The expressiveness of meat forms of cattle depending on the content of adipose tissue under the skin and between the muscles

The paper covers the peculiarities of the degree of meat shapes in the bulls of the Ukrainian meat breed, depending on the adipose tissue content under the skin and between the muscles. They were evaluated according to their productivity from 8 to 18, 21, and 23 months. Bulls with better development of meat shapes are characterized by fat deposition in the carcass and between the muscles earlier and more intensively. They have from 15.1 to 44.7% more fatty tissue in the carcass, including under the skin – from 3.8 to 44.1%. With a different degree of meat shapes, subcutaneous fat is deposited more than between muscles. The content of adipose tissue under the skin relative to its total amount in the body of animals tends to decrease by 6.5 points with age for a better degree of meat shapes, and on the contrary, to increase by 2.6 points for a worse degree. If the fat under the bull skin at 18 months in the best shapes is 72.1% of the fat in the carcass, and in the worst – 72.3%, then at 23 months, its amount decreases by 13.6 and 4.4 points, respectively. The fat between the muscles, on the contrary, increases from 27.9 and 27.7% by the same amounts, respectively. With a greater degree of meat shapes and subcutaneous fat thickness on the carcasses of 18-month-old bulls, intramuscular fat (marbling) content is lower by 75.0%. 18-month-old bulls with better-developed meat shapes have fat cuts off from the carcass by 15.2% more than animals with less developed shapes, 23 – by 11.3%. A large amount of produced waste in the body of animals in the best meat shape leads to excessive (from 0.9 to 14.5%) feed consumption (feed unit) for the increase in live weight. The subcutaneous fat content and the number of cuts off from 16 to 24 months positively correlate with the degree of meat shapes in bulls at 15 months and have correlation coefficients of 0.26 and 0.17, respectively.


INTRODUCTION
The degree of meat shape development is affected by the development of adipose tissue under the skin and between the muscles and inbreeding [1].The covering of adipose tissue on the carcass is related to the beef quality by protecting the muscles from drying out during the cooling of the carcass in the refrigerating chamber, which can lead to their stiffness.The carcass must have a sufficient fat thickness to guarantee its preservation and the desired quality for consumption [2].Deposition of a large amount of fat under the skin contributes to an increase in the sexual precocity of animals [3], excessive feed consumption [4] and its costs for live weight gain [5].A low tendency to deposit fat is a problem for animals breeds with less adipose tissue under the skin and in the middle of the muscles [6].The amount of adipose tissue in cattle varies depending on the breed and stock [7] and homozygosity [8].Beef fat has a low nutritional value in the processing industry.The healthy nutrition of people is now aimed at the partial replacement of animal fats with triglycerides with polyunsaturated fatty acids, and the introduction of raw materials of plant origin into recipes [9].The biological value of beef proteins is improved [10] by the enzymatic method, and its use by people and health-promoting properties are improved by the addition of rosemary extract [11] and iodine compounds [12].The issue has not been sufficiently resolved regarding the formation of the degree of meat shapes in animals with different fat content under the skin and between the muscles.This information would help explain its differences.Since the distribution of fat by fat depots is also the subject of accounting for the generation of waste, the disclosure of the features of the formation of the degree of meat shapes in cattle is necessary for the effective and purposeful production of beef for the optimal yield of its valuable quantitative and qualitative components.
This paper aims to establish the relationship between the degree of meat shapes in bulls of the Ukrainian meat breed and the content of various types of adipose tissue in their carcasses and cuts off from them.

Scientific Hypothesis
Previous studies have shown that the better degree of meat shapes in bulls harms their growth rate and breeding value, and the factors of its formation have not been confirmed.It is assumed that animals with less developed meat shapes acquire the shallow-bodied type, closely related to the body's increased metabolic processes.They should have a lower growth rate, a mass of fat in the middle of the muscles and their cuts off because the worse degree of meat shapes affects the development of individual organs that participate in them.Deposition of fat for different degrees of meat shapes may differ from the general trend of increasing the growth of animals.

