Fatty acid composition and meat quality traits of organically reared Korean native black pigs

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1 Available online at Livestock Science 120 (2009) Fatty acid composition and meat quality traits of organically reared Korean native black pigs D.H. Kim a, P.N. Seong a, S.H. Cho a, J.H. Kim a, J.M. Lee a,c.jo b, D.G. Lim a, a Quality Control and Utilization of Animal Products Division, National Institute of Animal Science R. D. A., 564 Omockchun-Dong, Suwon , Republic of Korea b Department of Animal Science and Biotechnology, Chungnam National University, Daejeon, , Republic of Korea Received 14 September 2007; received in revised form 7 April 2008; accepted 2 May 2008 Abstract Current study investigated the effect of feeding systems (conventional vs organic rearing) on carcass characteristics, meat quality and fatty acid composition of Musculus longissimus dorsi of Korean native black barrows (KNP). Thirty pigs were reared under a conventional feeding system at indoor area of 1 m 2 per head, while another thirty pigs were fed an indoor area with organic saw dusts of 1 m 2 and an outdoor area with free ranges of 1 m 2 for each pig for organic system. Diet for the organic rearing was also provided according to the guideline for organic pork products. Warner Bratzler shear force was lower and water holding capacity was higher for pork produced under the organic guidelines. However, pork produced by an organic system did not affect sensory traits compared to pork produced by a conventional one. In addition, longissimus muscle from organically reared pigs had significantly (P b 0.05) higher myoglobin content and consequently higher CIE a -values compared with those for the conventionally-reared pigs (P b 0.05). The organic pork resulted in significantly (P b 0.05) higher polyunsaturated fatty acid (PUFA) and unsaturated fatty acid contents, as well as a higher n-3 PUFA than the conventional one (Pb0.05) Elsevier B.V. All rights reserved. Keywords: Pigs; Rearing system; Organic; Fatty acid composition; Meat quality 1. Introduction Current pig production system, predominantly an intensive indoor system, has provided pork meat at a reasonable price and quality for consumer. However, public concerns on animal welfare, environmental pollution and hygienic safety of meat products have been grown (Dransfield et al., 2005). In recent years, Corresponding author. Tel.: ; fax: address: elpollo9@snu.ac.kr (D.G. Lim). organic animal products have received a significant attention in most developed countries, as the environmentally friendly products are considered to be a healthier and safer than those produced by intensive production system (Sundrum, 2001; Hansen et al., 2006). In this respect, the public interest and demand for the organic pork products also has been increased in Korean market, although there is no statistical figure available. Korean native black pig (KNP) comprises approximately 0.74% of a total of 9.19 million pigs in Korea (Ministry of Agriculture and Forest, Korea, 2003) /$ - see front matter 2008 Elsevier B.V. All rights reserved. doi: /j.livsci

2 D.H. Kim et al. / Livestock Science 120 (2009) However, the consumer highly demands for the meat from KNP because it has a particular high redness and intramuscular fat content compared with commercial landrace (Jin et al., 2001). The KNPs had been widely raised on farms in Korea until 1970s, but there was a significant recession in their numbers thereafter due to the introduction of improved breeds for both growth andleanmeatproduction(park et al., 2007). KNP showed a slower growth rate and lighter carcass weight (Hwang et al., 2004), but has been known to abilities with strong disease tolerance and a coarse feeding in organic rearing system (RDA, 2001). The fact might imply that KNP could be evolved more suitable for the traditional feeding system including organic pig farming system. In this respect, there has been great interest in Korean pig industry for organic pork products using the KNPs. According to the basic standards of the International Federation of Organic Agriculture Movements (IFOAM, 1996), an organic livestock farming is primarily based on home-grown feedstuffs with the objective of establishing an almost complete on-farm nutrient cycle. Major differences between organic and conventional nutrition are the ban on synthetic amino acid and products of genetically modified organism (GMO) origin. Antibiotics and growth promoters are prohibited as well. In present legislation, an organic feed has to consist of a minimum of 80% of organic feed ingredients, which limits the choice of ingredients. Due to particular agricultural practices, organic