Meat quality and fatty acid composition of chios male lambs fed under traditional and intensive conditions

R E G U L A R A R T I C L E Önenç, et al.: Meat quality of chios lambs Emir. J. Food Agric ● Vol 27 ● Issue 8 ● 2015 637 Non-breeding male Chios lambs commonly raised in Ege Region reach slaughter weight in early ages under intensive feeding conditions (Economides et al., 1990; Altınel et al., 1998, Zervas et al., 1999). However for healthier meat production with sensory attributes based on the changing consumer demands, producers prefer traditional feeding methods in animal production (Oliván et al., 2009). The objectives of this study was to compare the traditional and intensive feeding conditions in terms of the meat quality of Chios lambs for the consumer. MATERIALS AND METHODS The study was conducted using seventeen pairs of male twins at 3 months of age which were not kept for breeding and had been raised in a commercial Chios sheep farm in Ege region. All the lambs had the same male parent. A total of 34 animals were randomly distributed into traditional (T) and intensive (I) groups at equal numbers. Initial body weights means were 31.80±1.44 kg and 34.72±1.21 kg respectively for traditional and intensive group, Traditional group was fed two times a day (morning and evening) with local style prepared rations and allowed to graze for 8 hours every day under olive trees. Intensive group was fed with 255 dry alfalfa per animal and ad libitum commercial mixed feed on a daily basis. All the animals consumed ad libitum water. The nutrient requirements of the lambs in the intensive group were met by considering a 15% higher amount of daily dry matter intake reported by the NRC, (1985). The component contents of mixed feeds used in the experiment is given in Table 1 and the nutrient composition and energy values of the rations are given in Table 2. Proximate analysis of the feeds were carried out in accordance with standard methods described by AOAC, (2011). At the end of the trial, lambs were slaughtered at 5 months of age. Final body weights means were 46.85±1.70 kg and 49.99±1.75 kg for traditional and intensive group, respectively. Prior to slaughtering, the lambs were subjected to a 12 h fasting period. The animals were transported by light duty vehicles from the farm to the abattoir. After 1 h transport and 2 h lairage time, they were slaughtered., After slaughter the carcasses were kept at +4°C for 24h. Meat samples were taken from M. Longissimus dorsi (MLD) muscle between the 12th and 13th ribs for chemical composition, physicochemical characteristics, texture profile analysis and fatty acid composition analyses. They were packaged in vacuum bags, subjected to a vacuum process and stored at -18oC until the analysis. Analyses The pH of the carcass was measured directly on the MLD between the 12th and 13th ribs at 24 hours post mortem using a pH meter (Testo205). L * (lightness), a * (redness) and b * (yellowness) values were measured on the cross-sectional area of M. longissimus dorsi by spectrocolorimeter (Konica Minolta CR-400). Glycogen levels in the muscle samples (mg/g tissue) were determined according to Roe et al., (1961). The amount of collagen in muscle (g/100 g tissue) was determined using the Reddy and Enwemeka, (1996) method and calculated according to Edward and O’Brien, (1980). Tissue protein (%) was determined using the Bradford method as reported by Bradford (1976). Myoglobin was determined according to Hornsey, (1956) method. Myoglobin value (mg/g tissue) was measured with a spectrophotometer (Shimadzu UV-1700). The water content of the meat (%) was calculated based on the dry matter basis as described in the AOAC (2011) while the water holding capacity (%) was determined by the compression method of Grau and Hamm, (1956) (Barton-Gade et al., 1993). Thawing loss (%) was Table 1: Composition (%) of the feed in traditional and intensive group Component T I


