Effect of transport time on welfare and meat quality in pigs

Meat Science 61 (2002) 425–433 www.elsevier.com/locate/meatsci

Effect of transport time on welfare and meat quality in pigs M.P. Pe´reza, J. Palaciob, M.P. Santolariac, M.C. Acen˜ad, G. Chaco´nd, M. Gasco´nd, J.H. Calvoe, P. Zaragozae, J.A. Beltranf, S. Garcı´a-Belenguerd,* a Veterinario de Administracio´n Sanitaria, DGA, Huesca, Spain Departamento de Medicina y Cirugı´a Animal, Facultad de Ciencias Experimentales y de la Salud, Universidad Cardenal Herrera, C.E.U.-San Pablo, Valencia, Spain c Departamento de Produccio´n Animal, E.U. Polite´cnica de Huesca, Universidad de Zaragoza, Zaragoza, Spain d Departamento de Patologı´a Animal, Facultad de Veterinaria, Universidad de Zaragoza, Miguel Servet 177, 50013, Zaragoza, Spain e Laboratorio de Gene´tica, Bioquı´mica y grupos sanguı´neos, Facultad de Veterinaria, Universidad de Zaragoza, Miguel Servet 177, 50013, Zaragoza, Spain f Laboratorio de Tecnologı´a de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, Miguel Servet 177, 50013, Zaragoza, Spain b

Received 4 August 2001; received in revised form 12 October 2001; accepted 15 October 2001

Abstract The purpose of this study was to determine the effects of transport duration on some welfare and meat quality parameters. For the study 144 pigs were used. One group of 72 animals was subjected to 15 min and the others to 3 h transport time. Blood from all animals was analysed in order to detect stress-susceptible pigs and assess pre-slaughter stress. Meat quality parameters were analysed from Longissimus thoracis and Semimembranosus muscles. It was concluded that under normal Spanish commercial conditions, pigs subjected to short transport showed a more intense stress response and poorer meat quality than pigs subjected to moderately long transport when they were immediately slaughtered on arrival at the slaughterhouse. Transport of 3 h might have allowed the animals to adapt to transport conditions and then could act as a resting period like a lairage time. The effect of transport time on welfare and meat quality parameters was more important than genotype and sex. Nevertheless, from the point of view of blood enzyme activities, genetically stress susceptible females transported for 3 h were more sensitive to muscle damage. # 2002 Elsevier Science Ltd. All rights reserved. Keywords: Transport; Welfare; Stress; Meat quality; Pigs

1. Introduction In the last few years, the centralisation of the slaughtering industry, with more animals being killed in fewer larger plants, has modified the distance that animals must be transported to the slaughterhouse. In Spain, the majority of pig farms are located near the slaughterhouse and most pigs are transported less than 50 km and rarely more than 200 km, except for international transport. In general, it is accepted that the duration of the journey is an aspect of transport that can affect the welfare and meat quality of pigs (Bradshaw, Parrott, Goode, Lloyd, Rodway, & Broom, 1996; Grandin, 1993; Hevia, Quiles, & Ramirez, 1995; Warriss, Brown, Edwards, & Knowles, 1998). Palacio et al. (1996), in a * Corresponding author. Tel.: +34-976-761575; fax; +34-976761612. E-mail address: [email protected] (S. Garci´a-Belenguer).

retrospective study, found that the duration of the trip was a risk factor for pig’s mortality. This is an evident indicator of poor welfare during transport (Colleu & Chevillon, 1999; Guardia, Gispert, & Diestre, 1996; Warriss, 1995; Warriss & Brown, 1994). But welfare measurement is not always easy and several welfare indicators should be used. Behaviour, physiological changes related to the stress response and meat quality can yield very useful information (Fraser & Broom, 1990; Tarrant, 1988; Warriss, Brown, Edwards, & Knowles, 1998; Warris, Brown, Barton Gade et al., 1998). The likelihood of occurrence of dark, firm and dry (DFD) and pale, soft and exudative (PSE) meat is related to pre-slaughter stress (Gregory, 1998). Nevertheless there is not a consistent association between indices of stress and meat quality parameters (Bradshaw et al., 1999; Warriss, Brown, Barton Gade et al., 1998). Other factors besides transport time can influence animal welfare during road transport and subsequent

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meat quality. These factors are loading and unloading, stocking density, weather conditions (temperature, air velocity and humidity), vehicle characteristics, food and water deprivation or mixing animals from different groups (Abbott, Guise, Hunter, Penny, Baynes, & Easby, 1995; Barton Gade & Christensen, 1998; Bradshaw et al., 1996; Guise & Penny, 1989a, 1989b; Nanni Costa, Lo Fiego, Dall’Olio, Davoli, & Russo, 1999; Parrott & Misson, 1989; Warriss, 1998). Interactions among these factors, lairage time and treatment during lairage make it difficult to interpret the true effect of transport time on welfare and meat quality (Fernandez & Tornberg, 1991; Geverink, Engel, Lambooij, & Wiegant, 1996; Warriss, Brown, Bevis, & Kestin, 1990; Warriss, Brown, Edwards, & Knowles, 1998). Genotype can also influence susceptibility to stress, transport deaths and meat quality (Gispert et al., 2000; Murray & Johnson, 1998). Stress-susceptible pigs have an abnormality in their muscle metabolism, which makes the muscle over-reactive to stressful stimuli such as high temperatures. The muscle is prone to excessive metabolism and pigs develop hyperthermia and lethal blood potassium levels (Gregory, 1998). The purpose of this study was to determine the effects of transport duration on some welfare and meat quality parameters, comparing a short transport time and a long transport time, according to the actual commercial conditions in Spain. Special interest has been taken in relation to the individual genetic characteristics of the pigs. Animals submitted to exactly the same transport conditions have been compared in order to avoid interaction effects.

