Comparative study of gastrointestinal helminthiasis in sheep on 'clean' grazing and permanent pasture under field conditions.

An investigation of sources of helminth infection was carried out on three flocks: a traditional permanent pasture flock (A), one operating a 'clean' grazing system (B), and an East of Scotland College flock (C) which had operated a clean grazing system for nine years. Ewe and lamb worm egg output and pasture larval levels were recorded and tracer lambs were grazed during July and August on each farm. Considerable contamination was present on farm B fields compared with farms A and C, which resulted in higher worm burdens in late summer in farm B tracer lambs and lower weight gains. The main source of this infection was thought to be ewe periparturient egg output, as 21 per cent of ewes had positive worm egg counts over the lambing period. Differences in management practices between farms B and C, eg, earlier stocking of farm B fields, were also considered contributory factors.

Epidemiology of Nematodirus battus infection in eastern Scotland.

A field investigation was carried out from 1981 to 1983 on the prevalence of Nematodirus battus under different systems of lowland sheep management. Pasture larval counts, ewe and lamb worm egg counts, and tracer lamb worm counts were carried out. As expected, contamination was generally greater on permanent pasture than on new leys as measured by pasture larval counts and lamb worm egg counts. However significant contamination was also recorded on young grass fields for which alternate grazing with young calves may have been partly responsible. It is suggested that the 1983 hatch was delayed because of a drop in soil temperature in late March which may have increased subsequent scour problems involving N battus seen in May.

An outbreak of S typhimurium in sheep and its consequences.

An outbreak of Salmonella typhimurium in an upland sheep flock was characterised by rapid spread and heavy mortalities in ewes and young lambs. Clinical signs included diarrhoea and abortion. Abomasitis was the most striking and consistent post mortem lesion. Vaccination was the only control method that was apparently successful. Infection also occurred in the cattle, farm personnel, and a dog. Following the outbreak, pasture contamination and excreting cattle provided a reservoir of infection so that contamination of water courses and sporadic cases occurred over a year later.

Some problems in assessing the physiological and economic significance of hypocupraemia in beef suckler herds.

Factors influencing the incidence of hypocupraemia and responses to copper therapy were investigated in three beef suckler herds calving in spring and early summer. On farm A hypocupraemia was most severe (plasma copper less than 0.4 mg per litre) in March for the cows and in October/November for their calves. On farm B plasma copper levels were 30 per cent lower in five to eight-year-old cows than in two-year-old cows in late November. Administration of copper (100 mg) in late pregnancy significantly increased plasma copper in the suckled calves on farm A but not in their dams after parturition. Growth of the calves was not increased. The alleviation of severe hypocupraemia on a third farm (C) by injecting the calf with copper did not improve growth rate. It is concluded that in some areas a severe seasonal hypocupraemia may be tolerated without loss of productivity.

Field trials of an inactivated oil-adjuvant vaccine against louping-ill (Arbovirus group B).

A single dose of inactivated louping-ill oil-adjuvant vaccine elicited a sero-logically detectable immune response in sheep lasting for at least 1 year. These sheep when exposed to a natural focus of louping-ill virus were completely protected from clinical disease and 1 year after vaccination were able to pass on a substantial maternal immunity to their lambs.Twenty-nine per cent of unvaccinated sheep, exposed at the same time, died from clinical louping-ill; half of the survivors showed positive sero-conversion and became immune, while the other half remained susceptible. The incidence of fatal encephalomyelitis in sheep which were known to have circulated virus exceeded 50% in 2 out of 3 trials conducted simultaneously in different locations in Scotland in 1969.