Background and Objective: Poultry meat, especially broiler and cockerel, consumption is increasing gradually in the country. As income of common people has been upgrading, they are now choosing quality food for consumption considering nutrient contents, meat quality and so on. The current study aimed to compare the meat quality of broiler and cockerel chicken in terms of proximate composition, physico-chemical properties, meat color, microbial load and carcass characteristics. Materials and Methods: To achieve this, apparently healthy twenty (20) broilers of 42 days old weigh between 1320-1380 g and similar number of same aged cockerels weigh between 740-790 g were selected from the experimental house and related jobs were performed carefully. Results: Results showed that the crude protein content of cockerel breast meat was significantly higher (p<0.05) when compared to broiler. The drip loss, cooking loss and free fatty acid content of broiler breast meat were significantly (p<0.01) higher than the cockerel meat. Lightness (L*) and yellowness (b*) values were also significantly higher in broiler meat although redness (a*) was higher (p<0.01) in cockerel meat. In respect to microbial load, E. coli, S. aureus and TBARS value of broiler breast meat samples were found significantly higher (p<0.01) than the cockerel meat. The dressing percentage was found significantly higher (p<0.01) in broiler chickens. The results from this experiment showed that the broiler breast meat quality is comparatively lower than that of cockerel in terms of nutrient contents, pH, TBARS, free fatty acid, meat color and microbial load. Conclusion: Thus, it could be stated that meat quality of cockerel is better than broiler in terms of the above mentioned criteria.
How to cite this article:
CopyrightMd. Nazmul Hasan, Md. Ataul Goni Rabbani, Tahera Yeasmin, Moinul Hasan and Md. Harun Or Rashid, 2019. A Comparative Study of Carcass Characteristics and Meat Quality Traits of Breast Muscle Between Broiler and Cockerel Chicken. International Journal of Poultry Science, 18: 144-150.
© 2019. This is an open access article distributed under the terms of the creative commons attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.
Although annual growth of poultry industries has gained momentum in Bangladesh, per capita chicken meat consumption is nearly 3.63 kg here against the minimum requirement for maintaining global health standard around 18-20 kg per year1. Recently, predominantly in the developing countries, the consumption of poultry meat has increased rapidly and consumers have started to pay more attention to meat quality2,3. There are several factors affecting the quality of poultry meat, such as age, breed, sex, genotype of the birds as well as diet4,5. Day by day the demand of poultry meat is being increased, so farmers have been trying to improve the growth rate, feed efficiency and breast-meat yield of their birds.
Appearance and texture are the two most important attributes for poultry meat. Appearance is not only critical for the consumers' initial selection of any product but also final satisfaction from product consumption. That is why, farmers have given priority to produce products with the appropriate color targeting a particular market and to avoid appearance defects, which will negatively affect product selection or price6. There are some nutritional values related to poultry meat quality, such as high-value protein, unsaturated fatty acid, vitamins, cholesterol and other biologically active compounds. The important sensory traits are color, aroma and flavor. It can be stated that if poultry meat fully accomplish the consumer expectations then poultry meat is of good quality than other meats. Modern consumers seek some essential traits exists in meat that are low in fat, tender, juicy with good flavor and aroma7.
To completely describe the characteristics of breast meats, study related to sensory analysis, chemical analysis, physicochemical analysis, color and microbial load are necessary. The important information of each analysis contributes specific character on breast meat quality. Changes in muscle color and water holding capacity of breast meat is directly affected by changes in muscle pH. Besides, the changes in muscle pH ultimately affect protein structure and subsequent hydration properties of the meat proteins. In consideration of the above facts, this study was aimed to compare the meat quality traits by chemical composition, physico-chemical properties (pH, FFA, color, per-oxide value and lipid), color band and microbial load of the breast meat between broiler and cockerel.