MATERIAL AND METHODOLOGY Samples
For research before slaughter, at 18, 21 and 23 months old, two groups of experimental animals were formed using the method of balanced groups by age.The first group included the animals with a degree of meat shape development above the average value for the herd.At 18 months, this value was 56.0 points, at 21 -56.5, and 23 -54.2 points.The second group included young animals with a degree of meat shape development less than the average value for the herd.18 months -49.2 points, 21 -50.5, and 23 -48.0 points.
The research was conducted using Ukrainian meat animals (Figures 1, 2) at the Volia stud farm of the Zolotoniskyi district of the Cherkasy region.They were raised from birth to slaughter at 18, 21 and 23 months.After slaughter, fat (subcutaneous, intermuscular, its cuts off) was selected and a piece (300 g) of meat for weighing from M. Longissimus dorsi.

Laboratory Methods
The formation of balanced peer groups was carried out following the requirements of Fundamental concepts of experimentation in breading.Study guide.
To determine the amount of fat in animal carcasses, bulls were slaughtered at the Cherkasy meat processing plant following the requirements of DSTU 4673:2006 [13] and DSTU 3938-99 [14].Before that, the pre-slaughter live weight of bulls was determined by weighing them before and after a 24-hour starvation period with free access to water.After the animals were slaughtered and cleaned, their carcasses were weighed in even condition (slaughter weight) and the absolute weight of their cuts off.The left half-carcasses went through skinning and eviscerating.After that, the adipose tissue was weighed and divided into subcutaneous and intermuscular fat according to DSTU 3938-99.The absolute value and percentage of subcutaneous and intermuscular adipose tissue from the slaughter mass (carcass) were determined. Estimation

Description of the Experiment
Sample preparation: The research was conducted during the second calendar day after skinning and eviscerating slaughtered cattle at 18, 21 and 23 months.For this, 7 subcutaneous and intermuscular fat samples were selected, including 4 samples, each from animals with a better degree of meat shapes and 3 samples each with a worse degree.At the age of 21 and 23 months, samples were taken from 3 animals in groups.
Number of samples analysed: 19 samples from three conducted experiments were used for analysis.For chemical analysis of minced meat from M. Longissimus dorsi was taken in 18-month-old animals from both groups by three samples Number of repeated analyses: Using the carcasses of slaughtered bulls, the weight of subcutaneous fat was determined 3 times, fat between the muscles 3 times and cuts off 3 times, which amounted to 3 repetitions, respectively, at the age of 18, 21 and 23 months.

Number of experiment replication:
The study was repeated 3 times, and the experimental data were processed using mathematical statistics methods.
Design of the experiment: Research plan: the research was conducted at the "Volia" stud farm of the Zolotoniskyi district of Cherkasy region.Well-developed bulls of the Ukrainian meat breed from birth to 6-7 months were kept with their mothers as sucker bulls.After weaning, they got typical food and maintenance until 8 months.After weaning, the animals were tested for their performance from 8 to 18 months, 8 to 21, and 8 to 23 months.They were kept on a leash under individual control of the amount of given and consumed feed.Using the herd for slaughter at the age of 18, 21 and 23 months, two groups were formed, including welldeveloped bulls with different degrees of meat shapes.The first group included animals with a value of this indicator above the herd average, and the second group included animals below the herd average.Bulls were grouped by age using the method of balanced peer groups [19].The degree of meat shape development was evaluated at 15, 18, 21, and 23 months of age on a 60-point scale following methodological instructions [20].
The general level of the feeding of bulls was calculated on receiving average daily gains from 1000 to 1200 g.During this period, the animals were fed with a feed of their products according to the rations prepared according to the norms.The mass of fodder eaten by each bull was calculated every decade (two days in a row) by weighing the given fodder and its residues.Their energy value (in oat fodder units) and costs per 1 kg of live weight gain were calculated based on the consumed fodder.There was no discernible difference in the amount of feed consumed by the bulls of the groups from 8 to 18 months, 8 to 21 months, or 8 to 23 months (Table 1).

