Effect of dietary supplementation with green tea powder on performance characteristic, meat organoleptic quality and cholesterol content of broilers

Nguyen Hoang Thinh, Nguyen Thi Vinh, Nguyen Viet Linh¹, Nguyen Thi Phuong Giang, Bui Huu Doan and Pham Kim Dang

Faculty of Animal Science, Vietnam National University of Agriculture Trau Quy - Hanoi - Vietnam
nhthinh@vnua.edu.vn
¹ Vietnam Academy of Science and Technology, Hanoi - Vietnam

Abstract

The effect of green tea powder (GTP) supplementation in the diets on performance and organoleptic quality, cholesterol content in meat and plasma of colored broilers was evaluated in order to determine the optimum GTP dose. A total 240 colored broilers at 2 weeks of age were randomly allotted to four groups representing: Control (basal diet without GTP as well as antibiotic) as control group and three other test groups fed a basal diet with antibiotic, 0.5% GTP and 1% GTP, respectively. There were no differences among treatments in final body weight, ADG, feed intake, FCR, carcass characteristics and meat organoleptic quality during 12 weeks period (p>0.05). However, the GTP supplementation in the diets can reduce cholesterol content in plasma and meat of broilers (p<0.05). It was lowest in the diets with 1% GTP, followed by 0.5% GTP. The dietary supplementation with GTP had no effect on performance, carcass and meat organoleptic quality, but the meat and plasma of broiler are less cholesterol.

Keywords: meat quality, performance, prebiotics, poultry

Introduction

Antibiotics have been widely used as feed additives for swine and poultry since the early 1950s. However, antibiotic supplementation in animal feed results in bacterial resistance to the antibiotics and a residue of the antibiotics in animal products, which is a hazard to public health. Therefore, they have been banned from 2006 by European Union. An intensive search for alternatives antibiotic such as probiotics, prebiotics, symbiotics, enzymes, organic acid and other feed additives has started in the last decade (Fluton et al 2002).

Phytogenics are a group of natural growth promoters or non-antibiotic growth promoters, derived from herbs, spices or other plants. Green tea (Camellia sinensis) is included in the list of phytogenic substances. Green tea have been shown to improve body weight gain and feed efficiency in pigs (Sarker et al 2010b), cattle (Sarker et al2010a) and broilers (Biswas and Wakita 2001). The green tea leaves can be offered as an ingredient or as a supplement to broiler feed for reducing mortality in diseased birds (Cao et al 2005) and to hens for improving laying performance (Uuganbayar et al 2005; Uuganbayar et al 2006), and for reducing the cholesterol content of plasma and meat (Yang et al 2003). Hence, this study was to examine the benefit of adding green tea powder on performance, meat quality and cholesterol content in plasma and meat of broilers.

Materials and methods

Animals, diets and experimental design

A total of 240 colored broilers at 2 weeks old were allocated in a completely randomly design to four dietary treatments with three replications each of 20 birds and randomly housed in the pens in accordance with the National Institute of Animal Sciences (NIAS) care and management guidelines. The four dietary treatments were: basal diet as control (without GTP and without any antibiotic), positive control (basal diet with 0.005% antibiotic, basal die with 0.5% GTP (GTP 0.5%) and basal die with 1% GTP (GTP 1%). The broilers were fed experimental diets containing 17% CP and 2950 kcal ME/kg. Feed and drinking water were supplied ad libitum. Green tea powder is the by-product which was collected from Thai Nguyen province. The antibiotic was chlortetracycline which is the current antibiotic still allow to be used in feed additive in Vietnam according to the regulations of the Ministry of Agriculture and Rural Development of Vietnam. The dry matter, ash, ether extract, crude protein of feed and GTP were analyzed in using the method of AOAC 1990, and neutral detergent fiber (NDF), acid detergent fiber (ADF) (Van Soest. et al. , 1991).

Feed analysis

The basal diet and GTP were sampled for chemical analysis. The samples were analyzed of dry matter, ash, ether extract, crude protein (AOAC 1990), and neutral detergent fiber (NDF), acid detergent fiber (ADF) (Van Soest et al 1991). The formula and chemical composition of basal diet and GTP were given in table 1.

Measurements

The body weight was measured every week from the initial day to the final day of the experiment for calculation the body weight gain. Feed intake was determined daily by measuring feed residues. Feed conversion ratio was calculated by dividing feed intake by body weight gain.