mental conditions) in order to compare only the effect of transport time. It was assumed an error by not replicating the transport but many replications would be necessary in order to avoid that error and it would be impossible to control all the factors in transport. Then, transport time was the only difference between both groups. Group 1 covered the usual route from the farm to the slaughterhouse (17 km) and the journey took 15 min, with a mean speed of 68 km/h. Group 2 was transported for 3 h on national roads, travelling a distance of 204 km, with a mean speed of 68 km/h. The same lorry (spring suspension, two decks and six pens, natural ventilation with wide openings along the lorry), the same driver (an experienced driver) and the same loading density (275 kg/m2, mean density used in that slaughterhouse) were used. Both transports were carried out on the same day in the morning. Group 1 was loaded at 04:30 and group 2 at 05:30. On arrival at the slaughterhouse, each group was unloaded and slaughtered immediately under the same conditions during a normal working day. Environment temperature at the moment of unloading was 16 and 17  C for group 1 and 2, respectively, and relative humidity was 70% in both cases. All the animals were slaughtered by normal commercial practices after stunning (500 volts, 1.8 amps) using a restrainer system in an industrial slaughterhouse with an output of 350,000 pigs a year and a slaughter rate of 300 pigs per hour. Exsanguination was carried out with the animals suspended from their left leg in the first 15 s after stunning. Carcasses in the production line arrive at cold-storage room (4  C) 30 min after stunning, where they are kept until commercialisation. 2.2. Blood measurements

2. Material and methods 2.1. Experimental design One hundred and forty-four 110–120 kg (Landrace  Large White) fattened pigs of both sexes (50% of each) were used. All the animals were derived from the same breeding company and the same farm, where fattening pens held 24 mixed sex pigs. The farm was situated 17 km away from the slaughterhouse. The experiment was carried out in autumn. Travel conditions and handling were the same for all 144 pigs. At the moment of loading, the animals had been deprived of food for 12 h. A tailgate lift was used for loading and a ramp (15 slope) for unloading. Animals were always herded using pig boards and without using sticks or electrical goads. Vehicle pens held 12 pigs and the animals were not mixed during transport. Seventy-two pigs were submitted to a short transport time and the other 72 pigs to a long transport time. This design was proposed emphasising the control of all the factors associated the experimental treatment (genotype, sex and environ-

Blood measurements were carried out in order to assess pre-slaughter stress and muscle metabolism. Blood samples were collected at exsanguination and were kept refrigerated until arrival at the laboratory for immediate processing. Haematological parameters: packed cell volume (PCV), haemoglobin (Hb), red blood cells (RBC), and white blood cells (WBC) were analysed immediately with an automatic counter (Sysmex F800). Differential WBC counts were made using blood smears stained with Wright’s stain and examined under a light microscope. EDTA plasma and serum were quickly obtained by centrifugation and aliquots were frozen ( 30  C) for subsequent analysis of cortisol, lactate, glucose, potassium (K) and enzymatic activities of creatine kinase (CK: EC.2.7.3.2.), lactic dehydrogenase (LDH: EC.1.1.1.27.), aspartate amino transferase (AST: EC. 2.6.1.1.) and alanine amino transferase (ALT: EC. 2.6.1.2.). Plasma (EDTA K3) cortisol level was measured by radioimmunoassay (CT-RIA-I125, Biolink 2000 S.L.). Plasma (EDTA KF) lactate concentration

