Influence of rearing system and nettle supplementation (Urtica dioica) on the carcass traits and fatty acid composition of Redbro broilers

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1 1/ 10 Influence of rearing system and nettle supplementation (Urtica dioica) on the carcass traits and fatty acid composition of Redbro broilers Einfluss der Haltungsbedingungen und des Zusatzes von Brennnessel (Urtica dioica) zum Futter auf die Schlachtkörpermerkmale und das Fettsäuremuster im Fleisch von Redbro Broilern Mirjana Đukić Stojčić 1*, Lidija Perić 1, Alenka Levart 2 and J. Salobir 2 1 Department of animal Science, University of Novi Sad, Faculty of Agriculture, Serbia 2 Department of animal science, University of Ljubljana, Biotechnical faculty, Slovenia *Correspondence: djukic@polj.uns.ac.rs Manuscript received 4 February 2016, accepted 28 March 2016 Introduction In recent years, broiler meat production is turning more to free-range or organic production systems. This is caused by consumers growing interest in the nutritional importance of human diets. Many consumers assume that the meat of free-range chickens is tastier and healthier than that of birds kept in a poultry house (MOLEE et al., 2012). The investigation of PONTE et al. (2008a) showed that pasture intake in the Redbro genotype had a positive effect on carcass yield in contrary to the results from FANATICO et al. (2005), who reported no differences in carcass yield between birds kept indoor and those kept outdoor. From a nutritional point of view the grass grazed by free-range chickens has a favourable fatty acid composition, which also should be seen in the more favourable lipid composition of such chickens (ŽLENDER et al., 2000). The fatty acid composition of free range meat showed a higher fraction of total n-3 fatty acids compared to meat from indoor chicken (CASTELLINI et al., 2002). According to the report of PONTE et al. (2008b), meat from pasture-raised slower growing genotypes did not differ in nutritional quality (higher level of PUFA and n-3 fatty acids) as opposed to a fast growing genotype. SUN et al. (2012) also reported higher vitamin E and iron content in thighs and breast meat from broilers reared in grasshopper-rich alpine pastures, as well as lower cholesterol and higher omega-3 fatty acid content. Green pastures are a good source of α-linolenic acid and decrease the n6:n3 fatty acid ratio in ruminants (O SULLIVAN et al., 2004). Nettle (Utrica dioica L.) is from the family of Urticaceae, which is a perennial plant of relatively low cost with high availability in different parts of the world. Nettle has a high ratio of nutritious substances (vitamin C, pro-vitamin A, minerals), active compounds such as tannins, formic acid, salicylic acid, thymol and carvacrol and is a readily digestible food (VIEGI et al., 2003; GÜLÇIN et al., 2004). Pigs fed with nettle extract had a reduction of monounsaturated fatty acids and an increase of PUFA in muscle fat (SZEWCZYK et al., 2006). The share of 1% dry nettle in broiler fed had no effects on percent of breast, thigh, gizzard, liver and abdominal fat as opposed to those fed no nettle (SAFAMEHR et al., 2012). NOBAKHT (2011) reported that using different dried nettle powder levels (5 and 2%) in feed for male ROSS 308 broilers had positive effects on the weight of gizzard and liver. Also SOMAIEH et al. (2011) reported that varying levels of nettle in starter and grower feeds had large effects on carcass traits of broilers. However, little information has been published on the effects of fresh nettle in poultry diets. This research investigated the impact of the production system and dietary supplementation of fresh nettle in broiler diets. Fatty acid profile along with carcass traits of meat from free-range broilers and meat from poultry house birds reared extensively were investigated.

