Control of Sarcoptes scabiei var. suis with ivermectin: influence on scratching behaviour of fattening pigs and occurrence of dermatitis at slaughter.

The behaviour of fattening pigs, the occurrence of erythematous papular dermatitis in pigs at slaughter and the effects of treatment for mange with ivermectin at the start of the fattening period were evaluated at ten farms. At each farm, trial pigs were randomly allotted to a control or a treated group. At the start of the trial, the control group was injected intramuscularly with 5 mg kg-1 levamisole, and the treated group was injected subcutaneously with 300 micrograms kg-1 ivermectin. Skin scrapings, taken from each pig before medication at the start of the trial, and at slaughter, were examined for presence of sarcoptic mites. Pig behaviour was monitored at 2 week intervals from Week 5 to Week 13 of the trial. Carcasses of trial pigs were inspected for dermatitis at slaughter. Low to moderate Sarcoptes scabiei var. suis infestations were demonstrated at the start of the trial on five farms (S+ farms). At slaughter, the mean percentage of Sarcoptes-positive pigs per pen on S+ farms was 34.8% (range 11-60%) for the control group as compared with 0.5% (range 0-2.7%) for the ivermectin-treated group (P < 0.01). No S. scabiei was recovered from any pig at any time from the five other farms (mange-free (S-) farms). The low initial levels of mange in the controls at S+ farms resulted in a consistently high scratching index. Ivermectin treatment resulted in a significantly (P < 0.01) lower prevalence of scratching, comparable with the prevalence observed at S- farms. High prevalences of generalized dermatitis at slaughter were observed in control pigs from all S+ farms. Ivermectin treatment resulted in much lower prevalences, reflected in a significantly (P < 0.01) lower grand mean dermatitis index per pen for this group as compared with the controls. The majority of pigs from both treatment groups at all S- farms were free of papular lesions. These results indicate that low levels of sarcoptic mange at the start of fattening, left untreated, will result in a high prevalence of scratching during the fattening period and high prevalences of Sarcoptes and dermatitis at slaughter. Treatment with ivermectin at the start of fattening results in behaviour and dermatitis prevalences similar to those observed in mange-free herds.

[Aspects of meat inspection in the framework of a system of Integrated Quality Control for slaughtering pigs]. / Aspecten van de vleeskeuring in het kader van een systeem van Integrale Keten Beheersing voor vleesvarkens.

This article evaluates different aspects of meat inspection that are important in an integrated quality control system for slaughter pigs. The meat inspection service registers post-mortem abnormalities. However, to achieve a reliable registration, it is necessary to be able to identify individual animals on the slaughter-line. The information about post-mortem abnormalities can be used by the meat inspection service. Percentages of abnormalities in a shipment of pigs were included in meat inspection indices. It was not possible to predict the percentages of abnormalities in shipment of pigs from individual pig suppliers, but it was possible to classify fattening herds according to the meat inspection index. Information about the pigs delivered from a fattening herd was provided in two ways: by delivering relevant information on a quality control card, and by preselecting (done by the pig supplier) pigs according to the presence or absence of abnormalities. With both methods it was possible to divide pigs into a group with and a group without post-mortem abnormalities. It is necessary that the information supplied is accurate. Information can be checked by screening a number of animals for drug residues (and zoonoses) at the slaughterhouse, and by checking the information registered by the pig supplier in logbooks kept on the farm. From a comparison of results obtained with a meat inspection method based on visual inspection (no incisions, no palpitation) of the carcass with those obtained with the regular meat inspection method, it can be concluded that many abnormalities are detected equally well with both methods. Some recommendations for further research are given.

Use of information from pig finishing herds for meat inspection purposes.

In a field trial on Integrated Quality Control of finishing pigs we evaluated information written on Quality Information Cards (QUIC) for meat inspection purposes. These cards were sent with 3747 shipments of pigs going from the finishing herd to the slaughterhouse. Pig suppliers answered five questions dealing with health problems and the use of drugs during the finishing period. By comparing QUIC answers to recorded post-mortem abnormalities, we found that the information on the QUIC had some, albeit low, predictive value with respect to the abnormalities 'arthritis', 'condemned liver' and lung lesions. Shipments without a QUIC or with a faulty QUIC were considered 'suspect' because higher levels of abnormalities were found in these shipments. These results indicate the potential use of a QUIC.