Statistical Analysis
Variational statistics processed the obtained data according to the methods adopted in breeding and biology.Statistical processing was performed by Microsoft Excel 2016 in combination with XLSTAT.The average value and standard deviation evaluated indicators.The arithmetic mean (unweighted) value (M) and arithmetic mean were calculated.The accuracy of the obtained experimental data was determined using the Student's test for a confidence probability of ≤0.05 based on the number of parallel determinations at least 5.The results were analyzed using the ANOVA.

RESULTS AND DISCUSSION
Bulls with higher meat shapes are characterized by forming fat earlier and more intensively in the carcass (Table 2).This causes higher (from 0.9 to 14.5%) consumption of fodder (fodder unit) for live weight gain (Table 1).With the different degrees of meat shape development, subcutaneous fat is deposited more than between muscles.Bulls have better-defined meat shapes at 18 months; 44.7% more fatty tissue in the carcass, including 44.1% under the skin.A similar feature is observed in the 21st and 23rd months.For animals with a worse degree of meat shapes at the age of 21 months, compared to peers with a better degree of meat shapes, there is a tendency (by 17.6%) to increase the adipose tissue between the muscles, which in this period has the highest natural growth.
Table 2 The content of adipose tissue under the skin and between the muscles of bulls after slaughtering, depending on the degree of meat shapes.From 18 to 23 months, the content of adipose tissue under the skin relative to its total amount in the body of animals tends to decrease by 6.5 points in the case of a better degree of meat shapes, and vice versa to increase by 2.6 points in the case of the worse degree of meat shape.In animals, with different degrees of meat shape development, adipose tissue between muscles increases curvilinear, unevenly.If the fat under the bull skin at 18 months is 72.1% for the best meat shapes, and 72.3% for the worst, then at 23 months its share decreases by 13.6 and 4.4 points, respectively.The fat content between the muscles, on the contrary, increases by 27.9 and 27.7% by the same values, respectively.

Degree of meat
The obtained data on adipose tissue content in animals under the skin and between the muscles indicate that they achieve a better degree of meat shape due to the excess deposition of subcutaneous fat, which to some extent smooths out the defects of the exterior.With its greater accumulation, cattle is characterized by less angularity and better development of their meat shapes.A higher quantity of fatty tissue in the carcass between the muscles, which causes their displacement on the surface of the carcass, is thought to be why animals with better-defined meat forms have an advantage over peers with worse shapes [21].The yield of edible portions in the carcass diminishes when a lot of fat is under the skin.It is not utilized to enhance meat's tenderness and other aspects of its quality [22], [23].Subcutaneous fat is viewed as [24] waste since it has little commercial worth.
Intramuscular or marble fat is necessary to improve beef's juiciness, tenderness and taste [25].During cooking, it melts, soaking the meat.As a result, it is juicy and tender.The content of intramuscular fat in beef is the most important factor that determines its quality in Japan, Korea, Australia and the USA, while in the countries of the European Union, including France and Germany, leaner meat (with less marbling) is preferred [26], [27].With more meat shapes in 18-month-old bulls, the total fat content (marbling) in M. longissimus dorsi is lower by 75.0%compared to peers due to their poorer development (Table 3).[30].There was no significant difference in other components of beef's chemical composition between the groups' animals.The obtained data concerning 18-month-old animals of the Ukrainian meat breed do not confirm the connection between subcutaneous fat thickness and the marbling of M. longissimus dorsi, discovered [31], [32] in bulls from Ukrainian black-spotted dairy cattle at 22 months.Its data shows it is positive and high (r = 0.68).A greater amount of fatty tissue under the skin and between the muscles in animals with better-developed meat shapes is also subject to their excessive waste formation (Table 4).