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was measured using a Sigma Diagnostics kit and a spectrophotometer (Perkin Elmer Lambda 5). Serum enzyme activity levels, glucose and K concentrations were analysed by a multianalyser (Technicon RA-500) using Bayer reagents. 2.3. Meat quality measurements Post-mortem measurements of muscle pH were taken at 20 min (pH0), 2 h (pH2) and 24 h (pH24) from the Longissimus thoracis (LT) and at 2 h and 24 h from the Semimembranosus (SM), with a portable pH meter (Crison-507) and penetration electrode. The internal muscle reflectance value using a fibre optic probe (FOP; Diestre, Oliver, & Gispert, 1990) was measured in both muscles at 24 h post-mortem. LT and SM measurements were recorded at 3 cm depth in the region of the last rib and from the free (right) leg, respectively. At 24 h post-mortem, slices of LT muscle (2.5 cm) in the region of the last rib were taken for water-holding capacity evaluation. It was estimated as the drip loss from slices of muscle suspended inside polythene bags and held at 1  C for 24 h. Drip loss was expressed as a percentage of the initial sample weight. Data corresponding to carcass weight was collected individually but yield could only be calculated in relation to the group body live weight. Grading of the carcass was also carried out by a qualified person of the slaughterhouse using a five-point category scale (0= the worst, 4= the best). 2.4. Genetic study Blood from all the animals was analysed in order to detect stress-susceptible pigs. A DNA test for Porcine Stress Syndrome was performed typing the skeletal ryanodine receptor gene (ryr-1). DNA samples of the pigs were isolated from blood. It was amplified to 199 bp DNA fragment including the mutation of ryr-1 gene (exon 4 contains the 1.666 mutation C-T of the ryr-1 gene, X68247 Genebank). The reaction was performed for 30 cycles at a temperature of 62  C. In order to obtain the three different genotypes (CC: 199 bp, Stress Resistant Animals; CT: 199 bp+170 bp+29 bp, Carrier Animals; TT: 170bp+29bp, Stress Susceptible Animals), digestions were carried out with BSIHKAI. 2.5. Data analyses The data were analysed using the statistic program SPSS v. 9.0. A multiple analysis of variance (General Linear Model) was used to examine the effect of transport time (T), genotype (G), and sex (S) on welfare and meat quality parameters. Interactions among explanatory variables (TG, TS, GS) were also included in the model. Least square means and standard error of

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the blood and meat quality parameters for each main effect were obtained from the model. Six cases were missing with this analysis. Scheffe test was applied for multiple comparison among genotypes. Pearson correlation (P < 0.01) was applied between variables in order to establish whether welfare parameters were related to meat quality parameters.

3. Results and discussion This experiment was designed to study welfare and meat quality implications of transport time in actual commercial conditions in Spain, taking into account individual genetic characteristics and sex. Transport conditions were the same for all the animals, which were slaughtered immediately upon arrival in order to avoid interference arising from lairage time and treatment during lairage, as some authors have found (Geverink et al., 1996; Warriss, Brown, Edwards, & Knowles, 1998). Loading density during transit was 275 kg per m2 or 0.36 m2 per 100 kg, which is within the most usual range in Europe (0.35–0.39 m2 per 100 kg; Warriss, 1995). Barton Gade and Christensen (1998) pointed out the risk of increased skin damage with space exceeding 0.35 m2 per 100 kg during transport due to trampling and /or fighting. At this density pigs stay close together and provide support to vehicle motion. In our study, no skin damage and no deaths were registered during transport. Table 1 summarises the significant effects and interactions of explanatory variables (transport time, genotype and sex) on blood and meat quality parameters. 3.1. Effect of transport time on blood measurements Mean values of haematological and biochemical variables investigated in relation to transport time are shown in Table 2. These results show that differential leukocyte counts were significantly influenced by transport time. Both groups presented leukocytosis, but animals transported for 15 min presented lymphocytosis and animals transported for 3 h presented neutrophilia and eosinopenia. Leukocytosis in acutely stressed animals is caused by the endogenous release of corticosteroids or epinephrine. A transient leukocytosis with lymphocytosis is evident within minutes of epinephrine secretion whereas corticosteroid induced changes are not seen until some hours later and produce leukocytosis with neutrophilia and eosinopenia (Jain, 1993). Pigs transported for a short time seem to show a typical epinephrine response and the cortisol effects can be seen in longer transported animals. Red cell parameters did not show significant differences between the groups. Lactate and cortisol mean concentrations were significantly greater in the group transported for 15 min compared with the group transported for 3 h. Cortisol

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Table 1 Significant results of blood and meat quality parameters from multiple analysis of variance including transport time (T), genotype (G) and sex (S) as main effects and TG, TS and GS as interactions Main effects T Red blood cells Haemoglobin Packed cell volume White blood cells Monocytes Lymphocytes Neutrophils Basophils Eosinophils Lactate Glucose Cortisol Potassium Alanine amino transferase Aspartate amino transferase Creatine kinase Lactic dehydrogenase pH 0 Longissimus thoracis pH 2 Longissimus thoracis pH 24 Longissimus thoracis pH 2 Semimembranosus pH 24 Semimembranosus FOP 24 Longissimus thoracis FOP 24 Semimembranosus Carcass weight Carcass grading Drip loss 24 h

Interactions G

S

TG

TS

GS

* ** *** *** *** *

** * **

** *** *** ** ** * *

*

**

* P <0.05. ** P<0.01. *** P< 0.001.

release is probably very high at the beginning of the journey, as can be seen in pigs transported only 15 min. Loading at the farm involves considerable stress for pigs forced to move from the fattening units to the truck interior, although it may not have a negative effect on meat quality (Nanni Costa et al., 1999). After the first few minutes of transport, the animals probably adapt to travel conditions when these conditions are not too severe, as can be seen by the evident lower cortisol concentration observed in pigs transported for 3 h. Barton Gade and Christensen (1998) observed that pigs increasingly began to sit and lie down after 20–30 min of transport. In cattle, maximum cortisol levels can be found after 5–15 min of stimulus presentation and remain high during 15–30 min (Vessier & Le Neindre, 1988). In ovariectomized gilts, Dalin, Magnusson, Ha¨ggendal, and Nyberg (1993) found that plasma cortisol levels rose immediately after the start of transport and decreased rapidly after unloading. Nevertheless, in contrast to our results, Warriss, Brown, Edwards, and Knowles (1998) observed that pigs transported from farms over long distances (> 120 km) had higher cortisol concentration than those tra-

