Poultry Exam 18 June 2002 1. Name 3 breed related differences between commercial egg layers and broiler breeders. (3) Noem 3 rasverwante verskille tussen kommersiele le-henne en braaikuikenteelouers. Commercial layers : higher egg production Low feed consumption Low growth rate/body mass Less broodiness 2. a) What is the difference between minimum ventilation and summer ventilation? (4) Wat is die verskil tussen minimumventilasie en somerventilasie? b) How is ventilation provided in a longitudinally ventilated environmentally controlled chicken house? (3) Hoe word ventilasie voorsien in n omgewings beheerde hoenderhuis wat in die lengte geventileer word? c) Besides alteration of the ventilation, what other measures can be applied in the chicken house in (b) to minimize heat stress in the chickens when external temperatures are very high? (4) Behalwe veranderings in die ventilasie, watter ander stappe kan toegepas word in die hoenderhok wat in (b) genoem word om hittestress in die hoenders te verminder as buitetemperature baie hoog word? a) Minimum ventilation : supply oxygen, remove waste gases viz. CO2, H2O, dust, ammonia. Summer ventilation : effects of minimum ventilation plus airflow to allow cooling. b) air inlets at or near one end of the house, fans at other end, negative pressure ventilation. c) cooling - wet cooling pads at air inlet, cool water feed - high density diet, increase CHO decrease fat, feed at night, increase amino acids, fat soluble vitamins, treatments add NaHCO3 in water reduce stocking density 3. Discuss the role of photoperiod in the management of commercial laying hens in the following facets of the life of the laying hen: a) The first week of life. (1) b) During rearing (1) c) Inducing the onset of lay, including a brief summary of the hormonal pathways underlying the onset of lay. (3) Bespreek die rol van fotoperiode in die bestuur van kommersiele lehenne gedurende die volgende fasette van die lewe van die lehen. a) Die eerste week van die lewe. b) Gedurende grootmaak. c) Die induksie van le, sluit asseblief n kort opsomming van die hormone betrokke daarby en hulle rol in die prosess. 0-7 days : 23 hours light to find feed, 1 hour darkness to avoid panic. Rearing 1-16 weeks : 8-10 hours, never increase hours during rearing. Early lay : 17-30 weeks, increase by ½ hour per week to maximum of 15-17 hours, never decrease during lay. Late lay : maintain hours to cull at about 65-75 weeks. Used together with body weight to stimulate onset of lay. Increasing daylight length (artificial or natural) reduces secretion of melatonin by the pineal gland which stimulates release of FSH and LH by the pituitary gland, leading to onset of oestrus.
4. a) Draw a sketch graph showing the expected daily egg production (% eggs per hen day) of a flock of broiler breeder hens over the lifespan of the hens. (4) Teken n skets grafiek wat die verwagte daaglikse eierproduksie (% eiers per hen per dag) van n trop braaikuiken teelouers wys or die hele produksie leeftyd van die voels. onset of lay 24-25 weeks peak production around 33-34 weeks 40% production at around 60 weeks at cull graph with correct axis labels and correct graph curve b) How would this graph differ from the eggs per hen day graph of a flock of broiler breeders? You may describe the differences or draw a similar graph for broiler breeders which highlights the differences. (4) b) Wat is die verskil tussen die grafiek in a) en n soortgelyke grafiek vir n trop kommersiele lehenne?. Jy mag die verskille beskryf of n grafiel teken wat die verskille duidelik uitlig. onset of lay 16-18 weeks (earlier) peak production around 90% at 30-32 weeks (higher) drop to 60-70% by 70 weeks (longer and slower drop) 5. a) In what way do the eggs of older breeder hens differ from those of younger breeder hens? (2) a) Hoe verskil die eiers van ouer teelhenne van die eiers van jonger teelhenne? Older bigger eggs with thinner shells b) What is the significance of this difference for day old chick quality? (3) b) Hoe affekteer hierdie verskille dagoudkuiken gehalte? Older bigger chicks with more mushy due to porous shell 6. List 5 viruses that are vertically transmitted through the egg in chickens. (5) Maak n lys van 5 virusse wat vertikaal oorgedra word deur die eier in hoenders. ALV group, AE, CAV, EDS, reovirus 7. Name 3 effects of prolonged storage of eggs on the incubation of eggs. (3) Lys 3 effekte van uitgerekte stoor van eiers op die uitbroei van die eiers. Increased incubation Depressed hatchability Egg contamination and omphalitis 8. In point form, describe 6 characteristics of a good quality day old broiler chick. (3) Beskryf kotliks 6 eienskappe van n goeie gehalte dagoud braaikuiken. >40g, alert, no defects, no pathogens, healed navels, dry and fluffy, well hydrated, normal vaccination reactions. 9. This year the South African broiler industry has struggled to make good profits. What international economic factors contribute to this situation? (2) Die Suid-Afrikaanse braaikuiken bedryf het die afgelope jaar gesukkel om n goeie wins te maak. Watter wereldwye ekonomiese faktore het daartoe bygedra? Imports and dumping particularly from USA Increase in dollar denominated maize price. 10. Why should open sided poultry houses be more than 15 meters apart? (1)