MATERIALS AND METHODS
Experimental birds and their management: For this experiment, 150 day old cockerel chicks (ISA Brown) and 150 broiler chicks (Cobb 500) were purchased from a reputed hatchery of the country. The experiment was conducted at local farm in Boiler village under Trishal upazila of Mymensingh district of Bangladesh during later part of 2017 (October 20 to November 30, 2017). The chicks were reared without any antibiotic or probiotic except vaccination under open sided poultry house. During the experimental period, Broiler starter (CP 21.5%, Fat 3.5%, CF 5%, Moisture 12%, ME 2900 kcal kg1) feed was provided 0-16 days and Broiler Grower (CP 20%, Fat 3%, CF 5%, Moisture 12%, ME 3000 kcal kg1) was maintained rest period (17-42 days). Identical management (brooding, lighting, biosecurity) and care were ensured throughout the experimental period to get optimum results.
Sample collection and preparation: For this experiment, apparently healthy twenty broilers (42 days old and 1320-1380 g body weight) and twenty cockerels (42 days old and 740-790 g body weight) were collected from the experimental house. As far as possible, all connective tissues and visible fat were trimmed off. The muscles were rinsed and washed with clean water to remove blood and cut into small pieces. All of the meat pieces were mixed properly by hand.
Lab location: Laboratory analyses of the experimental samples were carried out in the relevant laboratories of the Departments of Animal Science, Department of Food Technology and Rural Industries at Bangladesh Agricultural University, Mymensingh.
Dry matter: Five gram meat sample was taken in pre-weighed porcelain crucibles. The crucible was kept at 105°C in an oven for a period of 24 h. After that the crucible was cooled in desiccators. The meat dry matter was calculated as a difference between the meat sample weights before and after drying.
Ether extract: Five gram ground meat sample was taken in a thimble and added 200 mL diethyl ether in a Soxhlet. At about 7-8 h extraction was done at 40-45°C. After extraction, the flask was dried at 100°C. Then the flask was cooled in desiccators and weighed.
Ash: Five gram sample was taken in porcelain crucibles and pre-ashed at 105°C for 24 h. The crucible was then placed in a muffle furnace and heated at 550°C for 6 h. The crucible was then cooled in desiccators and weighed.
pH: The meat pH was measured using a pH meter in meat homogenate, prepared by blending 10 g of meat with 50 mL distilled water. The laboratory pH meter was adjusted at room temperature (adjusted with buffer pH 7.0).
Drip loss: From each sample, a standardized muscle cylinder (30 g) was suspended in an inflated plastic box (4°C) for 24 h. This work was done within 48 hours of postmortem. The drip loss was calculated by the following formula:
Cooking loss: The meat sample was boiled to an internal temperature of hot water bath at 90°C for 30 min. Cooking loss was determined by the following calculation:
Color estimation: Samples were taken from the experimental longissimus dorsi (LD) muscles and Hunter color components lightness (L), redness (a) and yellowness (b) were recorded using Hunter Lab Tristimulus colorimeter model D25 m-2. Subsequently these samples were frozen and stored for cooking loss and shear force determinations.
Peroxide value determination: The peroxide value was determined according to Sallam et al.9.
|S||=||Volume of titration (mL)|
|N||=||Normality of sodium thiosulfate solution (n = 0.01)|
|W||=||Sample weight (g)|
FFA (%) = mL titration×Normality of KOH×28.2/g of sample
Crude protein: Determination of total protein was done by establishing the total nitrogen with the Kjeldahl method11, which consists in extracting the total nitrogen from a mineralized sample [as ammonium sulphate-SO4(NH4)2], then expressing it as ammonia (through distillation and caption on acid) and converting the total ammonia into protein with a correction factor. AOAC8 method was followed to determine CP using following formula:
N% = [(mL standard acid×normality acid) - (mL standard NaOH×normality NaOH)]×1.4007/g sample
Crude protein% (CP) = N%×6.25
TBARS determination: The TBARS value was measured according to Vyncke12. TBARS, expressed as micromole of malondialdehyde per kilogram of meat, was calculated using TEP/malonic aldehyde as standard.
Enumeration of Staphylococcus aureus : Baird Parker agar (Oxoid, England), a selective medium for the isolation and counting of coagulase positive staphylococci was used for the enumeration of Staphylococcus aureus as described by Bhandare et al.13.
