Physiological conditions, performance and meat quality of kampung chicken on free range system in peatland

Deni Fitra^1,2, Niken Ulupi³, Irma Isnafia Arief³, Rita Mutia⁴ and Luki Abdullah⁴

¹ Graduate School of Animal Production and Technology, IPB University, Bogor, Indonesia
deni.fitra@uin-suska.ac.id
² Department of Animal Science, State Islamic University of Sultan Syarif Kasim, Pekanbaru, Indonesia
³ Department of Animal Production and Technology, Faculty of Animal Science, IPB University
⁴ Department of Nutrition and Feed Technology, Faculty of Animal Science, IPB UniversityBogor 16680, Indonesia

Abstract

An alternative system for chicken production with grazing access and a solution to the negative effects of cage rearing is a free-range system. This study aims to evaluate the physiological conditions, performance, and meat quality of kampung chicken on free-range systems with different vegetations. This experiment used 300 kampung chickens with a completely randomized design of 4 treatments with 5 replications. The treatments in this study were control (intensive cage, without vegetation), paddock Brachiaria decumbens, paddock Axonopus compressus, and paddock Indigofera zollingeriana. Each paddock was placed in portable housing. 12 birds aged 6–12 weeks were reared in each paddock with a density of 6,67 m²/bird. The treatment without vegetation was reared in the postal housing. At the end of the study, the blood profile, plasma biochemistry, performance, and meat quality were analyzed. Results showed that the blood profile, plasma biochemistry, and meat quality of the four treatments were in normal condition despite experiencing free-range rearing with different vegetations. The final BW, ADFI, and ADG of the chickens in the free-range system were much lower than that of the intensive cages (P < 0.05) while the mortality in the free-range was higher. In conclusion, physiological conditions of kampung chickens reared in a free-range and intensive system show a healthy condition. Paddock peatland with forage Indigofera zollingeriana produces meat with lower cholesterol (43.77 mg/100g) although free-range system could significantly reduce BW and weight gain.

Keywords: Axonopus compressus, Brachiaria decumbens, free-range system, Indigofera zollingeriana, kampung chicken, performance

Introduction

Kampung chicken is one of the most widely distributed native chicken breeds in Indonesia. Kampung chickens have many advantages, can survive and breed well despite low feed quality (Junaedi and Khaeruddin 2018); resistance to Salmonella sp infection (Ulupi et al 2014); and produce meat with a low cholesterol content of 56.33 mg/100 g (Wardiny et al 2020).

Intensive maintenance of chickens is applied by farmers because it is believed to be more efficient in land use (Green et al 2009), facilitates feeding, drinking, and cleaning feces. However, the system causes stress which has an impact on the decline in health, performance, and product quality (Yakubu et al 2007). One alternative to the chicken rearing system with access to pasture is the free-range system.

Recently, agricultural land is often converted into residential, industrial, property, and toll roads. The area of rice fields decreased by 12.41% during 2014–2018 (BPS 2018). The increasingly limited fertile land will force farmers to be able to use marginal lands, including peatlands. Indonesia has the largest peat area in the tropical zone. Peatlands are estimated at 21 million ha or represent 70% of the peat in Southeast Asia or 50% of the tropical peat in the world. Riau Province has 4 million ha of peatland, equivalent to 45% of Riau Province's land area and 56% of Sumatra's peatland area (Wahyunto et al 2005).

The source of vegetation in a free-range system is usually obtained from grass or legumes that grow on grazing land. The level of vegetation succession on peatlands was limited and dominated by Stenochlaena palutris with low palatability, so the introduction of vegetation needs to be done. The introduction of vegetation in peatlands is carried out by planting superior types of vegetation that suitable and high nutrients. This study aims to evaluate the physiological conditions, performance, and quality meat of kampung chicken on peatlands with different vegetation.

Materials and method

Animals and Design Experimental

The research was conducted at the teaching farm, Faculty of Agriculture and Animal Husbandry UIN Sultan Syarif Kasim Riau, Indonesia. The grazing land used was shallow peatland and sapric type. The research procedure has been approved by the Animal Ethics Committee of IPB University (Ethical Approval Number: 170-2019 IPB). The study used 300 chicks (DOC Kampung Chicken) obtained from local breeders. The study used a completely randomized design with different vegetation in paddock peatlands as a treatment. Treatment T1: Control (intensive cage, without vegetation), T2:Brachiaria decumbens paddock (PBD), T3:Axonopus compressus paddock (PAC), and T4: Indigofera zollingeriana paddock (PIZ). Each treatment was repeated 5 times and each replication consisted of 12 chickens, except for the control treatment 6 chickens.