velling from farms only a short distance away (< 10 km). This difference may be due to the effects of the farm and travel conditions. Higher lactate concentration found in pigs transported over a shorter distance might also be an indicator of physical stress and might be one of the reasons for lower pH values obtained in this group (Klont, Lambooy, & van Logtestijn, 1993; Warriss, Brown, Edwards, & Knowles, 1998). Glucose concentration was within the normal range for the species in both groups (Kaneko, 1989), although pigs transported for 3 h were submitted to a longer starvation period. Cortisol released in the first minutes of transport might be the cause of glycemia in this group. Hicks, McGlone, Whisnant, Kattesh, and Norman (1998) described an increase of glycemie after 4 h transport by ship. Lethal potassium levels were detected in all the animals after stunning and slaughter and there was no effect of genotype on levels, as other authors have described (Gregory, 1998). High ALT, AST, CK and LDH plasma activities were observed in all the animals, which can be interpreted as an index of cell muscle damage and muscle fatigue

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Table 2 Least squares means (standard error) for blood and meat quality parameters in relation to transport time Transport timea

Red blood cells (106/mm3) Haemoglobin (g/dl) Packed cell volume (%) White blood cells (103/mm3) Monocytes (%) Lymphocytes (%) Neutrophils (%) Eosinophils (%) Lactate (mg/dl) Glucose (mg/dl) Cortisol (ng/ml) Potassium (mEq/l) Alanine amino transferase (UI/l) Aspartate amino transferase (UI/l) Creatine kinase (UI/l) Lactic dehydrogenase (UI/l) pH 0 Longissimus thoracis pH 2 Longissimus thoracis pH 24 Longissimus thoracis pH 2 Semimembranosus pH 24 Semimembranosus FOP 24 Longissimus thoracis FOP 24 Semimembranosus Carcass weight (kg) Carcass grading Drip loss 24 h (%) a

15 min (n=70)

3 h (n=68)

10.10 14.69 46.31 24.21 2.69 69.14 24.64 3.01 155.08 111.85 88.51 11.77 53.55 87.51 4352.50 1311.08 6.21 5.79 5.37 5.53 5.45 34.28 43.54 88.71 1.52 1.66

10.89 15.16 48.74 23.44 2.94 35.90 60.67 0.28 136.06 119.32 59.05 12.56 56.48 141.22 7104.86 1933.14 6.20 5.82 5.46 5.70 5.51 29.70 33.71 91.81 1.34 1.24

(0.31) (0.18) (1.60) (0.67) (0.36) (1.53) a (1.47) a (0.30) a (6.37) a (4.79) (6.45) a (0.27) (1.82) (3.77) (606.87) (80.95) (0.06) (0.07) (0.03) a (0.05) a (0.02) (2.22) (1.90) a (1.51) (0.14) (0.18)

(0.36) (0.20) (1.58) (0.77) (0.42) (1.78) b (1.71) b (0.35) b (7.39) b (5.55) (6.90) b (0.32) (2.12) (4.38) (704.08) (93.92) (0.06) (0.08) (0.03) b (0.06) b (0.03) (2.62) (2.24) b (1.75) (0.16) (0.18)

Different letters indicate significant differences between groups (P<0.05).

(Payne & Payne, 1987). Nevertheless, significant effects of transport time, genotype and sex on these enzymes activities were detected with also significant interactions among the main effects (Table 1). Since it is not possible to say anything about main effects when there are significant interactions, the levels of significance for main effects had not been included in tables. Table 5 shows mean values of the product transport time  genotype  sex for these enzymes and evidences that the effect of transport time on muscle enzymes depends on genotype and sex, being TT females the most sensitive ones to long transport. On the other hand, CK and LDH activities were significantly (P< 0.01) and negatively correlated with pH measurements in LT muscle (CK-pH0: r= 0.30; CKpH2: r= 0.27; LDH-pH0: r=0.39; LDH-pH2: r= 0.29; LDH-pH24: r= 0.38). Although this correlation could indicate a relationship between muscle cell damage and muscle pH, it may be also influenced by genotype. In fact, the effect of genotype on muscle enzymes is clear although it depends on transport time and sex (Table 5). In general, stress susceptible pigs presented the highest enzyme activities as other authors had already described (von Presuhn, Richter, & Krieter, 1997). Nevertheless, it was not observed as an effect of TT genotype on muscle pH in

this work. It might be that the effect of genotype on muscle enzymes was more consistent than its effect on muscle pH. In general, the changes seen in the blood profile indicate that moderately long transport (3 h) in normal Spanish commercial conditions does not increase the amount of stress exhibited by pigs at the abattoir when they are slaughtered immediately upon arrival. Nevertheless, from the point of view of muscle damage TT females could be more sensitive to long transport than pig males or other genotypes are. 3.2. Effect of transport time on meat quality Means of meat quality parameters in relation to transport time are shown in Table 2. Pigs transported for 15 min showed significant lower pH24 in LT muscle (P < 0.05) and also a tendency to show lower pH24 values in the SM (P=0.09) compared with animals transported for 3 h. LT and SM in pH24 values appear lightly lower than the normal range (5.6–6) in both groups. The animals transported for 15 min showed the most acid muscle pH24. The pH2 in SM was also significantly lower in group 1 (P < 0.01), showing a quicker post-mortem pH decrease in pigs transported for 15 min. FOP24 values in SM muscle of the animals trans-

