THE DEPENDENCE OF MEAT QUALITY ON THE CONDITIONS OF PIGS PREPARATION FOR SLAUGHTER

Matsiuk A.

AGRICULTURAL SCIENCES

THE DEPENDENCE OF MEAT QUALITY ON THE CONDITIONS OF PIGS PREPARATION FOR

SLAUGHTER

Matsiuk A.

Vinnytsia National Agrarian University, postgraduate

DOI: 10.24412/9215-0365-2021-59-2-3-6

Abstract

Proper transportation and pre-slaughter processes are important because they help preserve the quantity and quality of raw meat supplied to processing plants. Technological instructions on acceptance and pre-slaughter preparation provide optimal conditions of transportation and terms of pre-slaughter keeping of animals, as well as the use of biologically active drugs that have anti-stress effects (e.g. mixtures of choline chloride and vitamin PP), provide the opportunity to reduce losses of useful products and meat with PSE and DFD defects.

It has been found that transporting pigs for slaughter at a distance of 100 km or more is accompanied by a significant loss of live weight (3.23%) and reduces the meat output, as well as adversely affects its physicochemical parameters. According to research data, the transportation of pigs at a distance of 100-110 km caused the bound water decrease and this figure was 55.89%, while the meat of the first group of pigs transported to meat processing plant 40-45 km has 58.63%.

It has been established that pre-slaughter starvation of pigs should not be longer than 8 hours, longer one leads to a decrease in meat quality.

Keywords: pigs, transportation, keeping, slaughter, quality.

The pork production efficiency is caused by reducing pre-slaughter losses of raw materials and improving its quality. As rate of pork production had increased, farmers faced the problem of its sale at appropriate prices because weight and quality are lost during transportation, acceptance and slaughter of pigs.

Significant losses of pig live weight are observed during transportation for slaughter with speeding of vehicles and due to poor quality roads causing stress in animals.

The new market regulation systems are being created in the conditions of Ukraine's membership in the WTO. They must meet the European requirements for food quality and safety as much as possible.

The International Commission on WTO Accession has noted that there can be no compromise on food quality and safety requirements, they are quite strict and specific.

The share of Pale, Soft, Exudative (PSE) and Dark, Firm and Dry (DFD) raw meat in the total volume of processing meat has increased recently. According to Ukrainian and foreign researchers, it is 50% of the total amount of raw materials [1, 2]. The instability of the quality indicators and outputs is observed while processing such meat according to the traditional technological scheme.

Increasing share of PSE and DFD meat forces to find ways to identify it, to prevent the emergence of such raw materials, but also requires the use of rational methods of processing such meat, as it has uncharacteristic technological properties, texture, taste, colour and odour, these factors complicate the process of obtaining high quality meat products.

It was found that the proportion of animals with defects of PSE and DFD reaches 30% among pigs raised at industrial complexes [3].

Choosing the right solution for technological pro-

cessing of raw meat with these defects is not easy, because meat defects are not observed in all animals, so it is necessary as soon as possible to identify quality defects and make the right decision about the possibility and methods of processing such raw materials [4].

However, the growing shortage of raw meat and the increasing share of PSE and DFD meat dictate the need to improve existing technologies that would allow the rational and efficient use of raw meat with these defects.

Nowadays, only some producers and processors are interested in the problem of animal welfare. However, investigating reasons of dominating PSE and DFD meat we quickly found a relationship between the stress to which animals are exposed and the quality of meat [5].

The main principles of protection of animals during transportation are to ensure the absence of injury, pain, hunger, thirst, thermal stress and painful restrictions on movement causing animals fear. The main factors ensuring the absence of these negative manifestations are the appropriate technical conditions of transportation, thoughtful management of transportation (methods of handling animals, aids for their adjustment, load density, duration of pre-slaughter exposure, speed, etc.).

Improperly organized transportation of animals can lead to bruising, hemorrhage, bone fractures, bleeding, glycogen deficiency in meat, increased PSE and DFD meat share, maturation defects, deterioration of organoleptic characteristics and microbiological condition of raw materials, reduced moisture retention meat and the loss of useful products.

Currently, stress is defined as a set of general stereotyped reactions in response to the action of different (extraordinary, extreme) stimuli.