INTRODUCTION
Sheep farming has a multi-functional role by contributing beyond its productive function to include the management of rural areas, environmental sustainability, landscape conservation and regional development.In recent years, however, there have been substantial changes in response to numerous external factors, e.g., globalization, animal health and welfare concerns, environmental protection and consumer preferences (Boyazoglu, 2002).
The production of lamb meat in the region of Ege of Turkey is very important and traditionally based on lambs at the age of 4-6 months lambs.In this area, lamb production is constrained by the existing structure of sheep farming in the country and there is still a strong priority by the traditional consumer preferences for lamb meat.Besides, it is generally believed that Chios bred lambs has quality meat based on the lack of any negative feedback from either customers or markets so far (Önenç et al., 2009).In this regard, customers generally consider Chios lambs fed under traditonal conditions to have a good eating quality.As well known, meat quality of sheep is affected by breed, vegetation and feeding practices.Various aromatic compounds in natural vegetation during grazing may also affect the lamb meat quality (Kempt et al., 1981;Zervas et al., 1999;Özbey et al., 2000;Prioloa et al., 2002;Santos et al., 2008).It has been reported with previous studies (Esenbuğa et al., 2009;Yakan and Ünal, 2010) that there are important differences in animal feeding among geographical regions and even among districts.In addition, considering the expectations and demands of lamb customers, it is obvious that gourmet consumers prefer more delicious and healthier meat (Sarı et al., 2012).For that reason, many breeders have been revising their meat production methods, and endeavoring to update or improve the conventional methods in order to keep pace with market demands.These approaches include methods of lamb fattening within the extensive production system, performed according to regional conditions that can also be called "traditional" or "local" conditions.
Non-breeding male Chios lambs commonly raised in Ege Region reach slaughter weight in early ages under intensive feeding conditions (Economides et al., 1990;Altınel et al., 1998, Zervas et al., 1999).However for healthier meat production with sensory attributes based on the changing consumer demands, producers prefer traditional feeding methods in animal production (Oliván et al., 2009).
The objectives of this study was to compare the traditional and intensive feeding conditions in terms of the meat quality of Chios lambs for the consumer.

MATERIALS AND METHODS
The study was conducted using seventeen pairs of male twins at 3 months of age which were not kept for breeding and had been raised in a commercial Chios sheep farm in Ege region.All the lambs had the same male parent.A total of 34 animals were randomly distributed into traditional (T) and intensive (I) groups at equal numbers.Initial body weights means were 31.80±1.44kg and 34.72±1.21kg respectively for traditional and intensive group, Traditional group was fed two times a day (morning and evening) with local style prepared rations and allowed to graze for 8 hours every day under olive trees.Intensive group was fed with 255 dry alfalfa per animal and ad libitum commercial mixed feed on a daily basis.All the animals consumed ad libitum water.
The nutrient requirements of the lambs in the intensive group were met by considering a 15% higher amount of daily dry matter intake reported by the NRC, (1985).The component contents of mixed feeds used in the experiment is given in Table 1 and the nutrient composition and energy values of the rations are given in Table 2. Proximate analysis of the feeds were carried out in accordance with standard methods described by AOAC, (2011).
At the end of the trial, lambs were slaughtered at 5 months of age.Final body weights means were 46.85±1.70 kg and 49.99±1.75kg for traditional and intensive group, respectively.Prior to slaughtering, the lambs were subjected to a 12 h fasting period.The animals were transported by light duty vehicles from the farm to the abattoir.After 1 h transport and 2 h lairage time, they were slaughtered.,After slaughter the carcasses were kept at +4°C for 24h.Meat samples were taken from M. Longissimus dorsi (MLD) muscle between the 12th and 13th ribs for chemical composition, physicochemical characteristics, texture profile analysis and fatty acid composition analyses.They were packaged in vacuum bags, subjected to a vacuum process and stored at -18 o C until the analysis.

