The influence of age at the beginning of Montanera period on meat characteristics and fat quality of outdoor Iberian pigs

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1 Animal (2010), 4:2, pp & The Animal Consortium 2009 doi: /s animal The influence of age at the beginning of Montanera period on meat characteristics and fat quality of outdoor Iberian pigs J. A. Rodríguez-Sánchez, G. Ripoll and M. A. Latorre - Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda. Montañana 930, Zaragoza, Spain (Received 17 March 2009; Accepted 2 September 2009; First published online 5 October 2009) A total of 120 Iberian pigs of the Lampiña line that grew under outdoor conditions were used to study the effect of the age at the beginning of Montanera period (AM) on meat characteristics and fatty acid (FA) profile of subcutaneous fat. AM period is a free-range fattening phase from November to February in which pigs ate mainly acorns and grass. There were two treatments with two AM (20 pigs per treatment); 18 (P18) and 12 months (P12). Barrows and gilts were in the same proportion within each treatment. All the animals were slaughtered at the same time (at the end of Montanera period) reaching an average 160 kg of body weight. Meat from P18 had less protein and was more red (a*) ( P, 0.05), but tended to show higher intramuscular fat content ( P, 0.10) than meat from P12. Loin from P18 had lower thawing ( P, 0.001) and cooking losses ( P, 0.10) than loin from P12. The fat from P18 had higher monounsaturated FA content than fat from P12 pigs ( P, 0.01) due to the higher level of C18:1 ( P, 0.01) and C20:1 ( P, 0.001). However, fat from P12 had higher polyunsaturated FA content than fat from P18 pigs ( P, 0.01) because of the higher level of C18:2 ( P, 0.001). It is concluded that both 12 and 18 months are adequate AM for purebred Iberian pigs from the commercial point of view. However, if the aim is to produce high-quality dry-cured Iberian products, the P18 pigs would be more advisable because had better meat and fat characteristics than the P12 pigs. Keywords: age, Montanera period, outdoor, meat and fat quality, Iberian pigs Implications To optimize the Iberian outdoor pig production, sows must give birth twice per year (spring and autumn). However, although both groups have similar weight at the beginning of the outdoor finishing-phase (Montanera), the age is different (18 or 12 months, respectively). We have concluded from this study that older pigs provide better meat and fat quality than younger pigs. Therefore, if the objective is to produce high-quality and homogenous meat products, only older pigs should be produced or the price of the end products should be different. Introduction The Iberian is the only Spanish pig breed reared outdoors in Spain, with nearly two million animals slaughtered per year and an annual production of 2.6 million dry-cured hams (Ministerio Medioambiente, Medio Rural y Marino, 2009). The high amount of intramuscular fat (IMF), the great concentrations of heme pigments and the high levels of - malatorreg@aragon.es monounsaturated fatty acids (MUFAs) are the most relevant quality aspects in meat from Iberian pigs (Ventanas et al., 2006). The traditional productive cycle for Iberian sows is based on two litters per year (spring and autumn) and lactations of 56 days (Daza, 2001). Also, the traditional cycle for growing Iberian pigs includes a final free-range fattening phase (from November to February) named Montanera in which natural feed resources, mainly acorns and grass are consumed. Acorns are characterized by a high oleic acid content that strongly influences the physical properties of fat, leading to soft and oily lard (Ruiz et al., 2002). Pigs are usually slaughtered at the end of this period when they achieve 150 to 160 kg of body weight (BW) (López-Bote, 1998). To better adapt to free-range rearing, pigs should reach a minimum capacity of their locomotive and digestive systems. So, it is generally accepted that pigs should be at least 10 months old before the start of the extensively fattening period (López-Bote, 1998). In consequence, at the beginning of the first Montanera period, animals are not ready and have to wait until the end of the next Montanera period to be fattened and slaughtered. Because of this, spring-born pigs begin the Montanera phase at 18 months old and are slaughtered at 21 to 22 months of 289