At 15 weeks of age, 4 chickens (2 males + 2 females) in each replicate were used to evaluate live weight; weight after killing, the weight of carcass; heart, liver; thigh and breast. The pH of breast at 15 min and 24 h post-mortem was determined by Testo 230 (Germany). The meat color was measured in using a Minolta CR-410 colorimeter and expressed as color L*- (lightness), a*-(redness) and b*- (yellowness) values. After slaughter 24h, thigh and breast were collected to evaluate tenderness by using Warner - Bratzler 2000D machine (America).

Cholesterol concentration in plasma and carcass

At the end of the treatment (12 weeks of age), before slaughtered 12 hours, 2ml of blood was taken from the jugular vein and centrifuged to collect blood plasma (stored at -30°C until the analysis). For the meat, 5 g of mixture of breast were used to analyze according to method of AOAC 976.26.

Statistical analysis

All data was performed by SAS 9.1 to evaluate variance components for completely randomized design. Differences among treatments means were analyzed using Duncan’s Multiple Range Test.

Results and discussion

Performance characteristic

Non-significant differences in FCR, body weight, and feed intake of these two GTP doses in compare with control and antibiotic supplementation lot (p>0.05). However; for the diet with antibiotic and 0,5% GTP, the body weight gain and FCR tended to improve while the diet with 1% GTP slightly reduced body weight and increased FCR but as mentioned above, these differences were statistically non significant (Table 2). Biswas and Wakita (2001) reported that when added GTP at low level tended to improve FCR. Some researchers reported that when supplementation green tea at high level as 1.00%, 1.50%, 2.50% and 5.00% linearly reduced body weight gain of the chicks (Uuganbayar, 2004). And they also indicated that the growth of broiler chicks had a negative relationship with dietary catechin, tannin and fiber contents of green tea (Weisberg et al 2001). This results were in agreement with several studies (Yang et al 2003) observed that there were non-significant differences in feed intake and feed efficiency when compare the diets with green tea, antibiotic added and control.

Meat yield and quality

There were no difference among treatments in all carcass yield and quality characteristic (p>0.05). However, carcass weight, thigh, breast weight were slightly higher when broiler fed GTP 0.5% and antibiotic as compare with control while broilers fed the diet with GTP 1% tended to have lower carcass yield characteristic as compare with control and antibiotic and 0.5% GTP diets. There were no significant differences in pH at 15 min and 24 hour post-mortem of meat, meat color changes (lightness, redness and yellowness) and tenderness in GTP and antibiotic treatments (p>0.05). These results were in agreement with reports of (Sarker et al 2010) who indicated that green tea and antibiotic diets had no effects on meat color and sensory evaluation traits.

Cholesterol content in blood and meat

Cholesterol contents of blood and meat were lower when broiler fed GTP diets (P<0.05). Particularly, it was lowest in treatment with 1% GTP added, followed by 0.5% GTP. The diet with antibiotic supplementation had higher cholesterol content as compare with the diets containing GTP. Similar results indicated that the cholesterol content was lower in chicks fed GTB than in control, and lowest with 1% GTB (Sarker et al 2010). Abdel-Azeem (2005) found that the addition of powdered green tea flowers at 0.25%, 0.50% and 0.75% to growing Japanese quail diets significantly decreased blood lipid fractions. The addition of green tea by-product to diets tended to decrease blood low-density lipoprotein (LDL) cholesterol content compared to the control group (Sarker et al 2010).

The reduction of cholesterol content in blood and carcass can be explained by effect of catechin and fiber content of green tea. Green tea containing high tannin, in this study GTP containing 22.35% tannin, and catechin is one kind of tannin. According to Ikedaet al (1992) catechin may have an inhibitory effect on intestinal absorption of lipid. This may prevent an excessive accumulation of lipid in the liver and other tissues. The reduction in tissue cholesterol may also be explained by a negative effect of tea catechin on formation of micell that mediates reabsorption of bile acid (Muramatsu et al 1986). The second possible explanation is on tea fiber. There is a great deal of evidences (Evans et al 1992) that dietary fiber could reduce the level of cholesterol in animals through adsorbing bile acids and various lipids on it. In addition, the phenolic compound in tannic acid of green tea plays an important role in the catabolism of liver cholesterol (Yugarani et al 1992). Conversion of cholesterol to bile acids occurs exclusively in the liver and represents the major pathway for the elimination of cholesterol from the body. This may also explain the reduced cholesterol levels.

