Influence of propolis extract in Hubbard JV chickens nutrition on oxidative stabilty of meat

© Slovak University of Agriculture in Nitra Faculty of Agriobiology and Food Resources, 2014 http://www.fapz.uniag.sk/ DOI: 10.15414/afz.2014.17.02.47–51


Introduction
In recent years, poultry industry has grown very fast because of relatively low production costs, shortening of fattening period in particular poultry species, high nutritional value of meat and the large number of products offered to consumers (Barbut, 2002).Broiler chickens are the most abundant animal species in breeding and meat of broiler chicken is used for poultry products and foodstuffs (Perry et al., 2002;Moreki et al., 2010).In recent period, after the ban of antibiotics and coccidiostats in poultry nutrition in EU, different alternative supplements, e. g. probiotics, prebiotic preparations, plant essential oils and their extracts, enzymatic preparations and bee products (pollen, propolis or their extracts), have begun to use for their positive influence on health state, feed utilization, nutritional and sensory quality of product as well as economics of poultry industry production (Prytzyk et al., 2003;Wang et al., 2004;Haščík et al., 2005ab, 2007Shalmany and Shivazad, 2006;Seven et al., 2008).Vennat et al. (1995) stated, that propolis contains large amount of flavonoids and shows wide range of activities.Banková et al. (2002) and Moura et al. (2009) warned that propolis samples differ in content of these substances and result in different biological effects.Some research studies confirm that propolis has always antimicrobial properties regardless to its source and composition, although different chemical substances are mostly responsible for antimicrobial activity (Trusheva et al., 2006).In many experiments, different effects to immune system were discovered, e. g. propolis affects increasing of macrophages activity (Dimov et al., 1991).Nagei et al. (2003) and Kumazawa et al. (2004) have described antioxidant and anti-inflammatory properties of propolis.Namgoong et al. (2004) warn, that effects of propolis are related to inhibition of prostaglandins synthesis.
In term of nutritional composition, sensory properties and antioxidant stability, it is necessary to evaluate the carcass product, not only the production of poultry meat (Garlík et al., 2011).Antioxidant stability is important for storage and durability of meat, because the poultry meat and mainly the poultry fat contain higher amount of polyunsaturated fatty acids in compare with fat of other slaughtered animals (Bystrický and Dičáková, 1998;Martinez-Tome et al., 2001).
The aim of the study was to test the commercial feed mixtures supplemented by propolis extract and to verify its influence on oxidative stability of the most valuable parts of Hubbard JV chicken carcass during the storage process in freezer.

Material and methods
The experiment was under taken in poultry test station Zámostie Company (Slovak republic).The testing chickens were Hubbard JV hybrid combination.Totally, 300 one-day-old chickens were included in the experiment and there were created three groups: control group -C (without propolis extract application) and two experimental groups (E1 and E2) with different doses of propolis extract.Each group consisted of 100 chickens.Fattening lasted 42 days.Chickens were bred using technology on deep litter (wood shavings).
Feed mixture was administered by the tube feeders.Feed mixtures, applied in this experiment, were prepared and mixed according to requirements of Gazette of Ministry of Agriculture and Rural Development ( 2004) in Biofeed Company with the seat in Kolárovo (Slovak Republic).Feed mixtures were analysed in term of basic nutrients and energy value at the Department of Animal Nutrition (Faculty of Agrobiology and Food Resources, SUA in Nitra).Composition of feed mixtures is in the table 1.
Feed was manually administered in regular intervals each day.Chickens were fed by ad libitum system.They were fed to 21 st day by the same starter feed mixture HYD-01 (powder form) and from 22 nd to 42 nd day of fattening, they were fed by the same feed mixture HYD-02 (powder form) in all evaluated groups.Feed mixtures HYD-01 and HYD-02 were produced without antibiotics and coccidiostats.Nutritional value of feed mixtures was the same in all groups during the experiment, but experimental groups had feed mixtures HYD-01 and HYD-02 supplemented by propolis extract at a dose of 600 mg kg -1 (E1) and 800 mg kg -1 (E2).Propolis extract was prepared from milled propolis originated in Slovak Republic.Milled propolis was mixed with 80 % ethanol (Krell, 1996).Propolis solution was extracted in water bath at 80 °C under the reflux for 1 hour.After the extraction, mixture was cooled and centrifuged.Obtained supernatant was evaporated on rotary vacuum evaporator at the temperature of water bath 40-50 °C and then it was weighted.The evaporation residue at amount of 60 and 80 g was separately solved in 1000 cm 3 of ethanol (80% concentration) and applied to 100 kg of feed mixture for the experimental group of Hubbard JV chickens.Water was administered ad libitum by selfpowered system using nipple drinkers with drip tray.At the end of fattening (42 nd day), 60 pieces of chickens (30 male chickens and 30 female chickens) from each group in experiment were selected for slaughter analysis.To determine the degradation changes of fat (determination of thiobarbituric number -TBA), samples of breast and thigh muscles without bones were packed to polyethylene bags and stored at -18 °C for 6 months.TBA values, expressed as malondialdehyde amount, were determined in the 1 st day and 1 st , 2 nd , 3 rd , 4 th , 5 th and 6 th months of storage process.TBA number was found using method according to Marcinčák et al. (2004).Absorbance of samples was measured on UV-VIS spectrophotometer T 80 (PG Instruments Limited, Great Britain) at wave length of 532 nm and result was calculated on malondialdehyde (MDA) amount in 1 kg of sample.
Results (mean and standard error) were processed in statistical programme Statgraphics 5.0.F-test followed by t-test was used for determination of significant differences between the groups of experiment.