2 Rodríguez-Sánchez, Ripoll and Latorre age and autumn-born pigs begin it at 12 months old and are slaughtered at 15 to 16 months of age. Therefore, restrictions of feed intake in the older pigsandhigherfeedallowance for the younger pigs during the pre-montanera phase are necessary to afford that pigs with different ages achieve 160 kg BW at slaughter (Daza et al., 2006 and 2007). Several previous studies have reported the effect of age on meat and fat quality of commercial (not autochthonous) pigs reared indoors (Leach et al., 1996; Weatherup et al., 1998; Latorre et al., 2004). However, this information in Iberian pigs is scarce and based on empirical observations. The aim of this study was to evaluate the effects of the age at the beginning of Montanera period (AM) (18 or 12 months) (P18 and P12, respectively) on meat quality and fatty acid (FA) profile of subcutaneous fat of purebred Iberian pigs reared under free-range conditions and slaughtered at similar BW. Material and methods Animals and feeding management One hundred and twenty Iberian pigs of the Lampiña line (Finca La viñera, Alcuéscar, Cáceres, Spain) were used for the trial. There were two groups of animals with barrows and gilts at the same proportion in each group; pigs (n 5 60) born in May 2006 and pigs (n 5 60) born in November The May-born pigs were weaned in July (56 days of age and 14 to 16 kg BW). From July to October (during 105 days until reaching 35 to 40 kg BW), piglets were fed a starter diet at a rate of approximately 1 kg/day per pig. From October 2006 to February 2007 (during 113 days until reaching 60 to 65 kg BW), pigs made use of the Montanera period (Quercus ilex and Quercus rotundifolia forest, acorns and grass are fully available). The Novemberborn pigs were weaned in January 2007 (56 days of age and 14 to 16 kg BW). From January to February (during 42 days until reaching 20 to 25 kg BW), piglets were fed ad libitum a starter diet also making use of the end of Montanera period natural resources. From February to November 2007, both treatments received a growing diet (261 days at a rate of approximately 1.4 kg/day per pig for animals born in May, and 259 days at a rate of approximately 2.7 kg/day per pig for animals born in November). The starter and growing diets were common for both groups and were formulated to meet or exceed the requirements of pigs for that age (National Research Council, 1998). Feeds were analyzed for moisture by oven drying method (930.15), ash by muffle furnace (942.05), crude protein by the Kjeldahl method (984.13) and ether extract by Soxhlet fat analysis (920.39) (Association of Official Analytical Chemists, 2000). Ingredients and chemical composition of the diets are shown in Table 1. During the fattening period, from October 2007 to February 2008 (107 days), both groups of pigs were reared under the same conditions; 0.60 pigs/ha of stocking rate and making use of the natural feed resources of Montanera. The amount of feed provided to each treatment was calculated to get Table 1 Ingredient composition and estimated and determined analysis of the starter and growing diets for Iberian pigs (g/kg, as fed) Starter Growing Ingredient Maize 300 Wheat Barley Rye 100 Rye meal 250 Soybean meal 100 Carob bean meal Sunflower seed 75 Peas Sunflower oil 25 Whey powder 50 Soybean protein hydrolyzed 20 Dicalcium phosphate 6 Calcium carbonate 3 Sodium chloride 3 Vitamin and mineral premix a 5 3 Calculated analysis Dry matter Ash Crude protein (N ) Ether extract Crude cellulose Lysine Determined analysis Dry matter Ash Crude protein (N ) Ether extract a Supply per kg diet: vitamin A, 7500 IU; vitamin D3, 1000 IU; vitamin E, 10 IU; riboflavin, 3 mg; D-calcium pantothenate, 6 mg; nicotinic acid, 10 mg; thiamine hydrochloride, 1.0 mg; vitamin B12, 20 mg; choline chloride, 180 mg; Mn, 60 mg; Zn, 118 mg; Fe, 75 mg; Cu, 13 mg; I, 1 mg; Se, 0.2 mg. similar BW at the beginning of the fattening phase (110 to 115 kg BW). The slaughter weight was 160 