Conclusion

• Base on this study it could be concluded that the addition GTP at 0.5 and 1% to the diets had no effect on performance parameters of broilers.
  
  
• It can be used as alternative of antibiotic and GTP supplementation to broiler chicken diets is favorable to the consumers because it makes broilers with less cholesterol deposition.

References

Abdel-Azeem F A 2005 Green tea flowers (Camellia sinensis) as natural anti-oxidants feed additives in growing Japanese quail diets. Egyptian Poultry Science Journal, 25(3): 569-588.

AOAC 1990 Official methods of analysis. Association of Officical Analytical Chemists Inc: the 15th Ed, W., Dc (ed.).

Biswas M A H and Wakita M 2001 Effect of dietary Japanese green tea powder supplementation on feed utilization and carcass profiles in broilers. J ournal of Poultry Science, 38: 50-57.

Cao B H, Karasawa Y. and Guo Y M 2005 Effects of green tea polyphenols and fructo-oligosaccharides in semi-purified diets on broliers’ performance and caecal microflora and their metabolites. Asian-Australasian Journal of Animal Sciences, 18: 85-89.

Evans A J, Hood R L, Oakenfull D G and Sidhu G S 1992 Relationship between structure and function of dietary fiber: a comparative study of the effects of three galactomannana on cholesterol metabolism in the rat. British Journal of Nutrition, 68: 217-229.

Fluton R N, Nersessian B N and Reed W M 2002 Prevention of Salmonella enteristidis infection in commercial duckling by oral chicken egg-derived antibody alone or in combination with probiotics Poultry Science Journal, 81: 34-40.

Ikeda I, Imasato Y and Sasaki E 1992 Tea catchins decrease micellar solubility and intestinal absorption of cholesterol in rats. Biochemistry and Biophysiology of Acta, 11 : 27-141.

Muramatsu K M, Fukuyo M and Hara Y 1986 Effect of green tea catchines on plasma cholesterol level in cholesterol fed rats. Journal of Nutrition Science and Vitaminol, 32 : 613-622.

Sarker M S K, Kim G M and Yang C J 2010 Effect of green tea and biotite on performance, meat quality and organ development in Ross broiler. Egyptian Poultry Science Journal 30(1): 77-88.

Sarker M S K, Ko S Y, Lee S M, Kim G.M, Choi J K and Yang C J 2010a Effect of different feed additives on growth performance and blood profiles of Korean Hanwoo calves.Asian-Australasian Journal of Animal Sciences, 23 : 52-60.

Sarker M S K, Yim K J, Ko S Y, Uuganbaya D and Kim G M 2010b Green tea level on growth performance and meat quality in finishing pigs. Pakistan Journal of Nutrition, 9(1): 10-14.

Uuganbayar D 2004 A study on the utilization of green tea for laying hens and broiler chicks . Dissertation for the degree of Doctor of Philosophy, Sunchon National University, Suncheon, Korea.

Uuganbayar D, Bae I H, Choi K S, Shin I S, Firman J D and Yang C J 2005 Effects of green tea powder on laying performance and egg quality in laying hens. Asian-Australasian Journal of Animal Science, 18(12) : 1769-1774.

Uuganbayar D, Shin I S and Yang C J 2006 Comparative performance of hens fed diets containing Korean, Japanese and Chinese green tea. Asian-Australasian Journal of Animal Sciences, 19(8): 1190-1196.

Van Soest P J, Robertson J B and Lewis B A 1991 Methods for Dietary Fiber, Neutral Detergent Fiber, and Nonstarch Polysaccharides in Relation to Animal Nutrition. Journal of Dairy Science, 74(10): 3583-3597.

Weisburger J H, Hosey J R, Larios E, Pittman B, Zang E, Hara Y and Cheraux G 2001 Investigation of commercial mitolife as antioxidant and antimutagen. Journal of Nutrition, 17: 322-325.

Yang C J, Yang I Y, Oh D H, Bae I H, Cho S G, Kong I G, Uuganbayar D, Nou I S and Choi K S 2003 Effect of green tea by-product on performance and body composition in broiler chicks. Asian-Australasian Journal of Animal Sciences, 16 : 867-872.

Yugarani Y, Tan B K H, Tech M and Das N P 1992 Effects of polyphenolic natural products on the lipid profiles of rats fed high fat diet. Lipids, 27: 181-186.

Received 30 June 2018; Accepted 12 August 2018; Published 3 September 2018

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