The effect of stocking density in transit on the carcass quality and welfare of slaughter pigs: 2. Results from the analysis of blood and meat samples

In a trial involving 2496 pigs, the influences on blood profile and pork quality of stocking densities ranging from 201 to 321 kg m⁻² were examined. The pigs came from four different farms and were killed in 16 weekly batches. They were transported for on average 3 hr and held in lairage for 1 hr. Higher stocking densities resulted in more physical stress to the pigs based on the activity of the enzyme CPK in the blood. Stocking density did not apparently affect psychological stress and high densities did not result in dehydration. The colour, water holding capacity and instrumentally-determined texture of the pork from the carcasses of the pigs were not affected by stocking density. The experimental design and precision of the measurements were sufficient to detect numerous differences in blood profile and pork quality between pigs from the four source farms. These differences probably related to different degrees of stress-susceptibility. The results suggest that the highest stocking density examined (321 kg m⁻²) is unacceptable for the transport of pigs. The second highest density (281 kg m⁻²) produced relatively little evidence of an adverse effect on the welfare of pigs. It may be scientifically acceptable for short journeys (≤3 hr) but not for longer ones where pigs need more space to lie down.     

Effect of different stocking densities during transport on welfare and meat quality in Danish slaughter pigs

Four stocking densities (0.35, 0.39, 0.42 and 0.50 m² per 100 kg pig) were investigated under Danish early Autumn conditions (16–24 ° C) in a study of the effect of transport conditions on pig welfare and meat quality. Two transports were carried out for each stocking density, the two producers concerned delivering pigs to the upper and lower tiers, respectively, of a specialist pig transport vehicle. Total average journey time was 2 hr 39 min and total average transport time 1 hr 47 min. After arrival at the factory pigs were lairaged in groups of 15 for about hr and then slaughtered using minimal stress with group CO₂-stunning. Pig behaviour was monitored during transport in the front compartment of the lower tier. Blood samples were taken at slaughter for analysis of creatine phosphokinase, lactate and cortisol and carcasses were evaluated for skin damage and meat quality. Stocking density, as such, had relatively little effect on blood profile or meat quality. Creatine phosphokinase levels were lowest with a stocking density of 0.50 m² and the incidence of unacceptable skin damage was generally lowest with a stocking density of 0.35 m² and highest with 0.42 m². The main source of variation in this experiment was day of transport/slaughter within stocking density so that factors other than stocking density have affected the results obtained. Stocking density had a direct effect on pig behaviour during transport. Giving pigs more space during the short transport did not result in them lying down. On the contrary there was continuous disturbance from other pigs and at 0.42 and 0.50 m² pigs had difficulty maintaining balance, when the vehicle negotiated bends or poor road surfaces. Variations in pig behaviour during transport could account for the observed differences in skin damage.     

The effect of the sticking method on the welfare of slaughter pigs

A project was undertaken to investigate the causes of inadequate sticking encountered during a survey of pig abattoirs. The results of the investigation identified the length of the sticking (exsanguination) wound as a major contributor to the problem. Experimental abattoir trials conducted on slaughter pigs comparing two sticking lengths indicated that the rate of bleed out was delayed with short sticking wounds. In addition, information about the identity of blood vessels severed following sticking was obtained. The results indicate that following head-only electrical stunning, a relatively long sticking wound should provide better welfare in slaughter pigs. The study has also highlighted the health and safety problems for the operatives as well as the welfare concerns associated with manual application of electrical stunning.     

The effect of journey time and stocking density during transport on carcass and meat quality in rabbits

Four hundred and fifty hybrid commercial rabbits (half males and half females) at the end of their productive cycle (82 days old) were transported in cages (98 × 52 × 24 cm, length × width × height) at high or low density (75.5 or 49.0 kg/m² – 15 or 10 animals per cage) on an uncovered truck for 1, 2 or 4 h. Live weight before and after transport as well as slaughter data were recorded for each rabbit. A subset of 180 carcasses were evaluated for meat quality on the basis of meat pH, colour (CIELab system), cooking loss, drip loss and shear force. As a representative of the whole carcass muscle/bone ratio, the left hind leg was separated, dissected and its meat analysed in order to determine its water, protein, ash and lipid content. It was found that a longer journey significantly increases the live weight losses (3.3% vs. 2.0% vs. 1.6% for 4, 2 or 1 h, respectively; P < 0.001), as a result not only of urine and fecal losses, but also of a decrease in carcass weight (P < 0.01) during transport. Ultimate pH (pH_u) was higher and pH drop lower in rabbits transported for 4 h compared to those transported for 2 h (P < 0.05). Moreover, the meat from animals that had undergone the longest journey was more purple-red (P < 0.05), darker (P < 0.0001), and firmer when raw and showed less cooking loss than meat from those that underwent shorter journeys. Transport density did not influence any of the considered parameters and there was no interaction between transport time and density.     

