Evaluation of growth performance and slaughter traits of Aseel chicken grown with and without outdoor access


 A study was conducted to investigate the effects of free-range, part-time free range, and confinement rearing systems on growth performance and slaughter traits in Lakha, Mushki, Peshawari, and Sindhi Aseel for 10-week duration (7-16 week). In total, 216 Aseel cockerels (6-wk-old), 54 from each variety, were allotted to 12 experimental groups, in a 3 × 4 (rearing system × Aseel variety) factorial arrangement under a randomized complete block design, replicated 3 times with 6 birds in each. Final body weight, weight gain, folds of increase, and mortality parameters of growth performance and carcass yield, breast, thigh, drumstick, wing, liver, gizzard, and heart parameters of slaughter traits were evaluated. Data were analyzed by using 2-way ANOVA under factorial arrangement. The results indicated increased body weight gain, folds of increase, breast and drumstick in both confinement and part-time free range (P<0.05), whereas enhanced body weight, dressing, thigh, liver, and gizzard only in confinement rearing system. Among the Aseel varieties, Sindhi showed enhanced final body weight, weight gain, thigh and drumstick yields, whereas breast and gizzard weights were found to be greater in Lakha and Sindhi. Carcass yield, however, remained higher in all varieties except Peshawari. In conclusion, indoor rearing system had positive effects on growth and carcass-related parameters. Among the varieties, Sindhi showed better growth and slaughter-related performance traits in alternative rearing systems and hence, can be used as slower growing meat chicken in the aforesaid systems of poultry production in developing countries for better livelihood.


Introduction
In recent days, alternative rearing systems are becoming attractive due to limited use of chemical additives, synthetic fertilizers and antibiotics (Castellini et al. 2008). Natural environment in free-range provides fresh vegetation and grasses to the birds (Glatz et al. 2005) and their droppings act as organic fertilizers, enhancing soil fertility yielding greater beans and crops (Hilimire et al. 2012). High quality forages like grasses, legumes and clover improve nutrient intake in birds (Mikulski et al. 2011). Birds in free range disperse in small groups, having complete freedom of expressing their natural behavior (Chen et al. 2013;Tong et al. 2014; Wang et al. 2015). Similarly, part-time free range rearing system improves behavioral activities as well as their performance of the birds ( Barbosa-Filho et al. 2005). Variable pasture intake in free range system, however, may adversely affect weight gain and feed e ciency in chicken ). Pasture management plays a crucial role in making free range healthier and more welfare friendly for the growing ocks (Sossidou et al. 2015).
In Pakistan, poultry farming has developed from a small scale family operation to a large scale, big business operation, resulting in closure of traditional open-sided poultry houses (Rehman 2017). This alarming situation urges poultry geneticists to explore such chicken breeds, which would be suitable for natural meat production in open environment, reviving the prestigious agro-based poultry culture and rehabilitation of livelihood in rural households (Rehman 2017;Desta 2021). Slow-growing chicken, being scavenging in nature, has an ability to survive on insu cient feed resources under traditional free range conditions (Fanatico et al. 2005a). Indigenous chicken is reared mainly by small poultry farmers within limited resources, generating income for their households (Magala et al. 2012). Aseel chicken is a wellknown indigenous breed of Indo-Pak subcontinent; popular for its better adaptability, hardiness, and low mortality in sub-tropical region like Pakistan ).
Mainly 16 Aseel varieties are inhabitant to Pakistan (Khan, UAF: Personal Communication), out of which, Lakha is characterized by reddish-brown plumage with black or white mottling, Mushki has a black plumage with black pigmentation in beak and shanks, Peshawari has a wheaten-colored plumage (Babar et al. 2012), and Sindhi possesses a reddish-brown plumage with hard and short feathers ). On the basis of robustness, disease resistance, better adaptability to the inclement climatic conditions, and excellent meat producing qualities, Aseel may be used for meat production in alternative rearing systems and help in the revival of small-scale rural poultry farming in open-sided houses. A lot of work has been done in India using Aseel chicken in the farm as well as in eld conditions, however, no speci c work has, so for, been conducted to investigate the performance of Aseel chicken under freerange, part-time free range, and con nement rearing systems. The present study, therefore, was planned to evaluate the growth performance and slaughter traits in 4 varieties of Aseel chicken (Lakha, Mushki, Peshawari, and Sindhi) under free-range, part-time free range, and con nement rearing systems.

