RU2489026C1 - Method of neutralisation of trichinella larvae by freezing in the carcass of some fur-bearing animals - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: invention relates to agriculture, namely to veterinary helminthology and sanitation. Under the influence of a temperature of minus 70°C with exposure from 1 to 18 hours, the cell membranes of cuticle of helminth larvae are damaged by ice crystals, as well as destruction of the internal organs and systems of the parasite occurs, which is localised in a capsule of muscle fiber of animal carcass. After exposure to low temperature of Trichinella larvae become quickly devitalised. The method does not require any additional preparing infested carcasses for neutralisation after skinning. Muscle tissue of neutralised animal carcasses can be used without limitations in feeding fur animals, pets and poultry, as well as for the technical processing, for example, for meat and bone meal tankage.

EFFECT: method provides reduction in the incidence of zoonotic disease among population, and can be used in feed production in preparation of bait or feed of raw meat infested with larvae of Trichinella in nurseries of hunting economy and in specially protected areas.

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Description

The invention relates to the field of agriculture, namely to veterinary helminthology and sanitation, and can be used to disinfect carcasses of some game animals from trichinosis infestation. The method of neutralization can also be used in feed production for the preparation of bait or feed from meat raw materials invaded by Trichinella larvae both in nurseries of hunting farms and in specially protected areas.

Trichinosis is a dangerous parasitic disease of omnivorous, carnivorous animals and humans, caused by a small nematode of the genus Trichinella.

Adult trichinella parasitize in the intestines, and their larvae in the muscles. Infection of animals occurs when they eat trichinosis meat. In the stomach, the meat is digested and the larvae are released from the muscles. In two days they become adults, fertilize, after which the males die, and the females in the small intestine penetrate into the submucosa and attach. On 3-4 days after infection of the animal, the females give birth to live larvae. By the blood flow, the larvae are carried throughout the body, but only those that develop into the striated muscles develop. In the muscles, they grow, develop, twist into a spiral, reach the invasive stage, making two or three turns by the 25-30th day after infection, and then wrap themselves in a capsule. In this form, the larvae remain viable up to 25 years. The size of the capsules with trichinella 0.3-0.4 mm. In order to prevent cases of human infection with zoonosis in many countries of the world, special laws have been issued categorically prohibiting the sale of meat without prior veterinary and sanitary examination, and a set of preventive measures are being taken to neutralize meat from the causative agent of trichinosis with high and low temperatures or destruction [1, 2, 5] .

Trichinella is quite resistant in the carcasses of dead and dead animals, these parasites for a long time (up to 5 months or more), without losing their invasive ability, tolerate winter colds. When processing meat in large pieces with high temperature or baking ham, not all trichinella die. Existing methods for the preparation of kebabs, sausages and ham, including salting, smoking and cooking, cannot guarantee the killing of Trichinella. Only at a temperature in the deep layers of pork not lower than plus 80 ° C can trichinosis meat be reliably neutralized.

For a long time it was believed that low temperatures did not kill Trichinella larvae in meat, although they act adversely on them. Wild carnivorous mammals are often infected with Trichinella larvae resistant to low temperatures. When freezing meat of wild animals in domestic refrigerators at a temperature of minus 12 ° C, Trichinella larvae of individual cold-resistant Trichinella isolates remain viable and invasive for a long time.

According to the recommendations of the International Commission on Trichinosis (MKT) [2] for inactivation of Trichinella spiralis larvae in pork, the minimum freezing time at minus 17.8 ° C is 106 hours, at minus 23.3 ° C - 63 hours, and at minus 28, 9 ° C - 35 hours. Pork freezing at minus 15 ° C, depending on the size of the pieces, is recommended for at least 3-4 weeks.

SanPiN 3.2.1333-03 regulates the freezing of pork carcasses at an air temperature in the chamber of minus 12 ° C for 10 days.

The development of a high-quality and quick method for the neutralization of carcasses of commercial animals from trichinosis invasion is an urgent task today for the prevention of helminthiasis.

Known methods for the neutralization of Trichinella larvae in muscle tissue: low and high temperatures, through salting and smoking, vacuum drying, solutions of acids and alkalis, ionizing radiation, microwave radiation, ultrasound, using electric discharges, drying and long-term storage of meat. The disadvantages of using these methods of neutralization are the long exposure in time, the lowest efficiency of neutralization, the impossibility of further technological processing of carcasses or require additional processing (grinding muscle tissue, cutting into half carcasses, grinding pieces of meat no more than 8 cm thick) for neutralization.