The relationship between exsanguination blood lactate concentration and carcass quality in slaughter pigs

A group of 128 cross-bred barrows were used to determine the relationship between exsanguination blood lactate concentration ([LAC]) and carcass quality following commercial marketing conditions. After 10 h of feed withdrawal, pigs were loaded on a truck with a hydraulically lifted second deck and transported approximately 1 h to the slaughter facility. Pigs were rested for 8 h and stunned with carbon dioxide. Blood lactate concentration was measured on exsanguination blood. Fourteen pork quality measurements were obtained following normal post-mortem processing. Pearson correlations were used to determine the relationships between [LAC] and the meat quality parameters. Exsanguination blood lactate concentration ranged from 4 to 19.7 mM. Higher lactate was associated with lower 60 min pH (P = 0.0004) and higher drip loss (P = 0.02). These results suggest that under low-stress loading and standard marketing conditions, exsanguination [LAC] is predictive of the rate of early post-mortem metabolism.     

The effect of stocking density during 4 hour transport to slaughter on behaviour, blood constituents and carcass bruising in Friesian steers

The aim of this work was to assess the response of Friesian steers to road transportation at low, medium and high (ca 200, 300 and 600 kg/m(2)) stocking densities in terms of physiology, behaviour and carcass bruising. Stocking density was determined by adjusting the number of animals per pen (3 runs) or by adjusting pen size (3 runs). Plasma cortisol and glucose increased (P < 0·001) with stocking density, as did plasma CK activity (P < 0·001) and carcass bruising (P < 0·01) both of which indicate muscle damage. At constant stocking density stress increased with pen location towards the tail of the truck, as reflected by a significant increase in plasma cortisol. Stocking density influenced standing orientation within the truck. At low stocking density animal movement was unrestricted and the preferred orientation was standing parallel to the direction of travel; there was a strong bias against diagonal orientations. Losses of balance were associated with specific driving events, notably braking and cornering. Minor losses of balance were observed at all stocking densities, but major losses of balance including animals going down underfoot were associated with high density. When an animal went down at high stocking density it did so involuntarily and was sometimes trapped down, destabilizing other members of the group in a domino effect. Exploratory, sexual and aggressive behaviours were inhibited at high stocking density, with the exception of mounting and pushing, which increased in frequency with stocking density. It was concluded that the high stocking density adversely affected animal welfare and lowered carcass quality when compared with the medium and low stocking densities.     

Effects of slaughter weight on carcass composition and meat quality in pigs of two different growth rates

Three hundred and forty (340) Duroc×(Landrace×Yorkshire) crossbred piglets were allotted to a 2×2×3 factorial design experiment. The independent variables were the growth rate (fast: around -10 days at 100kg and slow: around +2 days at 100kg), based on two different EBV's (estimated breeding value) of the sire-line for age, the sex (barrows and gilts) and the live weight at slaughter (107, 115 and 125kg). A sub-population of 119 pigs (10 carcasses per treatment) was selected for the carcass and meat quality evaluation trials. As live weight increased there were significant increases in hot carcass weight and dressing percentage (P<0.05). Lean, fat and bone proportions were not affected by weight. Gilts had higher lean proportion (P<0.05) than barrows. Furthermore, carcasses of fast growing pigs were fatter (P<0.05) than those of slower growing ones. Loin muscle pH, drip loss and reflectance values did not vary significantly with any of the treatments. Intramuscular fat was higher in barrows (P<0.05) than in gilts and soluble collagen content decreased with increasing weight (P<0.05). Muscle protein (%) increased (P<0.05) from 107 to 115kg and gilts had a higher (P<0.05) content than castrates. No evidence was found that increasing slaughter weight detracts from carcass characteristics or meat quality.     