feeds may differ in composition and the content of minor constituents (Millet et al., 2005). The different diets used in organic and conventional production systems may influence nutrient and fatty acid composition in pork (Bosi, 1999). Differences in space allowance, stocking density, and climatic conditions might also influence the composition and quality of pigs reared out-of-doors. A number of studies reported that organic pork was tougher and contained a higher content of unsaturated fatty acid (Danielsen et al., 2000; Nilzen et al., 2001; Hansen et al., 2006). On the other hand, organically reared pigs had a higher percentage of lean meat and wholesale carcass value than pork from a confinement system (Hansen et al., 2006; Sundrum et al., 2000). Recently, Jin et al. (2001) reported the characteristics of growth performance and meat quality of KNP under a commercialized insensitive feeding system in comparison with Landrace pure-bred. In this study, meat quality of KNP was more favourable for consumer's demand, while growth performance was inferior to the Landrace (Jin et al., 2001). The objective of the present study was to investigate the effect of free-range outdoor and conventional confined-indoor feeding systems on growth performance, meat quality and fatty acid compositions. 2. Materials and methods 2.1. Animal and experimental design Sixty barrows (KNPs) were sampled from a herd for breeding program of the NIAS (National Institute of Animal Science), and randomly divided into two equal groups; thirty pigs were reared in a conventional stable and another group were grown in a special stable, according to the National regulation on Korean Organic Farming Standard (Ministry of Agriculture and Forestry, 2003). Under the current experiment, each pig for conventional rearing system had an indoor area of 1m 2, while each pig for the organic rearing system had an indoor area with organic saw dusts of 1 m 2 and an outdoor area with free ranges of 1 m 2. The surface in the conventional pens consisted of slats. The conventional stable had climate control, whereas the organic stable only had natural ventilation. Organic saw dust was replaced weekly. Self-feeders and nipples were provided in each pen. Organic pigs were fed restrictedly for 7 months in accordance with the Korean Organic Farming Standard, while conventional pigs were fed for 7 months in a conventional manner. Ingredient composition of the experimental diets for conventional and organic KNPs is presented in Table 1. None of the feeds contained growthpromoter and antibiotics for organic feeding. Diets and water for both conventionally and organically reared Korean black pigs were given ad libitum. Calculated nutrient composition and fatty acid composition of the experimental diets for KNPs are presented in Table 2. Pigs (approximately 95 kg live weight) were slaughtered at a commercial slaughter house. Pigs were transported to the abattoir the day before slaughter and lairaged overnight with free access to water. Animals were conventionally slaughtered after an electrical stunning (Park Table 1 Ingredient composition (%) of the experimental diets for conventionally and organically reared Korean black pigs a Ingredient diets Organic diets Corn (%) (Organic) Soybean meal (%) (Organic) Fishmeal (%) 3.0 Wheat bran (%) 3.0 Molasses (%) 1.5 Tallow (%) 2.6 Calcium phosphate (%) 0.85 Limestone (%) NaCl (%) Mineral and vitamin premix (%) L-lysine (%) Choline chloride 0.07 DL-methionine (%) 0.04 a diets during the feeding period between 20 and 95 kg.

3 98 D.H. Kim et al. / Livestock Science 120 (2009) Table 2 Calculated nutrient and fatty acid composition of the experimental diets for conventionally and organically reared Korean black pigs diets Organic diets Nutrients Moisture (%) Crude protein (%) Crude fat (%) Ash (%) Crude fiber (%) Ca (%) P (%) Lysine (%) Methionline (%) Threonine (%) Tryptophane (%) Calorie (cal/g) Fatty acid composition SFA (%) USFA (%) MUFA (%) PUFA (%) PUFA n-3 (%) PUFA n-6 (%) PUFAn-6/PUFAn-3 (%) MUFA/SFA (%) PUFA/SFA (%) The symbols used mean as followed: SFA, USFA, MUFA and PUFA refer to Saturated, Unsaturated, Monounsaturated and Polyunsaturated fatty acid, respectively. et al., 2007). Musculus longissimus dorsi were taken from each left side and immediately transported to NIAS for analyses Measurements Carcass traits and proximate composition After the carcasses were chilled overnight, carcass weight and back fat thickness were measured by pork grading experts. Moisture content, crude protein, crude fat and ash of M. longissimus dorsi were determined by using methods of the AOAC, 1996) procedure Meat quality measurements Muscle ph was measured using portable needle-tipped