The closest method is the physical method of neutralization at low temperatures [5]. According to the recommendations on the neutralization of pork, meat slaughter waste and carcasses of fur animals when trichinella was detected in the first series of experiments (according to A.S. Bessonov, 1966), the neutralization of trichinella larvae not resistant to low temperatures was carried out only in pork meat (in decapitated and initially processed carcasses (pigs 3-9.5 months) and half-carcasses (sows 14-24 months) pigs), in the above experiments used an effective temperature of neutralization to minus 50 ° C.

The purpose of the present invention is the development of a faster and more effective method of neutralization of freeze-resistant trichinella larvae in carcasses of commercial fur animals without additional technological processing of meat raw materials (cutting, grinding into minced meat). A secondary objective of the invention was the development of a safe method of feeding meat raw materials, which would stop the spread of trichinosis with carcasses of animals, and due to this, sanitary and hygienic conditions were gradually improved and some environmental issues were solved in nurseries, hunting grounds and in specially protected areas. And also the prevention of trichinosis in domestic animals, in particular in dogs of hunting, guard, service breeds, would be carried out.

The essence of the invention lies in the fact that under the influence of low temperature (minus 70 ° C), ice crystals damage the cell membranes of the cuticles of helminth larvae, destruction of the internal organs and systems of the parasite, which is localized in the capsule of the muscle fiber of the animal carcass. After exposure to this temperature, Trichinella larvae quickly become non-viable. This method does not require additional preparation of invasive carcasses for disposal after skinning. Moreover, the muscle tissue of neutralized animal carcasses can be used without restrictions in feeding fur animals and birds, as well as for technical processing (for meat and bone meal) [3].

The proposed method for the neutralization of meat products for the prevention of trichinosis in game animals by deep-freezing animals infected with trichinella that go to feed the animals is simple to implement, technically feasible both in the laboratories of veterinary and sanitary expertise, and in fodder houses of animal farms or at home, where there is low temperature freezers or freezers. The method does not require special training of service personnel, since freezers are used for their intended purpose (deep freezing of carcasses), and only requires maintaining the proposed predetermined technological parameters - freezing time, weight of processed meat products.

The effectiveness of the proposed method for the disposal of Trichinella larvae in the carcasses of some fur animals is reflected in the following examples.

Example 1. Resistance to low temperatures of Trichinella larvae in the muscle tissue of an ordinary fox. When studying the resistance to low temperatures of Trichinella larvae isolated from an ordinary fox, shot in the Ryazan region, it turned out that they remained viable and invasive for a long time. The fox carcass was divided into samples 2-5 cm thick and weighing no more than 15 g, which were placed in freezers at minus 16 ° C and 23 ° C. Samples were examined after 8, 19, 42, 78, 107, 134, 157 and 192 days of continuous freezing at these temperature conditions.

During the study, it was found that when freezing muscle samples from the common fox at minus 16 ° C for 107 days, the number of viable Trichinella larvae decreased from 96% at the beginning of the experiment to 80%, and at minus 23 ° C to 65%. Trichinella larvae during this period remained invasive, as evidenced by the results of bioassays on white mice.

However, the invasiveness of Trichinella larvae after freezing for mice — a biological test at the same dose of infection with viable larvae (10 Trichinella larvae per 1 g of animal weight) decreased: at minus 16 ° C, the intensity of invasion of white mice decreased to 67 larvae per 1 g of animal weight, and at minus 23 ° C to 43 larvae per 1 g of mass.

The viability of Trichinella larvae was maintained during the entire period of freezing - 192 days at minus 16 ° C and 134 days at minus 23 ° C. The experiment was completed due to the lack of a sufficient number of muscle tissue samples from the fox. The high frost resistance of Trichinella larvae in the muscle tissue of an ordinary fox characterizes their belonging to the helminth species that is resistant to negative temperatures.

Example 2. Experience in the disposal of naturally carcassed carcasses of animals naturally infected with capsule trichinella. The invaded trichinosis material consisted of carcasses without skins of various types of game animals caught in hunting farms (foxes, raccoon dogs, martens). The presence of invasion and the degree of invasion of the material was determined by compressor trichinoscopy. For this, from each muscle sample weighing about 50 g, along the muscle fibers with curved scissors, 24 slices of muscle the size of an oat grain (total weight about 0.7-1.0 g) were cut. Sections were squeezed between the glasses of the compressor and microscopic at a small magnification of the microscope. The invasion intensity was determined by counting Trichinella larvae in 1 g of muscle tissue. During the production neutralization test, the carcasses of invaded animals were isolated from uninfected carcasses, packed separately from each other and tied in plastic bags up to 30-200 liters in volume.