Analyses
The pH of the carcass was measured directly on the MLD between the 12th and 13th ribs at 24 hours post mortem using a pH meter (Testo205).L * (lightness), a * (redness) and b * (yellowness) values were measured on the cross-sectional area of M. longissimus dorsi by spectrocolorimeter (Konica Minolta CR-400).Glycogen levels in the muscle samples (mg/g tissue) were determined according to Roe et al., (1961).The amount of collagen in muscle (g/100 g tissue) was determined using the Reddy and Enwemeka, (1996) method and calculated according to Edward and O'Brien, (1980).Tissue protein (%) was determined using the Bradford method as reported by Bradford (1976).Myoglobin was determined according to Hornsey, (1956) method.Myoglobin value (mg/g tissue) was measured with a spectrophotometer (Shimadzu UV-1700).The water content of the meat (%) was calculated based on the dry matter basis as described in the AOAC (2011) while the water holding capacity (%) was determined by the compression method of Grau andHamm, (1956) (Barton-Gade et al., 1993).Thawing loss (%) was  calculated by quantifying the water released from the meat (Honikel, 1997).
Cooking loss was determined in 1.5 cm thick meat samples of similar geometry, individually placed inside polyethylene bags in a water bath at 75 °C for 20 min until an ultimate temperature of 70 °C was reached and then cooled for 60 min.They were then taken from the bags, dried with paper and weighed (Campo, 1999).The weight loss, expressed as a percentage of the initial weight, was the cooking loss.After measurements of cooking loss, the same samples were used for determination of the texture parameters.
Texture Profile Analysis was performed on the meat samples (1 cm 3 ).The samples (five repetitions) were cut in parallel to the direction of the muscle fiber and TPA parameters, including hardness, chewiness, resilience and gumminess were determined according to the procedure suggested by Bourne, (1982).Full-scale load was set at 50 kg and chart drive and crosshead speeds were 5 mm/sec.
For determining fat and fatty acids contents, muscle samples were minced into a homogeneous mixture before analyzing.Fat in minced meat was extracted by homogenization with a standard chloroform: methanol mixture (2:1, v/v) as reported by Christie, (1992).The resulting fats were then subjected to an esterification process (Christie, 1992).Analysis of fatty acid methyl esters (FAME) was performed using an Agilent 6890N (Hewlett Packard) model gas chromatograph (GC), ion detector (FID) and HP-88 capillary column (100 m, 0.25 mm i.d. and 0.2 μm).The injector and detector temperatures of the device were increased to 250 and 280 °C, respectively.The initial oven temperature of 60°C was increased by 20 ºC/min for 6.5 min and kept at 190° C for 60 minutes.Then, it was increased by 1°C/min to 220 ºC, at which it was held for 10 min.The total running time was 107.5 min.Helium (1 mL/min) was used as a carrier gas.Prior to analysis of the samples, fatty acid standards (Alltech) were analyzed by GC in order to identify the peak retention times.The results were calculated as percentages (%) of the total fatty acid methyl esters.Each sample was repeated 3 times, and the results for fatty acid content were averaged.
The data were analysed using the ''General Linear Model'' procedure of SPPS, (1999).The model used accounted for the effects of group.The t-test was used to locate differences between means at the 5% level of probability.

