Ochratoxin A in swine blood used for evaluation of cereal handling procedures.

In a survey during the years 1985, 1986 and 1987 the quality of Swedish feeding grain was followed by the analysis of ochratoxin A in blood collected from swine at slaughter. The swine herds sampled were selected on feed handling procedures used. From information about the feed used, risk parameters for ochratoxin A contamination were identified. The results showed annual variation in the content of ochratoxin A in the grain and that ochratoxin A increased during storage of grain, particularly in the harvest of 1985. Drying of the grain with forced ambient air was found to be inferior to the use of heated forced air. It was also noticed that more than 9% of the grain was contaminated with ochratoxin A regardless of handling. The pronounced difference between the samples studied was seen mainly as a function of geographical origin, with the island of Gotland having a much higher frequency of positive samples than the rest of Sweden. No correlation between ochratoxin A in swine feed and post mortem signs of infectious diseases in the swine herds was found.

Actinobacillus (Haemophilus) pleuropneumoniae infections in swine: serological investigations and vaccination trials in combination with environmental improvements.

The present investigation comprised six integrated herds (100-150 sows each) and one specialized fattening herd. Serologic tests by ELISA were performed on blood samples from piglets and growing pigs during various rearing phases in order to determine the presence of Actinobacillus infection and to estimate the age of the animals at onset of the disease. Using this information, herd-specific vaccination programs were designed against Actinobacillus pleuropneumoniae serotype 2. The weaned piglets in the integrated herds were vaccinated twice before being moved to the fattening unit. In the specialized fattening herd, the pigs were vaccinated on arrival at the growing unit and just before transfer to the finishing unit. The frequencies of chronic pleuritis at slaughter demonstrated that a vaccination program adapted to the herd-specific problem, in combination with environmental improvements, reduces the prevalence of chronic pleuritis. On the other hand, only a moderate reduction of the prevalence of chronic pleuritis occurred as a result of vaccination if no environmental improvements were made. In two of the herds during the vaccination period, the number of feeding days and food consumption decreased, while growth per day increased. There was also an apparent correlation between higher serum titres and a decreased prevalence of pleuritis at slaughter in three of the herds.

Virulence factors in Escherichia coli strains isolated from Swedish piglets with diarrhea.

Parenteral vaccination of sows against Escherichia coli diarrhea in their newborn piglets has become more common during the last decade in Sweden, and the vaccination has generally had positive effects. For more than 20 years we have investigated E. coli strains isolated from piglets and weaned pigs with enteric disorders, noting the presence of O groups, enterotoxins, and adhesins. There has been a continuous change in the frequency of these virulence factors. The present study was performed during 1983 and 1984 to follow this change, since such information is essential for the proper choice of vaccines. A total of 856 E. coli strains were obtained from 683 herds divided into three age groups: 1 to 6 days old, 1 to 6 weeks old, and weaned pigs. O group 149 still dominated in the last two age groups, while O group 101 was, for the first time, the most frequent O group in neonatal piglets. All but four O149 strains carried the K88 antigen, which was found in only one other strain (O group 8). K99 antigen was most often found in O groups 101 and 64, and among all the K99 strains ST mouse was the most common (44 of 57), followed by ST mouse-ST pig strains (12 of 57). The 987P antigen was demonstrated in 26 strains belonging to O groups 141 and OX46 and nontypable strains. Two strains belonging to O group 101 were positive for F41 antigen; one of them also carried the K99 antigen. Among all non-O149 strains, ST mouse was the most common type of enterotoxigenic E. coli ( n = 88), followed in decreasing order by ST mouse-ST pig strains ( n = 69) and ST pig strains ( n = 33). In 114 strains producing enterotoxins no adhesive factor was found. Thus, vaccination of the Swedish sow population for more than 5 years with vaccines containing O149 and K88 antigens has apparently changed the pattern of enterotoxigenic E. coli in neonatal diarrhea. The frequency of O149:K88 strains has been reduced, and O101:K99:ST mouse strains now dominate. However, O149 strains remain the dominant O group in piglets older than 1 week. In spite of all our diagnostic efforts, no virulence factors were detected in about one third of the piglets and weaned pigs with enteric disorders.

Ochratoxin A in blood of slaughter pigs.

The global ochratoxin A contamination of Swedish feed cereals was studied by analysis of pig blood samples from 122 different herds. The samples were collected at seven Swedish slaughterhouses. The ochratoxin A analysis showed 21% of the samples to contain greater than or equal to 2 ng ochratoxin A per ml. Samples from Visby showed a significantly higher frequency of contamination compared with the rest of the country.

Clinical trial of a PMSG/HCG preparation combined with natural oestrus induction in sow herds with oestrous problems.

The effect of a consistent programme for oestrus control and oestrus induction has been investigated in some herds with oestrous problems already participating in the efficiency control programme (RASP). Forming part of the project was a clinical trial of a PMSG/HCG preparation (SUIGONAN VET.) to be applied in cases where natural stimulation of sows did not lead to oestrus. The other herds participating in the efficiency control programme of the same area were used as control herds. In the trial herds the below treatment programme was followed: Gilts not showing oestrus at the age of 8 months were treated with hormones. Sows which had farrowed at least twice and did not show oestrus less than 10 days after weaning were also treated with hormones. All primiparous sows were treated with a hormone preparation on the day after weaning. These animals were observed during an additional reproduction cycle to demonstrate the possible negative effect of the hormones on the following oestrus/pregnancy. The results of the gonadotropin treatment of gilts and older sows were not encouraging. However, the treatment may have a certain prognostic value as slaughter should be considered in cases where the sows do not show signs of oestrus within a week after treatment. The results of the treatment of primiparous sows were satisfactory with respect to oestrus as well as to the result of parturition after service. Treatment of primiparous sows on the day after weaning must be limited with regard to time (max. 1--2 months) to remedy occasional oestrous irregularities which it has not been possible to cure by natural oestrus induction.

On porcine toxoplasmosis in Sweden.

An outbreak of fatal toxoplasmosis in piglets, probably of congenital origin is described. Although this is the first known manifest case of porcine toxoplasmosis in Sweden it is concluded that it is based on a well established latent infection of the pig population in the area concerned. Of a random sample of clinically healthy slaughtered pigs from the area 40.3 per cent were positive in Sabin-Feldman dye-test.