Wooden-Breast, White Striping, and Spaghetti Meat: Causes, Consequences and Consumer Perception of Emerging Broiler Meat Abnormalities.

Ten years ago, the occurrence of macroscopic defects in breasts muscles from fast-growing broilers challenged producers and animal scientists to label and characterize myopathies wholly unknown. The distinctive white striations in breasts affected by white striping disorder, the presence of out-bulging and pale areas of hardened consistency in the so-called wooden breast, and the separation of the fiber bundles in breasts labelled as spaghetti meat, made these myopathies easily identified in chicken carcasses. Yet, the high incidence of these myopathies and the increasing concern by producers and retailers led to an unprecedented flood of questions on the causes and consequences of these abnormal chicken breasts. This review comprehensively collects the most relevant information from studies aimed to understand the pathological mechanisms of these myopathies, their physicochemical and histological characterization and their impact on meat quality and consumer's preferences. Today, it is known that the occurrence is linked to fast-growth rates of the birds and their large breast muscles. The muscle hypertrophy along with an unbalanced growth of supportive connective tissue leads to a compromised blood supply and hypoxia. The occurrence of oxidative stress and mitochondrial dysfunction leads to lipidosis, fibrosis, and overall myodegeneration. Along with the altered appearance, breast muscles affected by the myopathies display poor technological properties, impaired texture properties, and reduced nutritional value. As consumer's awareness on the occurrence of these abnormalities and the concerns on animal welfare arise, efforts are made to inhibit the onset of the myopathies or alleviate the severity of the symptoms. The lack of fully effective dietary strategies leads scientists to propose whether "slow" production systems may alternatively provide with poultry meat free of these myopathies.

Histology, composition, and quality traits of chicken Pectoralis major muscle affected by wooden breast abnormality.

Only a few years ago, the poultry industry began to face a recent abnormality in breast meat, known as wooden breast, which frequently overlaps with white striping. This study aimed to assess the impact of wooden breast abnormality on quality traits of meat. For this purpose, 32 normal (NRM), 32 wooden (WB), and 32 wooden and white-striped (WB/WS) Pectoralis major muscles were selected from the same flock of heavy broilers (males, Ross 708, weighing around 3.7 kg) in the deboning area of a commercial processing plant at 3 h postmortem and used to assess histology, proximate (moisture, protein, fat, ash, and collagen) and mineral composition (Mg, K, P, Na and Ca), sarcoplasmic and myofibrillar protein patterns, and technological traits of breast meat. Compared to the normal group, WB/WS fillets showed more severe histological lesions characterized by fiber degeneration, fibrosis, and lipidosis, coupled with a significantly harder texture. With regard to proximate and mineral composition, abnormal samples exhibited significantly (P < 0.001) higher moisture, fat, and collagen contents coupled with lower (P < 0.001) amounts of protein and ash. Furthermore, increased calcium (131 vs. 84 mg kg(-1); P < 0.05) and sodium (741 vs. 393 mg kg(-1); P < 0.001) levels were found in WB/WS meat samples. The SDS-PAGE analysis revealed a significantly lower amount of calcium-ATPase (SERCA, 114 kDa), responsible for the translocation of Ca ions across the membrane, in normal breasts compared to abnormal ones. As for meat quality traits, fillets affected by wooden abnormality exhibited significantly (P < 0.001) higher ultimate pH and lower water-holding/water-binding capacity. In particular, compared to normal, abnormal samples showed reduced marinade uptake coupled with increased drip loss and cooking losses as well. In conclusion, this study revealed that meat affected by wooden breast or both wooden breast and white striping abnormalities exhibit poorer nutritional value, harder texture, and impaired water-holding capacity.

Relationship between pectoralis major muscle histology and quality traits of chicken meat.