RESULTS AND DISCUSSION
Chemical composition of MLD muscle in Chios lambsis given in Table 3.As shown in the table, there were no significant differences for dry matter, glycogen, protein, collagen and myoglobin in the MLD muscle between the two groups.When examining the results of the chemical analyses performed on MLD muscle of the lambs in this study, it was seen that changes in the feeding system did not affect the levels of dry matter, protein, collagen or myoglobin.However, glycogen level was higher in group I compared to group T although significant differences were not found.
Our findings, like those of (Zervas and Tsiplakou, 2011;Carrasco et al., 2009;D'Alessandro et al., 2012) confirm that feeding does not affect muscle chemical parameters such as glycogen, protein, collagen and myoglobin.
Physicochemical characteristics and colour parameters for traditional and intensive groups are given in Table 4. Significant differences were not found for the examined characteristics between the two groups.
Although feeding system in this study appeared to have no effect on thawing loss, cooking loss, pH 24 , a number of studies have reported that these parameters do change along with changes in feeding system (Skapetas et al., 2006;Rodriguez et al., 2008;Santos et al., 2008).However, our findings are in agreement with the findings of Cerdeno et al., (2006) who found no significant differences neither in meat pH value nor in colour between different feeding practices.Likewise Ripoll et al., (2008) reported that the final pH was not significantly different among lambs with 4 different grazing and feeding systems, contrary to the findings of Diaz et al., (2002).Besides other factors, the development of meat colour after the oxygenation of the meat surface is believed to be dependent on the final pH of the muscle, with meat lightness, being generally lower in meat with high ultimate pH (Confort and Egbert, 1985,  Young et al., 1999).This has been proposed as a possible explanation for the lower lightness (lower L*values) often observed in meat from pasture-fed animals compared to that from concentrate-fed ones (Priolo et al., 2002).
In the present study, no differences in lightness were observed between meat from intensive-fed animals and meat from traditional-fed lambs.However, in the present study, traditional fed lambs had pale and dark meat colour compared to intensive group.These results, together with the lack of difference in meat redness (a*) and saturation (C*) between treatments, confirm previous findings showing that, in lambs (Luciano et al., 2009), differences in meat colour between concentrate-and pasture-fed animals are not evident when animals are allowed to grow at comparable rates.Moreover, it is also evident that colour differences of one CIE-LAB coordinate can be discerned by most normal observers (Hunter and Harold, 1987) and consumers can detect one CIELAB unit change in colour coordinates (Zhu and Brewer, 1999).Thus colour development in two groups could be detected by eye.
As shown in Table 5, texture parameters were lower in intensively fed lamb compared to the traditional fed lambs.These results show that the way of feeding of group I prevents glycogen level in muscle and so improves meat texture.Likewise, Immonen et al., (2000) reported lower shear force values in meats of high and intermediate glycogen contents compared to meats of low glycogen content.
The meat hardness, chewiness, resilience and gumminess values did not differ between groups.But, cooked meat from the MLD were better in intensive group, with their lower values indicating the meat was more tender, and less force was needed to cut it.
Less tender meat in group T is thought to be associated with higher daily movement activity.Therefore, higher muscle activity due to larger grazing fields appears to affect the textural measurements rather than feeding.Previous studies on this subject also reported the effect of physical activity on textural properties of meat (Martinez-Cerezo et al., 2005;Miranda-de la Lama et al., 2009;Majdoub-Mathlouthi et al., 2013).
According to previous research that yielded similar results, grain and roughage rich in polyunsaturated fatty acids have significant effects on tenderness and flavour of ruminant meats (Rousset-Akrim et al., 1997;Fisher et al., 2000;D'Alessandro et al., 2012).Meat from lambs fattened traditional has less odor and tenderness as compared to those with intensively fattening (Priolo et al., 2002;Resconi et al., 2009;Juarez et al., 2009).Another finding on this subject associated the presence of n-3 or n-6 PUFA in meat of lambs fed with roughage or grain.In Turkey, people have different taste preferences against lamb meat.As a result, some people have higher levels of n-6 PUFA.
Strong odor and tenderness can vary depending on the meat composition.
In this study, it was obser ved that some fatty acids in the MLD muscle such as heptadecanoic (C17: 0), octadecanoic (C18: 0), cis-11-octadecenoic (C18: 1 c11), cis-9-octadecenoic (C18: 1 c9), cis-9 cis-12-octadecadienoic (C18: 2 c9,12), cis-9, trans-11-octadecadienoic (C18: 2 c9t11) and total conjugated linoleic acid (CLA Σ) were changed by feeding practices.Variation in the group T were likely to due to their grazing in fields with olive trees.In previous studies, it has been reported that certain fatty acids and the CLA group are likely to change depending on feeding differences or pasture-based feeding (Auroussea et al., 2007;Lind et al., 2009).Thus, some fatty acids taken with feed can be directly subjected to conversion in the rumen (conversion to CLA fatty acids) while some fatty acids of the C18: 0, C18: 1 and C18: 2 groups are not converted in the rumen but rather retained in muscle and fat tissues (Griinar et al., 2000;Díaz et al., 2002;Loor and Herbein, 2003;Manso et al., 2009, Vasta et al., 2008).On the other hand, Petrova et al., (1994) reported that the fatty acids taken with intense feeding ration did not stay long enough in the rumen for bio-hydrogenation; therefore the fatty acid composition of meat could be affected by that of the ration.

CONCLUSION
This study showed that chemical properties of MLD muscle, textural parameters and the levels of certain fatty acids varied under traditional and intensive conditions.However, the effects of feeding practice on meat quality and color parameters as well as certain muscle chemical properties were not statistically significant.Textural attributes of lamb fed intensive appeared lower than those of the lam fed traditional.
It was found that the fatty acid composition of MLD muscle in Chios lambs statistically changed due to different feed resources.It is noteworthy that C18 fatty acid group changed and fatty acids of CLA group were particularly higher in the group T.

Table 2 : Chemical composition and energy contents of experimental
T: Traditional group, I: Intensive group

Table 5 : Texture profile analysis parameters of MLD muscle in
1 : Least squares mean and standard errors, T: Traditional group, I: Intensive group