Methodology Experimental Station, Birds and Rearing Systems
The present study was conducted at Indigenous Chicken Genetic Resource Centre (ICGRC), Department of Poultry Production, Ravi Campus (located at 31° 10' North and 73° 51' East longitudes) University of Veterinary and Animal Sciences (UVAS), Lahore, for 10 week duration (7-16 weeks). The summers are sweltering, humid and clear whereas the winters are short, cool and dry. Long-term average annual temperature at Pattoki varies from 28°C to 40°C. Average annual relative humidity ranges between 40 and 75%.

Bird, s Husbandry
In total, 216 Aseel cockerels, 54 from each variety were randomly assigned to 12 experimental groups, in a 3 × 4 (rearing system × Aseel variety) factorial arrangement under a randomized complete block design.
Each experimental group was replicated 3 times with 6 birds in each replicate. All birds in each variety were weighed before the start of experiment and they were uniform in body weight. Experimental birds were maintained in an independent open-sided poultry house, measuring 6.1 × 6.1 m (37.21 m 2 ) with East to West dimension, opening towards North in free range. The house was equipped with a 3-tiered growing cage, measuring 1.52 × 4.57 m (20.84 m 2 , 6.91 birds/m 2 ), with removable dropping trays and automatic nipple drinking system. Trough feeders were available for feeding of the birds. Free-range area (speci ed for free range and part-time free range; stocking density, 0.27 birds/m 2 ) was surrounded by a 2.44 m high enclosure to avoid the entry of predators. Seasonal legumes (cereals, beans, cowpeas, lentils, and grasses) and non-legumes were cultivated in free range. Replication in free range was done with the help of sh-net and fresh water in each replicate was available through nipple drinking system. Birds under con nement rearing system remained 24 h in cages with 100 allowance (0800 h) of cornsoybean based broiler grower ration ( Table 1). The ration used was iso-nitrogenous and iso-caloric (20.00 CP, 3,050 kcal/kg ME). The birds under part-time free range system had access to free range from 0800 to 1200 h. Subsequently, they were maintained in cages from 1200 to 0800 h and offered 50 of feed allowance at 1700 h. However, birds under the free range system had free access to free range area from 0800 to 1600 h. Thereafter, they were shifted to the house and maintained on oor from 1600 to 0800 h (stocking density, 2.38 birds/m 2 ), with rice husk as bedding material (15 cm) and offered 25 feed allowance (1700 h). Natural light and similar prophylaxis and hygienic measures were adopted in all rearing systems. The experimental birds were vaccinated against Newcastle disease (ND), infectious bronchitis (IB), and infectious bursal disease (IBD), following the recommendations of vaccine manufacturing company under the supervision of a quali ed veterinarian. Throughout the trial, temperature and RH remained in the range of 13 to 30 and 52 to 67 , respectively. Such variations in daily temperature and humidity (%) were noted using a wet and dry bulb hygrometer (Mason's type, Zeal, England) and later an average of the temperature and humidity were derived on weekly basis as shown in Fig. 1.

Data Collection
Initial and nal body weights were recorded by using electronic balance (accuracy of 0.01 g) (WANT ® Wt-G) to calculate the body weight gain and folds of increase. Daily mortality, if any, was recorded to calculate the percentage of mortality. At the end of 16 th week, a total of 72 birds, 2 from each replicate with average body weight, were picked and tagged according to variety and rearing system. They were kept off-feed for 4 hours before slaughtering. Birds were weighed and slaughtered manually according to the Halal (Farouk et al. 2014) method of slaughtering, allowed to bleed for 3-4 minutes, and feather plucking was done after scalding the carcass at 50-60 for 1-1.5 minutes. Carcass yield was taken as weight of hot eviscerated carcass without skin after removing shanks, head, feathers, and abdominal fat (except the lungs and kidneys) in relation to the live weight multiplied by 100 (CFIA 1999). Percentages of breast, thigh, drumstick and wing were calculated as their individual weight relative to the dressed weight multiplied by 100, whereas liver, gizzard, and heart percentages were calculated as in relation to the live weight multiplied by 100.

Statistical Analysis
The data were tested for homogeneity of variance across the experimental groups, veri ed for the normality of variance and subjected to the 2-way ANOVA under factorial arrangement by using GLM procedure of SAS version 9.1 (SAS Institute Inc., 2002-03). Variety and rearing system were considered as main effects and their interaction was also tested. Means among treatments were compared through Duncan's Multiple Range test (Duncan 1955) (SAS Institute Inc., 2002-03) at 5 % probability level.
Page 6/20 The statistical model used was: Where, Y ijk = Observed dependent variable; μ = Overall mean; R i = Effect of rearing system; V j = Effect of Aseel variety; (R×V) ij = Interaction in rearing system & Aseel variety; and ε ijk = Residual error.