A trial was conducted to evaluate the influence of myodegeneration of pectoralis major muscle on quality traits and chemical composition of breast meat of heavy-size male broilers. For this purpose, a total of 72 pectoralis major muscles were randomly collected from broilers farmed under homogeneous conditions and graded into three categories (mild, n=22; moderate, n=33; and severe, n=17) based on the presence of abnormal fibers (giant fibers, fibers with hyaline degeneration, and damaged and/or necrotic fibers) evaluated by histological and immunohistochemical analysis. Color, pH, drip loss, Allo-Kramer shear values, and chemical composition (moisture, proteins, total lipids, ashes, and collagen) were determined on nonmarinated breast meat. Purge loss and cook loss, total yield, and Allo-Kramer shear values were measured on vacuum-tumbled samples. Samples showing moderate myodegeneration had the highest mean cross-sectional area of the fibers, while samples with severe myodegeneration had myofibers of different diameter and without the characteristic polygonal shape, multifocal degeneration and necrosis, as well as infiltration of CD3-immunoreactive cells. Cooking losses of nonmarinated meat were lower in the mild group with respect to moderate and severe groups (21.4 vs. 24.7 and 24.7%; P<0.001). Breast muscles with severe damage, in comparison with mild degenerated samples, showed higher moisture (75.4 vs. 74.4%; P<0.05) and lower protein percentages (21.1 vs. 22.6%; P<0.001). The lipid percentage of severely degenerated samples was higher than that from moderate group (2.94 vs. 2.36; P<0.05), while collagen content was not modified by histological lesion levels. Marinated meat from the mild group had higher uptake and total marinade yield after cooking. In conclusion, almost all breast fillets of heavy broiler chickens produced under intensive farming systems had histological lesions, which reflected on the chemical composition of the meat and the impaired water holding/binding capacities of the meat.

Effect of genotype, gender and feed restriction on growth, meat quality and the occurrence of white striping and wooden breast in broiler chickens.

Due to their importance for the control of meat quality in broiler chickens, the present study aimed at identifying the factors associated with the occurrence of myopathies and characterizing the meat properties when affected by myopathies. To this aim, a total of 768 broiler chickens were reared until slaughter (46 d) to evaluate the effect of genotype, gender, and feeding regime (ad libitum vs. restricted rate, 80% from 13 to 21 d of age) on performance and meat quality. Standard broilers were heavier (3,270 vs. 3,139 g; P<0.001) and showed lower feed conversion (1.56 vs. 1.61; P<0.001) than the high-yield broilers. Males showed higher final live weight (3,492 vs. 2,845 g) and lower feed conversion (1.54 vs. 1.63) than females (P<0.001). Feed restriction decreased final live weight (3,194 vs. 3,142 g; P<0.01) and feed conversion (1.60 vs. 1.57; P<0.01) compared to ad libitum feeding. At gross examination, feed restriction tended to increase white-striped breasts (69.5 vs. 79.5%; P<0.10), whereas females showed less wooden breasts than males (8.0 vs. 16.3%; P<0.05). White-striped fillets had higher pHu (5.87 vs. 5.83), and lower a* (-0.81 vs. -0.59) and b* color indexes (13.7 vs. 14.5) (P<0.05), whereas wooden breast fillets exhibited higher cooking losses (25.6 vs. 22.1%) and AK-shear force (4.23 vs. 2.84 kg/g) compared with normal fillets (P<0.001). At histological examination, 3.1% of pectoralis major were normal, 26.6% mildly degenerated, 45.3% moderately degenerated, and 25.0% severely degenerated. In conclusion, genotype had a moderate effect on growth without modifying myopathy occurrence. In contrast, gender and feed restriction affected performance, meat quality, and breast abnormalities.

Quantity and functionality of protein fractions in chicken breast fillets affected by white striping.

Recently, white striations parallel to muscle fibers direction have been observed on the surface of chicken breast, which could be ascribed to intensive growth selection. The aim of this study was to evaluate the effect of white striping on chemical composition with special emphasis on myofibrillar and sarcoplasmic protein fractions that are relevant to the processing features of chicken breast meat. During this study, a total of 12 pectoralis major muscles from both normal and white striped fillets were used to evaluate chemical composition, protein solubility (sarcoplasmic, myofibrillar, and total protein solubility), protein quantity (sarcoplasmic, myofibrillar, and stromal proteins), water holding capacity, and protein profile by SDS-PAGE analysis. White-striped fillets exhibited a higher percentage of moisture (75.4 vs. 73.8%; P < 0.01), intramuscular fat (2.15 vs. 0.98%; P < 0.01), and collagen (1.36 vs. 1.22%; P < 0.01), and lower content of protein (18.7 vs. 22.8%; P < 0.01) and ash (1.14 vs. 1.34%; P < 0.01), in comparison with normal fillets. There was a great decline in myofibrillar (14.0 vs. 8.7%; P < 0.01) and sarcoplasmic (3.2 vs. 2.6%; P < 0.01) content and solubility as well as an increase in cooking loss (33.7 vs. 27.4%; P < 0.05) due to white striping defects. Moreover, gel electrophoresis showed that the concentration of 3 myofibrillar proteins corresponding to actin (42 kDa); LC1, slow-twitch light chain myosin (27.5 kDa); and LC3, fast-twitch light chain myosin (16 kDa), and almost all sarcoplasmic proteins were lower than normal. In conclusion, the findings of this study revealed that chicken breast meat with white striping defect had different chemical composition (more fat and less protein) and protein quality and quantity (low content of myofibrillar proteins and high content of stromal proteins) with respect to normal meat. Furthermore, white striped fillets had lower protein functionality (higher cooking loss). All the former changes indicate that white striping has great impact on quality characteristics of chicken breast meat.

