EFFECTS OF NATURAL ANTIOXIDANT EXTRACTS SUPPLEMENTATION ON GROWTH PERFORMANCE, CARCASS TRAITS, MEAT QUALITY AND SHELF-LIFE OF BROILER CHICKENS

ABSTRACT

Five experiments were conducted to evaluate the effect of three natural antioxidants: sweet orange peel extracts (SOPE); shaddock peel extracts (SHPE) and lemon peel extracts (LMPE) on performance, carcass traits, meat quality and lipid oxidation of broiler chickens. The peels of ripe sweet orange, shaddock and lemon fruits were oven-dried and extracted using standard methods. The qualitative and quantitative phytochemical contents and diphenyl 2- picrylhydrazyl (DPPH) abilities of SOPE, SHPE and LMPE, were also evaluated. Steroids, flavonoids, coumarins triterpenes and alkaloids were the phenolic compounds found in SOPE, SHPE and LMPE. While phlobatanin, anthocyanin and amino acid were not detected. SOPE contains significantly higher steroids (34.43 mg/100g), flavonoids (161.82 mg/100g), terpenoids (17.09 mg/100g), triterpenes (128.27μg/100g) and alkaloids (32.44 mg/100g) than SHPE and LMPE. SHPE contains significantly higher phenolics (26.76 mg/100g) than SOPE and LMPE. While LMPE contains significantly higher tannins (1.74 mg/100g), coumarins (18.15 μg/100g) than SOPE and SHPE. Three hundred Abhor acre- day old broiler chicks were assigned into 5 treatments (T) and 3 replicates each in a completely randomised design. The feeding trial was for 8 weeks period each. The birds were fed starter diets (23 % CP and 2879 Kcal/kg ME) for the first 4 weeks and finisher diets (20 % CP and 3000 Kcal/kg ME) for the remaining 4 weeks. The first feeding trial was based as follows; T1 (butylated hydroxy anisole BHA, 0.02 % per litre of water, + control), T2 (water OW as – control) and T3 (SOPE), T4 (SHPE), T5 (LMPE), 0.02 % per litre of water respectively. While in the second feeding trial, the supplementation was T1 (BHA as control), T2 T3, T4 and T5 (SOPE 0.02, 0.04, 0.06, 0.08 and 0.10 %) per litre of water respectively. In the first feeding trial, LMPE had better weight gain (WG) and FCR compared to other treatments. Treatment OW was significantly higher (p<0.05) in white blood cell (WBC) than other treatments. Whereas, red blood cell (RBC) of both SHPE and LMPE treatments were higher (p<0.05) than other treatments. Total protein (TP) and cholesterol (TC) were significantly higher (p<0.05) in OW and SOPE treatments. Treatment LMPE had a higher (p<0.05) carcass weight compared to other treatments. Sensory parameters of SOPE treatment were significantly higher (p<0.05) than other treatments. Thiobarbituric  acid  reactive  substance  (TBARS)  value  at  day  0;  for  cooked  meat  in  SHPE treatment and raw meat in OW and SOPE treatments were significantly lower (p>0.05) than other treatments. In storage day 2; the TBARS value in SHPE cooked meat was significantly lower (p>0.05) than other treatments. Whereas, for raw meat storage day 2, the TBARS values were similar in BHA, SOPE, SHPE and LMPE treatments but significantly lower (p>0.05) to OW treatment. In the second feeding trial, the WG and feed intake were significantly higher (p<0.05) in SOPE (0.04 %) compared to other treatments. Whereas, there were similarities in the FCR of BHA, SOPE (0.04 and 0.10 %) treatments and were significantly lower (p>0.05) to SOPE (0.06 and 0.08 %) treatments. Treatment SOPE (0.10 %) was significantly higher (p<0.05) in WBC compared to other treatments. Whereas, the RBC of SOPE (0.08 %) treatment was higher (p<0.05) than other treatments. Total cholesterol (TC) was significantly higher (p<0.05) in SOPE (0.06 %) treatment. Treatment SOPE (0.04 %) had a higher (p<0.05) carcass weight compared to other treatments. Sensory parameters of SOPE (0.10 %) treatment were significantly higher (p<0.05) compared to other treatments. TBARS value at day 0; for both cooked and raw meat in BHA, SOPE (0.04, and 0.08 %) with the exception of cooked meat of treatment SOPE (0.06 %), were significantly lower (p>0.05) than other treatments. It was concluded that SOPE had significant effect in most of the parameters of interest with better performance recorded in birds fed higher doses (0.04, 0.06 and 0.10 %) of SOPE in the second experimental feeding trial.

