodies anti-era give virtually immediate protection but it's shortlived compared with that produced by a vaccine antisera are usually prepared by actively immunizing horses and collecting the antibodies they produce but they're rapidly lost in the Sheep because being of horse origin they're foreign to it and the body exerts itself to destroy them quickly so protection will only last up to 3 weeks because the Sheep doesn't have to work to produce the antibodies but merely receives them this is known as passive immunity antia can be used to protect sheep during short periods of high risk such as at docking time they can also give immediate protection if an outbreak occurs in an unvaccinated flock lamb dentry is fatal in Lambs less than 14 days old so the use of antiserum is ideal for them although finding each lamb as soon as possible after birth can be a major drawback there is another and more important type of passive immunity natural passive immunity which occurs when a lamb receives antibodies by sucking colostrum from its vaccinated mother as long as it gets the colostrum before it's 12 to 15 hours old a lamb is able to absorb these antibodies through its gut this way the protection is far superior to that from a dose of antiserum both in numbers of antibodies and the length of time they will remain before being completely destroyed as the antibodies are of sheep origin they will persist for 12 to 16 weeks superb protection indeed returning to active immunization it must be remembered that the injected sheep is required to produce its own antibodies a sheep with no immunity against tostal diseases requires about 14 days after the first injection before any antibodies appear they will increase to only a moderate Peak and then decline to very low amounts after about 12 weeks a second injection after a sufficient time lapse produces quite a different effect the Sheep is now able to produce large numbers of antibodies quickly there's no 14-day gap before starting to increase instead high peak levels are reached in that time the same response will occur every time the Sheep is reinjected with the same vaccine although it's after the second dose that proper immunity is achieved it is paradoxically the very first dose of vaccine which is important this dose is the very foundation on which a sound immunity is built 14 days elapse between the injection of the first dose and the appearance of antibodies because the Sheep's defense mechanism not having met this Invader before has to recognize it and train its antibody forming tissues to produce antibodies against it the most important function of the first dose is to train or sensitize the defenses so that antibodies can be produced rapidly When Future contact with the antigen is made the injected vaccine disperses to make contact with the antibody forming tissues which respond by becoming sensitized some antib iodes will be produced but the main purpose of the first dose is to sensitize this is one of the most important basic principles in immunity to clustal diseases in some cases it's been shown that a larger volume is desirable for the first dose the quantity of the first dose has an effect upon responses to Future doses because the wider the spread of vaccine the greater the amount of antibody forming tissues which become sensitized to apply these basic principles to the Sheep farming program the covexin system can be taken as a model as it fully illustrates all the principles sheep are brought into the system by an initial course of two injections the first dose is 5 milliliters of vaccine whereas the second and all subsequent doses are 2 millit at least 6 weeks should elapse between these injections because the body defenses need time to recognize the an and then organize antibody production 6 weeks later when the tissues are thoroughly sensitized the second dose completes the protection 5 mlit are used for the first dose because it's the Keystone of any vaccination program particularly when aiming to protect against eight diseases with a single vaccine the larger volume at this stage will provide the best possible preparation for the future if the defenses have been properly prepared by the first dose then sub subsequent doses can be reduced to 2 ml without loss of Effectiveness after the second dose antibodies will be at their Peak within 2 weeks and will persist for about 6 months for continuous protection it is therefore necessary to give booster injections every 6 months it's important to give a booster to pregnant use about 2 weeks before lamming is due in the flock this ensures that the use have Peak levels of antibodies when they lamb providing high concentrations in the col [ __ ] when needed to be passed on to the newborn Lambs the lamb which sucks colostrum in the first 12 to 15 hours will receive antibodies enough to protect it for 12 to 16 weeks a lamb which is put to a foster mother will not receive colostrum and it is colostrum which is richest in antibodies such lambs will not be protected unless they're either put to a u which has colostrum or fed with it from a bottle when an orphan lamb is is bottle-fed it must have received colostrum in the first few hours of life in order to utilize the protective antibodies the covexin system is an 8-in-1 vaccine 8-in-1 vaccines are increasingly used because they possess several obvious advantages firstly the Sheep are protected economically against eight diseases by inoculation with only one vaccine not by eight single inoculations secondly it cannot be predicted Ed which disease will occur or where or when for instance unsuspected outbreaks of black disease or black leg have many times ruined a sheep Farmers program an 8-in-1 program caters for all the permutations wherever they may occur thirdly now that sheep are moved about the country more than ever before they're often faced with a variety of disease risks fourthly as antibodies are produced specifically for each particular antigen that that is for each separate disease it's an advantage to sensitize sheep to all the important clustal antigens so that they can respond readily to any or all of them at a later date a sufficiently powerful first dose will do this if a vaccine with limited cover has been used originally for example a vaccine against tetanus and ppy kidney disease then it's more difficult to ensure a balanced response should it become necessary to use a vaccine with wider cover because of new disease risks for instance if a risk of black disease now arises and the Sheep is given a 2ml dose of full cover vaccine then it would respond best to the tetanus and pulpy kidney components of the new vaccine probably at the expense of the other components if a larger quantity of vaccine is used for the first dose as in the 5ml first dose of covexin this tendency to unbalanced response is largely overcome lastly there are the economics to consider clustal diseases are notoriously difficult to diagnose they're probably responsible for the odd unaccountable deaths among sheep each year after all the bacteria are always present in the soil the cost of vaccine is low the cost of the loss of one sheep will probably pay for the first dose of vaccine for over a 100 sheep or a maintenance dose for nearly 300 vaccination is a form of insurance and a good 8 in1 vaccine is the most comprehensive form against clustal disease it's not only comprehensive but it's also simple and logical in its application as becomes apparent when following a Year's cycle in the covexin system the most suitable time to put use into the system with a 5ml dose is in the late summer or Autumn at tupping time in an area where there's a risk of clostridial disease in the winter months a 2ml second second dose should be given 6 weeks after the first followed later by a pre- lamming injection when there is no risk the second dose can be left until the flock is 2 weeks from the start of lamming so that the in Lam use can create high amounts of antibody by the time lamming begins not only will the use be protected but they will pass onto their lambs sufficient passive protection to last from 12 to 16 weeks provided the lamb suck colostrum in the first 15 hours of life if they do not they will not be protected Lambs from vaccinated use will thus be protected through all the main risk periods of their early life but as their passive protection wears off it must be replaced by active protection if they're kept longer than about 4 months Lambs to be retained can be given their first 5 ml dose at 10 to 12 weeks of age then after another 6 weeks the second dose of 2 milliliters should be given with the older stock they now fall into the regular six-monthly pattern of booster injections Autumn and spring in areas where there's no risk of clostridial disease in the winter the Autumn injection need not be given but there is then a risk of a period just before the pre- laming injection when antibodies may not be sufficiently high to prevent disease one must not forget of course that hygienic measures should be practiced when injecting sheep whether the traditional single dose syringe or a modern pre-sterilized disposable automatic syringe is used one of the advantages of the automatic syringe is that it fills itself mechanically every time the plunger is released thus saving valuable time when a number of sheep have to be injected remember though that the time saved is in filling and that due care must always be taken when making the actual injection this then is the simple effective and economical way to protect sheep although losses may run at a low level for several years in an unvaccinated flock sooner or later they can assume sizable proportions and it's far better to be safe than sorry vaccination is a form of insurance which only the Gambler [Music] [Applause] [Music] ignores [Applause] [Music]