Comparison of meat quality characteristics and oxidative stability between conventional and free-range chickens.

The aim of this research was to evaluate quality traits and oxidative stability of meat products from free-range (FR) and conventionally (C) raised chickens as they actually reach consumers in the Italian retail market. Free-range female and male chickens (n = 1,500 + 1,500), medium growing ISA strain, were raised under commercial conditions for 56 (1.8 kg of live weight) and 70 d (3.1 kg of live weight), respectively; C female and male birds (n = 5,000 + 5,000) were a fast growing hybrid (Ross 708) and were separately raised for 39 (1.9 kg of live weight) and 50 d (3.1 kg of live weight), respectively. A total of 96 chickens (equally divided by production system and sex) were slaughtered in 2 separate sessions to obtain the main 2 commercial categories (rotisserie and cut-up, respectively). After slaughtering, 12 carcasses of each treatment group were randomly selected and used to assess quality properties, chemical composition, and oxidation stability of breast and leg meat. The C birds had dramatic higher carcass and breast meat yield, whereas FR had higher wing and leg yields. The FR birds exhibited higher water holding capacity in both breast and leg meat. Although shear force did not differ in breast meat, legs from FR birds were tougher. Fatty acid composition of FR breast and thigh meat of both categories were characterized by a higher polyunsaturated fatty acid n-6-/n-3 ratio. In general, a low lipid oxidation level (peroxide value < 1.3 mEq O2/kg of lipid and TBA reactive substances < 0.2 mg malondialdehyde/kg of sample) was found in breast and legs, regardless of the commercial category. However, the C system significantly increased peroxide value in rotisserie thigh meat, whereas FR led to a significantly higher TBA reactive substances in breast meat. Our results demonstrated that free range can modify the properties of chicken meat and also highlighted the importance of the bird genetic background to select nutritional strategies to improve meat quality traits and oxidative stability in poultry.

Dietary guanidinoacetate reduces spaghetti meat myopathy risk in the breast muscle of broiler chickens.

The global demand for white chicken meat along with the increase in the occurrence of growth-related breast muscle myopathies (BMMs) [namely white striping (WS), wooden breast (WB), and spaghetti meat (SM)] highlights the need for solutions that will improve meat quality while maintaining the high productivity of modern broilers. Guanidinoacetate (GAA), a precursor of creatine, is used as a feed additive and has previously shown the potential to affect the quality of breast meat. This study investigated growth performance, meat quality and the risk ratio for the development of BMMs in broilers assigned to two dietary treatments: control (CON) group, fed a commercial basal diet, and supplemented GAA (sGAA) group, receiving the control diet supplemented on top with 0.06% GAA. Growth performance indicators such as BW, daily weight gain, daily feed intake, feed conversion ratio and cumulative feed conversion ratio were recorded on a pen basis. As a trait affecting animal welfare, the occurrence of foot pad dermatitis was also evaluated. At day 43, birds were processed, and breasts were scored for the incidence and severity of BMMs (n = 166 and 165 in CON and sGAA groups, respectively). Quality traits (ultimate pH, colour) and technological properties (i.e., drip and cooking losses, marinade uptake, shear force, and oxidation levels of the lipid and the protein fractions) of breast meat were assessed in both treatments on samples not showing any macroscopic sign of BMMs (n = 20 breast fillets per group). Data of myopathy risk ratio were analysed as the risk for each group to develop WS, WB, and SM myopathies. Our results show that while sGAA and control groups did not differ significantly in growth performance, a remarkably beneficial effect of GAA was observed on the incidence of BMMs with significantly reduced risk of sGAA group to develop SM myopathy. The risk of sGAA group to develop SM was 30% lower compared to CON (P = 0.028). Finally, a significantly lower drip loss was observed in sGAA in comparison with CON (1.78 vs 2.48%, P = 0.020). Together, our results show that the inclusion of 0.06% GAA in feed can improve the water-holding capacity of meat and reduce the risk to develop SM myopathy without compromising the performance of broilers.

Dietary supplementation with Chlorella vulgaris in broiler chickens submitted to heat-stress: effects on growth performance and meat quality.

