**5. Animal welfare: possible changes due to the occurrence of wooden breast and white striping**

Brazilian poultry stands out in the international meat market, and according to data from the Brazilian Association of Animal Protein (ABPA 2018), Brazil was in 2nd place in the world production of chicken meat (2017) with 13.05 million tons, second only to the United States, which produced 18.6 million tons. As for exports, Brazil occupies 1st place, exporting approximately 4.3 million tons [48].

Poultry intended for meat production must be assisted to comply with specific conformities for farms, such as maximum animal density, minimum lighting intensity, air quality, water and food availability, among others. Also, meat mortality and inspection data are considered to establish maximum values of stocking density. Dermatitis, parasitic infections and systemic diseases should also be measured to identify signs of poor well-being [49].

Some factors that have directly influenced this growth system are: improvement of lines and inputs, automation of process systems, sanitary conditions for the creation of controlled birds, integrated production system, among others [50].

*Advances in Poultry Nutrition Research*

condemnation.

**4. Microbiota**

prioritizing animal welfare.

the slaughter plants that these animals have the most fragile skin, with lesions that occur both within the farms and during the plucking process, there may be a greater correlation of bone fractures with these anomalies and consequently a considerable economic loss for the sector, since the carcasses may have partial or total

Research developed by [33] related WB myopathy with problems associated with the formation of bone tissue. These authors evolve an interesting line of reasoning based on the development of bone marrow-forming cells and how the increase in adipocytes can influence this process. As a result, they obtained positive correlations, and the levels of calcium and phosphorus in the bone matrix of animals that

develop WB are lower when compared to those not affected by myopathy.

supplement to mitigate the development of WS and WB myopathies.

A study by [34] that analyzed the efficiency of magnesium in the control of oxidative processes in birds, as well as its correlation with the decreased incidence of development of WS and WB myopathies, concluded that magnesia supplementation protected the tissue against protein oxidation and that it reduced the incidence of WS and WB myopathies to almost half the occurrence in fed animals supplemented with this mineral. In the same study, these authors report that even Calcio and Magnesium use unusual mechanisms of divalent ions for their absorption, one does not harm the absorption of the other, and the same occurred for Phosphorus. The results were innovative since magnesium did not interfere with the action of other minerals, a positive factor, since this benefits the bone matrix, so supplementation with magnesium in the feed of broilers can be a promising alternative as a

Another parallel approach to be considered is the intestinal microbiota of birds, as this is an innovative aspect of the proposal since recent studies have verified the importance of the intestinal microbiota in animal performance, health and wellbeing [35–37]. There is still a close relationship between the diet, microbiota and bioactive compounds that may be present or that are used commercially in poultry feed. Studies that address the interaction of the microbiota are still limited and are at the frontier of knowledge under the paradigm of sustainable poultry production,

The microbiota is recognized as the "fifth organ" and the literature suggests that the microbiome plays a crucial role in signal processing and interaction with the environment [38]. The composition of the bacterial microbiota is affected by the bacteria present in the intestine and by the natural microorganisms in the environment [39]. Chicks born in natural conditions receive the microbiota from adults, mainly from the mother. Industrial poultry farming has altered this condition, preventing the chick from coming into contact with the mother, which leads to a delay in the development of the protective intestinal microbiota [40, 41]. The balance of the microbiota can be affected by several factors, both endogenous and exogenous. Poor hygienic-sanitary conditions, stress, food, intoxication and illness, can trigger the increase in bacterial proliferation that can compete for nutrients. They can also determine inflammatory processes, which leads to thickening of the intestinal wall, which will reduce absorption, increase the excretion of metabolites and toxins that trigger enteritis and decrease the transit time of the digesta. Besides, it can increase the turnover of epithelial cells, which allow bacterial and endotoxin translocation to other organs, leading to septicemia [42]. According to [43] it is important to understand and have control over the possible changes in the intestinal microbiota to adapt the management and to include in a rational way additives that

**180**

There is a projection of a 46.4% increase in chicken meat production by 2023 Simultaneously, there is a growing demand for information on ethical aspects of animal production. In a study conducted between the states of Paraná, Santa Catarina and Rio Grande do Sul, evaluating the condemnation of birds, it was observed that injuries were the main cause of condemnation in 2015, followed by dermatoses. These same authors report that the third highest incidence of condensation is associated with dorsal skull myopathy [49]. In the State of Paraná, which slaughter more than the others in absolute numbers, the percentage of convictions increases. The progressive increase in rates of injury conviction, inadequate bleeding, arthritis and aerosaculitis can indicate important aspects of well-being.

The increase in convictions caused by arthritis may indicate that the industry has undergone significant changes in recent years, which result in a negative impact on the welfare of birds [51]. This information goes from other information obtained with the weight gain of these animals since birds are gaining weight very quickly. These same authors indicate that genetics may be the main cause of skeletal disorders in fast-growing breeds, causing a lack of activity in the birds, which because they are very heavy, aggravates the problem [52, 53]. The high stocking density is also related to the reduction of air quality, increased thermal stress and increased transmission of infectious diseases.

A study by [30] observed that for birds with WB there were changes in the birds' behavior since they associated this difference with the change in the way of walking of these animals. Which may suggest possible effects associated with loss in the welfare of these birds. Another study by [16] have already reported a possible change in the growth conditions of these birds, directly affecting their welfare.

Approach to the welfare of these birds is essential, as it compromises the structure of the carcass as a whole and can directly compromise its mobility. In reference [29] it was observed a degree of structural abnormality in all samples of chickens with rapid weight gain. However, in another study by [16] reported that there are symptoms in birds that did not affect all individuals affected by WB, however, there may be possible links with the environment. However, there is still no quantitative information on whether WS or WB affects the behavior, ability to walk or the welfare of these birds. There is a chance that these myopathies would harm mobility and, therefore, have welfare implications for animals. With this information, it would be interesting to study a variable that can correlate the stress level of birds with the myopathies associated with this proposal, with cortisol being an excellent marker for this purpose.
