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ANIMAL PRODUCTS |
* Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda. Montañana, 930, 50059 Zaragoza, Spain;
and
Jamones y Embutidos Altomijares S.L., 44440 Formiche Alto, Teruel, Spain; and
Integraciones Porcinas S.L., Portillo, 9, 44550 Alcorisa, Teruel, Spain
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Abstract |
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 Top Abstract INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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Key Words: carcass quality • dry-cured ham • growth performance • pig • sex • slaughter weight
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INTRODUCTION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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). The Denomination of Protected Origin (DPO) "Teruel ham" was the first Spanish DPO to control and guarantee ham production. Teruel ham is a trademark of high-quality dry-cured hams from heavy white pigs produced in a specific area of Spain. Since 1997, it has been included in a list of special quality products produced by the European Community. Teruel ham production has increased considerably in recent years from 2,000 pieces in 1985 to 500,000 in 2006 (Consejo Regulador de la Denominación de Origen Jamón de Teruel, 2007).
The regulation of DPO Teruel ham (Boletín Oficial de Aragón, 1993) establishes minimum levels of carcass weight (84 kg), fat thickness over the gluteus medius muscle (GM, 18 mm), and weight of fresh ham (11.3 kg) to improve uniformity and quality of the end product. Latorre et al. (2005) reported that the main causes of elimination were the lack of weight and fat in carcass; therefore, an increase of current slaughter weight (SW), which is 120 to 125 kg of BW, would be desirable. An increase in SW impairs growth performance but might improve some carcass characteristics (Latorre et al., 2004; Lo Fiego et al., 2005) and meat traits (Ripoll et al., 2007), which would be beneficial for the dry-cured ham industry.
On the other hand, it has been observed at the slaughterhouse that a greater proportion of carcasses from gilts than from barrows are unsuitable for Teruel ham. Some studies have suggested that castrated males might be better than females for the ham industry (Latorre et al., 2003a,b; Peinado et al., 2008).
Although there have been previous studies comparing barrows and gilts and the influence of SW on performance and carcass quality of heavy pigs, to our knowledge, there is no information available specific to Teruel ham production. The aim of this study, therefore, was to investigate the effect of sex and SW on growth performance and carcass traits of pigs intended for Teruel ham.
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MATERIALS AND METHODS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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All of 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 del Estado, 2005).
Husbandry and Growth Performance
Crossbred barrows (n = 100) and gilts (n = 100) 182 ± 3 d of age (107.0 ± 2.4 kg of BW) were used. All pigs were the progeny of Duroc sires (Asociación Turolense de Industrias Agroalimentarias, Teruel, Spain) and Landrace x Large White dams (Hypor España G.P., Barcelona, Spain). Males were castrated at 5 ± 3 d of age. On the farm, pigs were randomly allotted to 20 groups of similar initial weight within sex and SW. There were 5 treatments with 5 SW (120, 125, 130, 135, and 140 kg of BW). Each of the 5 SW was replicated 4 times and the experimental unit was a pen with 10 pigs (5 barrows and 5 gilts allotted together).
Animals were housed in flat-deck pens (3.50 m x 3.00 m) in a natural environment barn and had free access to pelleted barley-wheat-soybean meal diet and water throughout the trial. Diets were formulated to meet or exceed the requirements of pigs for each age (NRC, 1998). The composition and the estimated (Fundación Española para el Desarrollo de la Nutrición Animal, 2003) and determined nutrient value (AOAC, 2000) of the diets are shown in Table 1. Live weight per pig and feed consumption per pen were recorded at 0, 13, 20, 27, 34, and 41 d of trial and these data were used to calculate ADG, ADFI, and G:F per replicate. Once the preplanned SW treatment average was achieved, all the pigs belonging to each SW group were slaughtered on the same day.