Heat stress can greatly challenge growth and meat quality of broiler chickens where research is looking for sustainable ingredients, such as microalgae, that could also alleviate its negative impacts. Thus, in the present study, 576 1-D-old chicks (Ross 308) were housed until commercial slaughtering (42 D) in 36 pens in 2 rooms of a poultry house, according to a full factorial design encompassing 2 room temperatures (standard vs. high), 2 sexes (females vs. males), and 3 dietary treatments, that is, diet C0 (control diet), diet C3, and diet C6 containing 0, 3, and 6%, respectively, of C. vulgaris meal replacing the same quantities of soybean meal. The highest inclusion level of C. vulgaris decreased feed intake (P < 0.001) and body weight (P < 0.0001) compared to the control diet; it increased yellow and red indexes (P < 0.0001) of the breast muscle, besides the proportion of n3 polyunsaturated fatty acids (PUFA) (P = 0.028). Heat stress decreased feed intake (P = 0.001), breast (P = 0.001) and p. major yields (P = 0.036), and increased meat pH (P= 0.008) and cooking losses (P < 0.001), umami (P = 0.021) and brothy flavor (P < 0.001), and the proportion of n3 PUFA rates (P = 0.027), while reducing the contents of several amino acids in the breast meat (P ≤ 0.05). Compared to females, males displayed higher feed intake and growth, and more favorable feed conversion (P < 0.001). Carcass and p. major yields were greater in females (P < 0.001) which also showed a higher occurrence of spaghetti meat compared to males (P < 0.001). In conclusion, C. vulgaris can be used to replace until 3% of soybean meal in diets for broiler chickens without negative implications, while positively affecting breast meat color according to consumers' preferences. However, the microalgae inclusion did not mitigate the negative effects of a chronic heat stress on growth performance nor reduced the occurrence of any myopathies.

Comparison of breast muscle traits and meat quality characteristics in 2 commercial chicken hybrids.

A trial was conducted to compare muscle traits and meat quality characteristics of the pectoralis muscle in 2 chicken commercial hybrids having standard (SBY) and high breast yield (HBY), respectively. A total of 2,124 one-day-old male chicks, equally divided into 2 experimental groups represented by strains (SBY and HBY), were grown using homogenous conditions and fed the same standard diets until reaching live weight of 4.2 kg at 53 and 55 d for the SBY and HBY groups, respectively. Thirty-six birds per each genotype were randomly selected, and their pectoralis major muscles were used to assess meat quality properties (color attributes, pH, drip loss, cook loss, Allo-Kramer shear values after cooking, moisture, proteins, total lipids, and ashes) as well as histological traits (cross-sectional area, frequency of abnormal fibers, and intramuscular fat infiltration). As expected, HBY genotype had higher breast yield (31.0 vs. 30.0%; P ≤ 0.05). Histological evaluations showed that HBY pectoralis muscles had higher cross-sectional fiber area coupled with a dramatically higher (P ≤ 0.001) incidence of abnormal fibers and more abundant infiltration of intramuscular fat. Moreover, histopathological anomalous features such as central nuclei, proliferation of endomysial and perimysial collagen, inflammatory infiltrate, and necrosis of the fibers were also observed. As for meat quality, SBY hybrid showed lower ultimate pH values (5.97 vs. 6.07; P ≤ 0.01), whereas overall color parameters were not affected by genotype. Breast meat from the HBY genotype also exhibited significantly lower ability to retain liquid during refrigerated storage (drip loss, 2.46 vs. 2.06%; P ≤ 0.05) and cooking (26.2 vs. 21.1%; P ≤ 0.05) as well as higher shear-force values (2.59 vs. 2.11 kg/g; P ≤ 0.001). Finally, with regard to chemical composition, significant differences (P ≤ 0.05) were detected in protein (22.8 vs. 23.5%) and lipid (1.65 vs. 1.82%) contents, which were significantly lower in the HBY hybrid, whereas moisture content tended (P = 0.07) to be inferior in the SBY hybrid.

Occurrence of white striping under commercial conditions and its impact on breast meat quality in broiler chickens.