combination electrode (NWK binar ph-k21 CE, Germany) in the center of the M. longissimus dorsi. Meat color of samples was measured using a Minolta Chroma Meter CR-300 (Osaka, Japan) set for L (lightness), a (redness), and b (yellowness) values after 30 min blooming at room temperature. It was standardized with a white tile (D65 Y = 93.0, x = , y = ). The myoglobin content was calculated from the reflectance curve according to Krzywicki (1979) using a 40 mm phosphate extraction buffer (ph 6.8). Reflectance values at wavelengths not given by the instrument (473, 525 and 572 nm) were calculated using linear interpolation. Cooking loss and textural analysis was performed. The samples were put in a polyethylene bag. The packages were heated in a water bath at 75 C for 30 min and cooled at room temperature for 30 min. Cooking loss values were calculated based on the weight loss of meat before and after cooking. Warner Bratzler (WB) shear force was measured on cooked samples using an Instron Universal Testing Machine (Model 4465, Instron Corporation, MA, USA) at a crosshead speed of 100 mm/min according to the method described by Wheeler et al. (2000). Textural analysis (hardness, springness, cohesiveness, gumminess and chewiness) was evaluated on cores ( cm) obtained from the mid-portions of the cooked samples by cutting them perpendicularly to the fibre direction, using an Instron Universal Testing Machine (Model 4465, Instron Corporation, MA, USA) according to the method described by Malcolm (1978). With the following operating parameter: load cell, 50 kg, crosshead speed, 100 mm/min, sample height 2.54 cm, puncture diameter mm (0.5 in.). Water-holding capacity (WHC) was determined according to a filter paper method using the procedure of Honikel and Hamm (1994). Briefly, 0.5 g of muscle tissue was placed on glass and filter paper was pressed against the meat sample at kg/cm 2 for 2 min. It was calculated by using a planimeter. Sensory profiling by a trained sensory panel (8 assessors) was performed. The panelists were asked to score the samples for tenderness, juiciness and aroma by a six-point assessment scheme Fatty acid composition Total lipids of samples were extracted by using chloroformmethanol (2:1, v/v) according to the procedure of Folch et al. (1957). An aliquot of total lipid extract was methylated as described by Morrison and Smith (1964). Then, the fatty acid methyl esters were analyzed by a gas chromatography (Varian 3,600, USA) coupled with a fused silica capillary column, omegawax 320 (30 m 0.32 mm ID, 0.25 μm film thickness). Oven temperature was at 200 C and carrier gas velocity was 25 cm/s. The injection port was at 250 C and the detector was maintained at 300 C. Results were expressed as percentages of the total fatty acid detected based on the total peak area Statistical analysis The Statistical Analysis System (1997) was used to determine means, standard errors and analysis of variance. T- test was used to compare differences between the pork from conventionally and organically reared pigs. An alpha level P b 0.05 was used to determine significance. 3. Results and discussion 3.1. Carcass traits and proximate composition Comparison of the slaughter traits and proximate composition in conventionally- and organically reared KNP is shown in Table 3. Pigs for conventional and

4 D.H. Kim et al. / Livestock Science 120 (2009) Table 3 Comparison of the slaughter traits and proximate composition of conventionally and organically reared Korean black pigs Items organic system were slaughtered at 7 months. The feeding periods were determined based on these are practically performed under Korean feeding systems. The current result showed no noticeable differences in live weight, carcass weight, average daily gain and back fat thickness between conventional and organic feeding (Table 3). For crude fat, organic pigs had a slightly higher than conventional pigs, but it was not statistically different (P = 0.12). It is assumed that differences in feeding levels and fat content of the diets may affect carcass response to rearing systems. Only crude ash was significantly (P b 0.05) higher in the conventional than in the organic one. This is not in agreement with Olsson et al. (2003), who reported that the crude protein and ash content was significantly higher in meat of the organically produced pigs due to a higher iron content resulting from higher pigment content. This opposite result might be due to different feeding diets and rearing condition between the two systems in this experiment Meat quality traits Organic Mean SE Mean SE Slaughter traits Age at slaughter (day) Live weight (kg) Carcass weight (kg) Average daily gain (g/day) a Backfat