Analysing the specificity of stress, H. Selye has divided the body's response to it into three stages. The

first stage of stress develops during the transportation of animals for slaughter. We can observe an excited state of animals, muscle tremors, convulsive movements of the limbs, timidity, trembling of the tail, a small amount of foam, shortness of breath during transport stress. There is an increased risk of meat with PSE and DFD properties when the respiratory rate is 30 breaths per minute, heart rate is more than 100 beats per minute, and rectal temperature is more than 39°C. The strength of the stress during transportation depends on mental, physical, vestibular loads, high and low ambient temperatures [6].

We concluded that excitability is the most important factor causing PSE pork, which depends on the breed of the animal.

The development of stress and its consequences differs significantly in individual breeds and lines within the species.

Depending on the sensitivity of the animals to the load, regardless of their age, it has been found that there are different cases of PSE and DFD meat quality defects caused by fatigue transiting into irreversible symptoms of swine stress syndrome.

The starvation is widely applied at the meat plant, it prevents pigs from resting before slaughter due to increased activity and possible fights resulting in DFD

pork.

Research of transportation duration and conditions and pre-slaughter cattle management effect on the amount of heat shock protein, glucose and cortisol (stress hormone) showed that long transportation and pre-slaughter keeping increased expression of heat shock protein HSPA1 and cortisol, while the glucose level decreases affecting the final pH value.

Issakowicz et al. [7] study the effect of transport duration and pre-slaughter keeping on lamb behavior and meat quality. The animals were divided into two groups, they had 2 or 6 hours of transportation and 12 or 24 hours of pre-slaughter, respectively.

Thus, studies of foreign scientists show the exceptional importance of compliance with the conditions of transportation and pre-slaughter and the impact of these factors on product quality.

The purpose of the work is to research the impact of the transportation distance and the duration of pre-slaughter preparation on the quality of raw pork.

The object of study is pigs of large white breed.

Firstly, we investigated the effect of transport distance on pig slaughter rates. The scheme of the experiment is presented in Table 1.

Table 1

Scheme of the first experiment

Group Transportation distance, km

I group 40-45

II group 100-110

The animals of the first group were slaughtered in the conditions of the meat-packing plant at a distance of (40-45 km), and the second group was delivered to the meat-packing plant at a distance of (100-110 km).

Qualitative indicators of pork depending on different terms of pre-slaughter maintenance were also investigated. To do this, 20 heads of large white pigs were slaughtered in a meat processing plant at a distance of more than 100 km. The pigs were divided into four groups.

The first group (5 heads) was slaughtered immediately after delivery (approximately 1.5-2 hours), the second group (5 heads) was slaughtered after 8 hours of keeping, the third group (5 heads) was slaughtered after 18 hours of keeping, the fourth group was slaughtered after 24 hours of keeping.

Slaughtered animals were sold in accordance with SSU [8].

The general scheme of researches is presented on Fig. 1.

Fig. 1. General scheme of research

Fattening young pigs of large white breed are sold from the farm to processing enterprises when they reach a live weight of 100-110 kg; they are sold in the morning.

The period from first group of pigs loading to slaughter in the conditions of the meat-packing plant

(40-45 km) was no more than 2.5 hours (including delivery time). Slaughter animals of the second group were delivered to the meat processing plant (distance 111 km) and were slaughtered immediately (without starvation); it took 5.5 hours. The results of slaughter of animals depending on the transportation distance to processing plants are given in table 2.

Table 2

The results of pigs control slaughter

Indicators 1 group 2 group

Average live weight of 1 head before transportation, kg 107.7Г0.61 111.3Г1.03

Average live weight of 1 head before slaughter, kg 106.8810.24 107.7Г0.09

Slaughter weight, kg 81.2 79.5

Slaughter output, % 75.9 73.8

According to the results of control pigs slaughter, their transportation for slaughter to a processing plant located at a short distance from the farm (40-45 km) is accompanied by a small loss of live weight; it is 0.82 kg or 0.76% per head.

Transportation of slaughter animals to the processing plant at a long distance (more than 100-110 km) significantly affects the loss of live weight, it averaged 3.6 kg or 3.23% per head. The total live weight loss of the second group of pigs was 16.85 kg.