2 2/ 10 Material and Methods Birds, housing and experimental design The trial was carried out on the experimental farm of the Department of Animal Science of the Faculty of Agriculture in Novi Sad (19 51Е, 45 20N, 84 m above sea level). During the spring season (April-Jun) 400 Redbro mediumgrowing chickens were reared in two different production systems: extensively in the poultry house or in a traditional free range system. During the first 28 days, all chickens were reared in the poultry house in a deep litter system (11 birds/m 2 ). At the age of 4 weeks chickens were divided into 4 groups based on 4 treatments with 4 subgroups of 25 chickens each. Two groups of chickens were reared ina free range system (3 m 2 /bird) with (group A) or without (group B) added fresh cut nettle. The other two groups were reared extensively in the poultry house (11 birds/m 2 ) with (group C) or without (group D) added fresh cut nettle. The nettle was collected from a nettle planted field, left one day on the floor to wilt and then it was cut into small pieces by a machine for chopping straw. Only edible parts without thick stems were used and directly included into the feed mixture. Chickens were given 40 g of fresh nettle per bird per day from 28 to 42 days and from 42 to 63 days it was increased to 80 g. The free range broilers were provided with a grass range of 2 m 2 /bird with overnight pens in order to protect the birds from predators and weather conditions. The following plants were present in the free range system: Dactylis glomerata, Festuca pratensis Huds, Phleum pratense, Lolium italicum,lolium perenne, Festuca arundinacea, Festuca rubra and Medicago sativa. Pasture areas were equipped with small sheds under which chickens could hide from the sun during the day. The automatic drinking nipples and feeders were located on the pasture under the shelters and in the pens. Birds of all groups were fed ad libitum with three consecutive feeds. A broiler starter diet was used in the period of 1 4 weeks, a grower mixture in the period 5 7 weeks of age and a finisher was used in the period 8 9 weeks (Table 1). Basic environmental parameters as well as the lighting program were in accordance to the technological demands of the used hybrid. Table 1. Feed composition and basic chemical analysis of feed Zusammensetzung und analysierte Hauptnährstoffgehalte der Futterrationen STARTER GROWER FINISHER Maize Wheat bran 7.00 / / Lysine 0.01 / / Metionin Soyabean meal Full fat soya Sunflower meal / 6.00 / Dicalcium phosphate 1.30 / / Monocalcium phosphate / Sodium chloride Sodium bicarbonate Molasses / 1.00 / Premix Chemical composition Dry matter DM % Crude protein CP % Crude fat % Ash % Crude fibre % ME (MJ/kg) Calcium (Ca) % Total phosphorous (P) %

3 3/ 10 Data collection and Analysis At the end of the experiment at 9 weeks of age, 6 males and 6 females were randomly selected from each group, manually slaughtered and processed in the same way. Upon slaughter and primary carcass processing, the processed carcasses were cooled in a cooling chamber for 24 h at 0 4 C. Following the chilling procedure, the carcasses were weighed to obtain the dressing percentage of the broilers. Thereafter, following the method prescribed by the Regulation on Poultry Meat Quality (RAŠETA and DAKIĆ, 1994), the dressed cold carcass of each broiler was dissected into primal cuts (breast, drumstick, thigh, wing, pelvis and back). The separated tissues were weighed, and their respective proportions in the main carcass were recorded. The breasts meat patterns together with skin were homogenised, packed into PE bags, frozen and kept until the analyses at 21 C. The fatty acid composition of breasts muscle samples were analysed using a gas chromatographic (GC) method after the in situ transesterification of lipids. Fatty acid methyl esters (FAME) were prepared according to the procedure of PARK and GOINS (1994). Analysis of FAMEs was performed by gas chromatography using an Agilent 6890 series gas chromatograph (Agilent Technologies, Santa Clara, CA, USA) equipped with an Agilent 7683 Automatic Liquid Sampler, a split injector, a flame ionisation detector (FID) and a fused silica capillary column Omegawax 320 (Supelco, Bellefonte, PA, USA). The chromatograms were evaluated by the Agilent GC Chem Station software. Separated FAMEs were identified and quantified using external FAME standard mixtures (Nu-Check Prep, Elysian, MN, USA). Results are expressed as a percentage of the total fatty acids. Using the results of total fatty acids analysis the atherogenic index (AGI) and the thrombogenic index (TI) were calculated according to the ULBRICHT and SOUTHGATE (1991) investigation. AGI is calculated as follows AGI = (C12:0 + 4 C14:0 + C16:0)/(MUFA + PUFA) and TI = (C14:0 + C16:0 + C18:0)/[(0.5 MUFA) + (0.5 n-6 PUFA) + (3 n-3 PUFA) + (n-3 PUFA/n-6 PUFA)], in which C12:0, C14:0, C16:0, C18:0, MUFA, PUFA, n-6 PUFA, and n-3 PUFA are the contents (% of total fatty acids) of C12:0, C14:0, C16:0, C18:0, MUFA, PUFA, n-6 PUFA, and n-3 PUFA, respectively. All procedures were conducted according to ethical norms proposed by the European Convention for the Protection of Vertebrate Animals Used for Experimental and Other Scientific Purposes, confirmed by Serbian authorities (Službeni glasnik RS-Međunarodni ugovori, 1/2010). Statistical analysis Data were analysed by ANOVA and means were separated by Duncan s post hoc test using StatSoft computer package (STATSOFT, STATISTICA 11, 2012). Significance was determined at P 0.05, P 0.01 and P Results Effect of housing system and dietary supplementation of fresh nettle on carcass traits Table 2 shows body weights (before slaughter, carcass eviscerated and dressed carcasses, ready to grill), percent yield of major primal cuts (breast, drumsticks, thighs), percentage of liver, gizzard and abdominal fat. These results suggest that neither housing system nor supplementation with cut fresh nettle had any significant effect on weights before slaughter, carcass eviscerated weights, dressed carcasses weights (ready to grill), percent yield breast, drumsticks, thighs and abdominal fat. The treatment addition of cut fresh nettle had statistically significant effect on the percent of liver and gizzard. The differences exhibited in terms of the housing system effect on the percent of gizzard were statistically highly significant, in favour of chickens kept on free range.