thickness (mm) Proximate composition Moisture (%) Crude fat (%) Crude protein (%) Crude ash (%) 1.06 A B 0.02 A-B Values with different superscripts in the same row differ significantly (Pb0.05). a Mean values of the feeding period between 20 and 95 kg. As shown in Table 4, meat from organic pigs exhibited a lower shear force and a greater WHC than meat from conventional pigs (Pb0.05). Olsson et al. (2003) reported that the WHC of fresh meat from the organically raised pigs was less than that of conventional meat. Other studies (Sather et al., 1997; Nilzen et al., 2001; Heyer et al., 2006) indicated that the production system did not affect ultimate ph and the decreased WHC was explained by the slightly changed muscle traits of the exercised outdoor animals. Many studies showed higher shear force values in organically produced meats than in conventional produced ones (Van der Wal et al., 1993; Enfält et al., 1997; Sather et al., 1997; Olsson et al., 2003), whereas Nilzen et al. (2001) found no such differences. Several explanations for the higher shear force values in organically produced meat than in conventional produced meat was reported by Olsson et al. (2003). Firstly, the lower intramuscular fat of the organic meat could result in higher shear force values. Secondly, possible slower growth rate decreased muscle proteolysis and then led to an increased shear force in organic production. Thirdly, differences in collagen content might have occurred between the two systems. Any combination of these factors may play a role in the increased shear force found in organic pork (Olsson et al., 2003). However, in our study, the organically reared pigs had lower shear force values than the conventionally-reared ones. This opposite result might be due to different feeding diets and rearing condition between the two systems. Heyer et al. (2006) observed that WB shear force tended to be lower for pigs in the outdoor systems than for pigs in the indoor systems. Meat quality characteristics between conventional and organic pigs did not differ with regard to ph and cooking loss (Table 4). For textural and sensory characteristics, sensory evaluation between the two groups did not affect carcass traits in this experiment. Previous studies have shown Table 4 Comparison of meat characteristics and myoglobin contents of M. longissimus muscle between conventionally and organically reared Korean black pigs Items Organic Mean SE Mean SE ph Cooking loss (%) Shear force (N) 3.89 A B 0.11 WHC (%) B A 0.57 Juiciness Tenderness Aroma Hardness (kg) Springiness A B 0.43 Cohesiveness 0.69 A B 0.04 Gumminess 1.81 B A 0.10 Chewiness (kg) A B 2.35 CIE L A B 1.15 a 6.81 B A 0.52 b 2.93 B A 0.61 Myoglobin content (mg/g) 0.38 B A 0.06 A B Values with different superscripts in the same row differ significantly (Pb0.05).

5 100 D.H. Kim et al. / Livestock Science 120 (2009) that conventional pork is often more tender than pork from organic pork production systems due to lower daily gain in organic production (Danielsen et al., 2000), which is known to decrease the proteolytic potential of the muscle at the time of slaughter (Therkildsen et al., 2002). Josäll et al. (2002) found that loins from the organically raised animals were less juicy and production system did not affect off-odour, acidulous taste, offtaste or tenderness. And they also reported that a consumer preference test showed no significant difference between the organically and conventionally produced meats. The meat of the organically reared pigs showed significantly (P b 0.05) higher CIE a (red) and b (yellow) values than that of the conventionally-reared pigs, with similar lightness. This result is consistent with the previous research that the meat of the organically reared pigs showed a higher redness and yellowness (Millet et al., 2004; Heyer et al., 2006). The darker color of organically reared animals could probably be due to an enlarged spontaneous activity, leading to an increased mean fiber cross-sectional area (Petersen et al., 1998). This might due to differences in fibre type proportion, with higher percent of oxidative type I and oxidativeglycolytic type IIA fibres in organically exercised pigs. This was confirmed by significantly higher myoglobin content for the organic pigs (Table 4) and was likely related to a larger playing ground for the organic production system. Previous studies have shown that organic feeding did not affect carcass quality traits (Fisher and Linder, 1998; Sundrum et al., 2000; Millet et al., 2004). In the present experiment, some meat quality characteristics did affect between conventional and organic ones but others did. However, pork produced by an organic system did not affect sensory