Table 4
The quantity (kg) of cuts off from the carcasses of bulls depends on the degree of the meat shapes.

Age of slaughter, months
Better 18-month-old bulls with better-developed meat shapes have 15.2% more fat cuts off from the carcass than animals with less developed forms at 23 -by 11.3%.A large amount of waste (internal fat, under the skin and between the muscles) from the body of animals with the best meat shapes, for which the processor does not pay the producer, leads to an increase (from 0.9 to 14.5%) of feed costs (feed units) on the increase in live weight (see Table 1).Thus, these cattle are less efficient for beef production.[33], [34].
Recently, the population of Ukraine has had a demand for marbled beef.An analysis of the latest research and publications on this issue was carried out to understand how to solve the related problems.It is believed [35], [36], that any food, including meat, performs the main functions of nutrition, taste and disease prevention.Concerning beef consumption in Ukraine in 2022, 6.4 kg of the need (36 kg) per average citizen, now the issue is being solved by increasing its quantity, not quality, unlike many foreign countries, where it is consumed as a source of disease prevention.An important aspect of beef quality, identified [37] by parts of the production chain (producer, processor, consumer), is fat deposition in the middle of the muscles.The content of intramuscular fat in beef and its nutritional quality is affected by factors that are divided [38] into those that occur on the farm and in the period before slaughter (breed, sex, age at the time of slaughter, housing system, feed and handling before slaughter) and after death (handling after slaughter, packaging and cooling temperature), individual genetic predisposition of animals.Therefore, we will consider only a few factors that affect the deposition of intramuscular adipose tissue and cause the most problems during its production.Genetic factors (breed, gender and heredity).
The black breed of Wagyu cattle in Japan has the highest intramuscular fat content (marbling) in the world (more than 30%) [39], and the Korean Hanwoo has the second highest content [40].In animals of European breeds, the content of intramuscular fat is only 0.6-4.7%[41].Wagyu is known [42] for a significant content of monounsaturated fatty acids and a higher ratio of them to saturated than other breeds.This does not lead to health benefits for people who consume beef with high marbling rates.Increasing the content of useful polyunsaturated fatty acids and conjugated linoleic acid in the middle of beef muscles improves its taste properties and shelf life [43].Aberdeen-Angus cattle meat has the highest intramuscular fat concentration and sensory properties among European breeds.In Ukraine, no beef is not produced from Wagyu animals, and Aberdeen-Angus is not a purebred of Scottish origin but a hybrid (1/2 Aberdeen-Angus x 1/2 black and spotted Holstein), from embryos, imported once from the USA.
Heifers deposit more fatty tissue in the body than steers and bulls.The insignificant ratio of omega n-6 to omega n-3 fatty acids indicates that beef from heifers contributes to human health.Castration of bulls increases adipose tissue deposition in the middle of the muscles [44].The beef of uncastrated bulls is of the worst quality and is valued lower by the consumer [45].During the delivery of young animals at the meat processing enterprises of Ukraine, bulls are rated the best, and heifers the worst.Prepared bulls are not practically sold because, on farms, bulls are not castrated at a young age.The markets sell mainly not beef but veal, which practically has no intramuscular fat.
The marbling of beef increases as the animals mature and their live weight increases [46], but the ratio of omega n-6 to omega n-3 fatty acids is higher in heavyweights (p >0.05) compared to lightweight [47].The deposition of adipose tissue in the muscles of cattle is facilitated by feeding them with concentrated feed with a high energy content [48].However, concerning the beef of animals raised on concentrated feed, there is a lower level of mono-and polyunsaturated fatty acids than in bulls fed with grass on pastures [49].Increasing unsaturated fatty acids in muscles makes them more susceptible to lipid oxidation.As a result, various aldehydes, ketones, alcohols, esters and carboxylic acids are formed, affecting beef's taste.Thanks to the fattening (grazing) of animals on the grass, extraordinary juiciness of the meat were achieved.Feed energy costs for feeding young animals increase during live weight gains due to the increase of internal, subcutaneous, and intermuscular adipose tissue, which has a low commercial value and is considered [50] waste from beef production.For its formation, animals spend 2.25 times more feed nutrients than for forming carcass muscles.Excess energy supplied to animals in the late period of fattening significantly reduces feed efficiency due to a decrease in its digestibility, increases the amount of fat waste from them and worsens the efficiency of livestock management.
In contrast to the complexities arising in enterprises during the production of marbled beef, the processor considers the excess fat deposited in the body a problem because it must be removed from the animal or an important ingredient in the processed product.The processor does not pay the producer for a significant amount of removed internal fatty tissue, which cuts off from the carcass.Payment is made only for slaughter weight (carcasses).And with an increase in the grade of marbling of beef, which appears simultaneously with an increase in the body's fat, the percentage of carcass yield decreases [51].