4 4/ 10 Table 2. Effect of housing system and dietary supplementation of fresh nettle on bodyweight, carcass weight, dressing percentage, proportion of cuts, proportion of edible giblets (liver and gizzard) and abdominal fat (mean ± SD) Einfluss des Haltungssystems und und der Zulage von frischer Brennnessel zum Futter auf das Lebendgewicht, das Schlachtkörpergewicht, die Schlachtausbeute, die Anteile der Teilstücke, die Anteile der essbaren Innereien (Leber, Muskelmagen) und dem Abdominalfett Housing system Body wight before slaughter, (g) Carcass eviscerated weight, (g) Ready to grill, (%) Breast, (%) Drumsticks, (%) Thighs, (%) Liver, (%) Gizzard, (%) Abdominal fat, (%) Free range A 2210 ± ± ± ± ± ± ± a a 3.20 ± ± B 2139 ± ± ± ± ± ± ± b a 2.94 ± ± Poultry house C 2177 ± ± ± ± ± ± ± b b 2.57 ± ± 1.23 D2263 ± ± ± ± ± ± ± b b 2.3 ± ± ANOVA p Housing system *** Treatment ** * Housing system Treatment a-c Means within the same column with different superscript letters are significantly different; *= P 0.05; **= P 0.01; *** =P 0.001, SD = Standard deviation, A free range system with added fresh cut nettle, B free range system without added fresh cut nettle, C poultry house with added fresh cut nettle, D poultry house without added fresh cut nettle. Fatty acid composition of the plants and nettle The fatty acid composition (% fatty acid from all fatty acid) of the plants in the free range and nettle is presented in Table 3. The predominant fatty acids in pasture or nettle were palmitic acid (C16:0), linoleic acid (C18:2n-6) and linolenic acid (C18:3n-3). The nettle contained greater percentages of oleic acid and linoleic acid and lower percentages of linolenic acid than the pasture. Compared to pasture the nettle contained greater percentages of MUFA and n-6 PUFA and lower percentages of n-3 PUFA. Table 3. Main fatty acid composition (% of total fatty acids) of the plants of free range (pasture) and nettle Fettsäurezusammensetzung (% der Gesamtfettsäuren) der Pflanzen im Auslauf und der Brennnessel Plants from free range system Nettle C14: C16: sum C16: C18: sum C18: C18:2 n C18:3 n C20:4 n-6 Nd 1.79 SFA MUFA PUFA n-3 PUFA n-6 PUFA n-6/n-3 PUFA

5 5/ 10 The effect of housing system and nettle on fatty acid composition Table 4 reports the data concerning the fatty acid composition of breast meat. The housing system showed no significant effects on almost all individual and total fatty acids, except stearic (C18:0; P 0.05), arachidic (C20:0; P 0.001), eicosapentaenoic acid, EPA (C20:5 n-3; P 0.01) and docosahexaenoic acid, DHA (C22:6 n-3; P 0.05). Almost all traits were significantly influenced by the addition of fresh cut nettle. There was no significant difference between groups based on the concentration of myristic (C14:0), palmitic (C16:0), palmitoleic acid (C16:1), margaric (C17:0), docosapentaenoic acid (22:5 n-3) and saturated fatty acid (SFA) in breast meat. The concentration on pentadecanoic (C15:0; P 0.001), linoleic (C18:2 n-6; P 0.01), linolenic