Procedure

A total of 15 units of portable cages measuring 2 m² as shade were placed on 1,200 m² grazing land (400 m² per treatment). Each treatment consisted of 5 replications with grazing land of 80 m² (4x20m) which was fenced using a barrier net. Portable cages were placed in each paddock equipped with holes in and out of chickens, feeders, and drinking water. The control treatment used postal housing consisting of 5 experiment cage units as replicates. Density in treatment T2/T3/T4 refers to The Australian Code of Practice, which is a maximum cage of 30 kg/m² and grazing land 1,500 birds/ha (SCARM, 2002), so in this study using a cage density of 6 birds /m², and the density of grazing land is 6.67 m²/bird.

The grazing land has been processed and fertilized first. Dolomite and cow manure was given at a dose of 2 tons/ha each. After one week later, 3 types of forage were planted according to the treatment. Brachiaria decumbens and Axonopus compressus grass were planted using pols with a spacing of 30x30 cm. Indigofera zollingeriana was planted using 1.5-month-old seedlings with a spacing of 1x1.25 m. Plants are maintained and cleaned of weeds for 60 days until the plants are ready for grazing. Then the forage was cut for uniform growth before the chickens go down to the grazing land. Chickens are released into the grazing land during the day and at night in the cage to avoid predators and bad weather

All chicks before treatment were kept communally in postal housing until the age of 42 days. Then, a total of 210 chickens with the same bodyweight (455.7±10.29 g) were selected as research samples. Treatment started at 43–84 days (6–12 weeks). The feed used during the starter period was commercial feed produced by PT. Charoen Pokphand Indonesia, code 311-VIVO® with 22% crude protein content. Chickens after 6 weeks of age were transferred to the grazing land, except for the control treatment which remained in postal housing. Then, the feed was replaced with native chicken feed (N582®) with a crude protein content of 16–17.5%. Chickens in grazing land were still fed for 1 week as an adaptation, while drinking water was adlibitum.

Photo 1. The chickens grazed directly in the paddock

Variables and data Collection

Blood samples were taken to analyze the physiological conditions. Physiological conditions can be described from the blood profile and plasma biochemistry based on Rasheed (2017). The number of erythrocytes, leukocytes, hemoglobin, and hematocrit was calculated using the Hematology Analyzer. Total triglycerides, cholesterol, and glucose were calculated using the Microlab 300.

Recording of the performance data of kampung chicken production was carried out during the study. The weight of the chickens was recorded until the age of 12 weeks to determine body weight gain. Chickens that died until the end of the study were recorded to determine the Mortality Rate. Feed supplement consumption was calculated by comparing the feed given to the rest of the feed. Collection of feed and feed residues every day, then composited every one week.

Forage consumption was calculated according to Horsted et al (2006) using the estimated removal of herbage formula.Every 14 days of paddock rotation, Brachiaria decumbens and Axonopus compressus grasses inside and outside the plot were harvested approximately 2 cm above the soil surface, while for Indigofera zollingeriana, only the leaves without stems were harvested, assuming only the parts that could be consumed. The harvested biomass was weighed for each forage area then stored for dry matter (DM) analysis. Dry matterBrachiaria decumbens, Axonopus compressus, and Indigofera zollingeriana were 22.38%, 27.69%, and 28.62%, respectively. The difference in the amount of biomass inside and outside the plot was then divided by the number of days of grazing to get the average daily vegetation consumption.

Macrofauna diversity of soil insect species was identified using the Pitfall Trap method (Photo 2.). Pitfall Trap was a trap used to catch insects that are above the ground around plants. Each paddock is installed 5 traps randomly. The traps were made of 660 ml plastic cups containing 70% alcohol and planted parallel to the ground. Protectors were installed above the traps to prevent rainwater from entering and then left for 24 hours. Insects trapped in plastic cups were collected for identification of macrofauna diversity and analyzed descriptively.

Photo 2. Diversity of macrofauna in the paddock free range system

The meat quality variables analyzed were the physical and chemical properties of the meat. The pH of the meat was calculated based on the AOAC (2005). Meat after 6 hours of slaughter has measured the pH with a pH meter (Hanna Instruments) calibrated at pH 7 and 4. Moisture content was calculated by weighing 1 g of the sample in a cup. The sample was put in an oven at 105°C for 8 hours then cooled in a desiccator and weighed. The water content was calculated by the formula according to the AOAC (2005). Water holding capacity and cooking loss were calculated according to Soeparno (2005). The cholesterol content of meat was calculated using gas Chromatography analysis according to AOAC (2005).