The aims of this study were to evaluate the incidence of white striping (WS) under commercial conditions and assess its effect on some quality traits in broiler breast fillets. In the first experiment, occurrence of WS (absence = normal; presence classified in 2 levels as moderate or severe) was assessed in a major commercial processing plant on 28,000 breast fillets (pectoralis major muscles) chosen at random from 56 flocks of broilers processed at 45 to 54 d of age. In the second experiment, 153 fillets were selected based on WS degree (normal, moderate, or severe) and used to assess ultimate pH, color, drip loss, cook loss, and Allo-Kramer-shear force on raw meat as well to determine marinade uptake, purge loss, cook loss, total yield, and Allo-Kramer-shear force after tumbling with a 15% (wt/wt) solution containing sodium tripolyphosphate (2.3%) and sodium chloride (7.6%). The total incidence of white striped breast fillets was 12.0% (8.9 and 3.1% in moderate and severe degree, respectively). Considering the effect of genotype, high-breast yield hybrids exhibited a higher overall incidence of WS compared with standard breast yield birds (15.2 vs. 10.0%; P ≤ 0.001). Severe fillets showed higher pH than moderate and normal groups (5.95 vs. 5.88 and 5.86; P ≤ 0.05). Fillets with severe and moderate WS also exhibited lower marinade uptake compared with normal fillets (7.92 vs. 10.97 vs. 12.67%; P ≤ 0.05). Moreover, cook losses increased as the degree of WS increased from normal to severe groups in both raw (21.27 vs. 23.20 vs. 26.74%; P ≤ 0.05) and marinated meat (14.59 and 14.84 vs. 15.93%; P ≤ 0.05). Finally, nonmarinated fillets with severe striping had lower Allo-Kramer-shear force compared with moderate and normal ones (3.69 vs. 4.41 and 4.91 kg/g; P ≤ 0.05). In conclusion, this study revealed the importance achieved by WS defects in the production of broiler meat as well as its very negative impact on water holding and binding capacity of breast meat.

The use of sodium bicarbonate for marination of broiler breast meat.

This study aimed to evaluate marination performances and the effect on meat quality traits of sodium bicarbonate, used alone or in combination with sodium chloride, when compared with sodium trypolyphosphate by using advanced analytical tools, including low-field nuclear magnetic resonance and differential scanning calorimetry. In total, 140 samples (cylindrical shape of 1 × 4 cm size) were obtained from a batch of 24-h postmortem broiler breast meat (Ross 708, females, 47 d old). Six of the groups were used for subsequent marination treatments, whereas the last group was kept as a nonmarinated control. Samples were subjected to vacuum tumbling in a special equipped laboratory rotary evaporator with a 12% (wt/wt) water:meat ratio using 6 marinade solutions: 7.7% (wt/wt) NaCl (S); 2.3% (wt/wt) Na(4)O(7)P(2) (P); 2.3% (wt/wt) NaHCO(3) (B); S and P; S and B; S, P, and B. Samples marinated with bicarbonate alone or in combination (B, SB, and SPB) significantly increased (P < 0.05) the meat pH by approximately 0.7 units compared with that of the control, whereas phosphate alone or in combination with salt increased (P < 0.05) the pH by 0.2 units. The combination containing all of the ingredients (SPB) produced the highest marinade performances; however, SB was able to guarantee a better marinade uptake and water retention ability with respect to that of SP. According to low-field nuclear magnetic resonance, the combined use of B and P with S determined a remarkable increase in proportion of entrapped water into the myofibrillar spaces, while the extramyofibrillar water fraction was not modified. Moreover, water gain following marination does not correspond to an increase in the freezable water amount, as detected by differential scanning calorimetry. In conclusion, B is a very promising marinating agent, and it can be exploited to develop processed poultry products with no added phosphates to match the request to avoid the nutritional drawbacks recently indicated with the use of phosphates.

Review: Production factors affecting poultry carcass and meat quality attributes.

Poultry meat mainly comes from standard production system using high growth rate strains reared under indoor intensive conditions. However, it is possible to find also different alternative systems using outdoor extensive rearing conditions and slow-growing lines. These different production systems can affect carcass and meat quality. In this review, quality has been broken down into six properties: commercial, organoleptic, nutritional, technological, sanitary and image, the latter covering the ethical, cultural and environmental dimensions associated with the way the meat is produced, as well as its origin and being particularly valued in many quality labels. The quality of meat is built and can deteriorate along the continuum from the conception of the animal to the fork. Our review details the different factors implicated in the determinism of poultry meat properties and pinpoints critical periods, such as the preslaughter and slaughter periods, and key factors, such as the feeding regimen, via its direct effect on the fatty acid profile, the antioxidant and volatile compound contents, and indirect effects mediated via the growth rate of the bird. Our review also highlights potential antagonisms between different dimensions of quality. The genetic selection for breast meat yield, for example, has been effective in producing carcasses with higher meat yield, but resulting since a decade in the increased occurrence of quality defects and myopathies (white striping, wooden breast, spaghetti meat and deep pectoral disease). Outdoor access has positive effects on the image and nutritional properties (through its effect on the fatty acid profile of meat lipids), but it increases the exposition risk to environmental contaminants and pathologies (parasites, virus, bacteria); it also increases the variability in meat quality linked to the variability of animal performance and slaughter age. The orientation towards more agro-ecological low-input farming systems may present benefits for the image and nutritional properties, but also risks for the commercial (low carcass weight and low breast yield, irregularity in supply), organoleptic (stronger flavour, less tender and darker colour of the meat) and in terms of variability of the different properties that constitute quality. Efforts should be made in the future to better take into account the various dimensions of quality, in consumer information, payment to farmers and genetic selection.

