**1. Introduction**

Approximately 60 years ago, there was a considerable advance in the broiler industry. Consequently, new technological and biological processes have

accompanied the development of both animals and inputs. In the last 20 years, there has been an increase in the preference for chicken meat by the general population, the trigger for this event being the affordable price of this protein source, ease and diversity in its preparation, as well as properties associated with the healthiness generated when it comes of white meats. These factors led to an increase in the poultry sector, seeking fast-growing strains, to increase production in a shorter time [1].

With these new possibilities and growth in the sector, there was also the emergence of new paradigms, one of which being the different types of myopathies. In the poultry industry, the breast is one of the parts considered noble and therefore, the occurrences, alterations and/or different myopathies that alter the quality characteristics of the breasts have been studied a lot. The most common are: Pale, Soft and Exudative (PSE), Dry, Firm and Dark (DFD), Deep pectoral myopathy or Green chest, Acid chest, White striping (WS), Wooden breast (WB) and Spaghetti meat (SM). The last three myopathies are the most recent when compared to the others mentioned. Still, there is a need to investigate further, due to changes in quality characteristics and considerable losses for the sector. In addition to permeating hypotheses to better describe what happens, why it occurs and possibly, understand the mechanism to minimize or even suppress them. Several researchers from different countries such as the USA, Italy, Spain, Brazil, Finland, Canada, China and England are looking for these answers. However, until now, little is known about the effects or action of specific proteins and protein groups on these anomalies. The difference between protein content and collagen and protein degradation rate was described in [2]. Although, protease groups are crucial to understanding what can happen with muscle activity.

Although information about the incidence of these myopathies is limited and sometimes contradictory, it is assumed that myopathic chicken breasts appear in all countries where fast-growing hybrids are used, with WS being the most common affecting up to 50% of the breasts of chicken in Italy, France, Spain and Brazil. In the Northeast of Brazil, the proportion of these myopathies is reported between 10% and 20%. In the USA there is an incidence of 98% of birds developing these myopathies, of which 55% were classified as moderate and severe [1].

The trend in the production of Brazilian chicken cuts is to continue increasing, and with that, there is a concern with the quality of this product and with the need to slaughter larger chickens with higher yield and in less time. When all these factors are achieved, a satisfactory result is achieved for the industry and the producer [3]. In a relatively short time (**Table 1**) [4], genetic selection, associated with management, nutrition and other factors, significantly accelerated the development of the muscle tissue of these birds, especially the breast (Pectoralis major), which


#### **Table 1.**

*Advance in the production of breast meat (proportional to the carcass size) concerning the commercial Ross 308 line between the years 2001 and 2017 [4].*

**175**

**Figure 1.**

*White Striping and Wooden Breast Myopathies in the Poultry Industry: An Overview of Changes…*

currently exceeds one-fifth of the total weight of the birds, and certainly represents

The results of this project on White striping (WS) and Wooden breast (WB) in poultry will be useful to better understand what happens in these animals, what their impact on meat and carcass as a whole and ensures the slaughtering and consumer industries that will have, even with myopathies, viable products in terms

The birds are staying on the farms for 9 days less and increasing 6.2% in their weight in brisket. This gain is significant for the sector since to keep these animals on the farms, generates costs of food, handling and maintenance of the production system as a whole. In this sense, [5] described that a great ally for the sector's economy is the genetic selection (**Figure 1**), as it brought standardization of broilers concerning body weight, carcass yield and feed conversion, reaching thus, a possibility of slaughtering birds with greater weight in a shorter time. It is known that genetic selection in conjunction with the accelerated growth of these animals does not always achieve positive responses and the incidence of abnormal physiological consequences begins to appear more frequently and is extremely visible and

According to information published by [6], one of the most common changes in the broilers' breasts is deep pectoral myopathy (or green muscle disease) which, according to [7], occurs when oxygenation in the smaller pectoral muscles (commercially known

of nutritional, physical–chemical, biochemical and technological aspects.