kg BW in both cases. All the experimental procedures used in this study were in compliance with the Spanish guidelines for the care and use of animals in research (Boletín Oficial Estado, 2005). Slaughter and sampling In February 2007, Montanera period ended and pigs were transported 130 km to a commercial slaughterhouse (Mazafra SL, Zafra, Badajoz, Spain). At the abattoir, animals were resting for 15 h with full access to water but not to feed. Then, pigs were electrically stunned (225 to 380 V/0.5 amps for 5 to 6 s), exsanguinated, scalded, skinned and eviscerated according to standard commercial procedures and split down the midline. The hot weight of each carcass was recorded. Carcasses were then blast chilled at 28C (1m/s) for 2 h. At 45 min post mortem, fatoverthegluteus medius (GM) muscle and depth of back fat (BF) between the third and the fourth last ribs on the midline of the carcass (skin included) were measured. In addition, at 45 min and at 24 h post 290

3 Age at Montanera period in outdoor Iberian pigs mortem, the ph was measured in the Semimembranosus muscle using a portable ph meter equipped with a glass electrode (Model no Crison Instruments S.A., Barcelona, Spain). Carcasses were processed according to the simplified European Community-reference method (Branscheid et al., 1990). Afterwards, a total of 20 carcasses from each group, barrows and gilts at the same proportion within each treatment were chosen at random for the meat and fat quality study. A section of g of longissimus dorsi (LD) muscle was excised at the level of the last rib from the loin of each left carcass. The subcutaneous fat samples, including fat layers, skin and lean, were taken at tail insertion in the coxal region of the each left carcass. Both meat and fat samples were vacuum package and stored in bags at 2208C until subsequent analysis. Meat quality The LD frozen samples were thawed for 24 h at 48C, removed from packages, blotted dry and weighed. Thawing losses were calculated in percentage of fresh weight. Meat color was evaluated with a chromameter (CM 2002 Minolta, Minolta Camera, Osaka, Japan), previously calibrated with a pure white color tile, using objective measurements (Commission International de l Eclairage, 1976). An average of three observations per sample were used to measure the lightness (L*) and two color coordinates (redness, a*; yellowness, b*). Additionally, chroma (c*) as c* 5 O(a* 2 1b* 2 ) and hue angle (H8) as H85arctg (b*/a*) were calculated (Wyszcecki and Stiles, 1982). The IMF, crude protein and moisture content of the meat samples were determined by using a near infrared transmittance meat analyzer (Infratec 1265; Tecator, Höganäs, Sweden). First, the chops were trimmed free of intermuscular fat, minced and distributed in the cup ring equipped with a plastic bottom plate with 100 mm diameter and 15 mm deep. The monochromator contained a 50 W tungsten lamp and a diffraction grating, which created monochromatic light. The measured spectra were separated in the range from 800 to 1100 nm. In addition, cooking losses of the meat samples were determined (Honikel, 1998) and expressed in percentage of thawed weight. Briefly, an LD slice was taken from each chop, weighed ( g), placed in a plastic bag and cooked to an internal temperature of 708C in a 758C water bath (Precisterm; J.P. Selecta S.A., Barcelona, Spain). Internal temperature was monitored during cooking with a handheld temperature probe (Hanna Instruments R, Woonsocket, RI, USA). FA profile of subcutaneous fat The determination of FA profile of fat was performed according to Boletín Oficial Estado (2004). Briefly, a 200 mg sample of subcutaneous adipose tissue was homogenized and saponified and the FA was extracted, methylated and analyzed with a gas chromatograph (Autosystem XL Agilent Technologies 6890N Net Work GC System; Perkin Elmer, Boston, MA, USA) equipped with a flame ionization detector, a Hamilton injector and a Omegawax 320 (Supelco R, Bellefonte, PA, USA) capillary column (30 m mm with a film thickness of 0.25 mm) with 0.4 ml/min of He as the carrier gas. The temperature of the inlet detector was 2608C and the initial temperature of the oven was 1908C for 2 