Effect of different carbon dioxide concentrations and exposure times in stunning of slaughter pigs: Impact on animal welfare and meat quality

The objective of this study was to determine the impact of different slaughter procedures on animal welfare and meat quality. Before slaughter in a dip-lift, one-gondola system, 460 pigs were exposed to an atmosphere containing either 80% or 90% CO(2) for 70 or 100s, and at the longer exposure time with stun-to-stick intervals of either 25-35 or 40-50s. Clinical parameters (reflexes, catecholamines and lactate) showed deficiencies in animal welfare after stunning with 80% CO(2) for 70 and 100s, with an interval of 40-50s, and with 90% CO(2) for 70s. Stunning with 80% CO(2) for 70 or 100s always induced stress, as indicated by higher lactate levels, and reduced meat quality as indicated by low pH(24) values (5.4 in Musculus longissimus and 5.5 in Musculus semimembranosus) and low impedance (Py(24)) values, especially in combination with the longer stun-to-stick interval (40-50s). Stunning with 80% or 90% CO(2) in a dip-lift system was found to be acceptable for animal welfare (percentage of clinical reflexes) only in combination with the longer exposure time of 100s and the shorter stun-to-stick times of 25-35s. When 90% CO(2) was used, the longer stun-to-stick interval of 40-50s also gave results acceptable with regard to animal welfare. Generally, in comparison to 80% CO(2) stunning meat quality was superior (higher pH(24) and Py(24) values) after stunning with 90% CO(2).     

Effect of stocking density and group size on growth performance,carcass traits and meat quality of outdoor-reared rabbits

The effect of stocking density (16 rabbits/m², 5 rabbits/m², 2.5 rabbits/m², n = 60, Experiment 1) and group size (4 rabbits/cage, 8 rabbits/cage, 16 rabbits/cage, n = 88, Experiment 2) on productive performance, carcass and meat quality of a slow-growing rabbit population reared outdoors was investigated in two experiments. The highest stocking density induced the highest skin percentage. Lower stocking densities showed lower lightness of Biceps femoris and higher redness of Longissimus lumborum muscles. Four rabbits/cage group (Experiment 2) showed the highest daily weight gain and slaughter weight and the lowest skin percentage. The muscles of 16 rabbits/cage showed significantly higher pHu than 8 and 4 rabbits/cage. BF of 16 and 4 rabbits/cage showed higher L* value. Productive performance and meat quality of rabbits reared outdoors improved in low group size while stocking density needs more experiments. The best combination of density, group size and total available surface that showed the best production and carcass traits was of 5 rabbits/m², 4 rabbits/cage, and 0.8 m².     

Salmonella in slaughter pigs: the effect of logistic slaughter procedures of pigs on the prevalence of Salmonella in pork

A substantial part of the finishing pigs in the Netherlands is infected with Salmonella. Infection of pigs with Salmonella can occur already on the farm. Pigs can also get infected or contaminated during transport, lairage or slaughter. The aim of this study was to evaluate the effect of separating pigs from Salmonella-infected farms from pigs from Salmonella-free farms during transport, lairage and slaughter on the prevalence of Salmonella on pork after slaughter. Two experiments were carried out. In the first experiment, farms were selected to participate, based on serology of the pigs (Dutch Salmonella ELISA). The pigs were slaughtered at the beginning of the day: firstly, sero-negative herds, secondly, sero-positive herds and thirdly, again sero-negative herds. The latter were slaughtered to investigate the effect of a contaminated slaughterline due to a previously slaughtered positive herd. In the second experiment, farms were selected to participate, based on both serology and bacteriology of the pigs on the farm. Two hundred pigs from Salmonella-free farms were slaughtered after 200 pigs from Salmonella-infected farms. Results showed that the prevalence of Salmonella in pork samples of sero-negative herds was lower than in samples of sero-positive herds. Results also showed that Salmonella contamination of carcasses after slaughter was partially caused by Salmonella-infected herds that were slaughtered before, and partially by residential flora of the slaughterhouse. It is concluded that separate slaughter of sero-negative pig herds can be useful to decrease the prevalence of Salmonella-contaminated pork after slaughter. To avoid cross-contamination by residential flora from trucks, lairage and slaughterline, cleaning and disinfection have to be improved.     

Effect of housing system, slaughter weight and slaughter strategy on carcass and meat quality, sex organ development and androstenone and skatole levels in Duroc finished entire male pigs

This study aimed at evaluating the effect of housing system (HS), slaughter weight (SW) and strategy (SS) on carcass a nd meat quality, sexual organ development and boar taint in entire males. Twelve pens of 10 pigs were used (two trials). Half of male pens were allowed visual contact with females (MF) and half with males (MM). Half MM or MF were slaughtered at 105 or 130 kg in trial 1, or penwise or by split marketing in trial 2 at 120 kg. Housing system showed no significant effect on carcass or meat quality. MF presented significantly longer testicles and heavier bulbourethral glands compared to MM. The distribution of androstenone and skatole levels was affected by SW but not by HS or SS, samples with androstenone >1 μg/g of the different groups falling within the range of 16 to 22%. All correlations between androstenone and sex organs were significant. Housing system and slaughter strategy did not reduce the risk of boar tainted carcasses.     