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At preplanned SW (120, 125, 130, 135, and 140 kg of BW or 189, 196, 203, 210, and 217 d of age, respectively, according to experimental treatment), pigs were individually weighed and transported 100 km to a commercial slaughter plant (Jamones y Embutidos Altomijares, S.L., Formiche Alto, Teruel, Spain) where they 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 A for 5 to 6 s), exsanguinated, scalded, skinned, and eviscerated according to standard commercial procedures, and split down the center of the vertebral column. Hot carcass weights were recorded and used to calculate dressing percentage. Also, carcass weight was the first criterion used to identify the suitable carcasses for Teruel ham. Carcasses weighing no less than 84 kg received punctuation 100 and those under this weight received punctuation 0. Carcasses were then blast chilled at 2°C (1 m/s) for 2 h.
At 45 min postmortem, carcass length from the posterior edge of the symphysis pubis to the anterior edge of the first rib, ham length from the anterior edge of the symphysis pubis to the hock joint, and ham circumference at its widest were measured on the left side of each carcass using a flexible ruler with a precision of 0.5 mm. In addition, fat at GM, and depth of backfat (BF) between the third- and fourth-last ribs on the midline of the carcass (skin included) were measured. The fat at GM was the second criterion used to identify suitable carcasses for Teruel ham. Therefore, carcasses with fat at GM no less than 18 mm received punctuation 100 and below this fat depth received punctuation 0.
At 45 min and 24 h postmortem, the pH of the left ham was measured in the semimembranosus muscle using a portable pH meter equipped with a glass electrode (Crison Instruments S.A., Barcelona, Spain). Carcasses were processed according to the simplified EC-reference method (Branscheid et al., 1990). Then, loins, hams, and shoulders were trimmed of external fat and weighed to calculate trimmed loin, ham, and shoulder yields. The ham weight was the third criterion used to identify the carcasses suitable for Teruel ham. So, carcasses with ham weight no less than 11.3 kg (calculated as the average of the sum of both hams of each carcass) received punctuation 100 and those below this weight received punctuation 0.
Statistical Analyses
Data were analyzed as a completely randomized design using the GLM procedure (SAS Inst. Inc., Cary, NC). For productive performance, the model included SW as main effect, the experimental unit was a pen with 10 pigs, and initial weight of pigs was used as a covariate. For carcass quality, data were analyzed as a completely randomized design with treatments arranged factorially, the model included sex and SW as main effects as well as their interaction, and the experimental unit was a carcass. The REG procedure was used on each trait to analyze the responses as SW increased. A value of P < 0.05 was classified as a significant difference and P from 0.05 to 0.10 was classified as a tendency.
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RESULTS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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No sex x SW interactions were detected for any productive performance parameter; therefore, only main effects and the linear response to SW are reported. Barrows were heavier than gilts at the beginning (109.9 vs. 104.8 kg; P < 0.001) and at the end (134.3 vs. 128.8 kg; P < 0.01) of the trial (Table 2). However, both sexes showed similar ADG throughout (Table 2) and at the end (920 vs. 887 g/d for castrates and females, respectively; P > 0.10) of the study (Table 3).
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). Even though ADFI was not affected by SW (P > 0.10), G:F tended to decrease linearly (R2 = 0.41; P < 0.10) with increasing SW at a rate of 0.01 kg for every 10 kg of extra BW at slaughter. Carcass Traits
No sex x SW interactions were detected for any carcass trait; therefore, only main effects and the linear response to SW are reported (Table 4). Even though carcasses from barrows had more BF (28.9 vs. 24.7 mm; P < 0.001) and fat at GM (27.3 vs. 23.4 mm; P < 0.001) than carcasses from gilts, no differences were detected in dressing percentage (78.5 vs. 78.4%; P > 0.10). No influence of sex was observed on carcass or ham length (P > 0.10) but ham circumference was greater for barrows than for gilts (78.4 vs. 77.1 cm; P < 0.01). Castrates showed heavier shoulders (14.4 vs. 14.0 kg; P < 0.05) but lighter loins (6.4 vs. 6.7 kg; P < 0.01) than females. However, gilts had a greater yield of shoulder (13.9 vs. 13.7%; P < 0.05), loin (6.6 vs. 6.0%; P < 0.001), and ham (26.1 vs. 25.3%; P < 0.001) than barrows. Therefore, the yield of total trimmed primal cuts (shoulder + loin + ham) was greater in females than in castrates (46.6 vs. 44.9%; P < 0.001). No effect of sex was found on initial or final pH (P > 0.10).