acid (C18:3 n-3; P 0.001) and arachidonic (20:4 n-6; P 0.05) acid and the proportion of polyunsaturated fatty acid (PUFA; P 0.001), n-3 and n-6 fatty acids ware increased in breast meat of chickens fed with fresh cut nettle (P 0.05). The concentration on myristoleic (C14:1; P 0.01) and oleic acid (C18:1; P 0.01) and the proportion of monounsaturated fatty acids (MUFA; P 0.05) were significantly lower in broilers fed with fresh cut nettle. The increase of linolenic acid in the breast meat of chickens with added nettle caused by rearing on free range (A) was followed by the decrease in MUFA, mainly oleic acid. The other three groups (B, C, D) had no significant differences in the content of MUFA. The proportion of polyunsaturated fatty acid (PUFA) increased in breast meat of chickens with added fresh cut nettle. The ratio of n-6 to n-3 fatty acids was lower in breast meat of the free-range group with added fresh cut nettle (A) than that of the other groups, but a significant statistical difference was found only between this group and group B.

6 6/ 10 Table 4. The effect of housing system and dietary supplementation of fresh nettle on fatty acid composition of breast meat (wt.% of total fatty acids, mean ± SD) Einfluss des Haltungssystems und der Zulage von frischer Brennnessel zum Futter auf das Fettsäuremister im Brustfleisch (in Gew.% der Gesamtfettsäuren) Fatty acid (%) Housing system ANOVA Free range Poultry house Housing system Treatment Housing system Treatment A B C D p C ± ± ± ± C14: ± 0.02 b ± 0.02 b ± 0.02 a a ± ** C15: ± 0.01 a ± 0.01 b ± 0.01 a b ± *** C16: ± ± ± ± C16: ± ± ± ± C ± ± ± ± C18: ± a ± a ± b b ± * C18: ± ± ± ± ** C18:2 n ± 1.25 a 27.8 ± 1.36 ab 28.6 ± 2.01 a b 26.6 ± ** C18:3 n ± a 2.38 ± b 2.54 ± a b 2.33 ± *** C20: ± 0.01 a ± 0.01 a ± 0.01 b b ± *** C20:4 n ± a 1.39 ± b 1.53 ± ab ab 1.48 ± * C20.5 n ± b ± b ± a a ± ** C22:5 n ± ± ± ± C22:6 n ± a ± b ± b c ± * 0.036* SFA 29.6 ± ± ± ± MUFA 35.3 ± 2.15 b 37.1 ± 2.48 a 36.2 ± 2.12 a a 37.8 ± * PUFA 35.1 ± 1.71 a 33.4 ± 2.01 b 34.6 ± 2.45 a b 32.2 ± *** n-3 PUFA 3.36 ± a 3.04 ± b 3.27 ± a b 3.02 ± *** n-6 PUFA 31.7 ± 1.59 a 30.3 ± 1.75 a 31.3 ± 2.14 a b 29.2 ± ** n-6/n-3 PUFA 9.45 ± b 9.98 ± a 9.60 ± b b 9.67 ± * AGI ± ± ± ± TI ± b ± a ± b a ± * a-c Means within the same column with different superscript letters are significantly different, *= P 0.05; **= P 0.01; *** =P 0.001, SD = Standard deviation, A free range system with added fresh cut nettle, B free range system without added fresh cut nettle, C poultry house with added fresh cut nettle, D poultry house without added fresh cut nettle. ULBRICHT and SOUTHGATE (1991) took on a new approach in their study and used two indices: the atherogenic (AGI) and thrombogenic (TI) index, to highlight the different effect of the varying fatty acids. In this study no significant differences were found between the 4 groups concerning atherogenic index. The thrombogenic index was significantly lower in groups with added nettle.