min, increasing to 2058C at a rate of 58C/min for 3 min. The percentages of total saturated FA (SFA), MUFA, polyunsaturated FA (PUFA) and unsaturated FA (UFA 5 MUFA 1 PUFA) were calculated. Statistical analyses ANOVA was employed to determinate the main effect (18 or 12 months as AM) by using the GLM procedure of Statistical Analysis Systems Institute (1990). Each treatment was replicated 60 times for carcass traits and was chosen 20 times randomly for meat and fat traits. The experimental unit was the pig. Results Carcass quality The carcass weight was similar for both treatments (130.4 v kg for P18 and P12, respectively; P. 0.10) (Table 2). However, P18 had fatter carcasses at BF (64.8 v. 60.6mm; P, 0.01) and tended to show thicker fat at GM muscle (56.2 v. 53.1mm;P ) than P12. No effect of AM on ph at 45minorat24hpost mortem was observed. Meat quality The effect of AM on meat characteristics is shown in Table 3. Meat from P18 had less protein (212 v. 218 g/kg; P, 0.05), but tended to show higher IMF content (59 v. 51 g/kg; P ) than meat from P12. Loin from P18 was redder (a*) (8.5 v. 6.8; P, 0.05), but showed lower H8 value (63.3 v. 68.8; P, 0.01) than loin from P12. Meat from P12 had lower thawing losses (63.4 v g/kg; P, 0.001), and tended to show lower cooking losses (165 v. 173 g/kg; P, 0.10) than meat from P18. Table 2 The effect of age at the beginning of Montanera period on carcass characteristics of Iberian pigs reared outdoor 18 months 12 months s.e. (n 5 60) P-value Carcass weight (kg) Backfat depth (mm) ** Fat at gluteus medius (mm) ph 45 min ph 24 h **P,

4 Rodríguez-Sánchez, Ripoll and Latorre Table 3 The effect of age at the beginning of Montanera period on Musculus Longissimus dorsi characteristics of Iberian pigs reared outdoor 18 months 12 months s.e. (n 5 20) P-value Chemical composition (g/kg) Moisture Intramuscular fat Protein * Color Lightness, L* Redness, a* * Yellowness, b* Chroma, c* Hue angle, H ** Water holding capacity (g/kg) Thawing losses *** Cooking losses *P, 0.05; **P, 0.01; ***P, FA profile of subcutaneous fat The effect of AM on FA profile is shown in Table 4. The fat from P18 had higher levels of C14:0 (P, 0.10) and C15:0 (P, 0.05), but lower of C18:0 (P, 0.05) than fat from P12. Therefore, no differences were detected on SFA content (287.7 v g/kg for P18 and P12, respectively). On the other hand, fat from P18 showed higher levels of C18:1 (P, 0.01) and C20:1 (P, 0.001) than that from P12. In consequence, fat from P18 had higher MUFA content than fat from P12 (608.8 v g/kg; P, 0.01). Also, fat from P18 tended to show higher level of C18:4 (P, 0.10), but had lower level of C18:2 (P, 0.001) than that from P12. Therefore, PUFA content was lower in subcutaneous fat from P18 than in that from P12 (103.5 v g/kg; P, 0.01). Finally, no effect of AM was observed in UFA content (712.3 v g/kg for P18 and P12, respectively). Discussion No differences were detected on carcass weight between treatments because both groups of animals were slaughtered at similar average BW (approximately 160 kg). The individual slaughter weight was not available and therefore dressing percentage could not be statistically analyzed. However, the average slaughter weight within each treatment was available and was slightly lower in P12 than in P18 (159.2 v kg BW, respectively), which might provide lower dressing percentage in older pigs. In this respect, it has been reported lowercarcassyieldinpigsthatstartedthefatteningphaseat 12 months of age compared with pigs that started it at 8 months being slaughtered at similar BW (Daza et al., 2006). This could be explained because P18 were reared free range for a longer time and ate more grass throughout their life (two Montanera periods completed) than P12 (the end of the first Montanera period and the second one completed). In fact, it has been found that an increase in crude fiber intake leads to a higher development of the large intestine and a consequent reduction in carcass yield (Hawe et al., 1992). Table 4 The effect of age at the beginning of Montanera period on fatty acid profile (g/kg) of subcutaneous fat of Iberian pigs reared outdoor 18 months 12 months s.e. (n 5 20) P-value C10: C12: