THE PREVALENCE AND RISK FACTORS FOR MORTALITY IN SPRING LAMBING FLOCK: A CROSS SECTIONAL STUDY

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1 THE PREVALECE AD RISK FACTORS FOR MORTALIT I SPRIG LAMBIG FLOCK: A CROSS SECTIOAL STUD L.E. Green, I. Cox, S. Rizvi, R. Hanagan and S. Knox Department Clinical Veterinary Science, University of Bristol, Langford. Introduction An area of great con cern within the sheep in dus try world-wide is the level of lamb mor tal ity. Losses of be tween 10% and 15% have been gen er ally ac knowl edged within the UK; this re flects over 4 mil lion lambs per year, the ma jor ity of these die within the first seven days of birth. Small, male lambs from mul ti ple births are at great est risk. The overwhelming majority of lamb deaths can be divided into four categories: starvation /hypothermia/exposure, stillbirth/dystocia, infectious disease and abortion. These share common underlying risk fac tors, for ex am ple poor ma ter nal nu tri tion, in suf fi cient colostrum in take, poor hy giene at lamb ing and cold stress. Lamb mor tal ity not only rep re sents a con sid er able fi nan cial loss, it has also been high lighted as an area of poor wel fare and may af fect pub lic per cep tion of the sheep in dus try. The United King dom has the larg est sheep flock in the Eu ro pean Un ion and also has his tor i cally high wel fare stan dards, it is there fore very im por tant that we lead the field in re duc ing lamb mor tal ity. The aims of this pro ject were there fore to: a) es ti mate the pro por tion of neo na tal (less than 7 days old) lamb deaths from spring lamb ing flocks scat tered through the UK in 1997, b) to iden tify the man age ment fac tors as so ci ated with these deaths and c ) to identify areas where information transfer from researchers to farmers needs im prov ing. Materials and Methods A ques tion naire was de signed to col lect the in for ma tion listed above. It was pi lot-tested on a lo cal sheep farmer and sent to the Sheep Vet er i nary So ci ety ex ec u tive com mit tee and also to the co-ordinating members of staff at Bris tol, Cam bridge, Ed in burgh, Glas gow, Liv er pool and Lon don vet er i nary schools for com ment. The fi nal ver sion was dis trib uted to the co-ordinators and for warded to all first year vet er i- nary un der grad u ates to fill in dur ing their lamb ing prac tice in the Easter va ca tion of Spring

2 L.E. Green, I. Cox, S. Rizvi, R. Hanagan and S. Knox Each stu dent re ceived: Lambing Re cord Sheet: re corded num ber of lambs born alive, dead or mum mi fied, plus any fos ter ing, for 300 ewes per farm. Lamb Death Sheet: re corded sex, age at death, plus num ber of sib lings for up to 100 lambs per farm. Flock His tory Ques tion naire: re lated to man age ment pro ce dures in the last year, the occurrence of abortion, disease and vaccination, nutrition throughout the year and production Tables. Lambing Ques tion naire: di vided into sep a rate sec tions for in door/ out door lamb ing, and in clud ing de tails of aid dur ing lamb ing, clean ing prac tices, and gen eral lamb man age ment. Con di tion score sheet: each stu dent was re quested to per son ally con di tion score 50 ewes. A 100 prize for the best stu dent re port at each uni ver sity was ad ver tised us ing post ers to en cour age students to participate in the study and return the questionnaires. The ques tion naires were re turned to Bris tol be tween April and Au gust The data were en tered into a da ta base (FoxPro 3.2); fre quency dis tri bu tions and sim ple anal y sis were then per formed in Epi Info Results Of the 585 ques tion naires is sued, 108 were re turned, re flect ing an av er age re turn rate of just un der 20%. This was highly vari able be tween schools, one school did not re turn any ques tion naires. Over all lamb mor tal ity re ported by farm ers for ranged from 9 to 11%, with lambs be ing most likely to die in the im me di ate post-partum pe riod (Ta ble 1). Male lambs and those with sev eral sib lings were at in creased risk. There were as so ci a tions be tween low pre-turn out mor tal ity (<2%) and farm ers re port ing, rou tine use of an ti bi ot ics (OR=2.67), pres ence of hot boxes (OR=3.64), pres ence of iso la tion Ta ble 1 Lambing per cent age and mor tal ity by flock type Lambing results Geographical flock type Hill Upland Lowland Lambing percentage Lambs born dead (%) Lambs dying before turn out (%) Lambs dying after turn out (%)