Preselection of finishing pigs on the farm as an aid for meat inspection.

The ability of pig suppliers to separate pigs with abnormalities from pigs without abnormalities at the end of the finishing period was investigated. Nineteen hundred and seventy-eight pigs, delivered by 22 pig suppliers, were involved in the experiment. The pigs were inspected on the farm by the pig supplier and, separately, by a veterinary expert. The animals were sent in 22 deliveries to one slaughterhouse. A veterinary meat inspector carried out the ante- and post-mortem inspections. The results of the inspections were compared. The measure of agreement, Cohen's Kappa (CK), indicated a poor (CK less than 0.40) to fair (0.40 less than CK less than 0.75) agreement among the results of the different inspection procedures, depending on the abnormality under investigation. There was a fair to good agreement for the abnormality 'tail lesion' among all inspections. Some findings of the live animal, such as 'straggler', were associated with a wide range of post-mortem abnormalities. It is concluded that preselection is possible and that the economic and practical feasibility of preselection should be investigated.

Investigations with enzyme-linked immunosorbent assays for Trichinella spiralis and Toxoplasma gondii in the Dutch 'Integrated Quality Control for finishing pigs' research project.

In the framework of the Dutch field trial 'Integrated Quality Control (IQC) for finishing pigs' ELISA (screening) techniques were used to detect animals seropositive for Toxoplasma gondii and/or Trichinella spiralis. The aim was to determine whether farms which consistently delivered seropositive pigs could be detected and monitored (defined as 'problem farms'). The investigation involved 120 farms and three slaughterhouses, and a total of 23,348 serum samples were examined. In addition, all pigs were also screened for the presence of Trichinella spiralis with the digestion method (pooled samples). The prevalence of seropositivity for Trichinella spiralis and Toxoplasma gondii was 0.3% and 2.1% respectively. Parasitological examinations concerning T. spiralis were negative. Considering the characteristics of the used methodology, the conclusion was drawn that there were no parasitological or serological indications for T. spiralis infections, and that with respect to T. gondii the infection rate seemed to be equally low for all farms involved. In addition, a longitudinal pilot study during a whole finishing period was undertaken at two finishing farms. Animals seropositive for Toxoplasma gondii were found from the earliest days of the finishing period. Housing and management may (still) play an important role in the prevention of contact with this parasite.

Predictability of post mortem abnormalities in shipments of slaughter pigs as an aid for meat inspection.

This paper reports on the predictability of post mortem abnormalities in individual deliveries of pigs, shipped from the fattening herd to the slaughterhouse. The percentage of pigs in a delivery having post mortem abnormalities was expressed in a Meat Inspection Index. This index is based on data about relevant abnormalities, weighted on the specific significance of each for meat inspection. It was investigated whether Meat Inspection Indices of previous deliveries of pigs could be used for prediction of indices of future deliveries. Results suggest that the Meat Inspection Index cannot be used in such a predictive capacity, partly because of great variation among individual shipments. However, a Meat Inspection Index could play a role in signalling farms that are likely to deliver pigs with a higher level of abnormalities. More attention could then be paid to animals coming from these herds.

[On the way to an optimal system of meat inspection for slaughtering pigs]. / Op weg naar een optimale vleeskeuring van slachtvarkens.

A brief historical review of meat inspection is followed by a discussion of the objectives of meat inspection and the possibility of achieving an optimum form of inspection. In the EC system of meat inspection no requirements with respect to information supplied by the farmer are incorporated. The current system of meat inspection is based on relatively rigid legal requirements. Particularly, examination of meat for veterinary drug residues may involve difficulties in testing and give rise to financial problems. Assuming the producer of slaughtered animals to be the first to be responsible for the wholesomeness and the quality of the products delivered, he should also have the opportunity to bear this responsibility. However, this responsibility should be rewarded. A method by which a warranted system of meat inspection could be built up in addition to the regular EC system of meat inspection is suggested.