Bags with carcasses of animals infected with trichinella larvae were placed in the compartment of the freezer, previously turned on before neutralization (8 hours before work). The invasive material in the freezer was kept for a certain time, depending on the type and weight of the animal carcass (table).

To neutralize the invasive material, you should gradually bookmark the freezer. From 30 g to 20 kg were placed in an empty freezer with a volume of 2 5 m ³ . At the same time, the invasive material was gradually filled up, 10 kg portioned, after every 4 hours of operation of the freezer, but not more often.

The quality control of neutralization of invasive material in the muscle tissue of animals after thawing carcasses on the viability and invasiveness of larvae of the causative agent of trichinosis was carried out according to the method for determining the viability and invasiveness of trichinella larvae. When larvae were isolated by digestion in artificial gastric juice, it turned out that the isolated larvae were not viable.

Table Neutralization of carcasses of game animals from Trichinella larvae during deep freezing Type of carcasses of animals (Latin name) Carcass weight, kg Neutralization temperature, ° C Exposure time, h one 2 3 four Common Fox (Vulpes vulpes) 3,5-8,0 minus 70 eighteen Raccoon Dog (Nyctereutes procyonoides) 2.5-9.0 eighteen Marten stone, forest (Martes foina, martes) 0.4-1.8 6 Gray Rat (Ratus norvegicus) up to 0.5 5 Laboratory white rat Vistar (Rat white) up to 0.5 5 Laboratory white mouse (Mouse white) up to 0.035 one

Example 3. Conducting a biological test in laboratory animals after the neutralization of Trichinella larvae by deep freezing. After neutralization by deep freezing at minus 70 ° C of trichinella carcasses of commercial animals (fox and raccoon dog) that were naturally infested with capsule larvae for 18 hours, martens - 6, rats - 5, mice - 1), a biological test was conducted on laboratory animals (white animals) from trichinosis pathogen outbred mice). Trichinosis carcasses of animals frozen at minus 23 ° C for the same period of time as in the experimental group and carcasses not susceptible to freezing served as a control. The muscle tissue of animals was dissected from bones and minced in a meat grinder. Stuffed meat was placed in a mill gas (mesh size 1 mm). Then the mill gas with minced meat was placed in freshly prepared gastric juice (per 1 liter of distilled water: 10 ml of concentrated hydrochloric acid and 3 g of pepsin 100,000 units of activity). The ratio of minced meat and gastric juice should be 1:20. The minced meat prepared for artificial digestion in gastric juice was placed in a thermostat at 37 ° C for 18 hours. After exposure, the precipitate was washed three times in distilled water. An isolated suspension of Trichinella larvae after artificial fermentation from each group of animals was introduced at a dose of 5 larvae per 1 g of the mass of a white outbred mouse. Further, laboratory mice of each group were kept according to generally accepted sanitary and veterinary rules. After 45 days, laboratory animals were euthanized with medical ether in a mold with a ground lid. For the diagnosis of trichinosis in mice, compressor trichinosis was performed. In the experimental group of laboratory animals, trichinella larvae did not develop in muscle tissue; in both control groups of white mice, capsule trichinella larvae were recorded.

The proposed method, which includes the use of freezers with a significantly low cooling temperature, provides quick and effective neutralization of Trichinella larvae in muscle tissue.

Information sources

1. Bessonov A.S. Epizootology (epidemiology) and prevention of trichinosis. Mintos, Vilnius, 1972.- 304 p.

2. Bessonov A.S. Recommendations of the International Commission on Trichinosis (MKT) on methods for controlling trichinosis of domestic and wild animals, the meat of which is eaten by humans. // Veterinary medicine. 2001. - No. 8. - S. 57-63.

3. Veterinary legislation. - M., 1988. - T.IV. - 162 p.

4. Sanitary Rules and Norms, 3.2.1333-03. “Prevention of parasitic diseases in the Russian Federation”, Moscow, 2003

5. Trichinosis. Scientific works of VASKHNIL, Moscow, Kolos, 1976, 338 pp.

Claims (1)

A method of neutralizing Trichinella larvae in carcasses of fur animals, including the use of low temperature, characterized in that at minus 70 ° C during exposure from 1 to 18 hours, depending on the type of animals and carcass weight, ice crystals damage cell membranes of the cuticle of helminth larvae, destruction of internal organs and systems of the parasite located in the capsule of the muscle fiber of the carcass, which become non-viable and safe for further use.