Having analyzed the indicators of physical and chemical qualities of raw meat, we found that the meat of first group pigs, which were delivered for slaughter with a distance of 40-45 km was characterized by a higher rate of moisture retention.

The pH indicator is one the most important physico-chemical parameters of meat, it characterizes its suitability for making various pork products.

The tenderness of a meat characterizes the degree of its stiffness; it depends on the thickness of the muscle fibers, i.e. the thicker the muscle fibers, the harder the meat.

Moisture-retaining ability is one of the important indicators of meat quality, it affects the outputs and is closely related to its juiciness and other culinary properties.

Meat moisture content is an important property, it is determined by the amount of bound water in it. Good quality meat has a moisture holding capacity of 53-66% (Table 3).

Table 3

Physico-chemical parameters of pig meat depending on the transportation distance to slaughter

Indicators 1st group 2nd group

Tenderness of meat, kg / cm2 0.695±0.17 0.836±0.04

рН 5.38 5.82

Free water, % 27.65 26.15

Bound water, % 58.63 55.89

According to research data, if pigs are transportated at a distance of 100-110 km the amount of bound water decreases, this figure was in 55.89 % range. This figure averaged 58.63% to the meat of first group pigs transported 40-45 km to plant.

The first group pork was more tender. Its tenderness is largely determined by the quantity and quality of connective tissue in muscle bundles, the content of intramuscular fat, and the diameter of muscle fibers. Pork tenderness decreases if connecting fabric is increased.

The meat acidity (pH) determines the degree of its further preservation. The higher the pH of the meat, the better it is stored. According to our research, this figure was better in the meat of pigs of the first group.

Pre-slaughter keeping of pigs affects the pH value. The longer the animals are kept, the lower meat pH caused by the stress during transportation and the lack of food. Researches show that the recommended pigs keeping time at the meat-packing plant before slaughter is not more than 8 hours because it provides the highest pH values in 1.5-2 hours after slaughter reducing the possibility of obtaining meat with deviations from the classical autolysis process.

The economic efficiency of the pre-slaughter pigs' regimes was assessed by the total revenue from the sale of meat products; data on the actual slaughter output and the current state procurement prices for pork were used in the calculations (Table 4).

Table 4

According to research data, if pigs are transportated at a distance of 100-110 km the amount of bound water decreases, this figure was in 55.89 % range. This figure averaged 58.63% to the meat of first group pigs transported 40-45 km to plant.

The first group pork was more tender. Its tenderness is largely determined by the quantity and quality of connective tissue in muscle bundles, the content of intramuscular fat, and the diameter of muscle fibers. Pork tenderness decreases if connecting fabric is increased.

The meat acidity (pH) determines the degree of its further preservation. The higher the pH of the meat, the better it is stored. According to our research, this figure was better in the meat of pigs of the first group.

Pre-slaughter keeping of pigs affects the pH value. The longer the animals are kept, the lower meat pH caused by the stress during transportation and the lack of food. Researches show that the recommended pigs keeping time at the meat-packing plant before slaughter is not more than 8 hours because it provides the highest pH values in 1.5-2 hours after slaughter reducing the possibility of obtaining meat with deviations from the classical autolysis process.

The economic efficiency of the pre-slaughter pigs' regimes was assessed by the total revenue from the sale of meat products; data on the actual slaughter output and the current state procurement prices for pork were used in the calculations (Table 4).

Table 4

Economic efficiency of research

Indicator Transportation distance, km

40-45 100-110

Average live weight of 1 head before transportation, kg 107.7Г0.61 111.3Г1.03

Average live weight of 1 head before slaughter, kg 106.8810.24 107.7Г0.09

Loss, kg 0.82 3.6

Loss, UAH 28.7 126

Thus, having analysed the data on the transportation distance effect on slaughter of animals, i.e. the loss of live weight, it should be noted that transportation at a distance of 100-110 km will lead to a loss of 3.6 kg per animal, it will be 126 UAH. Therefore, you need to choose processing plants at a shorter distance than 100 km.

References

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Резвицкий Т.Х.

Студент Кубанского Государственного Аграрного Университета имени И. Т. Трубилина