*Growth, efficiency and productivity of commercial chickens from 1957, 1978 and 2005 [6].*

*DOI: http://dx.doi.org/10.5772/intechopen.96513*

significant in chicken breasts [6].

the most valuable and noble part for the broiler industry.

#### *White Striping and Wooden Breast Myopathies in the Poultry Industry: An Overview of Changes… DOI: http://dx.doi.org/10.5772/intechopen.96513*

currently exceeds one-fifth of the total weight of the birds, and certainly represents the most valuable and noble part for the broiler industry.

The results of this project on White striping (WS) and Wooden breast (WB) in poultry will be useful to better understand what happens in these animals, what their impact on meat and carcass as a whole and ensures the slaughtering and consumer industries that will have, even with myopathies, viable products in terms of nutritional, physical–chemical, biochemical and technological aspects.

The birds are staying on the farms for 9 days less and increasing 6.2% in their weight in brisket. This gain is significant for the sector since to keep these animals on the farms, generates costs of food, handling and maintenance of the production system as a whole. In this sense, [5] described that a great ally for the sector's economy is the genetic selection (**Figure 1**), as it brought standardization of broilers concerning body weight, carcass yield and feed conversion, reaching thus, a possibility of slaughtering birds with greater weight in a shorter time. It is known that genetic selection in conjunction with the accelerated growth of these animals does not always achieve positive responses and the incidence of abnormal physiological consequences begins to appear more frequently and is extremely visible and significant in chicken breasts [6].

According to information published by [6], one of the most common changes in the broilers' breasts is deep pectoral myopathy (or green muscle disease) which, according to [7], occurs when oxygenation in the smaller pectoral muscles (commercially known

**Figure 1.** *Growth, efficiency and productivity of commercial chickens from 1957, 1978 and 2005 [6].*

*Advances in Poultry Nutrition Research*

happen with muscle activity.

time [1].

accompanied the development of both animals and inputs. In the last 20 years, there has been an increase in the preference for chicken meat by the general population, the trigger for this event being the affordable price of this protein source, ease and diversity in its preparation, as well as properties associated with the healthiness generated when it comes of white meats. These factors led to an increase in the poultry sector, seeking fast-growing strains, to increase production in a shorter

With these new possibilities and growth in the sector, there was also the emergence of new paradigms, one of which being the different types of myopathies. In the poultry industry, the breast is one of the parts considered noble and therefore, the occurrences, alterations and/or different myopathies that alter the quality characteristics of the breasts have been studied a lot. The most common are: Pale, Soft and Exudative (PSE), Dry, Firm and Dark (DFD), Deep pectoral myopathy or Green chest, Acid chest, White striping (WS), Wooden breast (WB) and Spaghetti meat (SM). The last three myopathies are the most recent when compared to the others mentioned. Still, there is a need to investigate further, due to changes in quality characteristics and considerable losses for the sector. In addition to permeating hypotheses to better describe what happens, why it occurs and possibly, understand the mechanism to minimize or even suppress them. Several researchers from different countries such as the USA, Italy, Spain, Brazil, Finland, Canada, China and England are looking for these answers. However, until now, little is known about the effects or action of specific proteins and protein groups on these anomalies. The difference between protein content and collagen and protein degradation rate was described in [2]. Although, protease groups are crucial to understanding what can

Although information about the incidence of these myopathies is limited and sometimes contradictory, it is assumed that myopathic chicken breasts appear in all countries where fast-growing hybrids are used, with WS being the most common affecting up to 50% of the breasts of chicken in Italy, France, Spain and Brazil. In the Northeast of Brazil, the proportion of these myopathies is reported between 10% and 20%. In the USA there is an incidence of 98% of birds developing these

The trend in the production of Brazilian chicken cuts is to continue increasing, and with that, there is a concern with the quality of this product and with the need to slaughter larger chickens with higher yield and in less time. When all these factors are achieved, a satisfactory result is achieved for the industry and the producer [3]. In a relatively short time (**Table 1**) [4], genetic selection, associated with management, nutrition and other factors, significantly accelerated the development of the muscle tissue of these birds, especially the breast (Pectoralis major), which

**Year Carcass weight (kg) Age (days) Breast size (%)** 2001 2.207 43 15.8 2007a 2.200 36 18.6 2012a 2.200 35 21.1 2014a 2.200 34 21.5 2017a 2.200 34 22.0

*Advance in the production of breast meat (proportional to the carcass size) concerning the commercial Ross 308* 

myopathies, of which 55% were classified as moderate and severe [1].