Growth Performance
In the present study, nal body weight was signi cantly affected (P<0.05) by the rearing systems and the Aseel varieties. Highest (P<0.05) body weight was observed in birds reared in con nement ( Table 2) followed by those in part-time and free range. Among the varieties, Sindhi birds showed the highest (P<0.05) nal body weight followed by those of Lakha, Mushki and then Peshawari. Birds reared in con nement and part-time free range exhibited increased (P<0.05) weight gain as compared with those in free range. Among the varieties, birds of Sindhi showed the highest (P<0.05) weight gain followed by those of Lakha, Mushki and then Peshawari. Folds of increase were found to be greater in con nement and part-time free range than free range whereas Aseel varieties independently and in interaction with rearing systems did not affect (P=0.584) folds of increase. Mortality was found to be lower (P<0.05) in birds reared in con nement followed by those in part-time free range and free range whereas varieties independently and in interaction with the rearing systems did not in uence (P>0.05) mortality percentage.

Slaughter Traits
In the current study, carcass yield increased (P<0.05) in birds reared indoor (Table 3) followed by those in part-time free range and free range. Among the Aseel varieties, birds of Sindhi, Mushki, and Lakha showed higher (P<0.05) carcass yield than those of the Peshawari (Table 4). Breast yield increased (P<0.05) in free range than part-time free range and con nement rearing systems. Among the varieties, birds of Lakha and Sindhi showed increased (P<0.05) breast yield than those of the Peshawari. Thigh yield was found to be greater (P<0.05) in birds reared indoor followed by those in part-time free range and free range. Among the varieties, birds of Sindhi showed higher (P<0.05) value of thigh yield than those of the Mushki and Peshawari. Birds reared indoor showed higher (P<0.05) drumstick yield compared to those under part-time free range and free range systems. Among the varieties, Sindhi showed increased (P<0.05) value of drumstick yield than the Peshawari.
In the present study, all treatments including rearing systems (P=0.189), Aseel varieties (P=0.098), and their interaction (P=0.216) showed did not in uence wing percentage whereas value of liver percentage was found to be highest (P<0.05) in birds reared in con nement followed by those in part-time free range and free range. Among the varieties, Lakha demonstrated increased (P<0.05) liver weight compared with the Peshawari and Mushki. Birds under the con nement rearing system showed the highest (P<0.05) value of gizzard weight followed by those under part-time free range and free range. Among the varieties, birds of Lakha and Sindhi exhibited higher (P<0.05) gizzard weight than those of the Mushki and Peshawari. Rearing systems as well as Aseel varieties did not in uence heart percentage (P=0.998; P=0.408). In the present study, birds reared indoor achieved the highest (P<0.05) body weight ( Table 2)  Con nement and part-time free range demonstrated increased (P<0.05) weight gain compared with free range. As mentioned above, birds reared indoor achieved greater (P<0.05) body weight ( Table 2) that might have resulted in increased weight gain of the birds. Similar to these ndings, Castellini et al. (2002a) and Dou et al. (2009) observed increased weight gain in indoor rearing system than freerange, indicating that indoor system of poultry production is better than free-range in term of weight gain ). More locomotor activity and less rest could be the reasons for poorer growth rate of birds in free-range. Jin et al. (2019) reported that average daily gain decreased signi cantly (P<0.05) for chickens assigned to free-range treatment from 56 to 70 D of age. Similarly, Li et al. (2017) reported that the body weight gain of free-range broilers were lower than in those kept in cage and indoor-range systems. The negative effect of the organic rearing system of chickens on body weight gain was also reported by Castellini et al. (2002b) for Ross cockerels aged 56 and 81 days. Among the varieties, Sindhi showed the highest (P<0.05) weight gain followed by Lakha, Mushki and then Peshawari. Patterns of growth depend largely on inherent ability of the birds for growth (Santos et al. 2005); hence, increased gain in Sindhi may be attributed to its better genetic potential.

Discussion
In the present study, higher folds of increase was observed in con nement and part-time free range. This may be attributed to the balanced diet and better management of the birds in con nement. Similarly, Dou et al. (2009) reported higher folds of increase in birds reared indoor than free range, supporting the argument that indoor rearing system regarding growth is better than the other rearing systems (Magala et al. 2012). Aseel varieties independently and in interaction with the rearing systems did not in uence (P=0.584) folds of increase. Mortality percentage was found to be lower in birds reared indoor followed by part-time free range and free range. Balanced diet, better management and relatively improved biosecurity in con nement rearing system are assumed to cause reduction in mortality. Similar to these ndings, reduced mortality in indoor system of poultry production compared to free-range has previously been reported (Farooq et al. 2002; Poltovics & Doktor 2011). According to Baeza et al. (2001), free-range access caused increased mortality. Varieties independently and in interaction with the rearing systems indicated no effect (P>0.05) on mortality.