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ported 15 min were significantly higher than in the animals transported longer. Bradshaw et al. (1999) classified pigs with FOP values in excess of 40 in LT or SM muscles as PSE, considering values of 40–50 as slightly PSE. In the present study, pigs submitted to the shorter journey were in this FOP range for SM muscle. From these results it seems that pigs subjected to short journeys have higher tendency to produce PSE meat than pigs transported longer, when transit is in line with normal commercial conditions in Spain. Valenta and Provaznik (1996) also described higher incidence of PSE meat after short transport (< 40 km) although they rested the pigs for 1–4 h before slaughter. In the same way, other authors have found that when transport distance increased, the incidence of meat with high ultimate pH increased (Scheper, 1971). Nevertheless, Warris, Dudley, and Brown (1983) found a lack of effect of transport time on ultimate muscle pH and Gispert et al. (2000) found a lower proportion of acceptable meat quality in pigs subjected to long transport (> 2 h) compared with short transport (< 2 h). Fernandez and Tornberg (1991) in a wide review of the causes of variation of ultimate pH in pigs, observed that it was difficult to draw a conclusion regarding the effect of transport time because of the different results obtained from different

authors and that this might point to the fact that several factors interact. In our study and in spite of the lack of replication in the experimental design, all other factors have been controlled. Transport of three hours could allow the animals to adapt to transport conditions and then could act as a resting period like a lairage time, which may be beneficial in reducing the level of PSE meat (Honkavaara, 1989; Warriss, Brown, Edwards, & Knowles, 1998). From these results, probably pigs submitted to short transport could need longer lairage time as resting time. Other meat quality characteristics did not show significant differences between groups. Total mean from hot carcass weight, yield and carcass grading was 89.2  8.9 kg, 77.7% and 1.5  0.7, respectively. Association between welfare and meat quality parameters was not very consistent but the results described above and the significant correlation between FOP24 SM and cortisol (r=0.41, P < 0.01), might imply more tendency to poorer meat quality in pigs showing a more intense stress response. In general, most authors have not found a consistent relationship between indices of stress and meat characteristics (Barton Gade & Christensen, 1998; Bradshaw et al., 1999; Warriss, Brown, Barton-Gade et al., 1998).

Table 3 Least squares means (standard error) for blood and meat quality parameters in relation to genotype and the levels of significance between the different genotypes Genotypea

Red blood cells (106/mm3) Haemoglobin (g/dl) Packed cell volume (%) White blood cells (103/mm3) Monocytes (%) Lymphocytes (%) Neutrophils (%) Eosinophils (%) Lactate (mg/dl) Glucose (mg/dl) Cortisol (ng/ml) Potassium (mEq/l) Alanine amino transferase (UI/l) Aspartate amino transferase (UI/l) Creatine kinase (UI/l) Lactic dehydrogenase (UI/l) pH 0 Longissimus thoracis pH 2 Longissimus thoracis pH 24 Longissimus thoracis pH 2 Semimembranosus pH 24 Semimembranosus FOP 24 Longissimus thoracis FOP 24 Semimembranosus Carcass weight (kg) Carcass grading Drip loss 24 h (%) a

CC (n=41)

CT (n=85)

TT (n=12)

10.29 15.03 47.35 21.73 2.61 53.14 41.37 2.47 131.46 111.06 68.07 11.83 49.36 69.32 1910.5 1066.2 6.28 5.97 5.46 5.66 5.52 29.02 35.93 91.95 1.71 1.45

10.58 14.86 47.10 23.44 3.12 52.92 41.96 1.38 134.62 107.60 79.49 12.28 49.82 80.60 3541.1 1229.6 6.18 5.69 5.38 5.61 5.48 32.66 39.18 88.13 1.46 1.45

10.60 14.88 48.12 26.31 2.72 51.47 44. 65 1.09 170.63 128.10 81.25 12.38 65.86 193.18 11734.5 2570.5 6.15 5.75 5.40 5.56 5.43 34.29 40.78 90.70 1.13 1.45

(0.30) (0.17) (1.34) (0.65)a (0.35) (1.51) (1.45) (0.30) a (6.26) a (4.71) (6.16) (0.27) (1.79) (3.71) (596.6) (79.6) (0.06) (0.06) a (0.03) (0.05) (0.03) (2.50) (2.14) (1.48) (0.14) (0.14)

Different letters indicate significant differences between groups (P<0.01).

