The incidence of lamb mortality from birth to 8 months of age has been studied over a 6-year period in an upland, grassland flock of sheep comprising the Scottish Blackface, Cheviot and Welsh Mountain breeds and the crosses among these breeds. Each breed and cross-bred type was maintained at varying levels of inbreeding. Approximately half the lambs which died were stillborn or dead on the day of birth, nearly 40 % died thereafter but before weaning and about 10% after weaning.Post-mortem examinations on 586 of the 632 lambs which died from among the 2453 born attributed death on average to two causes per lamb. Approximately 11 % of the causes were stillbirths or delayed births; 11 % were cases of dystokia; congenital defects of various types accounted for about 10% of the causes; 25% made reference to weakly lamb, exposure or starvation; 14% to infectious diseases and 16% to noninfectious diseases. The extent to which causes of death occur together is examined.Breeds differed in mortality rate with the Welsh the lowest and Cheviot the highest. Cross-breds were better than the average of the pure breeds but this advantage emerged only in the period between 3 days and. 6 weeks of age. Inbreeding, both of dam and of lamb, increased mortality. Lambs from dams which were crosses of inbred lines had the best survival. Litter size, type of rearing, parity of dam, sex of lamb and birth weight also had significant effects on mortality rate. INTRODUCTION describe breed differences in relation to specific causes of death. Many studies of sheep flock performance provideThe present study was initiated primarily with information on the incidence of lamb mortality in the latter end in view: to document the lamb different countries and farming circumstances and mortality rate in relation to three breeds and their at different periods between birth and weaning, crosses kept together as a single flock and also subSome describe the effect of factors such as number jected to intense inbreeding. The effects of breed, of lambs born, parity, management, nutrition and cross-breeding and inbreeding were further studied other environmental variables and a smaller number m relation to the causes of death as identified at of papers present information on causes of death, post-mortem examination. Other factors affecting Although these reports encompass many breeds and variation in overall mortality and the incidence of crosses of sheep, only a few can be interpreted as different causes are also examined, showing whether genetic variation contributes sigAn early finding in this flock was that both breed nificantly to lamb survival and even fewer papers a n d breeding system affected overall lamb mortality

Hepatic lipodystrophy has been recognised in pedigree Galloway calves since 1965. Between 1975 and 1984 15 cases from five farms were examined. The calves initially appear normal and in good bodily condition but invariably die by five months of age. The characteristic clinical and neurological changes lead to body tremors, opisthotonus, and dyspnoea before the animals become recumbent and die. On postmortem examination the most significant finding in all cases was an enlarged, pale and mottled liver weighing up to 2.75 kg. Limited histopathological examinations of the brain and liver revealed changes suggestive of hepatic encephalopathy. Exhaustive investigations of the farms failed to reveal any significant findings and the small number of cases made it impossible to determine whether the disease was genetically determined; limited evidence suggests that a 'storage disease' cannot be excluded.

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Following accidental overdosage with monensin, nine deaths occurred in a batch of 40, four-to-seven-month-old calves. A description of the incident is given including the findings on post mortem examination. Inaccurate on-farm feed mixing can present problems as was highlighted by this outbreak.

An outbreak of listeriosis occurred in five-week-old lambs in a flock of 200 Dorset ewes and 240 lambs in-wintered. Nine lambs were lost within a period of 10 days. No cases of stillbirth or abortion or cerebral listeriosis occurred in the ewes. Silage had been fed on this farm to both cattle and sheep for 10 years without any previous problems. A description of the outbreak and the findings are reported.