Effect of transport time on welfare and meat quality in pigs

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.     

Effect of the insulin-like growth factor-II and RYR1 genotype in pigs on carcass and meat quality traits

Recently, a new QTN (quantitative trait nucleotide), which is located in the regulatory sequence of the imprinted IGF-II gene was discovered in the pig and is associated with a significant increase in IGF-II mRNA expression in skeletal muscle during postnatal growth. The aim of the current study was to investigate the effect of the IGF-II paternal allele (Apat and Gpat animals that inherited, respectively, the mutant and wild type paternal allele of interest) on carcass and meat quality traits in Nn and NN RYR1 genotypes. A total of 141 animals were measured, almost equally distributed over the IGF-II and RYR1 genotypes and gender. The Apat allele increased carcass lean meat percentage with approximately 4.5% (P < 0.001) as a result of decreased backfat thickness. Average live weight daily gain was not affected, hence average daily lean meat gain was significantly higher for Apat compared to Gpat animals. The IGF-II mutation had no noticeable effect on meat quality in contrast with the RYR1 mutation. No interaction effects of both mutations on meat quality were noticed.     

Influence of loading method and stocking density during transport on meat and dry-cured ham quality in pigs with different halothane genotypes

The effect of loading method and stocking density in transit on meat and dry-cured ham quality was investigated in pigs with different halothane genotypes. A total of 507 Italian heavy pigs, supplied by two farms, were loaded by ramp or lift and transported unmixed for 35–55 min to the abattoir at a stocking density of either <0.4 or >0.6m² per 100 kg pigs. After overnight lairage in separate pens with free access to water, the pigs were slaughtered. Halothane genotype was assessed post mortem. Four hundred and thirty-nine pigs had a homozygous dominant (NN) genotype and 68 pigs were heterozygous (Nn). Carcass skin damage, meat quality traits and ham curing parameters were evaluated. Loading method and stocking density showed a negligible effect on meat and dry-cured ham quality while the predominant factor affecting these was the halothane genotype. Nn pigs produced meat with a faster rate of pH fall and lower water holding capacity as well as ham with higher weight losses in salting and greater incidence of defects in the dry-cured product. There were insignificant interactions between halothane genotype and loading method or stocking density. Overall, irrespective of pre-slaughter treatment, the Nn pigs were less suitable for the production of high quality products such as dry-cured ham.     

Influence of season, distance and mixed loads on the physical and carcass integrity of pigs transported to slaughter

To determine the influences of season, distance and multiple-farm loads on pigs transported to slaughter under Spanish commercial conditions, 496 journeys, involving 90,366 pigs, were analysed. Mortality, liveweight loss, transport yield, killing out percentage, carcass yield after overnight chilling and percentage of condemned and trimmed carcasses were recorded. Season significantly affected killing out percentage and trimmed carcasses, with the lowest values found in autumn and summer, respectively. Distance significantly affected liveweight loss and transport yield. Loads composed of pigs from a number of farms had more deaths and carcass problems. It can be concluded that, under Spanish climatic conditions, if journey planning and handling at loading are adequately performed, season and distance do not impair the welfare of slaughter pigs. On the other hand, loading at a number of farms, alone, or interacting with distance, can compromise pig welfare.     

Effect of gender and castration of females and slaughter weight on performance and carcass and meat quality of Iberian pigs reared under intensive management systems

A total of 360 Iberian dam × Duroc sire pigs was used to study the influence of gender and castration of females (CM, castrated males; CF, castrated females; IF, intact females) and slaughter weight (SW; 145 and 156 kg body weight, BW) on performance and carcass and meat quality. Each treatment was replicated four times (15 pigs). Intact females ate less, tended to have better feed conversion and had less carcass fat and more primal cuts yield than CM and CF. Pigs slaughtered at 156 kg BW ate more feed and had worse feed conversion than pigs slaughtered at 145 BW. An increase in SW improved carcass yield, but tended to decrease trimmed ham yield. Intact females are an alternative to castrated females for intensive production of Iberian pigs. Also, the reduction in slaughter weight from 156 to 145 kg BW is recommended for this type of production.     