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Suitable Carcasses for Teruel Ham
The effect of sex and SW on percentage of suitable carcasses for Teruel ham is shown in Table 5. Castrated males had greater proportion of carcasses that fulfill the minimum requirement of carcass weight (99.0 vs. 90.8%; P < 0.01) and of fat at GM (97.9 vs. 87.8%; P < 0.01) than females. However, no effect of sex was detected on proportion of carcasses that fulfilled the minimum ham weight (92.6 vs. 90.8%; P > 0.10). Therefore, barrows tended to show a greater percentage of final suitable carcasses for Teruel ham (carcasses that fulfill the 3 named requirements) than gilts (91.6 vs. 84.4%; P < 0.10).
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84 kg (P < 0.001). Also, the increase in SW to 130 kg increased the proportion of carcasses with fat at GM 18 mm (P < 0.05) and with ham weight 11.3 kg (P < 0.001) but no effect of SW on these parameters was detected above 130 kg of BW. Therefore, increasing the SW up to 130 kg of BW, but not thereafter, improved the percentage of final carcasses suitable for Teruel ham (P < 0.001).
An interaction between sex and SW (P < 0.01) was detected on the proportion of suitable carcasses that fulfilled the minimum carcass weight required for Teruel ham (Table 6). Whereas 125 kg of SW optimized the percentage of carcasses with weight 84.0 kg in castrates (95.0 vs. 100 vs. 100 vs. 100 vs. 100% for 120, 125, 130, 135, and 140 kg of BW, respectively), females needed 130 kg of SW (64.7 vs. 89.5 vs. 100 vs. 100 vs. 100%, respectively).
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DISCUSSION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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At the beginning of the trial, barrows were heavier than gilts because pigs were allotted to treatments on the basis of age, but both sexes showed similar ADG throughout the trial. These results agree with Ellis et al. (1996) but not with several reports that found greater daily growth in castrated males than in females because of the greater daily intake (Kanis et al., 1990; Augspurger et al., 2002). In the current trial, the information about ADFI and G:F by sex was not available because each box constituted 5 barrows and 5 gilts and provided a communal feeder. The reason was that we wanted to show the representative situation currently in Spain: castrates and females allotted together in the pen and slaughtered on the same day, therefore of the same age.
Consistent with the results of Candek-Potokar et al. (1997) and Peinado et al. (2008) with the same crossbred, ADG decreased with increasing SW. Moreover, the growth rate was reduced by 55 g/d for every 10-kg increase above 120 kg in the present study, which is greater than the 35 and 24 g/d reduction for barrows and gilts, respectively, from 90 to 115 kg of BW observed by Castaing and Leuillet (1976). Within the weight range of 116 to 133 kg, Latorre et al. (2004) reported that ADG decreased at a rate of 38 g/d for every 10-kg increase in BW, and Albar et al. (1990) observed that ADG declined at a rate of 23 g/d from 125 to 135 kg.
On the other hand, SW did not influence ADFI in the present study, in agreement with Latorre et al. (2004), but in contrast to Cisneros et al. (1996) and Piao et al. (2004) who found an increase of feed intake as SW increased. In fact, Albar et al. (1990) reported that ADFI increased 100 g/d for every 10-kg increase in BW, and Weatherup et al. (1998) observed an increase of 200 g/d for barrows and 120 g/d for gilts from 92 to 125 kg of SW. In the current study, pigs were fed in a commercial facility during the finishing phase (months of August and September when temperatures often reached 33°C). This warm rearing environment may be partly responsible for the observed reduction in ADFI, as well as depressing ADG, during the last period of the trial. The rearing environment (stocking density, health of the pigs, and humidity) might also explain, in part, some of the discrepancies.
The results of the regression analysis indicated that G:F was impaired as SW increased, in agreement with most researchers (Weatherup et al., 1998; Latorre et al., 2004; Piao et al., 2004). We determined that the rate of increase was 0.01 kg for every 10 kg of BW, which is similar to values reported by Latorre et al. (2004), with pigs slaughtered between 116 and 133 kg of BW (0.01 kg), and by Candek-Potokar et al. (1997) from 110 to 130 kg of BW pigs (0.018 kg). The decrease in ADG and G:F with increasing SW indicates that feed costs will be greater when pigs are slaughtered at a heavier SW. However, heavier weights imply fatter carcasses and meats, which might be beneficial for pigs intended for the dry-cured industry because curing for optimal quality requires a relatively high amount of fat (Guerrero et al., 1996).