Enumeration of Escherichia coli: Escherichia coli were counted as colonies with distinct metallic sheen13. Escherichia coli were enumerated on Eosin methylene blue agar (Oxoid, England) by plating an appropriate dilution on plates followed by aerobic incubation at 37°C for 24 h.
Dressing percentage and other organs weight: Dressing percentage (DP) = (carcass weight/live weight)×100. Weight of heart, liver, pancreas, gizzard, abdominal fat and spleen were taken with an electronic balance and the percentage of these organs to the carcass weight, were measured.
Statistical analysis: Data were analyzed using the SPSS version 2014 for windows. Results were presented as mean±standard deviation and significance level was set at 5%.
RESULTS AND DISCUSSION
Proximate composition: A significant (p<0.05) variation was seen while estimating CP in between broiler breast meat and cockerel breast meat (Table 1). The CP content of cockerel breast meat is significantly higher (p<0.05) when compared to broiler breast meat while no significant (p>0.05) differences were found in dry matter, ether extract and ash percentage. Barteczko and Lasek15 observed that broilers chicken was fed with mixtures of lower protein content (20 and 19%) showed lower body weight and protein percent in muscle tissue compared to broilers fed with higher protein content (23%).
|Table 1:||Proximate chemical composition of broiler and cockerel breast meat|
|DM: Dry mater, CP: Crude protein, EE: Ether extract, NS: Non-significant, *p<0.05, SD: Standard deviations|
|Table 2:||Comparison on different physicochemical parameters of broiler and cockerel breast meat|
|FFA: Free fatty acid, PV: Peroxide value, NS: Non-significant, *p<0.05; **p<0.01, SD: Standard deviations|
Wattanachant et al.16 observed the level of crude protein in the breast muscles of young broilers was lower than native chicken breeds (over 24%). The results of our experiment are similar to these findings. The dry matter and ash contents in breast meat of broilers and native bird were found almost similar by De Marchi et al.17 and Wattanchant et al.16. The present study results were also in agreement with these findings. Moreover, breast meat from the broiler tended to have higher moisture and significantly lower protein content.
Physicochemical properties: Table 2 shows the drip loss, cooking loss, moisture, pH, fat, free fatty acid and per-oxide value percentage of breast meat of broiler and cockerel. The fat percentage, drip loss, cooking loss and free fatty acid percentage of broiler breast meat were significantly (p<0.01) higher than that of cockerel. In this study, the peroxide value of broiler breast meat was significantly (p<0.05) higher. Breast meat from the cockerel had a significantly (p<0.05) higher pH when compared to the broiler breast meat group of chicken, whereas no differences were found in moisture percentage.
Fanatico et al.18 in their experiment found that the drip loss of slow growing birds were significantly lower than the fast-growing ones which supported the present study results. The results of our findings indicated that broiler meat had a lower pH and higher drip loss. According to El Rammouz et al.19, the pH (5.66) value of broiler chicken was less than the pH (5.73) of slow growing local birds. Le Bihan-Duval et al.20 also stated the same. These finding has similarities with the present results. Jakubowska et al.21 indicated that initial muscle pH determines some physicochemical traits such as water holding capacity, color, cooking loss or tenderness of heat-treated meat. Valsta et al.22 stated that broiler chicken fed with appropriate manipulation of diet could modify fatty acid profile and increase the nutritional value of meat. De Marchi et al.17 reported as the fat content of cockerel breast meat was higher than that of broilers breast meat but the present study results showed higher fat percentage in broiler. This may be due to fast growing nature of broiler compared to cockerel birds. Low peroxide values may also be acquired for any extremely rancid products, besides initially the peroxides formed have all undergone further oxidation reactions23. High peroxide values are a definite hint of a rancid fat.
