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Viral infection dynamics and bovine respiratory disease (BRD) treatment rates were studied over six years at a Swedish bull testing station with an 'all in, all out' management system. In August of each of the years 1998-2003, between 149 and 185 4-8-month-old calves arrived at the station from 99 to 124 different beef-breeding herds, and remained until March the following year. Only calves that tested free from bovine viral diarrhoea virus (BVDV) were allowed to enter the station and original animal groups were kept isolated from new cattle in their original herds for three weeks before admission. Although neither prophylactic antibiotics, nor BRD vaccines were used, less than 0.7-13.2% (mean 5%) of the calves (n=970) required treatment for BRD during the first five weeks following entry. This was probably due, at least in part, to the season (the summer months) when the animals were commingled. In the six-month period August-February, 38% of the animals were treated one or more times for BRD and mortality was 0.7%. Hereford and Aberdeen Angus calves had significantly higher treatment rates than Charolais, Simmental and Blonde d'Aquitaine. Serological testing on samples obtained in August, November and January indicated that bovine parainfluenza virus 3 (PIV-3) infections occurred each year before November after entry. Bovine coronavirus (BCoV) infections also occurred every year, but in 3/6 years this was not until after November. Bovine respiratory syncytial virus (BRSV) infections occurred only every second year and were associated with a treatment peak and one death on one occasion (December). The herd remained BVDV free during the entire study period. The infection patterns for PIV-3 and BCoV indicated a high level of infectivity amongst bovine calves, whereas the incidence for BRSV was observed at a lower level. Although the rearing of the animals differed from conventional beef production, the study has shown that commingling animals from many sources is not necessarily associated with high morbidity within the first few weeks after arrival. By preventing BRD soon after commingling the prerequisites for protective vaccination at entry might be improved. Applied management routines are discussed.

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Previous studies have shown that between-year transmission of Haemonchus contortus in Swedish sheep flocks is almost entirely as over-wintered populations within housed animals, and not on pasture. This suggests that eradication of this parasite is a realistic possibility. Thus, two sheep farms with a history of H. contortus infection on the Swedish island of Oland were selected for study. During the winter housing period of 2003/2004 all ruminants (sheep and cattle) on both farms were treated with ivermectin. Monitoring by faecal egg counts and infective larval differentials of ewes and lambs for the subsequent two grazing seasons, together with total abomasal worm counts of 10 lambs from each farm at the end of the first grazing year, showed that this objective was achieved.

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Postweaning multisystemic wasting syndrome (PMWS) is causally associated with porcine circovirus type 2 (PCV2) infection of pigs. PCV2 has been present in the Swedish pig population for at least ten years. Despite this, no signs of PMWS were observed in pigs of Sweden until 2003. Since then the disease has spread slowly in Sweden. The pig population of Sweden is geographically isolated, the density of pigs and the pathogen load in the country is low and the trade of animals is organised in a restricted way. To date, there has been little information placed in the peer-reviewed literature on the study of the spread of PMWS in a country during the early phase of the disease outbreak, mainly because diagnosis of PMWS has only occurred after the disease has been recognised on a number of farms. This manuscript documents the studies to date on the PMWS outbreak in Sweden which has been closely monitored since the initial outbreak of diseases on a single farm in 2003 was diagnosed. In Sweden PMWS was officially reported for the first time at a progeny test station during December 2003. One year later sixteen herds have been diagnosed and reported to the authorities: one progeny test station, one nucleus herd, thirteen piglet producers or integrated herds and one specialised fattening herd. Fifteen suspected cases have been deemed negative for PMWS with disease scenarios associated with Lawsonia intracellularis, Brachyspira pilosicoli, Mycoplasma hyopneumoniae, shortcomings in feed composition etc. To date, one year after the index case was reported ten other herds suspected for PMWS are under observation. The PMWS cases are concentrated into the southern part of Sweden. However, the disease is spreading slowly, and in general there are no obvious physical links between affected herds. The data generated to date in Sweden suggest that introduction of a new contagious microbe into the country that is responsible for the PMWS outbreaks appears unlikely, as does the spread of PMWS via semen.