A critical review of the mechanisms involved in the occurrence of growth-related abnormalities affecting broiler chicken breast muscles.

In the past decade, the poultry industry has faced the occurrence of growth-related muscular abnormalities that mainly affect, with a high incidence rate, the Pectoralis major of the fast-growing genotypes selected for their production performances (high growth rate and breast yield). These myopathies are termed as White Striping, Wooden Breast, and Spaghetti Meat and exhibit distinctive phenotypes. A spatiotemporal distribution has been demonstrated for these disorders as in the early stage they primarily affect the superficial area in the cranial portion of the muscle and, as the birds grow older, involve the entire tissue. Aside from their distinctive phenotypes, these myopathies share common histological features. Thus, it might be speculated that common causative mechanisms might be responsible for the physiological and structural perturbations in the muscle associated with these conditions and might underpin their occurrence. The present review paper aims to represent a critical survey of the outcomes of all the histologic and ultrastructural observations carried out on White Striping, Wooden Breast, and Spaghetti Meat affected muscles. Our analysis has been performed by combining these outcomes with the findings of the genetic studies, trying to identify possible initial causative mechanisms triggering the onset and the time-series of the events ultimately resulting in the development and progression of the growth-related myopathies currently affecting broilers Pectoralis major muscles. Several evidences support the hypothesis that sarcoplasmic reticulum stress, primarily induced an accumulation of misfolded proteins (but also driven by other factors including altered calcium homeostasis and accumulation of fatty acids), may be responsible for the onset of these growth-related myopathies in broilers. At the same time, the development of hypoxic conditions, as a direct consequence of an inadequate vascularization, triggers a time-series sequence of events (i.e., phlebitis, oxidative stress, etc.) resulting in the activation of response mechanisms (i.e., modifications in the energetic metabolism, inflammation, degeneration, and regeneration) which are all strictly related to the progression of these myopathic disorders.

Survey of skin pigmentation of yellow-skinned broiler chickens.

The appearance of whole carcass and skin-on cut-up products is an important attribute that deeply affects the consumer's choice. Skin pigmentation is affected mainly by genetics, concentration and dietary source of pigments, health status of the birds, and scalding-plucking conditions during slaughtering, although other factors might play an important role. Retailers request batches of broiler chicken carcasses characterized by uniform skin pigmentation to be sold as whole carcass or parts. The aim of this study was to evaluate the variability of skin color of yellow-skinned broilers reared under intensive conditions. For the study, a total of 2,300 medium size broiler chickens (2,300 to 2,500 g of live weight) from 23 flocks (100 birds/flock; n = 12 flocks of males and n = 11 flocks of females; n = 12 flocks of Ross 508 and n = 11 flocks of Ross 308) were randomly selected in a single slaughterhouse. The color measurements were carried out on both breast and thigh pterylae as well as on shank skin adopting the L* a* b* system and using a Minolta colorimeter CR 300. The overall range in measured yellowness (b*) was fairly large for all skin color measurement positions. For breast, a mean value of 22.77 (SD = 5.12) was observed, with values ranging from 7.45 to 39.12. Average values of thigh and shank were 20.23 (SD = 5.02; range 1.99 to 37.82) and 53.99 (SD = 8.13; range 24.22 to 78.65), respectively. A higher skin yellowness was observed in females in all body parts as well as in Ross 308. Yellowness values of breast and thigh were significantly correlated (r = 0.85; P < 0.01), suggesting that the color evaluation may be carried out only on one measurement position of the skin.

The European perspective on pale, soft, exudative conditions in poultry.

Over the past 15 yr, the European poultry processing industry has gradually increased the availability of poultry meat in a large variety of processed ready meals following what occurred a few years before in North America. This shift toward further processed products has emphasized the necessity for higher standards in poultry meat to improve sensory characteristics and functional properties. In parallel to this market change, the consciousness of the pale, soft, and exudative (PSE)-like meat issue has extensively grown. In poultry, PSE-like meat can be generally considered meat having low ultimate pH, pale color, and poor functional properties (i.e., low water-holding capacity). In the last 10 yr, some studies have been undertaken in Europe to both characterize and evaluate the overall incidence of PSE-like chicken and turkey breast meat. According to these studies, the occurrence of PSE-like meat can be up to 40% within a flock during hot climate. Several key factors have been identified and their effects have been analyzed, including genetics, season, antemortem factors, and slaughtering conditions.