**174**

*a*

**Table 1.**

*Ross 308 Broiler Performance Objectives.*

*line between the years 2001 and 2017 [4].*

as "chest file" ceases or "sassami") with degeneration, necrosis and atrophy. In reference [8] reported that this anomaly can also be caused when blood circulation ceases due to intense muscle exercise, with voluntary movement of the wings where the muscle is unable to expand and ischemic necrosis of the chest muscle occurs.

Therefore, during the deboning process, this muscle is condemned, however, when there is production of whole chicken, it is not possible to identify it, because according to Ordinance No . 210, of November 10, 1998, the supra-coracoid muscle is exposed only when the carcass follows a more detailed evaluation at the Department of Final Inspection (DIF) or in the boning room [9]. However, in a review published by [6] that mentions research by Pereira et al. [10] found that myopathy can be a technopathy caused by changes in technology and, if possible, adapt the pre-slaughter management to reduce the damage caused, and these can be consumed, because it is not an issue food security, but rather a product quality problem. Reference [11] pointed out that the green color probably came from the transformation of myoglobin in anaerobic conditions and not from inflammation process.

Others anomalies in the chest and small chest file have caused damage to the refrigerators. In [12] observed in Finland that there was an increase in chicken breasts with abnormalities that was characterized in the pectoralis major muscle, with pale and hard external areas with white streaks, in which they caused rejection by the consumer and, consequently, there were economic losses in industries. They did not find a relationship between these anomalies and any antemortem symptoms.

Through electron microscopy analysis, this type of anomaly was called WS (**Figure 2**). Still, concerning anomalies, another occurrence in chicken breasts was investigated by [13] and called WB, however, the breast had a yellowish color and a certain hardness accompanied by inflammatory processes and necrosis. Both anomalies had similar histological characteristics. However, there is no information about the implication of these anomalies in the quality of the products, as well as the training mechanisms.

White streaks of chicken breast called WS (**Figure 2**), according to [8] are related to adipose tissue according to histological and chemical analyzes. While the characteristics of chicken breast with WB are related to the connective tissue that was characterized by muscle hardening [12]. Thus, these two myopathies highlighted in the present proposal, present specific differences, being that WS was characterized by the development of white fibers of the connective tissue and that

#### **Figure 2.**

*Breast fillets displaying different degrees of white striping. Score 0 indicates no white striping and score 3 indicates severe white striping [8].*

**177**

necessary.

*White Striping and Wooden Breast Myopathies in the Poultry Industry: An Overview of Changes…*

was developed in parallel to the muscle fibers, with the inclusion of adipose decision [14]. While WB according to [15] presented heterogeneity of color, excessive

Published by [16] illustrates in a very creative way how the muscle affected with WB develops pressure resistance. These authors explain the probable etiologies for the development of myopathy and address interesting issues such as nutritional,

When or when the animal dies, there is blood circulation failure as a result of bleeding, which causes depletion of oxygen and nutrients. The metabolism then uses the oxygen associated with myoglobin to continue the aerobic process. When O2 reaches its critical limits, the main metabolic pathway for ATP generation becomes the glycogen reserve. This scenario fully characterized as anaerobiosis, generates lactic acid and reduces the concentration of ATP until it no longer exists in the process. In the sequence, the actin-myosin interactions begin, forcing the muscle to enter a phase of continuous contraction until the muscle enters an irreversible phase contraction known as rigor mortis. Thus, glycogen levels begin to decrease and lactic acid is the product of this metabolism, which accumulates in the muscle fiber, acting as an indicator of the post-mortem glycolysis rate and directly results in a reduction in pH after 24 hours of slaughter. Finally, there is a proteolytic rupture of the muscular structure, which can last up to two weeks, with increased flexibility and tenderness of the meat, this last stage is known as *post rigor* mortis [6, 17]. There are several negative consequences concerning the development of these myopathies directly on the quality of chickens cited by [1], which in turn affects consumer preferences. Therefore, the search for possible solutions to prevent this occurrence is one of the main objectives for food and animal production scientists. Therefore, a prior indication of the pathological pathways of these myopathies is