The data were analyzed for variance using SPSS version 16.0 and continued with the LSD Test. Data on mortality, IOFCC, and meat cholesterol were analyzed descriptively comparative.

Results and discussion

Physiological Conditions

Normal blood composition will result in a good performance (Durai et al 2012). Changed blood profile and plasma biochemistry will affect physiological conditions. The blood profile and plasma biochemistry of kampung chickens with different paddock vegetation are presented in Table 1. and Table 2.

Table 1 shows that the different paddock vegetation had no significant effect on the number of erythrocytes, hematocrit, and hemoglobin, except for leukocytes (P<0.05). However, the findings in this study were within the normal range. Erythrocytes in the control, PBD, PAC, and PIZ were still in the normal range, namely 2.5-3.9x10⁶/mm³ (Samour 2015). The findings in this study are in agreement with Olaniyi et al (2012) that the number of erythrocytes was not affected by differences in vegetation. Age factor is more influential on erythrocytes than the difference in production system factors (Suchy et al 2004). Leukocytes in Indigofera zollingeriana paddock are higher than in other treatments (P<0.05). This is presumably because the saponin content in Indigofera zollingeriana can trigger an increase in leukocytes even though it is still in the normal range. Indigofera zollingeriana has a saponin content of 0.036 ppm (Palupi et al 2014). Hematocrit and hemoglobin numbers were also in the normal range and relatively the same. This indicates that the ability to bind oxygen in chicken blood is still functioning properly. A normal blood profile indicates that the physiological condition of the chicken is in a healthy condition.

Plasma biochemical parameters are considered to be important indicators that reflect a chicken's physiological and metabolic status and can be influenced by numerous factors, among them the highly influential production system (Rehman et al 2017; Zhang et al 2018). Statistically, the differences of paddock vegetation affected the glucose and cholesterol content of chicken blood(P<0.05). Triglyceride content was relatively the same between treatments (P>0.05) and was still in the normal range, which was below 150 mg/dl (Basmacioglu and Ergul 2005). It is assumed that the provision of access to the paddock did not increase the chicken's energy needs excessively. The body will synthesize more triglycerides in the form of fatty acids when the energy needs in the body increase. Dong et al (2017) stated that triglycerides and cholesterol can be used as indicators of stress in chickens if their numbers are not normal. The findings of this study were lower than xianju chicken (local china) in the free-range system with triglycerides of 58.68 mg/dl (Dong et al 2017).

The high cholesterol in PAC may be due to heat stress. Axonopus compressus grass that grows horizontally covering the ground cannot provide shade for chickens from the hot sun. Compared to other forages, PIZ with Indigofera zollingeriana plants was able to produce the lowest cholesterol (149.88 mg/dl), although this study does not show a regular trend. This is presumably because Indigofera zollingeriana besides having a high protein content also contains xanthophyll and β-carotene of 507.6 mg/kg (Palupi et al 2014). The findings of this study agree with reports that dietary β-carotene reduces serum cholesterol (Silva et al 2013). Chicken cholesterol is normally in the range of 87-192 mg/dl (Basmacioglu and Ergul 2005). The glucose content in the PIZ treatment was higher than PAC and PBD, while the same as the control. Although the glucose is high in PIZ, it is still in the normal range of 230-370 mg/dl (Sulistyoningsih et al 2014). This indicates that the energy needs of chickens were still fulfilled, even for maintenance needs.

Growth Performance

Bodyweight (initial and final), ADFI, ADG, mortality, and IOFCC of kampung chickens with different paddock vegetation are shown in Table 3. and Table 4. The BW and ADG of kampung chickens in the free-range (in all vegetation treatments) were significantly lower than those of chickens in the control or intensive system (P<0.05). The many factors affected the free-range system, such as photoperiod, temperature, and light intensity, which are inherently variable and are not controlled. This is presumably due to differences in feed quality and the level of physical activity of chickens in the free-range system. Chickens in the free-range system produce less weight than those in the intensive system (Golden et al 2012). The weight of chickens in the free-range system was statistically the same, although the types of vegetation were different, namely 741.91–831.79 g/head. The findings of this study are relatively the same as Jin et al (2019) which uses wannan yellow chicken (Chinese local chicken) at the age of 84 days (785.03 g/head).