Carcass Traits
Barrows produced heavier carcasses than gilts due to the greater SW, but dressing percentage was similar, which agrees with Lo Fiego et al. (2005) and Peinado et al. (2008). However, Ellis et al. (1996) found that carcass yield was greater in gilts than in barrows. The discrepancies observed among researchers could be related to differences of the method used for trimming the reproductive system at the slaughterhouse.
Carcasses from barrows were fatter than carcasses from gilts, which is consistent with the greater intramuscular fat content detected in the longissimus muscle from castrates in a posterior laboratory analysis (Ripoll et al., 2007). The difference in BF between sexes was 17%, which is similar to values reported by Nieuwhof et al. (1991), Lebret et al. (2001), and Correa et al. (2006). On the other hand, carcass length was similar between sexes, in spite of the fact that castrates were heavier. This observation agrees with Cisneros et al. (1996) and Hamilton et al. (2000), but not with Leach et al. (1996) or Correa et al. (2006), who found longer carcasses in females when they were slaughtered at the same weight. heavier carcasses, the proportions of shoulder, loin, and ham were greater for gilts, which agrees with Unruh et al. (1996) and Latorre et al. (2003b). The greater primal cut yields in females is consistent with the fatter carcasses found in barrows suggesting that carcasses from gilts have greater lean proportion. In general, the pork industry prefers leaner carcasses, whereas the dry-cured product industry prefers fatter carcasses.
Although the weight of trimmed primal cuts was greater in barrows than in gilts, probably due to the heavier carcasses, the proportions of shoulder, loin, and ham were greater for gilts, which agrees with Unruh et al. (1996) and Latorre et al. (2003b). The greater primal cut yields in females is consistent with the fatter carcasses found in barrows suggesting that carcasses from gilts have greater lean proportion. In general, the pork industry prefers leaner carcasses, whereas the dry-cured product industry prefers fatter carcasses.
The finding that the increase in SW improved carcass yield agrees with Virgili et al. (2003) and Correa et al. (2006). This observation was expected because the rate of growth with age is greater for the carcass than for the whole body (Gu et al., 1992). Moreover, in this trial, dressing percentage increased by 0.42 percentage units per 10 kg of extra BW, a value within the range reported in the literature (Albar et al., 1990; Latorre et al., 2004) for crossbred-Pietrain offspring of similar age. However, Ficher et al. (2003) reported that the magnitude of the increase in carcass yield with SW is breed-dependent and greater in Pietrain than in Meishan pigs.
Carcass fat increased as SW increased, which is consistent with the linear improvement of intramuscular fat content with SW in the loin of the same pigs (Ripoll et al., 2007). In fact, the BF and the fat at GM increased by 2.10 and 2.06 mm, respectively, for each 10-kg increase in SW above 120 kg, similar values to those found by Latorre et al. (2004) in heavy pigs intended for dry-cured products (2.4 and 2.3 mm, respectively). Castaing and Leuillet (1976) also observed a linear increase in BF of 1.6 mm for barrows and 2.0 mm for gilts per 10-kg increase in BW, whereas Cisneros et al. (1996) reported an increase of 1.8 mm/10 kg of BW, regardless of sex.
Carcass length increased at a rate of 1.06 cm for every 10 kg of extra BW, less than the 2.16 cm reported by Martin et al. (1980) with selected pigs for lean, the 1.86 cm of Cisneros et al. (1996) with Hampshire sired-pigs, or the 2.4 cm of Latorre et al. (2004) with Pietrain-sired pigs. In addition, ham size increased with SW: 0.88 cm in length and 2.00 cm in perimeter for each 10 kg of SW, close to the 1.1 cm in length reported by Latorre et al. (2004). Ficher et al. (2003) reported that the increase of carcass, ham, and shoulder dimensions with SW depends on the breed. In general, slaughterhouses prefer shorter carcasses for easier manipulation. However, consumers of hams show a clear preference for long and narrow pieces because these characteristics are associated with Iberian hams (Serrano et al., 2008).