CHAPTER ONE

1.0 INTRODUCTION

1.1 Background to the Study

Meat  from  a  broiler  provides  various  nutritional  benefits,  including  a  high  level  of protein, low concentration of lipids, and a high polyunsaturated fatty acid concentration. When compared to red meat, this makes it a healthier option. During storage, however, broiler meat is especially sensitive to lipid oxidation and bacterial contamination (Dave and Ghaly, 2011). Meat quality criteria such as colour, juiciness, tenderness, and flavour, has been demonstrated to be harmed by lipid oxidation, resulting in a shorter shelf life for the meat (Min et al., 2008). Lima et al. (2013) suggested using dietary antioxidants to prevent lipid peroxidation in feed and animal products. Protein breakdown is unavoidable during the spoiling process. Temperature, pH, storage time, microbial protease, and endogenous variables all influence the degree of protein breakdown (Zhang et al., 2011). After a long period of storage, especially under unfavourable conditions, nitrogenous substances’ autolysis becomes more apparent (Smith, 2001). Often, spoiling is accompanied by the creation of biogenic amines and the development of oxidative rancidity (Estevez, 2015).  The use of synthetic chemicals has been discouraged as feed additives  in  recent  years  (Jonathan  et  al.,  2015).  As  a  result,  natural  antioxidants generated from plants are becoming increasingly popular, which have gained appeal because they are thought to be safer than synthetic antioxidants (Moyo et al., 2011). Because of their ability to prevent lipid oxidation, synthetic antioxidants are utilised for enhancing the oxidative stability in meat. Natural components are increasingly preferred by customers over synthetic compounds due to their inexpensive cost (Ahn et al., 2002). As  a  result,  more  data  on  the  potency of  various  natural  additives  which  enhances oxidative stability in meat is required. Several fruits have been found to have high levels of antioxidant chemicals like phenolic acids and flavanone glycosides (Abeysinghe et al., 2007), which extended the shelf life of broiler meats under various storage settings by reducing lipid peroxidation through dietary supplementation in feed and water (Botsoglou et al., 2002; Rababah et al., 2004; Jang et al., 2007; Sahin et al., 2010b).

Bioactive compounds, such as phenolic acids and flavanone glycosides, can be found in fruit peels. Peels are the most common by-products of citrus juice production, and if they aren’t utilised, they become waste and pollute the environment. Peels are the primary source of natural antioxidants in certain fruits (citrus, apples, berries and grapes), according to research (Rababah et al., 2004; Sallam et al., 2004; Lucia et al., 2008). Phenolic chemicals in peels and fruits are alternative to synthetic antioxidants in food preservation (Ignat et al., 2011). Many fruits include phenolic compounds, which are significant components (Miguel et al., 2004). According to Gelareh et al. (2009), there are about 5000 known plant phenolics, and investigations have shown that many of them have antioxidant properties.  The redox characteristics of phenolics, which primarily are responsible for their antioxidant action, can act as reducing agents, hydrogen donors, singlet oxygen quenchers, and metal chelators (Kumar et al., 2015).

Physicochemical properties of meat, such as shape, structure, proteolysis, and enzyme activity, can be affected by protein oxidation (Wangang et al., 2013). These changes may influence the qualities of meat products and regulate the quality of fresh meat (Wangang, 2009). Meat quality is influenced by time and temperature. When the freezer temperature is between -23 and -28 degrees Celsius, most meat will keep its good quality for long. Meat deteriorates more quickly at temperatures below -17 degrees Celsius (Emad et al., 2014).

Temperature fluctuations, such as those found in self-defrosting freezers, can degrade meat quality. The term “reactive oxygen species” refers to a group of chemicals that are responsible for the initiation of peroxidation processes (Kalam et al., 2012). Cellular damage caused by oxidation processes were linked to a number of degenerative health issues that have a negative impact on animal performance (Avanzo et al., 2001; Sharma et al., 2011; Yang et al., 2013;). The biological damage caused by lipid peroxidation is an important driver of food spoilage, significantly compromising food and meat qualities (Lima et al., 2013). Antioxidants are chemicals that considerably reduces or prevents oxidation in food (Srinvasan et al.,2008).