Feed consumption in the control was significantly higher than in the free-range system (P<0.05). This is presumably due to different feed sources. In the control treatment, the chickens received commercial feed without forage, while the PBD, PAC, and PIZ treatments were the opposite. Consumption of feed supplements is higher than consumption of forage. Consumption between types of forage is not different. Forage consumption in this study ranged from 7.14 to 12.60 g DM/day. this result is lower than Horsted et al (2006) which stated that laying hens in the free-range system consumed forage of 9–17 g DM/day and 51–73 g DM/day on chicory plants. Slow-growing broilers of the White Bresse L40 strain consumed forage in dry matter of 7.7 g/day in males and 5.1 g/day in females using the crop content analysis method (Almeida et al 2012).

In the free range system, all feed sources available in the paddock allow for consumption by chickens. Furthermore, chickens raised in a free-range system have access to pasture and the various forages, insects, and worms, which may be available. Observations in the paddock indicate that chickens get a source of protein from several types of soil insects. Xysticus fervidus and Gryllus vernalis were found in the PIZ and PAC treatments, while Dolichoderus thoracicus were mostly found in the PBD treatment.

The mortality rate of chickens in the free-range system in all forage treatments was higher than the control, but still below Bestman and Bikker (2020) who reported that the mortality in the free-range was 12.2%. The cause of the high mortality rate may be due to changes in weather during the study which coincided with the transition season (change from the rainy to the dry season).

Meat quality

The effect of different paddock vegetation on meat quality is presented in Table 4. There was a difference in the water, and water holding capacity among the treatment (P<0.05).

The pH of kampung chicken meat in this study was relatively the same (P>0.05), ranging from 5.78 to 5.79. The pH is formed due to the accumulation of lactic acid resulting from the breakdown of glycogen. The pH is usually determined by glycogen stores and is influenced by differences in body weight (Pragati et al 2007). The pH in this study was not significantly different (P>0.05), which was presumably due to the relatively the same bodyweight of chickens, especially in the free-range paddock. The pH measurement in this study was carried out 8 hours after slaughter so that the pH obtained was the same as the ultimate pH of the meat. The process of converting glycogen to lactic acid during rigor mortis occurs for 6-8 hours with the ultimate pH of normal meat ranging from 5.7 to 5.8 (Zhuang and Savage 2012).

The water content of chicken meat in the control treatment was higher than the free-range treatment in all forage stalls and statistically different (P<0.05). This is presumably due to differences in the bodyweight of chickens between treatments, according to Syamsuryadi et al. (2017) which states that the water content of chicken meat is directly proportional to the bodyweight of chickens. Chickens weighing 2,234 g have a water content of 69.47% and chickens weighing 1,889.5 g have a moisture content of 69.43% (Syamsuryadi et al 2017). The water content of chicken meat in this study (60.98–62.32%) was lower than the normal value, according to the opinion of Aberle et al (2001) which stated that 65–80% of the chemical composition of meat was water.

Cooking loss is the shrinkage value of meat due to the cooking process expressed in percent. The percentage of cooking loss in this study was 32.44–34.11% and was not significantly different (P>0.05). Cooking loss in this study was following the normal range, namely between 30–37% (Raj 2003). Cooking loss is strongly influenced by the pH value and fat composition of the meat (Souza et al 2011).

Water holding capacity is the ability of meat protein to bind water content in response to the application of external forces such as cutting, cooking, and grinding meat. The percentage of water holding capacity in this study was significantly different (P<0.05) and the highest was in theAxonopus compressus paddock, which was 72.11%. Kampung chickens in Indigofera zollingeriana paddock produce meat with cholesterol 43.77 mg/100g. Comparatively, this cholesterol was the lowest compared to other treatments including intensive housing. The high activity of chickens in grazing land may be the cause other than the tannin and β-carotene content in the Indigofera zollingeriana plant. Cholesterol in this study was lower than Wardiny (2020) who used kampung chickens aged 12 weeks, resulting in cholesterol 56.33 mg/100g.

Conclusion

• Physiologically, kampung chickens reared in a free-range and intensive system show a healthy condition. Paddock free-range with forage Indigofera zollingeriana is the better due to produces meat with lower cholesterol (43.77 mg/100g) although free-range system could significantly reduce BW and weight gain.

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