In the present study, the weights of ham, shoulder, and loin increased with SW by 1.95, 1.16, and 0.36 kg, respectively, for each 10-kg increase in SW and close to the results of Latorre et al. (2004) or Lo Fiego et al. (2005) with pigs intended for cured ham. However, although the trimmed shoulder yield was not affected by SW, the trimmed ham yield decreased by 0.4 percentage units for each 10 kg, similar to the 0.3 percentage units found by Latorre et al. (2004). Virgili et al. (2003) suggested that primal cut proportion decreases with increasing BW because the growth rate of primal cuts is lower with age than the growth rate of the whole body.
Several researchers have not found any effect of sex or SW on pH (Leach et al., 1996; Monin et al., 1999), which agrees with our data. No problems with PSE or DFD meat were detected in the carcasses of the current trial.
Suitable Carcasses for Teruel Ham
Barrows showed a 9.0% greater proportion of carcasses that fulfilled the minimum carcass weight required compared with gilts because castrates were 5.5 kg heavier than females on slaughter day. In addition, barrows had an 11.5% greater proportion of carcasses that fulfilled the minimum fat at GM required compared with gilts due to castrates being fatter than females. However, ham weight was similar for both sexes and therefore no effect of sex was detected in the proportion of carcasses that fulfilled the minimum ham weight needed. In consequence, an interesting finding in this study was that barrows showed an 8.5% greater proportion of final suitable carcasses for Teruel ham (carcasses that met the 3 named requirements) compared with gilts. This might indicate that barrows are better than gilts for Teruel ham because the costs of producing a pig for the ham industry are greater than those of producing a commercial pig. Therefore, having a significant percentage of unsuitable carcasses detected at slaughterhouse is economically harmful.
The increase in SW over 125 kg did not increase the proportion of carcasses with weight 84 kg. Neither did the increase in SW over 130 kg increase the percentage of carcasses with fat at GM 18 mm or with ham weight 11.3 kg. In consequence, the proportion of final suitable carcasses for Teruel ham increased up to 130 kg of BW but not thereafter; therefore, SW over 130 kg of BW would not be beneficial.
There was an interaction between sex and SW regarding the percentage of suitable carcasses that fulfilled the minimum carcass weight required for Teruel ham; whereas castrates required 120 kg of SW to optimize this trait, females needed 130 kg of SW. However, the percentage of carcasses with weight 84.0 kg was similar, although not optimum, when castrates were slaughtered at 120 kg and females at 125 kg of BW. The reason could be that slaughter was based on age; the average SW of 125 and 130 kg of BW (196 and 203 d of age) corresponded to 128 and 133 kg of BW in barrows and 123 and 128 kg of BW in gilts, respectively. Thus, there could be two strategies to maximize the percentage of carcasses that fulfill the minimum carcass weight required for Teruel ham; slaughtering all pigs, independently of sex, at 125 kg of BW or slaughtering castrates at 120 kg and females at 130 kg of BW. However, the optimum SW cannot be decided only on the basis of this parameter because there are other requirements that have to be taken into account.
In summary, at the same age, barrows were heavier and fatter than females and therefore showed a greater proportion of suitable carcasses for Teruel ham. In addition, an increase in SW of pigs up to 130 kg of BW impaired productive performance but increased the weight and the fat thickness of the carcass and of the ham, which is the most beneficial level for the drycured Teruel ham industry.
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Footnotes |
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2 Corresponding author: malatorreg{at}aragon.es
Received for publication November 29, 2007. Accepted for publication April 9, 2008.
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LITERATURE CITED |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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This article has been cited by other articles:
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  M. A. Latorre, G. Ripoll, E. Garcia-Belenguer, and L. Arino The increase of slaughter weight in gilts as a strategy to optimize the production of Spanish high quality dry-cured ham J Anim Sci, April 1, 2009; 87(4): 1464 - 1471. [Abstract] [Full Text] [PDF]
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