[Specific pathogen-free health programs]. / Specifieke pathogeen-vrije gezondheidsprogramma's.

SPF programs have been established in various countries, particularly in Denmark and Switzerland these programs are already well advanced. The system proves to be advantageous for export dealings but also with regard to public health. Dalland is an internationally operating Dutch pig breeding organisation. In 1989 a SPF nucleus breeding farm was established in North-East France. A special program was set up for the supply of animals from this SPF nucleus. In this paper it is concluded that SPF can be economically beneficial. Under certain well-described circumstances SPF breeding seems feasible. Its is suggested that in future pigs could be produced that will be free of enteropathogens of interest to public health, e.g. Salmonella, Campylobacter and Yersinia enterocolitica.

[Study of the possibility of breeding serologically negative animals from a breeding farm infected with serotype 2 Actinobacillus pleuropneumoniae]. / Onderzoek naar een mogelijkheid om vanuit een met Actinobacillus pleuropneumoniae serotype 2 geïnfecteerd fokbedrijf serologisch negatieve dieren op te fokken.

Two sanitation trials showed that it was possible to rear serologically negative animals from pigs on a breeding farm infected with Actinobacillus pleuropneumoniae serotype 2. This was achieved by the medication of sows and piglets during the farrowing-house period and by isolating the piglets from the infected stock of pigs immediately after weaning. Medication of the sows consisted in administering sulphamethoxazole-trimethoprim in the drinking water for a period from five days before to eight days after farrowing. The piglets were treated by injections of sulphadoxine-trimethoprim on days 3, 10, 17 and 24.

[Vaccination using an inactivated vaccine on a pig-breeding farm infected with the virus causing Aujeszky's disease (author's transl)]. / Vaccinatie met een geïnactiveerd vaccin op een met het virus van de ziekte van Aujeszky besmet varkensfokbedrijf.

When Aujeszky's disease was detected on a large pig-breeding farm, all normal sows and boars were vaccinated with an ethyl-ethylene-imine (EEI) vaccine produced in the Bundesforschungsanstalt für Viruskrankheiten der Tiere (Federal Research Institute for Viruses Diseases in Animals) in Tübbingen, Western Germany. The vaccine contained DEAE dextran as an adjuvant. The vaccine was inoculated twice by intramuscular route at a three weeks' interval, 5 ml. being inoculated at one time. Hyperimmune serum was inoculated in young pigs. In addition, hygienic procedures were adopted, consisting in disinfection and isolation. The disease was successfully controlled within eight weeks. Sows which developed Aujeszky's disease showed hardly any symptoms suggesting lesions of the central nervous system. Pulmonary lesions were the outstanding clinical feature. The semen quality of the affected male swine had markedly deteriorated. This was resorted to normal, however, within from five to ten weeks. The incidence of abortion and piglet mortality were low. In view of the results of virological and serological studies, it was concluded that the persistence of this strain of virus (causing Aujeszky's disease) was very slight.

[Anaphrodisia in gilts and sows(author's transl)]. / Anaphrodisie bij gelten en zeugen

The economy of pig breeding and rearing farms is determined mainly by the fertility of the animals. Anaphrodisia causes a considerable disturbance of the fertility. This has a direct effect on the number of litters born per sow per year and thus on the economic results. On the basis of several years of experience at the research station and the production unit of Varkensonderzoekcentrum Nieuw-Dalland the clinical symptoms in gilts and sows are described. Gilts should normally have come into oestrus at the age of about 8 months, and on a well-managed farm about 80% of the sows should come into oestrus within 10 days of weaning, provided that weaning takes place at 5 to 6 weeks. Different forms of anaphrodisia are described, based on the findings of post mortem examinations. These show that in 65-75% of the anaphrodisiac animals the ovaries were insufficiently active. In 20% of the animals that had not shown signs of oestrus, ovulation had in fact taken place. The causes of anaphrodisia must be sought in a disturbance of the hypothalamo-hypophysial ovarian system, in which genetic and health factors play an important role, besides housing and management (insluding feeding). A good keeping of records of sows is indispensable in the solving of the anaphrodisia problem on farms, and this hinges also on an analysis of the farm management and on the power of observation of the farmer. Finally, hormonal therapy is discussed, a distinction being made between breeding and rearing farms.