**2. Economic impact and losses for the poultry industry**

these factors are responsible for economic loss in the poultry sector.

values of the damage that WB and WS can generate.

A variable portion of chicken breasts affected by the aforementioned myopathies were reported by [1] and may be due to: This author lists in the following sequence, factors that are a consequence of myopathies, being: (a) condemnation/ cut (whole breast, carcass); (b) lower yield and value since there will be changes in the water retention capacity [WHC], emulsification and gelation capacity; (c) manual separation in the deboning line to be intensified (addition and training of personnel for classification/sorting - highest cost); and (d) there will be rejection from consumers, since undesirable sensory changes occur in this meat". Consequently, all

As there are different forms of myopathies already cataloged, if all of them manifested together, certainly a refrigerator could lose millions in a few hours of slaughter, taking into account that there are systems that work with 350.00 heads of birds slaughtered in a 12-hour period (personal note author). Knowing this, several studies were carried out to try to quantify the percentage and some of the dollar

In a study carried out in the United States, it was reported that more than 50% of the studied squad developed WB [18]. Additionally, study with growing birds on farms under commercial conditions observed that 96.1% developed WB [19]. In 2017, in Italy, [20] observed 474 carcasses and of these, 53.2% developed WB. Regarding values, there are two articles regarding this survey, with Kuttappan et al. [16] indicating annual economic losses for the American market in the range of \$ 200 million. For the Brazilian market, there are estimated values of

*DOI: http://dx.doi.org/10.5772/intechopen.96513*

environmental and genetic aspects.

superficial exudate and loss of muscle elasticity.

#### *White Striping and Wooden Breast Myopathies in the Poultry Industry: An Overview of Changes… DOI: http://dx.doi.org/10.5772/intechopen.96513*

was developed in parallel to the muscle fibers, with the inclusion of adipose decision [14]. While WB according to [15] presented heterogeneity of color, excessive superficial exudate and loss of muscle elasticity.

Published by [16] illustrates in a very creative way how the muscle affected with WB develops pressure resistance. These authors explain the probable etiologies for the development of myopathy and address interesting issues such as nutritional, environmental and genetic aspects.

When or when the animal dies, there is blood circulation failure as a result of bleeding, which causes depletion of oxygen and nutrients. The metabolism then uses the oxygen associated with myoglobin to continue the aerobic process. When O2 reaches its critical limits, the main metabolic pathway for ATP generation becomes the glycogen reserve. This scenario fully characterized as anaerobiosis, generates lactic acid and reduces the concentration of ATP until it no longer exists in the process. In the sequence, the actin-myosin interactions begin, forcing the muscle to enter a phase of continuous contraction until the muscle enters an irreversible phase contraction known as rigor mortis. Thus, glycogen levels begin to decrease and lactic acid is the product of this metabolism, which accumulates in the muscle fiber, acting as an indicator of the post-mortem glycolysis rate and directly results in a reduction in pH after 24 hours of slaughter. Finally, there is a proteolytic rupture of the muscular structure, which can last up to two weeks, with increased flexibility and tenderness of the meat, this last stage is known as *post rigor* mortis [6, 17].

There are several negative consequences concerning the development of these myopathies directly on the quality of chickens cited by [1], which in turn affects consumer preferences. Therefore, the search for possible solutions to prevent this occurrence is one of the main objectives for food and animal production scientists. Therefore, a prior indication of the pathological pathways of these myopathies is necessary.