3 THE PREVALECE AD RISK FACTORS FOR MORTALIT fa cil i ties (OR=4.14) and the use of intra-peritoneal glu cose in jec tions for hypothermic lambs (OR=3.16). (Ta ble 2). Table 2 s associated with pre-turnout mortality less than two percent. Associated < 2% 2% OR 95% CI P Antibiotics routinely used Presence of hot-boxes Presence of isolation facilities 5 11 Use of IP injections CI = con fi dence interval The rou tine use of an ti bi ot ics was as so ci ated with the farmer re port ing that wa tery mouth was not a prob lem (OR=3.03) (Ta ble 3). Keeping lambs in moth er ing pens for greater than 72 hours was as so ci ated with the farmer re port ing a prob lem with na vel ill (OR=3.25) (Ta ble 4). Flocks with a lamb ing pe riod of greater than 6 weeks had an in creased risk of pre-turnout deaths (OR=3.70) and pneu mo nia (OR=2.50) (Ta ble 5). Table 3 Association between antibiotics and watery mouth. Watery mouth es o OR 95% CI P Antibiotics routinely used Table 4 Association between time kept in and navel ill avel ill es o OR 95% CI P Lambs kept in for > hours

4 L.E. Green, I. Cox, S. Rizvi, R. Hanagan and S. Knox Table 5 Association between lambing duration and lamb pneumonia Lambing duration (weeks) 6 > 6 OR 95% CI P Pre-turn out mortality < 3% % Lamb pneumonia in Table 6 Students reports of body condition score of ewes (total examined = 4813) Body condition score umber of ewes % of ewes Warming aids were ab sent on 15% of farms, and when pres ent they were in low num bers and are mainly the less de sir able heat lamps rather than hot boxes. The tech nique of intra-peritoneal glu cose injec tions was also rarely used. Re sults from the farmer in ter view in di cated that, at tup ping, 15% of farm ers aimed for and 20% achieved av er age body con di tion scores (BCS) of sheep be low those rec om mended (2.5, 3 and 3.5 for hill, up land and low land flocks re spec tively). By lamb ing 30% of sheep had av er age con di tion scores below rec om mended lev els (2, 2.5 and 3) and 33% of these had BCS 1.5 or less (Ta ble 6). Over 75% of farms had at least one ewe with BCS 1.5 or less. BCS done by the stu dents in di cated sig nif i cant vari a tion be - tween farm types, hill sheep had lower BCS than up land or low land sheep. Stu dents taught to BCS by farm ers re ported sig nif i cantly higher BCS than stu dents taught by Vet. Schools. Discussion Results from this study indicate that farmer reporting of mortality is similar to previous estimates of lamb mor tal ity. Sev eral man age ment fac tors were seen to be sig nif i cantly as so ci ated with re duced lamb mor tal ity. These in clude the pres ence of both iso la tion and warm ing fa cil i ties, which if adopted by more farm ers may re duce mor tal ity fur ther. It was dis con cert ing, though per haps not sur pris ing to find that the rou tine use of an ti bi ot ics was as so ci ated with re duced mor tal ity. Finally, the re sults from this study 54

5 THE PREVALECE AD RISK FACTORS FOR MORTALIT in di cate that the tar get lev els for body con di tion score are not known by all farm ers and the cur rent method of body con di tion scor ing is not con sis tent be tween us ers which may make it an in ef fec tive technique. Since it is vi tal to the suc cess of all as pects of sheep pro duc tion that ewes and rams are in ad e quate body con di tion, this should be an area of con cern to all the sheep in dus try. Acknowledgements We would like to thank the co-ordinators at the schools who made this pro ject suc cess ful, all the students who dil i gently filled in their forms and the SVS for con trib ut ing to wards the fi nan cial sup port of this pro ject. Ian Cox ana lysed these data whilst in re ceipt of a Wellcome Trust Va ca tion Studentship. References Eales F.A, Small J., and Gilmour J.S., (1983) eo na tal mor tal ity in lambs and its causes. Sheep Pro duc tion; Haresign W (ed.), pp Butterworths, Lon don. Eales F.A., Gilmour R.M., Barlow R.M., and Small J., (1982) Causes of hy po ther mia in 89 lambs. Veterinary Re cord, 110; Green L.E. and Mor gan K.L., (1993), Mor tal ity in early-born housed lambs in South West Eng land. Pre ven tive Vet er i nary Med i cine 17; Green LE and Mor gan KL (1994). Risk fac tors as so ci ated with postpartum deaths in early born, housed lambs in south-west Eng land Prev Vet Med Henderson D.C., (1990), The vet er i nary book for sheep farm ers. Farming Press Books, 1 st Edi tion. Johnston W.S., Maclachan G.K., Murray I.S., (1980) A sur vey of sheep losses and their causes on com mer cial farms in the north of Scot land. V ete rin a ry R eco r d, 106; Mar tin W.B. and Aitken I.D., (1991) Dis ease of Sheep, Blackwell Sci en tific Pub li ca tions Mellor D.J. and Murray L., (1985) Ef fects of ma ter nal nu tri tion on the avail abil ity of en ergy in the body re serves of foe tuses at term and in colostrum from Scot tish Black face ewes with twin lambs. Re search in Vet er i nary Sci ence, 39 ;