Effects of a semi-intensive raising system on growth performance, carcass traits and meat quality of broiler chicks

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1 Indian J. Anim. Res., 52(2) 2018 : Print ISSN: / Online ISSN: AGRICULTURAL RESEARCH COMMUNICATION CENTRE Effects of a semi-intensive raising system on growth performance, carcass traits and meat quality of broiler chicks Serafettin Kaya* and Hakan Yildirim Mustafa Kemal University, Agriculture Faculty, Animal Science Department, Hatay/ Turkey. Received: Accepted: DOI: /ijar.v0iOF.8486 ABSTRACT The present study was carried out to compare the growth performance and carcass yield of broiler chickens reared in semiintensive and conventional systems (Ross 308, n=120). Chickens were raised in a pen on wooden shavings for 21 days. On day 21 of age, chicks were assigned to 2 treatments (indoor treatment and semi-intensive treatment). The experiment was conducted at until 6 weeks of age. Production system has a significant effect on wing (P<0.05) and heart weight (P<0.01), but has no any effect on final body weight, hot or cold carcass weight, thigh, breast, back and neck, gizzard, liver and abdominal fat weights (P>0.05). The final body weight, hot and cold carcass weight, thigh, wings and heart weights were affected by sex of birds (p<0.05) while breast, back, liver, gizzard and abdominal fat were not affected by sex (P>0.05). The nutrient level of carcass parts was not influenced by production system or sex (P>0.05). In our study, breast of birds reared under semi-intensive system had significantly lower L (P<0.05), higher a statistically different (P<0.01); while b value was significantly (P<0.01) higher in skin of semi-intensive reared birds. Key words: Broiler, Carcass quality, Performance, Production system, Semi-intensive. INTRODUCTION Factors involved in consumers to choose poultry products are healthy, quality of nutrition, quantity, cost (price) and labeling information. Generally, organic poultry, semiintensive and backyard poultry are named in the same sense. However, technically, these three production systems are different from each other. In organic poultry production, animal and feed materials must be obtained from organic production systems (animal and crop production). In semi-intensive system, the birds are given free access to pasture land. In village poultry, animal materials are native breeds and feeds are not necessarily commercial, and production period is longer than the conventional system. All systems have advantages and disadvantages with respect to animal health, welfare, and production period and product quality. Since the animal genetic resources used in organic, conventional and free range system are the same genotype, the product qualities and consumer preferences are affected by production systems (Fanatico et al. 2005). Castellini et al. (2002) found out that organically produced broiler meat had lower rate of fat than that of the commercially reared broiler chicks. They explained the underlying mechanism that organic birds build muscle instead of fat because of the higher physical activity. According to Motsepe et al. (2016), appearance, texture and sensory characteristic contribute to the overall consumer acceptability of poultry and other meat products. *Corresponding author s serafettinkaya@gmail.com Kishowar et al. (2005) tested breast meats of organic and free range broilers fed on maize with respect to appearance, texture and aroma and found out that the significant differences were marked by panelists. Consumers gave extra payment for organic and free range chicken meat since the difference between their production method, genetic, season affect their chemical content and organoleptic properties (Fanatico et al. 2007; Ponte et al. 2008a). Therefore, in the present study, it was compared semi-intensive and conventional systems in broiler production with respect to growth performance and meat quality. MATERIALS AND METHODS This trial was carried out at the Poultry Unit of Research Farm of Mustafa Kemal University, Hatay, Turkey with approval from the animal ethics committee of the University of Mustafa Kemal (protocol numbers / 6). Before the experiment, 120 broiler chicks (Ross 308, straight run chicks) were raised in a pen for 21 days. On d 21, all healthy chicks with similar body weight (BW) (456.37±14.41 g), were selected and randomly assigned to 2 treatments (indoor treatment and semi-intensive treatment). Each treatment was containing 60 birds. Chickens in the indoor treatment were raised in floor pens in a conventional poultry research house that contained a concrete floor, side curtains, and fans for ventilation and cooling. The raising