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The numbers of Eimeria oocysts per gram (opg) and the dry matter content of 449 faecal samples taken from 54 calves in 8 herds in south west Sweden were determined during the last 2 weeks before and the first 3 weeks after the animals were turned out to pasture. While they were housed only between 0 and 580 opg were found and in 2 of the herds the numbers of oocysts remained low after turn-out. In the other 6 herds the numbers of oocysts increased after 8 to 10 days and reached a peak of between 1080 and 80,803 opg 9 to 18 days after turn-out. By 21 to 24 days after turn-out the opg-values had declined to their initial levels. Eimeria alabamensis accounted for most of the increase, but small numbers of oocysts of E. auburnensis, E. bovis, E. bukidnonensis, E. cylindrica, E. ellipsoidalis, E. pellita, E. subspherica, E. wyomingensis and E. zuernii were also observed. The interval between turn-out and the start of the increase in excretion of oocysts corresponded closely to the prepatent period of E. alabamensis and overwintered oocysts were therefore the most likely source of the infection. In 6 of the herds the dry matter content of the faeces of the calves decreased after turn-out and 56% of the calves had clinical diarrhoea. Although it cannot be excluded that change of diet may have contributed to these symptoms, E. alabamensis infection is suggested as a potential cause of diarrhoea and loss of condition in calves in Sweden during their first weeks on pasture.

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The aim of the study was to investigate whether vitamin E supplements in larger amounts than recommended could reduce incidence of disease, improve immune competence, and increase rate of weight gain of conventionally barley-fed beef cattle. Mean daily intake of vitamin E by individual calves in the experimental group was 200 mg during the first 2 mo, 400 mg during the next 2 mo, and 600 mg during the rest of the period. Corresponding daily intakes of vitamin E for the control group were 50, 100, and 150 mg. Mean plasma vitamin E of the experimental group increased from .49 mg/L at the start of the trial to 2.03 mg/L at the end, but that of the control group was lower at the end (.36 mg/L) than at the beginning (.53 mg/L). No significant differences were observed between the groups concerning incidence of disease or magnitude of lymphocyte stimulation. The results indicated that there was a surprisingly poor biological availability of the dietary vitamin. Therefore, a comparison in reality was made between calves with inadequate and normal vitamin E status. The differences in daily BW gain and time to reach slaughter weight thus probably were effects of the low vitamin E status rather than positive effects of additional vitamin in the diet.

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During the 6 years 1979-1984, the use of the morantel sustained release bolus (MSRB) was monitored in first year grazing calves. Twenty-four to 30 calves each year were allotted to two groups (controls and MSRB-treated) and turned out at the end of May on the same pasture divided into two equal areas. After housing in October, each group was kept in boxes and fed concentrates, whey and hay. The calves were weighed at monthly intervals until the first animals were sent to slaughter. No cases of clinical ostertagiasis Type I were observed in the control calves during the grazing seasons, but in one year (1983) clinical signs occurred 2 weeks after housing. The number of overwintering larvae was influenced by pasture contamination the previous season and climatic conditions during winter and spring. The fecal egg output of the control animals during the grazing season did not reflect the level of pasture contamination at turnout. The build-up of pasture larval contamination during the later part of the grazing season was influenced by the climatic conditions. The fecal egg output of the treated calves was low during the entire grazing season resulting in a significantly reduced pasture contamination. A significantly reduced live-weight gain in the control calves was demonstrated at housing in five of the six years. When heavily infected at housing, the performance of the control calves was still influenced negatively during the fattening period indoors.

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A field trial was designed to compare the efficacy of a pregrazing treatment with a morantel sustained release bolus and two strategic treatments of levamisole in the prevention and control of gastrointestinal parasitism in first year grazing cattle. The infection of calves, pasture contamination and the subsequent effects on performance were recorded.