Food deterioration is caused by lipid oxidation (Lima et al., 2013). Due to their exposure to external elements such as light, temperature and air. Lipids oxidize and produce rancid odours and disagreeable flavours (Shah et al., 2014). Natural antioxidants are frequently provided with the chicken diet, while the body tissues synthesise some of the antioxidants in the body. Maintaining chicken health, productivity, and reproductive function requires a careful balance of antioxidants and pro-oxidants in cells, the digestive tract, and throughout the body (Fotina et al., 2013).

1.2 Statement of the Research Problems

The use of synthetic antioxidants such as butylated hydroxy anisole (BHA) and butylated hydroxy toluene (BHT) in meat refrigeration has long been proved to improve oxidative stability and preserve meat quality. However, the concerns about the negative effects of synthetic preservatives on human health, including their toxicity, coronary heart disease, and carcinogenic effect, have led to a shift in study focus to natural preservatives.

The  problem  associated  with  chicken’s  productivity and  reproduction  as  a  result  of oxidative stress  which  is  caused by free radical  generation  or a lack  of antioxidant defence, is also of a major concern in poultry industry and researchers.

1.3 Justification for the Study

Several research on the influence of dietary natural antioxidants on growth performance, oxidative stability, and meat quality in broiler chickens have been published (Li and Liu, 2012; Ismail et al., 2013; Loetscher et al., 2013; Saheed et al., 2015). The results, on the other hand, are mixed and inconsistent.  As a result, more research in various production systems  is  needed  to  allow  for  customised  decisions  and  informed  choices  in  the utilisation of dietary antioxidants in broiler chicken.

Citrus peels have been found to be high in phenolic chemicals, according to the studies of the following authors; Velasco and Williams (2011); Ding et al. (2015); Kumar et al. (2015). Differences in climatic conditions, cultivars utilised, and agronomic practices have all been shown to alter the phytochemical composition of citrus peels, and hence their antioxidant capacity.  As a result, evaluating the phenolic chemicals in fruit peels is justified.

In the meat and food industries, natural antioxidants have a lot of promises. Antioxidant capacity can be found in peel extracts, herbs, and spices. However, their use and usage in the meat business is limited due to a lack of evidence on their effectiveness and safety in large enough quantities to be used, necessitating more research in this field (Kumar et al., 2015).   Sweet orange peel (SOP), shaddock peel (SHP), and lemon peel (LMP) are currently considered wastes and potential environmental hazards. Specifically, the peels of the aforementioned fruits, which, if left to amass over time, may pollute portable water, streams, and rivers, or provide as a haven for toxic reptiles and insects through run-off (Manthey and Grohmann 2001).  As a result, a lot of money and time is spent getting rid of peels as a waste product. Similarly, any technology that converts these wastes into useful products will not only provide a valued product from a low-cost and widely available source, but will also aid in waste recycling. This would extend the raw material foundation for a low-cost supply of additional natural antioxidants.

1.4 Aim and Objectives of the Study

The aim of this research work is to evaluate the effect of dietary supplementation with natural antioxidant extracts on growth performance, carcass traits, meat quality and lipid oxidation of broiler chicken. The objectives are to determine the;

i.          phenolic compounds (quality and quantity) in sweet orange, shaddock and lemon peel powder.

ii.         use  of  SOP,  SHP  and  LMP  extracts  on  the  growth  performance  and  gut morphology of the broiler chickens.

iii.        effect of using SOP, SHP and  LMP extracts  on the haematology and serum biochemistry of the broiler chickens.

iv.        influence of SOP, SHP and LMP extracts on the carcass characteristics of the broiler chickens.

v.         effect of using SOP, SHP and LMP extracts on the meat quality of the broiler chickens.

vi.        suitability of SOP, SHP and LMP extracts on the oxidative stability of the broiler chicken meat.

vii.      effect of graded levels of the most outstanding of the natural antioxidant extract used on growth performance, carcass trait and meat quality of broiler chickens.

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