Influence of partial and complete caponization on chicken meat quality.

Caponization is a surgical technique adopted to alter the sexual maturation of male chickens with the aim of improving the quality characteristics of carcass and meat. Under commercial conditions within each flock, about 10% of the birds usually result with incomplete caponization and are called slips. A trial was conducted to compare quality traits of breast and thigh meat from capons (n = 12), slips (n = 12), and cocks (unoperated birds; n = 12) (Hubbard x Golden Comet) reared together and processed at 180 d old under commercial conditions. Capons exhibited the highest (P < 0.01) values of breast and thigh meat lightness and yellowness as well as the lowest values of redness (P < 0.01) compared with cocks and slips. These variations in meat color were related to a lower concentration of heme pigments in both breast and thigh meat from capons. Capons and slips presented lower Allo-Kramer shear values of cooked breast meat (P < 0.05) in comparison with cocks. As for chemical composition, capons showed a higher content of total lipid, cholesterol, and ash both in breast and thigh meat. Total saturated, monounsaturated, and polyunsaturated fatty acids were not strongly affected by caponization. However, capons exhibited a significantly higher (P < 0.01) content of linoleic and linolenic acids as well as a lower content of arachidonic, eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids in respect to slips and cocks. Overall, this study indicated that caponization can affect the main meat quality traits with special regards to appearance (color), texture, and composition. Finally, it was found that slips present intermediate meat quality characteristics between capons and cocks.

Effect of different arginine-to-lysine ratios in broiler chicken diets on the occurrence of breast myopathies and meat quality attributes.

This study was carried out to evaluate the effect of different digestible arginine-to-lysine (dig Arg:Lys) ratio in broiler diets on the occurrence of breast myopathies, productivity, and meat quality traits. A total of 1,755 1-day-old Ross 308 male chicks was randomly divided in 3 experimental groups (9 replications/group): CON, fed a 4 feeding-phases commercial diet (dig Arg:Lys ratio = 1.05, 1.05, 1.06, 1.07, respectively in starter, grower I, grower II and finisher phase), and ARG2 and ARG3 groups fed CON diet supplemented respectively with 20 and 30% higher levels of crystalline L-arginine (dig Arg:Lys ratio = 1.25, 1.25, 1.26, 1.27 and 1.35, 1.35, 1.36, 1.37, respectively). Productive performance was recorded throughout the rearing cycle. At processing (43 d), breasts (n = 150/group) were randomly collected to evaluate the incidence and severity of white striping (WS), wooden breast (WB), and spaghetti meat (SM) defects (3-points scale). Meat quality traits, such as color, pH, drip and cook losses, marinade performances, and proximate composition were determined on 12 fillets/group. Although productive performance and meat quality traits resulted not significantly affected, the occurrence of some breast myopathies was modified by the dietary treatments. ARG2 and ARG3 exhibited a significantly higher percentage of breast without WS compared to CON (28 and 41 vs. 17%, respectively; P < 0.001). ARG3 reported the lowest percentage of breasts with severe WS (11 vs. 27 and 31%, respectively for ARG3, ARG2, and CON; P < 0.001) and the highest of those showing no SM abnormality (81 vs. 69 and 65%, respectively for ARG3, ARG2, and CON; P < 0.01). Furthermore, a numerical reduction of breasts with severe WB was observed in ARG3 (12 vs. 25 and 19%, respectively for ARG3, ARG2, and CON; P = 0.12). In conclusion, the dietary supplementation of arginine to increase the dig Arg:Lys ratio by about 30% in respect to the current recommendations for broiler chickens has positive implications on the occurrence of some breast meat abnormalities.

Effect of broiler breast abnormality and freezing on meat quality and metabolites assessed by 1H-NMR spectroscopy.