The effect of repeat application of electrical stunning on the welfare of pigs

Although legislation requires the production of immediate insensibility, implying that a stun can be applied only once, the practice of repeat application of electrical stunning is common. However, the relative consequences of such repeat applications are unknown. This study investigated the effects of repeat applications of electrical stunning (200 V, 50 Hz) following different delays of 15, 60 or 180 s between the initial stun and the repeat applications. The parameters examined, following stunning, were the durations of spontaneous physical activity, time to return of reflexes and the duration of the epileptiform activity in the electrocorticogram. The results showed that repeat application of electrical stunning can produce successive epileptic activity and therefore an effective stun. The duration of tonic and clonic phase activity following repeat application was significantly shorter than after a single stun only. There was a tendency for the reflexes to return more quickly following repeat application. The use of electrical stunning to re-stun pigs appears to raise no welfare concerns and although commonly used, should only be applied out of necessity rather than as routine practice.     

Short communication: effect of stocking density on indices of cow comfort

The objective of this study was to evaluate the effects of increasing stocking density on indices of cow comfort measured over a 24-h period, during peak lying time (0000 to 0400 h), and 1 h after the afternoon milking. Holstein cows (n = 136) were assigned to 1 of 4 pens, and stocking densities of 100, 113, 131, and 142% were applied in a 4 × 4 Latin square. Video data were recorded continuously for 2 d after 5 d of acclimation to stocking density and analyzed with 10-min scan samples for the percentage of cows lying in a stall, standing in a stall, standing in the alley, and eating at the manger. Percentage of cows standing idly in the alley increased as stocking density increased above 113% (10.9, 12.0, 14.4, and 16.5% for 100, 113, 131, and 142% stocking density, respectively). Cow comfort index (CCI; cows lying down/cows contacting stalls) and stall standing index (SSI; cows standing in stall/cows contacting stalls) differed little as stocking density increased, but stall use index (SUI; cows lying in stall/cows in pen not eating) decreased beyond 113% stocking density (70.1, 70.2, 68.6, and 66.3 for 100, 113, 131, and 142% stocking density, respectively). During peak lying time, SUI decreased with increasing (80.3, 79.5, 74.8, and 69.6 for 100, 113, 131, and 142% stocking density, respectively) stocking density above 113%, whereas CCI and SSI showed little response. None of the indices varied by stocking density when they were assessed at 1 h after milking. These results suggest that more than 1 index of cow comfort may be needed at higher stocking densities to assess both stall usage and cows standing idly in an alley. At higher stocking densities, SUI was reduced, because it reflected not only stall usage but the number of cows standing idly in an alley and not actively feeding and unable to access a stall. The CCI and SSI appear to assess actual stall usage (% cows lying or standing) across the range of stocking densities evaluated in this study.     

Coherence of animal health,welfare and carcass quality in pork production chains

Aim of the study was to measure the potential impact of animal health and welfare on the carcass quality. 99 pigs under equal housing and feeding conditions were involved in the study. Effects of the immune system on carcass composition, meat quality and performance data of slaughter pigs became measureable by quantification of acute phase proteins (APP), haptoglobin (Hp) and pig major acute phase protein (Pig-MAP). The results were not significantly affected by gender or breed. The calculated correlations between chosen animal health indicators and carcass quality parameters prove an influence of health and welfare on performance, carcass composition and meat quality traits. The acute phase proteins could also be valuable as a predictive indicator for risk assessment in meat inspection, as increased Hp concentrations in slaughter blood indicate a 16 times higher risk for organ abnormalities and Pig-MAP concentrations above 0.7 mg/ml a 10 times higher risk.     

Carcass and meat quality of selected final hybrids of pigs in the Czech Republic

The objective of this work was to compare the quality of carcass and meat in the selected crossbred pigs used in the Czech Republic. A total of 200 pigs that arose from four crossbreeding was studied; the dam line was in all combination of hybrids represented by Czech Large White × Landrace. Sire line included Large White × Belgian Landrace (I), Hampshire × Pietrain (II), Duroc × Pietrain (III) and Czech meat pig (IV). Influence of crossbreeding on lean meat percentage and muscle depth was statistically highly significant (P<0.001), influence on fat depth was evident (P<0.05). Differences in pH(1) value among the individual final hybrids were not statistically significant but variance of pH(24) value was highly notable (P<0.001). All colour parameters (L(?), a(?), b(?) values), drip loss and exudate also were influenced by hybrid combination (P<0.001). Influence of crossbreeding on intramuscular fat content was not statistically significant (P=0.067). Higher content of intramuscular fat was determined in the hybrids with Duroc breed in sire line. In the whole group, 8.5% pig with PSE defect was found. By comparison of all the various hybridisation, positive influence of Hampshire breed on the carcass quality and negative influence on meat quality was confirmed. On the other hand, meat quality is positively influenced Duroc and Czech meat pig breeds.