Results and discussion
Results of oxidative stability in breast and thigh muscles of Hubbard JV chickens during the storage at -18 °C for 6 months are in the table 2.
Results are expressed as TBA number and evaluated by malondialdehyde (MDA) amount.In the 1 st day of storage, MDA values were low in the breast muscle (from 0.175 mg kg -1 in E2 to 0.212 mg kg -1 in C) as well as in the thigh muscle (from 0.194 mg kg -1 in E2 to 0.255 mg kg -1 in C).These results are in accordance with statements of Marcinčák et al. (2010).
In further storage of breast muscle, MDA values were increased gradually: after the 1 st month, we found 0.247 mg kg -1 in control group, 0.206 mg kg -1 in E1 and 0.202 mg kg -1 in E2.And after the 1 st month of thigh muscle storage, we found followed MDA values: 0.271 mg kg -1 in control group, 0.223 mg kg -1 in E1 and 0.214 mg kg -1 in E2.MDA values were higher in further months of breast and thigh muscles storage by freezing.In the 5 th month, we found the highest MDA value in control group (0.299 mg kg -1 -breast muscle, 0.326 mg kg -1 -thigh muscle), the lower MDA value in E1 (0.249 mg kg -1breast muscle, 0.264 mg kg -1 -thigh muscle) and the lowest MDA value in E2 (0.247 mg kg -1 -breast muscle, 0.258 mg kg -1 -thigh muscle).Experimental group E2 was the group with the highest amount of propolis extract in Hubbard JV chicken nutrition.
After the 6 months of storage, tendency of increasing MDA values was confirmed and the highest average concentration of MDA in breast muscle was found in control group (0.313 mg kg -1 ), the lower MDA value in E1 (0.264 mg kg -1 ) and the lowest MDA value in E2 (0.259 mg kg -1 ).Significant differences (P ≤0.05) between the control and experimental groups were found in oxidative stability of breast muscle from the 1 st day.The breast muscle of E2 group (after the application of 800 mg kg -1 propolis extract in Hubbard JV chickens nutrition during the whole period of fattening) can be considered as the most stable breast muscle.
After 6 months of storage in freezer, results of thigh muscle were very similar as in the breast muscle.We found the higher MDA values in control group (0.339 mg kg -1 ) in compare with experimental groups (0.279 mg kg -1 -group E1 and 0.268 mg kg -1 -group E2).Significant differences in oxidative stability of thigh muscle between the control and experimental groups were found from the 1 st day of storage.Thigh muscle of E2 group (with the highest dose of propolis extract) was considered as the most stabile.
Results of oxidative stability in chicken meat, obtained in this experiment confirm the statements of other researchers (Kennedy et al., 2005;Imik et al., 2010), that oxidative stability of chicken meat decreases by cooling or freezing.Higgins et al. (1998), Jensen et al. (1998), Fellenberg andSpeisky (2006) warned that oxidative yellowing of fat is one of the main reasons causing deterioration of human food and this factor is responsible for unpleasant odour, loss of taste, consistency, appearance, nutritional value, pigment, polyunsaturated fatty acids, fat-soluble vitamins, decreases the meat quality and eventually decrease its storability and safety.Different alternative supplements tested in poultry nutrition (including propolis and propolis extract) contain various antioxidants and prevent oxidation of lipids (Govaris et al., 2004;Kennedy et al., 2005;Šperňáková et al., 2007;Marcinčák et al., 2010;Skřivan et al., 2010) and increase the stability of meat during its storage by cooling or freezing.This statement was confirmed by results in this experiment, too.Sheehy et al. (1993) and Florou-Paneri et al. ( 2005) stated that higher antioxidant concentration in raw and cooked chicken meat resulted in decreasing of lipid oxidation and TBA values in storing and freezing.It was confirmed in our experiment, in evaluation of breast and thigh muscles of Hubbard JV chickens with application of propolis extract in their nutrition.Results of our experiment did not confirm the results of Šperňáková et al. (2007) and Luna et al. (2010), who applied extract of thymol and carvacrol (powdered rosemary) and found the higher stability of thigh muscle compared with breast muscle.In our experiment, we found opposite effect.It related with higher fat content in thigh muscle as in breast muscle.

Conclusions
In the experiment, we tested the influence of propolis extract applied to feed mixtures of Hubbard JV broiler chickens on oxidative stability of the breast and thigh muscles stored at -18 °C for 6 months.During the storage, the highest MDA values were found in control group and the best results (it means the lowest MDA value) were found in E2 group with application of propolis extract at a dose of 800 mg kg -1 .Obtained results indicate that propolis extract, tested as a supplement in Hubbard JV chicken nutrition, had a positive effect (P ≤0.05) on storability and oxidative stability of breast and thigh muscles.

Table 1
Composition of the diets

Table 2
Effect of storage in freeze (-18 °C) on the concentration of malondialdehyde in mg kg -1 in breast and thigh muscle (mean ± SE)