The present study aimed at investigating the impact of the current growth-related abnormalities (White-Striping-WS, Wooden Breast-WB, and Spaghetti Meat-SM) affecting broilers Pectoralis major muscles on the main quality traits, the oxidative stability of both the lipid and protein fraction as well as the water mobility assessed in fresh and frozen/thawed meat. In addition, Nuclear Magnetic Resonance spectroscopy (1H-NMR) was applied to quantify free amino acids, histidine-containing dipeptides and metabolites involved in energy-generating pathways. Overall, the occurrence of WS, WB, and SM abnormalities remarkably affected the quality traits (pH, color, and water holding capacity) and oxidative stability of the meat, with the WB condition leading to the most detrimental effects. However, overall, freezing and subsequent thawing only partially worsened the aforementioned traits. Significant variations in free amino acids and histidine-containing dipeptides were found between abnormal muscles and their unaffected counterpart by 1H-NMR spectroscopy and, aside from the occurrence of muscular defects, their content was remarkably reduced in frozen/thawed meat. The findings obtained by analyzing the metabolites through 1H-NMR spectroscopy allowed to advance the knowledge concerning the impact of freezing and subsequent thawing on meat quality traits and provided useful information concerning the underlying mechanisms responsible for the development of WS, WB, and SM abnormalities in broilers.

Gaping of pectoralis minor muscles: magnitude and characterization of an emerging quality issue in broilers.

Recently, a certain number of broiler abattoirs located in different Countries around the World have signaled an emerging quality issue termed "gaping" because of the separation of the fiber bundles affecting the external portion of the bipinnate pectoralis minor muscle. Thus, after defining the criteria to classify the muscles as Normal (NORM), Moderate (MOD), or Severe (SEV) cases, the incidence of gaping under commercial conditions was assessed on a total of 8,600 P. minor obtained from broiler chickens belonging to 43 flocks during a 6-mo period. Then, a total of 180 P. minor were selected based on previously defined criteria to evaluate the main quality traits (pH, color, water-holding/-binding capacity and tenderness), proximate composition, water mobility, and thermal properties as well as metabolic profile through 1H-Nuclear Magnetic Resonance spectroscopy. The average incidence of gaping defect was found to be 16.8% (8.8 and 8.0% MOD and SEV cases, respectively). As for the main quality traits, a reduction in ultimate pH was observed as the severity of the gaping defect increased, with SEV muscles displaying significantly lower values in comparison with NORM (5.96 vs. 6.02; P < 0.01), while MOD showed intermediate values (5.99). Concurrently, if compared with their NORM counterpart, MOD and SEV exhibited higher lightness (53.6 and 54.2 vs. 51.8; P < 0.01) coupled with higher (P < 0.05) cooking losses and longer (P < 0.05) transversal relaxation time of extra-myofibrillar water fraction. Overall, no significant differences were found concerning proximate composition and thermal properties. With regard to the metabolic profile, a significantly lower (P < 0.001) glutamine concentration was found in MOD and SEV muscles that, concurrently, revealed significant (P < 0.05) variations in the metabolites involved in energy-generating pathways. Overall, these findings evidenced that the gaping defect affecting broilers' P. minor muscles have strong similarities with the pale-soft-exudative condition previously described in poultry and likely results from the biochemical processes taking place during the post-mortem conversion of muscle to meat.

Black soldier fly defatted meal as a dietary protein source for broiler chickens: effects on carcass traits, breast meat quality and safety.

Finding insect meals as alternative sources of poultry feedstuffs is a recent research topic; therefore, the present study aimed to evaluate the effects of defatted black soldier fly (Hermetia illucens L., HI) larvae meal in broiler chicken diets on the carcass characteristics and meat quality parameters, proximate composition, fatty acid profile and the heavy metal content of the breast meat. Four dietary treatments were designed: a control diet (HI0) and three experimental diets (HI5, HI10 and HI15), corresponding to 50, 100 and 150 g/kg HI inclusion levels, respectively. The inclusion of 50, 100 and 150 g HI meal per kg feed supply 16.56%, 33.01% and 49.63% of required crude protein. The broilers were slaughtered at day 35, the carcasses were weighed and the breast muscles were excised from 16 birds per each feeding group (two birds per replicate pens) and used for meat quality evaluation. Linear and quadratic responses were observed, for increasing HI meal levels, in the live and carcass weights (maximum for HI10). As far as the colour of the breast meat is concerned, redness (a*) showed a linear response, while yellowness (b*) linearly decreased with increasing HI meal levels (minimum for HI15). As the HI larvae meal increased in the diets, the moisture content linearly decreased and the protein content increased. The total saturated fatty acid and total monounsaturated fatty acid proportions rose to the detriment of the polyunsaturated fatty acid fraction. The HI larvae meal, used in the current study, represents a valuable protein source for broiler chickens when included by up to 100 g/kg in their diets, as an improved slaughtering performance was observed without any detrimental effects on meat quality parameters or heavy metal residues in the meat.