顺丰电商产业园事业部:Epidemiological analysis and classification of the health status of pig herds

Carl-Philip Dickhaus. Epidemiological analysis and classification of the health status of pig herds – developing and valid a Herd Health Score (HHS)[D/OL].Hannover, Tierärztliche Hochschule: 2010.http://elib.tiho-hannover.de/dissertations/dickhausc_ss10.pdf

The health status of animals, which are kept on farms for food production, has become an increasing matter of public concern. For improving the husbandry systems towards better health and welfare conditions as well as towards reducing drug consumptions, the quantification of the heard health and indicators such as mortality, morbidity and the use of antibiotics is one of the major preconditions. Regarding the fact that data on the health status of slaughter animals has to be part of the food chain information to provide the required efficient risk assessment, it is essential to be able to quantify the health of food producing animal herds.

The objective is to develop, evaluate and validate a robust tool for quantifying the health status of batches of slaughter pigs and in consequence pig herds.

Within 377 inspections 16,086 pigs, which were separated into 60 groups being fattened on 19 farms of a cooperative, have been clinically examined. The first of the repeated clinical inspections was made three weeks after introducing the new stock, and the last examination took place just a few days before slaughtering the individual batches of fattening pigs. In this way each slaughter pig was examined at least six times over the whole rearing period.

The incidence and duration of the six criteria “respiratory diseases”, “diarrhea”, “limb lesions”, “skin diseases”, “cannibalism” and “evenness of weight gain within the pig group” have been measured and validated, so that each examination resulted in additive “health points”, which can range from 0 to 14 points.

At the time of slaughtering the additive health points, generated during the six examinations, were combined to one cumulative “Batch Health Point”, which presents the average of the single inspections. These batch health points of batches from one single farmer were again combined to a “herd health point”.

Based on this foundation, a comparison of the results of the described intensive clinical investigation to the indirect measuring of the health status using the Herd Health Score (HHS) was carried out.  

The Herd Health Score (HHS) consists of four combined direct health parameters, which can be detected without circumstance: “mortality rate”, “frequency of pathological findings in carcasses and organs of previous meat-inspections”, the “Animal Treatment Index (ATI)” and the “duration of the fattening period”. The values of each HHS-parameter get benchmarked by scoring points between 0 and 3. In the end the sum of the single scores is added to the Herd Health Score (HHS), which can vary between 0 and 12 points. The HHS can be calculated for single batches, for groups of fattening pigs, but also for herds for whatever period of time.

Although the basic prerequisite for pig fattening are comparable within the 19 farms, the single parameters and due to that the single HHS´s vary a lot.

The mortality rate within the single fattening groups ranges from 0% to 12.24% with an average of 3.93?%.

While gathering the previous slaughter check results it was noticeable that in most cases the overall organ lesion frequency of slaughter batches from one farm is quite consistent over time. Pigs from some farms show constantly no or very few findings, while pigs from other farms show repeatedly a high frequency of gross pathological findings in carcasses and the organs , which attests an intense occurrence and severity of diseases.

By evaluating the Animal-Treatment-Index (ATI) it can clearly be seen that the number of antibiotic-medicating-days within the single fattening groups likewise varies a lot. There are some farmers who use antibiotics very seldom, while pigs from other farms needed repeated antibiotic treatment. The variation in the ATI is 0 to 67. On average the fattening pigs in this study have been treated 13 days, which constitutes nearly two weeks of antimicrobial treatment for all animals within the group.

For fattening pigs from 29 up to 118 kilograms the farmers ordinary needed 125 days. The shortest fattening period of a batch of slaughter pigs is 67 days while the longest duration is made up of 219 days.

It must be underlined that no single parameter on its own allows a reliable prediction about the health status of slaughter pig batches.

In the study herds the HHS of single batches ranges from 0 to 12, the average is 4.7.

The evaluation of the HHS of the 19 herds ranges from 0 to 10, the average is 4.5.

The cumulative “Batch Health Points” of all 253 investigated batches reach from 0 to 9 with an average of 3.4.

By comparing the HHS with the “Herd Health Points”, both calculated for the single farms, it turns out that the Pearson product-moment correlation results in 0.8. The calculated level of significance amounts ≤ 0.1?%, which represents a highly significant result.

The concluding regression analysis shows that the significances of the four HHS-Parameters vary considerably. For instance the significance of the parameter “organ lesions” is 18 times higher than the significance of the parameter “mortality”.

By using the finally calculated regression equation it is possible to assess the “Herd Health Points” with a reliability of 96.6?%. Therefore this method is even more reliable for quantifying the health status of pig herds than using the Herd-Health-Score (HHS).

Against the background of the fact that the availability of standardized and validated herd health assessment tools is of increasing importance, further activities for validating the usability and usefulness of the developed HHS, respectively the calculated regression equation must be carried out.