7 7/ 10 Discussion The main purpose of the current study was to examine the effect of two alternative housing systems and dietary supplementation of fresh nettle in broiler diets on carcass traits and fatty acid composition in broiler breast meat. The results of the present study are in accordance with the investigations of FANATICO et al. (2005), BOGOSAVLJEVIĆ- BOŠKOVIĆ et al. (2006), POLTOWICZ and DOKTOR (2011), who also found no significant effect of housing system on dressing percentage. According to FANATICO et al. (2005) alternative poultry systems had no effect on growth performance and yield, only the genotype had. BOGOSAVLJEVIC-BOŠKOVIC et al. (2011) showed a significant effect of housing system on the proportion of breast, drumsticks and thighs. Free-range broilers had a lower proportion of drumsticks and thighs and higher breast proportion than the indoor bred broilers, which was not confirmed in the present research. Also in contrast to the present study, an investigation by PONTE et al. (2008a) showed that pasture intake in Redbro Cou Nu Redbro M genotypes had a positive effect on carcass yield and SOMAIEH et al. (2011) showed that the use of different levels of nettle in starter and grower feeds had significant effects on carcass traits of broilers. The increase in gizzard weight is considered to be caused by the increased intake of green pasture. There was a slight increase in weight of the liver found just in the group A. Furthermore, NOBAKHT (2011) reported that using different dried nettle powder levels (5 and 2%) and KESHAVARZ et al. (2014) using 5 g/kg nettle powder (NP) in feed for broilers had positive effects on carcass traits and increased weight of gizzard and liver, as confirmed in the present research. As opposed to this, SAFAMEHR et al. (2012) found in their studies that 1% dry nettle in broiler feed did not affect the size of gizzard and liver. In the present study the housing system showed less effects on fatty acid composition on breast meat than supplementation of nettle. The result of this experiment was in agreement with those from PONTE et al. (2008b), which suggest that free range medium growing genotypes may not produce meat with higher nutritional quality because free access to pasture seems to reduce the concentrations of linoleic acid (18:2 n-6) and linolenic (18:3n-3) acid. The linoleic and linolenic acid values obtained in this study were higher than those of PONTE et al. (2008b) and lower than those in the investigation of CASTELLINI et al. (2002) and SIRRI et al. (2011). Supplementation of fresh cut nettle changed the fatty acid profile of breast meat in the way that the share of linoleic and linolenic acid increased in both observed housing systems. Since the birds were eating the same basic diet, the increase in n-3 fatty acids could be attributed to the addition of nettle. The same situation occurred in the poultry house as well as on the pasture confirming the highly significant influence of nettle as a treatment. On the other hand, the influence of the pasture on n-3 fatty acids content in meat was not established despite the fact that plants on the pasture had higher content of n-3 fatty acids compared to nettle. This implies that the consumption of the grass from the pasture was low. While observing the broilers on the pasture, it was found that only a smaller part of it was used, a specific area around feeders, drinkers and below sheds. PONTE et al. (2008b) state that pasture is a poor source of EPA, but pasture intake could increase the EPA (LIU and ZHOU, 2013; CASTELLINI et al., 2002; SUN et al., 2012). The authors LÓPEZ-FERRER et al. (2001), MOURAO et al. (2008) and PONTE et al. (2008b) reported that linolenic acid was more effectively desaturated and elongated, which lead to higher levels of EPA and the broilers were able to use linolenic acid as a precursor for the synthesis of the EPA. This claim was not confirmed in the present study. Authors MOLEE et al. (2012) also reported no significant difference in the proportion of SFA in breast meat between free-range and conventional Thai indigenous chicken. Neither housing system, nor the treatment had any influence on the SFA of breast meat. This observation is in contrast to previous results from HUSAK et al. (2008), who found that free-range broilers had more SFA compared to indoor birds. In our investigation, the proportion of MUFA was decreased, while the proportion of PUFA was increased in breast meat of chickens with added fresh cut nettle. The results are in accordance with findings of SZEWCZYK et al. (2006), who state that the use of nettle extract in pig nutrition reduced MUFA and increased PUFA in muscle fat. In the present study, the addition of fresh cut nettle increased the content of PUFA in breast meat and lead to decreased thrombogenic risk fron this foodstuff. The above results suggest that dietary supplementation of fresh nettle to a broiler diet had a positive effect on fatty acid composition in broiler breast meat.