(0.19) (0.11) (0.85) (0.42) b (0.25) (0.96) (0.93) (0.19) ab (4.00) a (3.01) (7.16) (0.17) (1.15) (2.37) (381.1) (50.8) (0.04) (0.04) b (0.04) (0.04) (0.03) (2.50) (2.14) (0.95) (0.09) (0.19)

(0.61) (0.34) (2.69) (1.32) b (0.71) (3.04) (2.92) (0.60) b (12.61) b (9.48) (8.86) (0.54) (3.61) (7.47) (1201.2) (160.2) (0.11) (0.12) ab (0.04) (0.11) (0.04) (3.75) (3.21) (2.98) (0.28) (0.12)

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3.3. Effect of genetics and sex The genetic study showed the following distribution by groups. Group 1: CC 17%, CT 73% and TT: 10%. Group 2: CC 43%, CT 50% and TT 7%. Distribution by sex was approximately 50% of each in both groups. The multiple analysis of variance (Table 1) showed a significant effect of genotype TT on WBC and lactate concentration. Stress-susceptible pigs (TT) showed the highest levels of lactate in blood compared with the other genotypes, as it is shown in Table 3. Besides, interactions detected for blood enzyme activities also indicate a genotype effect on these enzymes (Table 5). These results would indicate a more intense physical stress response in TT pigs. This is in concordance with the results obtained by von Presuhn et al., (1997) but in contrast to that obtained by Cabadaj et al. (1993). In agreement with Klont et al. (1993) we found that under low pre-slaughter stress conditions the genotype effect on post-mortem pH fall was minimal. Murray and Johnson (1998) found that approximately 90% of the PSE condition in Western Canada were caused by factors other than the halothane gene, but the gene had a major negative influence on the frequency of preslaughter deaths. Other authors have found that serious PSE defect was directly linked to genotype frequency

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(Gispert et al., 2000). Surprisingly, from our results the effect of transport time on meat quality parameters was more important than genotype effect. Sex had a significant effect on haemoglobin and glucose concentration, which were higher in females, and on pH2 SM, which was higher in males indicating quicker pH fall in females (Table 4). Besides, significant interactions with transport time and genotype were observed for blood enzymes (Table 1). These results are difficult to interpret but it might indicate that females are more sensitive to physical stress of transport and specially female’s carriers of stress susceptible gene (Table 5). Interaction between sex and stress has already been described. Van der Wal, Engel, and Reimert (1999) found that gilts reacted more strongly to short periods of stress than did boars.

4. Conclusions From our results and taking into account the lack of replication of transports, we have observed that in normal Spanish commercial conditions, pigs subjected to short transport (15 min) showed a more intense stress response and poorer meat quality than pigs subjected to moderately long transport (3 h), when they are immedi-

Table 4 Least squares means (standard error) for blood and meat quality parameters in relation to sex Sexa

6

3

Red blood cells (10 /mm ) Haemoglobin (g/dl) Packed cell volume (%) White blood cells (103/mm3) Monocytes (%) Lymphocytes (%) Neutrophils (%) Eosinophils (%) Lactate (mg/dl) Glucose (mg/dl) Cortisol (ng/ml) Potassium (mEq/l) Alanine amino transferase (UI/l) Aspartate amino transferase (UI/l) Creatine kinase (UI/l) Lactic dehydrogenase (UI/l) pH 0 Longissimus thoracis pH 2 Longissimus thoracis pH 24 Longissimus thoracis pH 2 Semimembranosus pH 24 Semimembranosus FOP 24 Longissimus thoracis FOP 24 Semimembranosus Carcass weight (kg) Carcass grading Drip loss 24 h (%) a

Female (n=66)

Male (n=72)

10.37 15.25 47.01 22.98 3.08 53.05 42.00 1.64 152.65 126.09 80.23 12.33 56.64 135.50 6868.20 1882.76 6.20 5.80 5.45 5.52 5.47 29.72 37.76 88.94 1.34 1.32

10.61 14.61 48.04 24.66 2.56 51.98 43.31 1.65 138.49 105.09 67.33 12.00 53.39 93.23 4589.17 1361.46 6.21 5.80 5.38 5.70 5.49 34.26 39.50 91.59 1.52 1.52

Different letters indicate significant differences between groups (P<0.05).

(0.40) (0.23) a (1.76) (0.86) (0.47) (1.98) (1.91) (0.39) (8.25) (6.20) a (7.86) (0.35) (2.36) (4.88) (785.28) (104.75) (0.07) (0.09) (0.03) (0.07) a (0.03) (2.89) (2.48) (1.95) (0.18) (0.22)

(0.25) (0.14) b (1.12) (0.55) (0.29) (1.26) (1.21) (0.25) (5.22) (3.92) b (5.24) (0.22) (1.50) (3.09) (497.35) (66.34) (0.05) (0.05) (0.02) (0.04) b (0.02) (1.85) (1.58) (1.23) (0.11) (0.14)

M.P. Pe´rez et al. / Meat Science 61 (2002) 425–433

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Table 5 Least square means (standard error) for the variables with significant interaction effect of transport time, genotype and sexa Transport time

Genotypeb

Sex

CC ALT (UI/l)

15 minutes 3h

AST (UI/l)

15 min 3h

CK (UI/l)

15 min 3h

LDH (UI/l)