2 310 INDIAN JOURNAL OF ANIMAL RESEARCH density of each pen was 7 birds/m 2, where the temperature was 20 ± 3 C, the relative humidity (RH) was 65 to 75%, and the photoperiod was 23 h. Chickens in the semi-intensive treatment were housed in a similar indoor house (7 birds/ m 2 ). At 21 d old, they also had a semi-intensive grass paddock (red clover + fescue + brome grass area, 1 bird/m 2 ). Feed and water were also provided outdoors using trough feeders and water pans with reservoirs. Terrestrial predators were excluded by electric net fencing, and aerial predators were excluded by netting over the paddocks. Birds were confined to indoor pens at night. Feed and water were freely available, and all diets were formulated to contain adequate nutrient levels as defined by the NRC (1994). The wooden shavings were used for bedding material in closed areas. At 42 d old, 10 birds (5 males and 5 females) having representative equal body weight from each treatment group were killed humanly by neck dislocation after 10 h feed deprivation. Birds carcasses were stored at +4 C refrigerator for 24 h before determining body components, dressing percentage and relative carcass parameters (the weights of carcass, edible inner organs, abdominal fat pad, thigh, breast, neck, wings and back parts of the body). The nutrient contents (DM, CP, EE, ash) of carcass were determined as per AOAC procedure (AOAC 1995). The physical determination of pigments (Hunter L, a and b values, L; brightness, a; redness, b; yellowness) was done by using Minolta Colorimeter (CR 300, Minolta-Japan) on breast and thigh meats with and without skin. The higher L values are light, higher a values are red, and higher b values are yellow. Each measurement was carried out in three replications, taking their average value as the result. The experiment was continued up to 42 days of age. Organoleptic properties were ascertained according to the method of Awonorin and Ayoade (1992) in meat samples of skinless breast and thigh. It involved taking samples from each replicate, which were weighed before cooking for 15 min without salt. The samples were cooked at 180 C in the oven, collected and blotted with blotting paper. Then untrained 15 panelists who are non-smoker personnel were chosen from to test for palatability, tenderness and juiciness on a five-point descriptive scale (with 1=not tender, not juicy and not palatable; and 5=very tender, very juicy and very palatable). Each panelist after tasting the meat sample from a particular treatment group recorded the score and rinsed his/her mouth with water before tasting another meat sample from another treatment group. The ph of the meat was measured using a ph meter (Hanna digital ph meter) after calibrating between 4.0 and 7.0 values. The weekly body weight changes and feed intakes of birds were determined by using 10 g sensitive electronic scale. Feed conversion ratio was calculated by as per unit feed intake for per unit gain for weekly basis or whole experimental period. Water-Holding Capacity (WHC) of thigh and breast meat was determined by gravimetric method. It was estimated by centrifuging 1g of muscle for 4 min at 1500 rpm and determining the residual water by drying the sample at 70 C overnight. WHC was calculated as per following formula (Castellini et al. 1998): WHC= (M1-M2)/m x 100 In which; M1=Filter paper + sample weight (g), M2=Filter paper + dry sample weight (g) m= sample weight (g) The mathematical model of experiment as following; Yij=µ+ i+eij In which; Yij; i th housing group and j th animal s data ; mean of population i; i th effect of housing eij; error The data were statistically evaluated by using One Way ANOVA procedure of SPSS software (Kinnear and Gray, 1994). The data of obtained organoleptic properties of thigh and breast meat were analyzed by Friedman test. RESULTS AND DISCUSSION The total body weight gains, total feed intakes, daily feed intakes and feed conversation ratios of experimental groups are given in Table 1. In some previous studies (Mikulski et al., 2011;Jiang et al., 2011), outdoor access did not change the growth performance of chickens statistically. However, others found better productive performance in the semi-intensive groups (Ponte et al., 2008a; Ponte et al., 2008b). In our study semi-intensive birds consumed more feed and gained more compared to indoor birds without affecting feed efficiency (1.78 vs 1.77). Carcass traits or body components of experimental birds are given in Table 2. Except wing (P<0.05) and heart (P<0.01) weights, hot and cold carcass weights, thigh, breast, back, liver, gizzard and abdominal fat weights were not Table 1: The growth performance of broiler chicks reared in indoor and semi-intensive systems. Parameters Semi-intensive Indoor Total gain (g) Total feed intake (g) Daily feed intake (g) Feed conversion ratio

3 Volume 52 Issue 2 (Feburary 2018) 311 Table 2: Carcass traits of experimental birds. Parameters Semi-intensive Indoor P values Males Females Overall Males Females Overall SEM Tr Sex TrxSex Final body weight (g) Hot carcass (g) Cold carcass (g) Thigh (g) Breast (g) Wings (g) Back (g) Heart (g) Liver (g) Gizzard (g) Abdominal fat pad (g) affected by production systems either indoor or semiintensive (P>0.05). However, the final body weight, cold and hot carcass weights, thigh, wings and heart weights were affected by the sex of birds (P<0.01) while breast, back, liver, gizzard and abdominal fat weights were similar in males and females (P>0.05). While production system and sex did not affect the relative breast weight (P<0.05) but thigh meat of male birds was significantly heavier than females (P<0.01). These results are in agreement with that of sekeroglu and Diktas (2012). Relative carcass parts (%) are given in Table 3. There was no difference between treatment groups with respect to relative carcass parts yield (P>0.05), while males had higher percentage of thigh compared to females (P<0.01) and females had higher percentage of breast compared to males (P<0.05). There was no significant difference between nutrient contents of breast and thigh meat of broiler chicks (Table 4) as reported in many other works (Fanatico et al., 2007; Michalczuk et al., 2014). Also, Husak et al (2008) reported that, although statistically significant, differences in nutrient content between organic, semi-intensive and conventional rearing were not large and may not be practically important. In our study, breast of birds reared under semiintensive system had significantly lower L (P<0.05), higher a statistically different (P<0.01); while b value was significantly (P<0.01) higher in skin of semi-intensive reared birds (Table 5). Similar results in color of breast between indoor and outdoor chickens were obtained by Skrivan et al. (2015). According to Northcutt (2007) the color of chicken meat is affected by age, sex, genotype, feed, distribution of fat into muscle, water content of meat, conditions before slaughtering and processing methods. The parameter being a direct indication of meat quality is acidity (ph). Glycogen reserves in muscles effects the postmortem ph level. The rearing system had no effect on ph level of thigh meat in this study, but the ph of breast meat was significantly (P<0.05) lower in indoor group than semi-intensive group (Table 6). Similar differences in ph Table 3: Relative carcass parts (%). Parameters Semi-intensive Indoor P values Males Females Males Females SEM Tr Sex TrxSex Carcass yield Thigh Breast Wings Back Inner edible organs Table 4: The nutrient content of carcass parts (%). Parameters Parts Semi-intensive Indoor SEM P values DM Thigh Breast Crude ash Thigh Breast Crude fat Thigh Breast Crude protein Thigh Breast