C14: C15: * C15: C16: C16: C17: C17: C18: * C18: ** C18: *** C18: C18: C20: C20: *** C20: C20: SFA a MUFA b ** PUFA c ** UFA d *P, 0.05; **P, 0.01; ***P, a SFA 5Ssaturated fatty acids 5 C10:0 1 C12:0 1 C14:0 1 C15:0 1 C16:0 1 C17:0 1 C18:0 1 C20:0. b MUFA 5Smonounsaturated fatty acids 5 C15:1 1 C16:1 1 C17:1 1 C18: 1 1 C20:1. c PUFA 5Spolyunsaturated fatty acids 5 C18:2 1 C18:3 1 C18:4 1 C20:3 1 C20:4. d UFA 5Sunsaturated fatty acids 5 MUFA 1 PUFA. In spite of the similar carcass weight, P18 showed fatter carcasses than P12, which agrees with previous studies (Daza et al., 2007). Also, several researchers have reported that BF increases linearly as slaughter age increases (Cisneros et al., 1996; Latorre et al., 2008a). The BF values 292

5 Age at Montanera period in outdoor Iberian pigs found in the present trial (6.0 to 6.5 cm) are between those reported by other authors (5.0 cm, Daza et al., 2007; 7.0 cm, Mayoral et al., 1999) for free-range Iberian pigs slaughtered at similar weights. However, the fatter carcasses in P18 than in P12 could be also due to the different feeding regimen. Pigs that were fed a more restricted diet during the growing phase (P18) might have exhibited a compensatory growth during the finishing phase increasing the fat deposition in carcass. It was the finding of Daza et al. (2007) who studied the effect of the age at the beginning of the fattening period of Iberian pigs under free-range conditions. No influence of AM on ph measured at any time point was observed, in accordance with several authors who studied the effect of weight (Leach et al., 1996; Latorre et al., 2008a) or age (Weatherup et al., 1998; Latorre et al., 2009a) at slaughter on ph measured in the same muscle of heavy pigs. The IMF values observed in the present trial (50 to 60 g/kg) are reasonable for these type of pigs, but higher than those reported in Iberian pigs reared indoors and slaughtered at similar BW (39 g/kg, Morcuende et al., 2007; 42 g/kg, Ventanas et al., 2006). The IMF plays a major role in the quality of drycured meat products from Iberian pigs increasing juiciness and tenderness (García et al., 1996). In the current experience, meat from P18 had lower protein content, but tended to show higher IMF content than meat from P12. The reason for the differences in IMF proportion between treatments could be explained because it has been observed that IMF of the loin improved as age increased in commercial (not autochthonous) white pigs (Weatherup et al., 1998; Latorre et al., 2003) or in Iberian pigs (Daza et al., 2007). In addition, in the current trial, older pigs grew slower than younger pigs to achieve similar slaughter weight and the literature has been reported a moderate negative correlation (20.45) between average daily gain and IMF in three pig genotypes (Latorre et al., 2008b). Although some studies have shown no influence of age on meat color even for wide ranges of slaughter weight (Weatherup et al., 1998; Serrano et al., 2008a), most studies agree on the beneficial effect of increased age on redder, darker and higher myoglobin content (Mayoral et al., 1999; Latorre et al., 2004). The trend followed by the data agree with such observations (a* or myoglobin content increasing as age increased). In addition, animals were free range in a wide area and therefore they had to walk far to eat and drink. In this sense, a beneficial impact of exercise on myoglobin content has been reported, showing redder meat, mainly due to an increase in the proportion of oxidative muscle fibers (Petersen et al., 1997). The water losses were higher in loin from P18 than in loin from P12 in accordance with some authors who have observed lower thawing losses (Latorre et al., 2009a), drip losses (Peinado et al., 2008) or cooking losses (Latorre et al., 2009c) in pork as slaughter age increased. However, others have not found any effect (Leach et al., 1996; Unruh et al., 1996). The reason for these discrepancies is unknown, but either very high or very low water holding capacity, associated with dark, firm and dry (DFD) and pale, soft and exudative (PSE) problems have negative consequences on the quality of dry-cured meat products (Arnau et al., 1995). However, the