15 min 3h

a b

CT

TT

Female Male Female Male 49.4 (2.7) ab

56.2 44.6 47.3 50.9

(4.6) (3.9) (2.8) (2.4)

ac b ab ab

55.3 48.5 44.5 63.7

(2.0) (2.1) (2.7) (5.2)

ac b b c

Female Male Female Male

83.2 66.0 63.4 64.7

(9.6) (8.1) (5.7) (5.5)

ac ab b b

78.3 80.3 85.1 78.7

(4.1) (4.3) (5.5) (4.9)

a ac ac a

106.0 111.2 397.0 158.5

(15.1) cd (9.6) d (21.4) e (10.7) f

Female Male Female Male

2276 1434 1974 1957

(1538) ab (1300) a (919) a (888) a

3238 2891 5073 2964

(662) (688) (888) (789)

ab a b a

8230 8048 20420 10240

(2433) (1538) (3440) (1720)

Female Male Female Male

1146 1025 1052 1040

(205) (173) (122) (118)

1181 1106 1464 1166

(88) a (91) a (118) a (105) a

1420 1987 5032 1843

(324) (205) (458) (229)

a a a a

53.5 (7.3) abc 63.2 (4.6) c 83.0 (10.3) d

bc bc d c

a b c b

ALT, alanine amino transferase; AST, aspartate amino transferase; CK, creatine kinase, LDH, lactic dehydrogenase. Different letters indicate significant differences between groups (P <0.05).

ately slaughtered on arrival at the slaughterhouse. Transport for 3 h may have allowed the animals to adapt to the transport conditions and then could act as a resting period like a lairage time. Probably pigs subjected to short transport would need longer lairage time as resting time. From our results the effect of transport time on welfare and meat quality parameters was more important than the effect of genotype and sex. Nevertheless, TT females transported during 3 h were more sensitive to muscle damage.

Acknowledgements This work was funded by the Comisio´n Interministerial de Ciencia y Tecnologı´a (CICYT) of the Spanish Government (Project Reference AGF96/2309). The authors would like to thank the Official Veterinary Services (JA Angel, JC Lles, B Lobera, I Martı´n-Maestro, F Bayo and L Til), the management (specially A. Espada) and workers of the slaughterhouse. We also thank Diarmuid Magourty for his translation.

References Abbott, A., Guise, H. J., Hunter, E. J., Penny, R. H., Baynes, P. H., & Easby, C. (1995). Factors influencing pig deaths during transit: an analysis of drivers’reports. Animal Welfare, 4, 29–40. Barton Gade, P., & Christensen, L. (1998). Effect of different stocking densities during transport on welfare and meat quality in Danish slaughter pigs. Meat Science, 48, 237–247. Bradshaw, R. H., Parrott, R. F., Goode, J. A., Lloyd, D. M., Rodway, R. G., & Broom, D. M. (1996). Behavioral and hormonal responses

of pigs during transport: effect of mixing and duration of journey. Animal Science, 62, 547–554. Bradshaw, R. H., Randall, J. M., Forsling, M. L., Rodway, R. G., Goode, J. A., Brown, S. N., & Broom, D. M. (1999). Travel sickness and meat quality. Animal Welfare, 8, 3–14. Cabadaj, R., Lega´th, J., Pleva, J., Ma´te´, D., Turek, P., Lohajova´, L., Nagy, J., & Mala, P. (1993). Activity of some enzymatic parameters in halothane positive and negative pigs during their fattening and after transport to the slaughter-house. Folia Veterinaria, 37, 23–26. Colleu, T., & Chevillon, P. (1999). Incidence des parame`tres climatiques et des distances sur la mortalite´ des porcs en cours de transport. Techni Porc, 22, 31–36. Dalin, A. M., Magnusson, U., Ha¨ggendal, J., & Nyberg, L. (1993). The effect of transport stress on plasma levels of catecholamines, cortisol, corticosteroid-binding globulin, blood cell count, and lymphocyte proliferation in pigs. Acta Veterinaria Scandinavica, 34, 59–68. Diestre, A., Oliver, N. P., & Gispert, M. (1990). Me´todos predictores de la calidad de la carne en el porcino: dispersio´n interna de la luz y conductividad ele´ctrica. Anaporc, 89, 45–57. Fernandez, X., & Tornberg, E. (1991). A review of the causes of variation in muscle glycogen content and ultimate pH in pigs. Journal of Muscle Foods, 2, 209–235. Fraser, A. F., & Broom, D. M. (1990). Farm animal behaviour and welfare. London: Bailliere Tindall. Geverink, N. A., Engel, B., Lambooij, E., & Wiegant, V. M. (1996). Observations on behaviour and skin damage of slaughter pigs and treatment during lairage. Applied Animal Behaviour Science, 50, 1–13. Gispert, M., Faucitano, L., Oliver, M. A., Guardia, M. D., Coll, C., Siggens, K., Harvey, K., & Diestre, A. (2000). A survey of pre-slaughter conditions, halothane gene frequency, and carcass and meat quality in five Spanish pig commercial abbatoirs. Meat Science, 55, 97–106. Guardia, M. D., Gispert, M., & Diestre, A. (1996). La mortalidad en ganado porcino durante el periodo previo al sacrificio en mataderos comerciales. Investigacio´n Agraria: Produccio´n y Sanidad Animales, 11, 170–180. Guise, H. J., & Penny, H. C. (1989a). Factors influencing the welfare and carcass and meat quality of pigs. 1. The effects of stocking density in transport and the use of electric goads. Animal Production, 49, 511–515.