Slaughter Traits
Carcass yield is an important trait for poultry production that may affect both consumers' purchase intention and poultry production pro ts (Tong et al. 2015;Zhang et al. 2018b). In the present study, carcass yield increased (P<0.05) in con nement rearing system (Table 3) followed by part-time free range and free range. As stated above, birds assigned to con nement rearing system achieved larger body  (Table 4). Literature has shown that carcass yield depends largely on live weight of the birds (Moujahed & Haddad, 2013). Hence, increased carcass yield in Sindhi, Mushki, and Lakha may be attributed to their higher body weight (Table 2). Fanatico et al. (2005b) also indicated direct association of dressing percentage with nal body weight of the birds.
In the present study, breast yield increased (P<0.05) in birds reared outdoor than indoor. It is quite possible that more physical exercise and locomotor activity in free range might have promoted breast muscle accretion. Similarly, Sales (2014) and Tong et al. (2015) reported increased breast yield in birds reared outdoor than indoor, indicating that free range system of poultry production is better in term of breast yield (Castellini et  Increased (P<0.05) thigh yield was observed in con nement rearing system followed by part-time free range and free range. Birds assigned to con nement rearing system had larger body weight and weight gain than those under part-time free range and free range, which might have contributed to thigh yield. In Birds reared indoor showed higher (P<0.05) drumstick yield compared with part-time free range and free range. This may be related to less exercise and minimum activity of birds in con nement rearing system. Similar to these ndings, Ahmad et al. (2019) found that birds reared indoor achieved higher drumstick weight compared to free-range and part-time free-range systems. Inci et al. (2016), likewise, observed variations in drumstick weight of quails under different rearing systems. Among the varieties, Sindhi showed increased drumstick yield than Peshawari. This may be attributed to the higher body weight of Sindhi ( Table 2) ) had no effect on wing percentage. No signi cant effect of different rearing systems on wing weight has also been reported in literature (Tong et al. 2014). Like a study by Wang et al. (2009) showed no signi cant differences in the percentage of wing muscles between chickens reared in free-range and conventional systems. However, Ahmad et al. (2019) found higher wings weight in intensive birds compared to semi-intensive and free-range birds.
Value of the liver percentage was found to be highest (P<0.05) in birds reared indoor followed by those in part-time free range and free range, which can be attributed to the fact that lack of exercise (with fewer nutrients being expended for energy) and high energy diet stimulated hepatic lipogenesis. In line with these results, Bughio et al. (2021) reported that intensively reared birds had higher liver weight compared to free-range birds. Similarly, Hanyani (2012) and Zhao et al. (2012Zhao et al. ( , 2015 reported heavier livers in chickens raised in cages than those reared on the oor. Hrncar et al. (2014), likewise, reported higher liver weights in ducks reared in cages than those of deep litter oor systems. Ahmad et al. (2019), however, found that liver weight increased in semi-intensive birds as compared to free-range and intensive systems. Similarly, Adedeji et al. (2014) and Abdullah and Buchtova (2016) observed that the livers of organically raised chicken broilers were heavier than those of conventionally bred birds. Among the varieties, Lakha demonstrated increased liver percentage (P<0.05) than Peshawari and Mushki. Reasons for increased liver weight in Lakha compared to Peshawari and Mushki could not be readily ascertained. According to Musa et al. (2006), liver weight varies from strain to strain (Santos et al. 2005), variety to variety (Jatoi et al. 2015) and breed to breed (Ojedapo et al. 2008).
In the present study, value of gizzard weight was observed to be highest (P<0.05) in birds reared indoor followed by those in part-time free range and free range. Similarly, Santos et al. (2005)  ) showed no effect on heart weight. As mentioned above, rearing systems did not in uence heart weight. These ndings are in agreement with those of Inci et al.
(2016) whose study showed no signi cant effect of rearing systems on heart weight.
Based on the current ndings, it can be concluded that con nement rearing system had positive effects on growth and carcass-related parameters of indigenous Aseel chicken. Among the Aseel varieties, Sindhi showed better growth potential, hence could be used as slower growing meat-type chicken in alternative rearing system, reviving agro-based rural poultry activity, bringing small poultry farmers into business. Declarations 2410.
Housing systems interacting with sex and genetic line affect broiler growth and carcass traits. Poultry Science, 94, 1711-1717. Tables   Table 1 Dietary 3 Each value represents the mean of 12 replicates of 6 birds each. 4 Each value represents the mean of 9 replicates of 6 birds each. 5 NS=not signi cant (P>0.05). 6 Interaction of rearing systems and Aseel variety comprised 12 experimental groups (n=18).