range of water losses detected in the current trial is small and should have negligible influence on the quality of the elaborated products. The FA profile of subcutaneous fat observed in the current trial (approximately 290, 600 and 110 g/kg of SFA, MUFA and PUFA contents, respectively) was similar to that reported by other researchers for Iberian pigs reared outdoors (Daza et al., 2006; Estévez et al., 2006). However, in indoor Iberian pigs, a higher SFA content (390 g/kg) and a lower UFA content (610 g/kg), mainly due to a low content of MUFA (90 g/kg), have been found (Serrano et al., 2008a and 2008b). Also, in outdoor Duroc 3 (Landrace 3 Large White) pigs slaughtered at 170 kg BW, the SFA and MUFA contents reported were 348 and 472 g/ kg, respectively (Latorre et al., 2009b). The increase of slaughter age did not modify the level of SFA, which is in agreement with Daza et al. (2006) who found similar values of this parameter between pigs that began the fattening period at 12 and 14 months of age. On the other hand, in white pigs reared indoors, it has been found that SFA tended to increase as age increased mainly due to the increase of C16:0 (Cava et al., 1997). The level of C18:1 observed in the current trial (552 to 563 g/kg) is close to the results of previous studies (Estévez et al., 2006), but was higher than that found in Iberian pigs reared indoors (485 g/kg) (Lo Fiego et al., 2005) or in white pigs reared outdoors (435 g/kg) (Latorre et al., 2009b). This is likely due to the fact that acorns have a higher content of oleic acid and consequently of MUFA and a lower content of PUFA than concentrate feed (Raj et al., 2005). The subcutaneous fat of P18 showed a higher level of MUFA content than the fat of P12, mainly because of the higher content of C18:1 and C20:1. In this line, it has to be taken into account that P18 made use of two full Montanera periods (5 to 10 and 17 to 22 months, respectively), whereas P12 made use of the end of the first Montanera (3 to 4 months) and the second one full (12 to 16 months). The contents of C18:2 and C18:4, and consequently the PUFA content, were higher in P12 than in P18. It has been observed that this evolution was linear in Duroc 3 (Landrace 3 Large White) gilts slaughtered between 189 and 217 days of age (Latorre et al., 2009c). The C18:2 plays a very important role from a technological meat quality point of view because it can reduce the firmness and cohesiveness of adipose tissue and increase the fat oxidation rate (Wood et al., 2008). Literature data suggest an inverse relationship between the degree of unsaturation of lipids in fat and the age of the pigs. However, in the current trial, there were no significant differences between younger and older pigs for SFA and UFA proportions probably due, at least in part, to the inclusion of acorn and grass in the feeding plan. Conclusions It can be concluded that meat from P18 showed higher IMF content, red color and water holding capacity than P12. In addition, fat from P18 had higher C18:1 and MUFA content than fat from P12. Both 18 and 12 months were adequate age to begin the Montanera period from a 293

6 Rodríguez-Sánchez, Ripoll and Latorre commercial point of view. If the aim is to produce high-quality dry-cured Iberian products, P18 would be more advisable because they had better meat and fat characteristics than P12. Acknowledgements We would like to thank V. Collado (Agrícola y Ganadera La Viñera, Cáceres, Spain) and R. Álamo (Gourmet Ibérico Dos montaneras, Alicante, Spain) for the cession of the samples. References Arnau J, Guerrero L, Casademont G and Gou P Physical and chemical changes in different zones of normal and PSE dry cured ham during processing. Food Chemistry 52, Association of Official Analytical Chemists Official methods of analysis, 17th edition. AOAC, Arlington, VA, USA. Boletín Oficial Estado Orden PRE73848/2004 por la que se establecen los métodos oficiales de toma de muestras en canales de cerdos Ibéricos y el método de análisis para la determinación de la composición deácidos grasos de los lípidos totales del tejido adiposo subcutáneo de cerdos Ibéricos. 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