Consumers have different opinions about the content of intramuscular fatty tissue in beef.Some prefer lean meat; others consume beef with more fat.It is important to understand these additional requirements of various industry segments to consider how fat is deposited during the animal's life.In specific depots, inedible internal fat is deposited first, which is located in the abdominal cavity around the internal organs, then under the skin, between the muscles and in their middle (marble) [52].Intramuscular fat, which is desirable for improving the palatability of meat, has a general decrease in lipogenesis and an increase in the activity of the enzyme cholesterol-25 hydroxylase in cattle [53], which is synthesized from the carbon of glucose, not acetate, during intensive fattening already after the accumulation of "excess" fat between the muscles.
Marbling (intramuscular fat) in cattle is considered [54] to be a sign of late maturation, which becomes noticeable only after other fat depots, even though the relative rates of its increase are similar to theirs.Marbled beef generally contains more saturated fatty acids than subcutaneous fat [55].Probable differences in increasing the sensory parameters of beef steaks are manifested by lower indicators of the content of intramuscular fat in it [56].Therefore, a minimum level of its marbling is necessary to detect differences in the juiciness of the beef.
Intramuscular fat is deposited between primary and secondary muscle bundles in the perimysium of cattle and muscle bundles [57].However, the quality of beef depends not only on the content of fat inside the muscles but also on the coordinated relationship of three of their components -intramuscular connective tissue (general and insoluble collagen that surrounds each muscle fibre and their bundles and muscle as a whole), types of muscle fibres and intramuscular fat [58].
The quality of marbled beef is affected by the duration of its ripening, which also imposes costs on the cost price of the manufactured products.Beef for steaks goes under dry or wet ageing.During wet ageing, it is vacuum packed and placed in a chamber for 3-5 days in a special microclimate, during which the fibres soften, and the meat is saturated with juices.During dry maturation, beef cuts are placed in salt chambers at certain temperatures and humidity for up to 120 days.
Consumers are increasingly concerned about the negative effects of extremely marbling beef on the human body (cardiovascular diseases and atherosclerosis).Excess omega-3 polyunsaturated fatty acids (linolenic acid, docosahexaenoic acid, eicosapentaenoic acid) increase the risk of developing prostate cancer.The main polyunsaturated omega-6 fatty acids include linoleic and arachidonic acids.For human nutrition and good health, it is possible to use food containing fat (depending on the composition and number of fatty acids) compared to saturated with simple carbohydrates [59].
Thus, there are many challenges to beef production of bulls with a better degree of meat shapes, including high feed costs, disposal of untreated excreta, and food safety risks that can result from diseases caused by fatty beef.Despite the recent achievements in the world regarding the regulation of fat deposition in the muscles of cattle in the Ukrainian meat breed, this problem remains unsolved and deserves further research.We have started to develop a strategy to optimize the amount of fat deposited in the body of these animals.To predict the content of adipose tissue under the skin and between the muscles after slaughtering bulls aged 16 to 24 months based on the severity of their meat forms at 15 months of age, correlation coefficients were calculated between these indicators.The degree of meat shapes development correlates with the adipose tissue content between muscles slightly and negatively (r = -0.08)(Table 5).The highest (r = 0.26 and 0.17) positive relationship exists between the degree of meat shape development, the content of fatty tissue under the skin, and the number of cuts off the carcass.Thus, according to the degree of meat shapes, it is only possible to a certain extent to predict the amount of deposited non-commercial fat (subcutaneous and between the muscles) and waste (cuts off) obtained during the handling of carcasses.But it is difficult to judge it in terms of the amount of deposited intramuscular adipose tissue (marbling) of beef.A change in the composition of adipose tissue by any factor depends mainly on a person's ability to control its relative amount depending on the development degree of shapes of meat animals.Modern methods of regulating the deposition of adipose tissue in the middle of the muscles should limit the increase in its total content in the body, including inedible.Additional research is needed to develop methods for the production of beef with appropriate levels of marbling to satisfy its quality and taste, following consumer preferences, preserve human health and support the economy of cattle breeding under the condition of justification of the optimal degree of the meat shapes of the bulls without increasing the deposition of total inedible fat in the body, including internal and subcutaneous fat.
A deeper understanding of these complex mechanisms of body composition regulation can improve beef quality and consistency prediction, improve the selection of animals that achieve the desired final meat quality, and identify those better suited to specific diets and consumer treatments.Because of this, meat producers will be able to use a regulatory mechanism to justify the optimal degree of meat shapes of animals, determined by the demand for beef of different qualities, which helps to optimize the accumulation of fat in muscles by improving its ratio to the protein.In addition, understanding the mechanisms of increasing fat deposition and the efficiency of beef production while simultaneously reducing the degree of meat shapes and general conditions of animals will lead to better processing of animals and the overall health of the consumer.