M.P. Pe´rez et al. / Meat Science 61 (2002) 425–433 Guise, H. J., & Penny, H. C. (1989b). Factors influencing the welfare and carcass and meat quality of pigs. 2. Mixing unfamiliar pigs. Animal Production, 49, 517–521. Grandin, T. (1993). Livestock, handling and transport. UK: CAB International. Gregory, N. G. (1998). Animal welfare and meat science. UK: CAB International. Hevia, M. A., Quiles, A., & Ramirez, A. (1995). Produccio´n y bienestar animal del ganado porcino durante el transporte. Anaporc, 150, 101–108. Hicks, T. A., McGlone, J. J., Whisnant, C. S., Kattesh, H. G., & Norman, R. L. (1998). Behavioural, endocrine, immune and performance measures for pigs exposed to acute stress. Journal of Animal Science, 76, 474–483. Honkavaara, M. (1989). Influence of lairage on blood composition of pig and on the development of PSE pork. Journal of Agricultural Science in Finland, 61, 425–432. Jain, N. C. (1993). Essentials of veterinary hematology. Philadelphia: Lea & Febiger. Kaneko, J. J. (1989). Clinical biochemistry of domestic animals. New York: Academic Press. Klont, R. E., Lambooy, E., & van Logtestijn, J. G. (1993). Effect of preslaughter anesthesia on muscle metabolism and meat quality of pigs of different halothane genotypes. Journal of Animal Science, 71, 1477–1485. Murray, A. C., & Johnson, C. P. (1998). Impact of the halothane gene on muscle quality and pre-slaughter deaths in Western Canadian pigs. Canadian Journal of Animal Science, 78, 543–548. Nanni Costa, L., Lo Fiego, D. P., Dall’Olio, S., Davoli, R., & Russo, V. (1999). Influence of loading method and stocking density during transport on meat and dry-cured ham quality in pigs with different halothane genotypes. Meat Science, 51, 391–399. Palacio, J., Garcı´a-Belenguer, S., Gasco´n, F. M., Liste, F., Ortega, C., Lobera, B., Martı´n-Maestro, I., Angel, J. A., Lles, J. C., & Bayo, F. (1996). Mortalidad durante el transporte a un matadero en ganado porcino. Investigacio´n Agraria: Produccio´n y Sanidad Animales, 11, 159–170. Parrott, R. F., & Misson, B. H. (1989). Changes in pig salivary cortisol in response to transport simulation, food and water deprivation and mixing. British Veterinary Journal, 145, 501–505.

433

Payne, J. M., & Payne, S. (1987). The metabolic profile test. UK: Oxford Science Publications. Scheper, J. (1971). Research to determine the limits of normal and aberrant meat quality (PSE and DFD) in pork. In Proceedings 2nd International Symposium of Condition Meat Quality in Pigs (pp.271277). Zeist, Pudoc. Wageningen. Tarrant, P. V. (1988). Le stress du transport chez les animaux de ferme. Recuil de Me´dicine Ve´te´rinaire, 164, 823–833. Valenta, J., & Provaznik, J. (1996). PSE defects of meat. Meat Focus International, 5, 192. von Presuhn, U., Richter, L., & Krieter, X. (1997). Die Einbindung des Creatin-Kinase-Testes in das Selektionsschema eines Schweinezuchtprogrammes. Deutsche Tierarztliche Wochenschrift, 104, 379–380. Van der Wal, P. G., Engel, B., & Reimert, H. G. M. (1999). The effect of stress, applied immediately before stunning, on pork quality. Meat Science, 53, 101–106. Vessier, I., & Le Neindre, P. (1988). Cortisol responses to physical and pharmacological stimuli in heifers. Reproduction, Nutrition & Development, 28, 553–562. Warriss, P. D. (1995). Pig handling. Meat Focus International, 4, 491– 494. Warris, P. D. (1998). Choosing appropriate space allowances for slaughter pigs transported by road: a review. Veterinary Record, 142, 449–454. Warriss, P. D., & Brown, S. N. (1994). A survey of mortality in slaughter pigs during transport and lairage. The Veterinary Record, 134, 513–515. Warriss, P. D., Brown, S. N., Barton Gade, P., Santos, C., Nanni Costa, L., Lambooij, E., & Geers, R. (1998). An analysis of data relating to pig carcass quality and indices of stress collected in the European Union. Meat Science, 49, 137–144. Warriss, P. D., Brown, S. N., Bevis, E. A., & Kestin, S. C. (1990). The influence of pre-slaughter transport and lairage on meat quality in pigs of two genotypes. Animal Production, 50, 165–172. Warriss, P. D., Brown, S. N., Edwards, J. E., & Knowles, T. G. (1998). Effect of lairage time on levels of stress and meat quality in pigs. Animal Science, 66, 255–261. Warriss, P. D., Dudley, C. P., & Brown, S. N. (1983). Reduction of carcass yield in transported pigs. Journal of Science, Food and Agricultural, 34, 65–74.