8 8/ 10 Conclusion It can be concluded that neither pasture nor dietary supplementation of fresh nettle can improve carcass traits in Redbro chickens. Pasture intake and nettle had significant effect on percent of gizzard, while the addition of nettle had significant effect on liver percentage. The fresh nettle added to the diet could beneficially affect the fatty acid profile and improve the quality of chicken breast meat more than pasture intake. Moreover, nettle intake increased linoleic and linolenic acid, reduced MUFA and increased PUFA in chicken breast muscle. Acknowledgements Supported by the Ministry of science of the Republic Serbia (Project No. TR 31033). Summary The aim of the present study was to evaluate the effect of two alternative housing systems and dietary supplementation of fresh nettle in broiler diets on the carcass traits and fatty acid profile of Redbro chickens. A total of 400 chickens were reared in a poultry house. When chickens were 4 weeks old they were divided into 4 groups with 4 subgroups (25 chickens) each. Two groups of chickens were reared in free range system with (group A) or without (group B) added fresh cut nettle. The other two groups were reared extensively in a poultry house with (group C) or without (group D) added fresh cut nettle. At the end of the experiment, 48 birds (6 males and 6 females from each group) were slaughtered for determination of carcass traits and fatty acid composition of breasts with skin. The dietary supplementation of fresh nettle and poultry system had no effects on carcass weight, dressing percentage, abdominal fat and percent of parts of broiler chicken carcass. Nettle and pasture intake had significant effect on percent of liver (P 0.01) and gizzard (P 0.05). In the group A reared outdoor with added fresh nettle the proportion of MUFA (P 0.01) was significantly lower compared to other groups and the proportion of PUFA (P 0.001) was significantly higher in groups A and C. Moreover, supplementation of fresh nettle increased linoleic (C18:2 n-6, P 0.01) and linolenic acid (C18:3n-3, P 0.001) and reduced the ratio n-6/n-3 (P 0.05) in breast muscle. It can be concluded that dietary supplementation of fresh nettle can improve the quality of chicken breast meat better than pasture intake. Key words Broiler, housing system, nutrition, nettle, carcass quality, fatty acids profile Zusammenfassung Einfluss der Haltungsbedingungen und des Zusatzes von Brennnessel (Urtica dioica) zum Futter auf die Schlachtkörpermerkmale und das Fettsäuremuster im Fleisch von Redbro Broilern Ziel der vorliegenden Studie war die Untersuchung der Wirkung von zwei alternativen Haltungssystemen und der Zulage von frischer Brennnessel zum Futter auf die Schlachtkörpermerkmale und das Fettsäuremuster im Brustfleisch von Red Bro Hühner. Hierzu wurden 400 Küken aufgezogen und im Alter von vier Wochen auf vier Behandlungsgruppen mit je vier Wiederholungen a 25 Küken verteilt. Zwei Gruppen wurden in einem Freilandhaltungssystem gehalten und mit Futter mit (Gruppe A) oder ohne (Gruppe B) Zugabe frischer Brennnessel gefüttert. Die beiden anderen Gruppen wurden in einem geschlossenen Stall gehalten und mit Futter mit (Gruppe C) oder ohne (Gruppe D) Zugabe von frischer Brennnessel gefüttert. Am Ende des Versuchs wurden 48 Tiere (6 Hähne und 6 Hennen je Gruppe) geschlachtet und die Schlachtkörperzusammensetzung sowie das Fettsäuremuster des Brustfleischs bestimmt. Die Zugabe von frischer Brennnessel zum Futter und das Haltungssystem hatten keine Auswirkungen auf das Schlachtkörpergewicht, die Schlachtausbeute und die Anteile von Abdominalfett und Teilstücken. Die Zugabe von Brennnessel und die Freilandhaltung haben zu einer signifikanten Erhöhung der Leber- (P 0,01) und Muskelmagenanteile geführt (P 0,05). Bei Freilandhaltung und Zugabe von frischer Brennnessel (Gruppe A) war der Anteil an MUFA im Vergleich zu den anderen Behandlungen signifikant (P 0,01) geringer. In den Behandlungen A und C wurden signifikant höhere PUFA-Gehalte (P 0,001) ermittelt. Die Zugabe frischer Brennnessel erhöhte den Gehalt an Linolsäure (C18: 2 n-6 (P 0,01)) sowie Linolensäure (C18: 3 n-3 (P 0,001)) und verminderte das n-6/n-3-