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To study the preventive effect of supplementary iodine on interdigital phlegmon, 50 Swedish red and white calves weighing approximately 100 kg each were given 1 mg ethylenediamine dihydroiodide (EDDI) per kg bodyweight daily. Fifty calves in the same herd were untreated controls. As a result of severe side effects the experiment was interrupted after five weeks. No case of interdigital phlegmon was observed, but 31 calves in the EDDI group and one in the control group were treated for respiratory disease. Serum protein bound iodine increased on average from 68.0 to 213.0 micrograms/litre in the EDDI group compared to an increase from 59.9 to 70.7 micrograms/litre in the control group.

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During two consecutive grazing seasons, the strategic use of the morantel sustained release bolus (MSRB) was monitored each year in first season grazing calves (maintained both years on the same pasture). The object of the study was to determine the effects of bolus treatment in young calves during successive years on the level of pasture larval contamination available at the beginning of the second year, and on the pattern of pasture recontamination that occurred during the second year. The level of worm burdens acquired in the trial animals at the end of the grazing season was determined both years. Tracer worm counts were determined during the first year of the study, while faecal worm egg counts, herbage larval counts and weight gain were monitored both years. During the first year (1979) the selected pasture was equally divided into three separate paddocks. Two paddocks were grazed by control calves, while each animal grazing the third paddock received a bolus at the time of turnout. During the second year (1980) three groups of calves were used. One group was treated with the bolus and grazed the same paddock as calves treated with the bolus the previous year. The second group was treated with the bolus and grazed the control paddock from the previous year, while the third group of calves remained nontreated and grazed the remaining paddock grazed by control calves from the previous year. As a result of the bolus treatment during the first year, the number of overwintering nematode larvae recovered the following spring was considerably lower than the number recorded on the paddock grazed previously by control animals. Worm counts and efficacy calculations demonstrated that worm burdens accumulated during the season were considerably lower in the bolus treated cattle during the second year than during the first. These parasitological differences were reflected in the weight gain comparisons between the treated and control cattle. Although significantly improved weight gains were recorded for both groups of treated cattle compared with the control cattle during the second year, the treated cattle grazing the treated paddock had a greater improvement than the treated cattle grazing the control paddock from the previous year.

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The effect of a morantel sustained release bolus (MSRB) to control gastrointestinal parasitism in cattle grazing their first season was assessed under field conditions in Sweden. The MSRB was administered orally to calves immediately prior to turnout onto spring pastures in May 1978. The level of pasture contamination of infective larvae was decreased by 73 per cent in August and by 98 per cent in September. There was a 72 per cent reduction in worm burdens acquired over the entire grazing season. During the same period the mean improvement in weight gain was 21.5 kg per animal. Weight gains were also recorded during housing until slaughter in April 1979, i.e. 335 days after MRSB administration at which time the treated animals were on an average 17.1 kg heavier than controls.

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The efficacy of a morantel sustained release bolus (MSRB) to control gastrointestinal parasitism in first season grazing cattle was assessed under field conditions in Sweden. The MSRB was administered orally to calves immediately prior to turnout onto spring pastures in May, 1979, or in mid-season (July). The level of pasture contamination with infective larvae was reduced by 99 per cent in September by treatment at turnout. The corresponding figure was 89 per cent when the MSRB was administered in July. There was a 95 per cent reduction in worm burdens acquired over the entire grazing season in cattle treated in the early season and a 44 per cent reduction in worm burdens of cattle treated in the mid-season. During the 132 days grazing period a 19.1 kg (p less than 0.01) mean weight gain advantage was achieved by the early season treated animals, while a 10.0 kg mean weight gain advantage was achieved by the mid-season treatment. The weight gain advantage at the end of the grazing season in the early treated cattle increased continually during the winter with a resultant mean difference of 44.4 kg (p less than 0.01) by April 1980. Over the same period the mean weight gain advantage of the mid-season treated animals gradually fell to a final of 5.5 kg.

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