CONCLUSION
Bulls with different degrees of meat shapes, from 18 to 23 months, have more fat deposited under the skin than between the muscles.In animals with the best meat shapes, compared to the worst ones, there is more fat tissue in the carcass from 15.1 to 44.7%, including under the skin from 3.8 to 44.1%.The content of adipose tissue under the skin relative to its total amount in the body in animals with a better degree of meat shapes tends to decrease by 6.5 points, with a worse one -on the contrary, to increase by 2.0 points.18-month-old bulls with betterdeveloped meat shapes have 15.2% more fat cuts off from the carcass than animals with worse development, 23 -by 11.3%.The formation of a larger amount of internal adipose tissue under the skin and between the muscles in animals causes excessive (from 0.9 to 14.5%) feed consumption (feed unit) for live weight gain.With the content of fatty tissue under the skin and the number of cuts off from the carcass from 16 to 24 months, the degree of meat shapes at 15 months correlates slightly positively (r = 0.26 and 0.17, respectively).The degree of the meat shape development may be used to predict, to a certain extent, only the deposition of non-commercial fat (subcutaneous, between the muscles) and production waste (cuts off).Further research is needed to develop methods for the production of marbled beef, using bulls with less pronounced meat shapes without increasing the deposition of total inedible fat in the body, including internal and external (subcutaneous) fat and the appropriate level of intramuscular, to satisfy its quality and taste and save people's health.

Figure 1
Figure 1 Bull Pavlyn 7604 CHUM -62 has slightly better worse expressed meat forms (53.5 points).Live weight is 677 kg at the age of 18 months.

Figure 2
Figure 2 Bull Navodghik 6887 CHRUM -61 with slightly better expressed meat forms (59.5 points).Live weight is 610 kg at the age of 18 months.

Table 1
Fodder consumption by bulls by periods.

Table 3
Chemical composition of beef in 18-month-old animals with different degrees of meat shapes development.Ukrainian meat breed animals are characterized by rapid growth at the expense of muscle tissue and the formation of fat at an older age [

Table 5
Correlation coefficients between the degree of the meat shapes of bulls at the age of 15 months and the fat content in their carcasses, between muscles and cuts off from 16 to 24 months.