9 9/ 10 Verhältnis (P 0,05) im Brustmuskel. Daraus wurde der Schluss gezogen, dass die Brustfleischqualität eher durch die Zugabe von frischer Brennnessel zum Futter als durch die Freilandhaltung verbessert werden kann. Stichworte Broiler, Haltungssystem, Fütterung, Brennnessel, Schlachtkörperqualität, Fettsäuremuster References BOGOSAVLJEVIĆ-BOŠKOVIĆ, S., V. KURCUBIC, M.D. PETROVIC, V. RADOVIC, 2006: The effect of sex and rearing system on carcass composition and cut yields of broiler chickens. Czech J. Anim. Sci. 51, BOGOSAVLJEVIC-BOŠKOVIC, S., Z. PAVLOVSKI, M.D. PETROVIC, V. DOSKOVIC, S. RAKONJAC, 2011: The effect of rearing system and length of fattening period on selected parameters of broiler carcass quality. Arch. Geflügelk. 75, CASTELLINI, C., C. MUGNAI, A. DAL BOSCO, 2002: Effect of organic production system on broiler carcass and meat quality. Meat Sci. 60, FANATICO, A.C., P.B. PILLAI, L.C. CAVITT, C.M. OWENS, J.L. EMMERT, 2005: Evaluation of slower-growing broiler genotypes grown with and without outdoor access: growth performance and carcass yield. Poult. Sci. 84, GÜLÇIN, I, O.I. KÜFREVIOGLU, M. OKTAY, M.E. BÜYÜKOKUROGLU, 2004: Antioxidant, antimicrobial, antiulcer and analgesic activities of nettle (Urtica dioica L.). J. Ethnopharacology 90, HUSAK, R.L., J.G. SEBRANEK, K. BREGENDAL, 2008: A survey of commercially available broilers marketed as organic, free-range, and conventional broilers for cooked meat yields, meat composition, and relative value. Poult. Sci. 87, KESHAVARZ, M., REZAEIPOUR, V., S. ASADZADEH, 2014: Growth Performance, Blood Metabolites, Antioxidant Stability and Carcass Characteristics of Broiler Chickens Fed Diets Containing Nettle (Urtica dioica. L) Powder or Essential Oil. Int. J. Adv. Biol. Biom. Res. 2, LIU, H.W., D.W. ZHOU, 2013: Influence of pasture intake on meat quality, lipid oxidation, and fatty acid composition of geese. J. Anim. Sci. 91, LÓPEZ-FERRER, S., M.D. BAUCELLS, A.C. BARROETA, M.A. GRASHORN, 2001: n-3 enrichment of chicken meat. 1. Use of very long-chain fatty acids in chicken diets and their influence on meat quality: Fish oil. Poult. Sci. 80, MOLEE, W., P. PUTTARAKSA, S. KHEMPAKA, 2012: Effect of Rearing Systems on Fatty Acid Composition and Cholesterol Content of Thai Indigenous Chicken Meat. World Acad. Sci. Eng. Technol. 69, MOURAO, J.L., V.M. PINHEIRO, J.A.M. PRATES, R.J.B. BESSA, L.M.A. FERREIRA, C.M.G.A. FONTES, P.I.P. PONTE, 2008: Effect of dietary dehydrated pasture and citrus pulp on the performance and meat quality of broiler chickens. Poult. Sci. 87, NOBAKHT, A, 2011: Effects of different levels of chicory (Cichorium intybus L.), zizaphora (Zizaphora tenuior L.), nettle (Urtica dioica L.) and savoury (Satureja hortensis L.) medicinal plants on carcass characteristics of male broilers. J. Med. Plants. Res. 5, O SULLIVAN, A., K. O SULLIVAN, K. GAVIN, A.P. MOLONEY, D.J. TROY, J.P. RERRY, 2004: Influence of concentrate composition and forage type on retail packaged beef quality. J. Anim. Sci. 82, PARK, P.W., R.E. GOINS, 1994: In situ preparation of fatty acid methyl esters for analysis of fatty acid composition in foods. J. Food Sci. 59, POLTOWICZ, K., J. DOKTOR, 2011: Effect of free-range raising on performance, carcass attributes and meat quality of broiler chickens. Anim. Sci. Pap. Rep. 29,

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