Meat color: In the present study, differences in meat color parameters were found while comparing broiler and cockerel breast meat as shown in Table 3. The lightness (L*) and yellowness (b*) values of broiler breast meat were significantly (p<0.01, p<0.05 respectively) higher than that of the cockerel meat although redness (a*) was higher (p<0.01) in cockerel. Woelfel et al.24 found relatively higher L* value (60) which disagreed the current findings. Color may be the vital factor for measurement of good quality meat, besides it influences the appearance, attractiveness of breast meat to consumers. Consumer’s preferred different colors, depending on their place of residence, observed by Bianchi et al.25. For consumers’ decision, the breast meat color is a critical criterion. Mehaffey et al.26 suggested that the breast meat should have a pink color when raw. Qiao et al.27 suggested L* value of examined deboned breast meat as 48 <L*<51(normal), L*<46 (darker than normal); L*>53 (lighter than normal).
|Table 3:||Comparison on meat color of broiler and cockerel breast meat|
|L*: Lightness, a*: Redness and b*: Yellowness of meat, *p<0.05; **p<0.01, SD: Standard deviations|
|Table 4:||Escherichia coli (CFU/cm2), Staphylococcus aureus (CFU/cm2) and TBARS (μmol kg1) of broiler and cockerel breast meat|
|*p<0.05; **p<0.01, SD: Standard deviations|
|Table 5:||Carcass characteristics of Broiler and Cockerel chicken|
|wt: Weight, NS: Non-significant, *p<0.05, **p<0.01, SD: Standard deviations|
The present findings were consistent with previous observations27. Color and pH value is correlative to measure the meat quality. The L* value of broiler breast meat was higher than cockerel breast meat and this may be interrelated to the lower pH values of the broiler breast meat.
Microbial load: In respect to microbial load, the E. coli and TBARS value of broiler breast meat samples in the present experiment were significantly (p<0.01) higher than the cockerel meat (Table 4). Similar response were found in case of S. aureus (p<0.05). Voidarou et al.28 reported that the higher level of microbial contamination present in meat including S. aureus. Many researchers29,30 have been found the presence of E. coli strains in meat and meat products. Pointon et al.31 investigated the similar results for retail chicken (>90% incidence of E. coli) in Australia. Pikul et al.32 reported TBARS value as to be a good indicator of fat oxidation. Buckley and Connolly33 found a TBARS value of 1.0 to be a good cut-off point, of a rancid taste for raw pork. In this experiment, this cut-off point was considered as a guideline. In our findings, a positive correlation between microbial load and TBARS values was observed in broiler breast meat.
Carcass characteristics: The effect of mean values regarding various carcass characteristics and relative organ weight of the broiler and cockerel has been shown in Table 5. The dressing percentage was significantly (p<0.01) higher in broiler chickens than that of in cockerel. The proportion of liver, gizzard and abdominal fat showed significant (p<0.01) difference between broiler and cockerel chicken. Statistical analysis of the data regarding relative weights (g organ weight/100 g body weight) of heart, pancreas and intestine did not show any difference in the mean values among the treatment groups. Several studies17,34 have confirmed that low live weight has been associated with low carcass yield. Similar results were also reported by Mahmood et al.35 and Kamruzzaman et al.36. The present study results were in agreement with most of the previous findings might be due to type of birds used in the experiment.
In the present study, the CP content of cockerel breast meat was found significantly higher than that of broiler while drip loss, cooking loss and free fatty acid and fat percentage of broiler breast meat were significantly higher. Lightness (L*) and yellowness (b*) were also significantly higher in broiler meat but redness (a*) was found higher in cockerel. While considering microbial load (E. coli, S. aureus and TBAFRS value), cockerel meat was found better but dressing percentage was higher in broiler. From the above results, it can be concluded that there exists wide range of differences in proximate and chemical composition, meat color, microbial loads and carcass characteristics of broiler and cockerel meat. Further study is required in this regard.
The current study was undertaken to guide common people about the most consumed broiler and cockerel meat as these are very much popular to them. With the passage of time, people are becoming careful about the quality food products. This study results will definitely help people to choose quality meat between broiler and cockerel meat.
The authors would like to thanks to the Department of Animal Science, Department Poultry Science and Department of Food Technology and Rural Industries of Bangladesh Agricultural University and Poultry Production Research Division of Bangladesh Livestock Research Institute for providing technical cooperation to carry out research work successfully. Authors also like to acknowledge all out efforts of Mr Karim Mia, the farm owner from Boiler village under Trishal upazila of Mymensingh district where the trial took place.
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