traits compared to pork produced by a conventional one. Not only organic feeding is involved in meat quality differences, but also the overall organic rearing system, with access to an outdoor area. Further investigations should be studied to clarify the relationship between organic feeding and meat quality Fatty acid composition The fatty acid composition between organically and conventionally reared KNPs is shown in Table 5. We found higher levels of C18:2n6, C20:3n6 and C22:4n6 in pigs produced organically than those in pigs produced conventionally (P b 0.05). In contrast, organic KNP had lower C14:0, C16:0, C16:1n7, C18:1n9, C20:1n9 and C20:4n6 than conventional ones (Pb0.05). This is in agreement with the observation by Hansen et al. (2006) Table 5 Comparison of fatty acid composition (%) of M. longissimus muscle between conventional and organic pork from Korean black pigs Items Organic Mean SE Mean SE C14:0 (myristic) 1.69 A B 0.03 C16:0 (palmitic) A B 0.19 C16:1n7 (palmitoleic) 3.06 A B 0.11 C18:0 (stearic) C18:1n9 (oleic) A B 0.39 C18:2n6 (linoleic) B A 0.52 C18:3n6 (gamma-linolenic) ND C18:3n3 (α-linolenic) C20:1n9 (eicosenoic) 0.35 A B 0.01 C20:2n6 (eicosadienoic) C20:3n6 (eicosatrienoic) A 0.04 C20:4n6 (arachidonic) 0.38 A B 0.01 C22:4n6 (satetraenoic) 0.01 B A 0.02 SFA A B 0.24 USFA B A 0.24 MUFA A B 0.48 PUFA B A 0.59 PUFA n B A 0.07 PUFA n B A 0.56 PUFAn-6/PUFAn A B 0.14 MUFA/SFA 1.30 A B 0.01 PUFA/SFA 0.39 B A 0.02 A B Values with different superscripts in the same row differ significantly (Pb0.05). The symbols used mean as followed: SFA, USFA, MUFA and PUFA refer to Saturated, Unsaturated, Monounsaturated and Polyunsaturated fatty acid, respectively. who found that feeding with organic diets had higher C18:2 and lower C16:0, C16:1 and C18:1 than feeding with non-organic ones in pig muscles. For organic ones, the proportion of saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) was significantly lower, while that of unsaturated fatty acid (USFA) and polyunsaturated fatty acid (PUFA) was significantly higher (Pb0.05). It is known that fatty acid composition of the porcine intramuscular fat affected by feed composition as reviewed by Bosi (1999) and Wood and Enser (1997). Organic pigs had a higher proportion of n-3 and n-6 PUFA than conventional ones (P b 0.05). While the proportion of PUFA/SFA was significantly higher, the proportion of PUFA n-6/n-3 ratio and MUFA/SFA was significantly lower (P b 0.05). These results are consisted with those of the previous research that organic pigs had a higher content of PUFA and a lower content of SFA and MUFA (Hansen et al., 2006). Similarly, there were higher levels of C18:2n6 and PUFA n-6 in pigs fed organically than in pigs fed conventionally (Högberg et al., 2003). The difference in

6 D.H. Kim et al. / Livestock Science 120 (2009) fatty acid composition between conventional and organic KNP is most likely a consequence of the different feed. This suggestion indicated the previous research that the fatty acid composition of the intra muscular fat is affected by several factors, of which diet in general seems to be one of the most important (Nürnberg et al., 1998). Similarly, the higher content of PUFA in organically produced pigs may not only be a result of the different feed but also partially caused by the higher lean meat percentage (Hansen et al., 2006). Högberg et al. (2003) observed that fatty acid composition vary substantially between the organic and conventional feed. The conventional feed had a higher SFA, MUFA and PUFA. These differences corresponded with higher levels of n-6 and n-3 PUFA in the neutral fraction of intramuscular fat and higher levels of n-3 PUFA in the polar lipids of the conventional pigs when compared with the organic ones. The amount of intramuscular fat in organic pork has been reported to be higher (Sundrum et al., 2000), and the fatty acid composition to be more unsaturated compared with meat from traditionally reared pigs (Hansen et al., 2000). Because organic pigs had a higher proportion of n-3 and n-6 PUFA than conventional ones, lipid oxidation might be occurred in organic meat. This may result in inferior meat quality due to enhanced lipid oxidation and presence of soft fat (Nilzen et al., 2001). Therefore, inclusion of vitamin E should be recommended. Consequently, introduction of organic pig production system calls for establishment of quality assurance programs that ensure production of high quality pork, as demanded by the organic consumer segment. It was concluded that the organic rearing resulted in a higher PUFA and USFA level as well as a higher PUFA n-3, n-6 and PUFA/SFA in the muscle of KNPs. 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