Hoekom moet oop pluimveehuise meer as 15 meter uitmekaar wees? 11. Broiler chicks are submitted to your practice with the complaint that about 30% of the flock has developed nervous symptoms shortly after hatching. Twenty chicks are submitted to you alive for post mortem examination. Most of the chicks submitted exhibit non-specific nervous signs such as inco-ordination, paralysis and tremors. They show no other symptoms. The macroscopic post mortem examination is negative. a) Which viral infection is the most likely cause of the problem? (1) Avian encephalomyelitis - picornavirus b) What further tests/examinations could you do to confirm your diagnosis? (3) Histopathology encephalomyelitis Brain material of affected chicks injected into clean chicks, look for Sx Paired ELISA serology c) Explain how this disease problem probably arose in this group of chicks. (3) Parent flock became infected with virus while in lay. Resulted in vertical transmission of the disease to progeny. d) What treatment would you recommend in the affected birds? (1) None - cull e) How would you control the disease in the future? (4) Live virus vaccination of parent flocks between 8 and 16 weeks Elisa at 17 weeks to confirm successful vaccination. Can still revaccinate if poor response. Braaikuikentjies word by jou praktyk ingehandig met die klagte dat omtrent 30% van die trop het senuweesimtome ontwikkel kort nadat hulle uitgebroei het. Twintig kuikens word lewendig ontvang vir nadoodse ondersoek. Die meeste van die kuikens wys nie spesifieke senuweesimtome soos swak koordinasie, paraliese and skuddings. Hule wys geen ander tekens nie. Die makroskopiese nadoodse ondersoek is negatief. a) Watter virusinfeksie is die waarskynlikste oorsaak van die probleem? b) Watter verdere toetse/ondersoeke kan gedoen word om die diagnose te bevestig? c) Verduidelik hoe hierdie probleem onder hierdie groep kuikens waarskynlik ontstaan het. d) Watter behandeling sal jy aanbeveel vir die aangetaste kuikentjies? e) Hoe sal jy die siekte vorentoe beheer? 12. List the most important post mortem lesions you would expect to find in broilers infected with virulent infectious bursal disease (IBD). (3) Maak n lys van die belangrikste naddodse letsels wat jy sal kry by braaikuikens met Gumborosiekte. (IBD) Haemorrhagic/ oedematous bursa Haemorrhages in muscles and proventriculus Nephrosis Congested carcass. 13. Newcastle Disease. a) Name the aetiological agent. (1) b) Name the 3 organ systems affected by Newcastle disease. (3) c) Describe the clinical picture in a flock of unvaccinated broilers affected by velogenic Newcastle disease. (4) d) Give the full name of a test used to differentiate the pathogenicity of different types of Newcastle disease virus. (1) e) Describe a typical vaccination programme against Newcastle disease in broiler breeders during rearing. (4) Newcastlesiekte a) Noem die organisme wat die siekte veroorsaak. b) Noem die drie orgaansisteme wat deur die siekte geaffekteer word.
c) Beskryf die kliniesebeeld in n trop ongeente braaikuikens wat deur velogene newcastlesiekte aangetas word. d) Gee die volle naam van n toets wat gebruik word om die virulensie van verskillenede Newcastle virusstamme te onderskei. e) Beskryf n tipiese entprogram teen Newcastlesiekte in braaikuiken teelouers wat gedurende grootmaak gebruik word. a) Paramyxovirus b) GIT, respiratory, nervous c) >75% mortality, nervous signs, green diarrhoea, respiratory signs incl haem tracheitis. d) MDT or ICPI (in full) e) Live vaccines at day old, boost between 10 and 21 days, second booster Inactivated vaccines late rearing twice usually 14. Avian influenza a) Name the aetiological agent. (1) b) What are the most important signs/post mortem lesions would you expect to see in laying hens in the event of an outbreak of fowl plague in South Africa? How would these differ from an outbreak of Newcastle disease in laying hens? (3) Influenza van voels. a) Noem die organisme wat die siekte veroorsaak. b) Wat is die belangrikste tekens/nadoodse letsels wat jy sal verwag om te sien in lehenne as daar n uitbraak van hoenderplaag so gebeur in Suid Afrika? Hoe sal hierdie verskil van Newcastlesiekte in lehenne? a) orthomyxovirus b) acute high mortality (up to 100%) not ND as hens vaccinated generalized petechial haemorrhages in carcasses nervous signs 15. Which viruses are associated with egg shell changes in layers? (3) Watter viruses veroorsaak veranderings in die eierdop in lehenne? ND, IB, EDS 16. Broilers showing signs of dyspnoea are submitted for post mortem examination. On post mortem the birds show signs of a purulent sinusitis, a moderate tracheitis, lung congestion and thick off-white pus in the airsacs. The birds are 34 days old and there is a history of increased mortality over the past week. a) If you perform a bacterial culture of the pus in the airsacs, what organism are you most likely to isolate? (1) b) What other bacteria are you likely to isolate? (3) c) Assuming the bacteria are secondary pathogens, list some important possible primary causes of this problem. (not including primary pathogens) (4) d) List 4 viruses that may be the primary problem in this case. There may be other post mortem lesions which have not been described. (4) Braaikuikens wat tekens van dispniee ways word ingehandig vir nadoodse ondersoek. By nadoodse ondersoek tton die voels tekens van etterige sinusitis, trageitis, long kongestie en dik witterige etter in die lugsakke. Die voels is 34 dae oud en daar is n geskiedenis van verhoogde mortaliteite die afgelope week. a) As jy n bakteriese kweking van die etter in die lugsakke doen, watter organisme is die een wat jy die waarskynlikste sal isoleer? b) Watter ander bacteria sal jy waarskynlik isoleer?
c) Mens kan die aanname maak dat die bakterie sekondere infeksies is. Maak dan n lys van n paar belangrike moontlike primere oorsake van hierdie probleem.(primere patogene mag nie daarby ingesluit word nie.) d) Maak n lys van 4 virusse wat moontlike primere oorsake kan wees van die probleem. Daar mag wel verdere PM letsels wees wat nie genoem is nie. a) E.coli b) Pasteurella, ORT, Salmonellae. Staph. c) Poor ventilation - dust, ammonia damage muco-cilliary escalator Poor temperature control stress and immuno-suppression, high waste gases d) ND, IB, TRT, ILT, IBD,