4 312 INDIAN JOURNAL OF ANIMAL RESEARCH Table 5: Colour analysis of carcass parts. Semi-intensive Indoor P values Skin 53.31± ± L Thigh 44.84± ± Breast 42.94± ± Skin 6.08± ± a Thigh 6.84± ± Breast 4.87± ± Skin 6.69± ± b Thigh 0.16± ± Breast 0.45± ± Table 6: ph values of carcass parts of free range and indoor broiler chickens. Parameters Semi-intensive Indoor SEM P values Thigh Breast between commercial and semi-intensive groups were obtained many other studies (Ponte et al., 2008b and Stadig et al., 2016). Since poultry meat is present as parts or processed, color and water holding capacity have great importance in consumer preference. Carcasses of females and males were not different with respect to water holding capacity (P>0.05), however thigh meat of semi-intensive chickens had better water holding capacity than the meat of birds raised indoors (P<0.01). These results agreed with those of Mikulski et al. (2011). Taste is the main criterion for consumer preferences in accepting poultry meat. Taste and aroma both affect the acceptability of poultry meat for consumption. The organoleptic properties of thigh and breast meat were tested by 15 panelists, and the data were analyzed by Friedman test (Table 8). Production system either semi-intensive or indoor system did not significantly (P>0.05) affect the organoleptic properties of breast; whereas in thigh meat significantly higher values were observed in appearance (P<0.01), aroma (P<0.05), texture (P<0.01), taste (P<0.01) and general looking (P<0.01) was recorded in indoor reared Table 7: The water holding capacities of experimental carcasses. Parameters Semi-intensive Indoor SEM P values Thigh Breast Table 8: Organoleptic properties of legs and breast meats of broiler chicks. Parameters Parts Semi- Indoor P values intensive Appereance Breast Thigh Aroma Breast Thigh Texture Breast Thigh Taste Breast Thigh General looking Breast Thigh birds.husak et al. (2008) found that panelist gave significantly higher score for organoleptic properties to semiintensive thigh meat when compared with indoor group. CONCLUSION The results of the present investigation showed that the semi-intensive birds consumed more feed and gained more body weight compared to indoor birds without affecting feed efficiency. Also, the breast meat of semi-intensive birds was darker with low L values and more redness with high a values; whereas, skin of semi-intensive broilers is more yellow with high b values. With respect to appearance, aroma, texture, taste and general looking, thigh meat was better than breast meat in the present study. ACKNOWLEDGEMENT This study was supported by Scientific Research Funding of Mustafa Kemal University with project registration number. The autors also thanks to Prof. Dr. Ahmet SAHIN (Ahi Evran University Agri Faculty Anim Sci Dept) for the editing in English the final manuscript. REFERENCES AOAC. (1995). Official Methods of Analysis. 16th. Ed. Association Official Analysis Chemist Arlington, VA. Awonorin, S.O. and J.A. Ayoade. (1992). Texture and Eating Quality of Raw and Thawed Roasted Turkey and Chicken Breasts as Influenced by Age of Birds and Period of Frozen Storage. Journal of Food Service Systems. 6(4): Castellini, C., A. Dal Bosco, M. Bernardini, H.W. Cyril. (1998). Effects of dietary vitamin E on the oxidativestability of raw and cooked meat. Meat Science. 50(2): Castellini, C., C. Mugnai, A. Dal Bosco. (2002). Effect of organic production system on broiler carcass and meat quality. Meat Science. 60 (3): Fanatico, A.C., P.B. Pillai, L.C. Cavitt, C.M. Owens, J.L. Emmert. (2005). Evalution of slow growing broiler genotypes grown with and without outdoor Access; growth performance and carcass yield. Poultry Science. 84 (8): Fanatico, A. C., P. B. Pillai, J. L. Emmert, C. M. Owens. (2007). Meat quality of slow and fast growing chicken genotype fed low nutrient or standard diet and raised indoor or with outdoor Access. Poultry Science. 86 (10): Husak, R.L., J.G. Sebranek, K. Bregendahl. (2008). A survey of commercially available broilers marketed as organic, free-range and conventional broilers for cooked meat yields, meat composition and relative value. Poultry Science, 87:

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