Incidence of clinical diseases and prevalence of lesions at slaughter in pigs from Danish test stations

The epidemiologies of the most common diseases diagnosed in pigs at the Danish pig-breeding test stations were studied. In this article (one of three), the material and disease incidence are described. The population under study comprised 9 084 test pigs (corresponding to 3 028 test groups) housed at nine test stations from September 1983 to September 1984. Five stations housed groups from conventional herds and four stations groups from specific-pathogen-free (SPF) herds. The average incidence of respiratory disease at the conventional stations was 41.1%, but great variations existed between the stations (from 19.4% to 74.9%). The incidence of respiratory disease at the SPF stations varied from 0.2% to 24.8% (average 18.7%). The incidence of diarrhoea was 4.0% in the conventional system and 7.7% in the SPF system. The frequency of pigs culled because of disease was 7.6% at the conventional stations (range 2.2%–10.8%) and 2.0% at the SPF stations (range 0.9%–3.6%). Very low rates of mortality were found. The prevalence of pathological findings at slaughter (pneumonia and pleurisy) was lower for the test pigs than for total pigs slaughtered at the same abattoir in the same period (especially for the SPF system).     

Behavior,blood stress indicators,skin lesions,and meat quality in pigs transported to slaughter at different loading densities

A total of 1,936 pigs were transported through 8 trips (8.4 ± 0.5 hr) from 2 grow-to-finish farms to a commercial slaughter plant, all located in Southern Brazil. On each trip, a sub-sample of each load (36 barrows/load, weighing 118.9 ± 9.8 kg) was randomly allocated into one of the following loading densities during transport: 200 kg/m² (D200), 235 kg/m² (D235), and 270 kg/m² (D270). Behavioral recordings of postures and activities were made during transportation and lairage using video-cameras. At slaughter, blood samples were collected to assess the concentrations of creatine kinase (CK) and lactate. Carcass weights and skin lesion scores were assessed on-line, and meat quality was evaluated in the longissimus thoracis (LT) muscle by assessing pH, color, and drip loss. During transportation, the proportion of animals lying down was higher (P < 0.05) in D200 and D235 groups compared with D270. The proportion of sitting animals during transportation was higher (P < 0.01) in D270 compared with D200. In lairage, D200 and D235 pigs stood more compared with D270 (P = 0.01), while the proportion of lying pigs was higher (P = 0.02) for D270 pigs compared with D200 and D235. The frequency of drinking bouts in lairage was higher (P < 0.05) for D200 group compared with D235 and D270. The levels of CK were lower (P < 0.05) in D200 pigs transported compared with D270. Lesion scores tended to be higher (P = 0.06) in D270 carcasses compared with D200 and D235. A tendency for lower (P = 0.10) pH1 values in the LT muscle of D270 pigs compared with D200 pigs was also found. Based on the results of this study, the application of lower loading densities (≤235 kg/m²) in the truck allows pigs to have sufficient space to rest, travel more comfortably and arrive less fatigued at the slaughter plant.     

Prevalence of gastric lesions in the pars proventricularis in finishing pigs at slaughter in Switzerland

A cross-sectional study was conducted at two large abattoirs in the winter 2003/04 to determine the prevalence of gastric lesions in Swiss finishing pigs. The stomachs of 1897 pigs from 107 slaughter groups were examined for macroscopic epithelial lesion of the pars proventricularis. Severe hyperceratosis, erosion, ulceration and constriction at the transition between oesophagus and stomach were described as gastric lesions. Lesions were observed in 36% of all animals, with slaughter group prevalence ranging from 0% to 94%. Ulceration or constriction was present in four percent of the examined pigs. Associations between gastric lesions, farm management data, and data obtained at ante and post mortem examinations conducted at the slaughterhouse were analysed. A significantly higher prevalence of gastric lesions was found in pigs originating from conventional housing systems compared to pigs raised on farms with 'animal-friendly' housing systems providing straw bedding and outdoor exercise to pigs. In addition, significantly higher prevalence was observed in pigs originating from herds with clinical signs of tail biting and peritarsitis.     

The effect of three space allowances on the physiology and behavior of weaned pigs during transportation

Stocking density is an important aspect of transport, which could affect animal health and welfare, especially in pigs simultaneously experiencing weaning stress. The objective of this research was to evaluate the effect of three different space allowances on the physiology and behavior of weaned pigs during transport. A commercial semi-trailer with compartments that provided 0.05, 0.06 and 0.07 m²/pig was used throughout the study. All three space allowances were represented on both the upper and lower decks during each replicate. A constant of 100 pigs were loaded into each experimental compartment. Pigs were then transported for 112.5 ± 6.5 min to the wean-to-finishing site using the same route for each replication. This experiment was replicated 4 times. The experimental unit was the compartment. Prior to and after transport, blood samples were taken from a sub-set of pigs (n = 32 pigs/space allowance) for analysis of physiological and immune measures, and body weights and lesion scores were also recorded. Data loggers were fitted inside the trailer to record temperature, humidity, and wind speed. Cameras were placed in each experimental compartment to record behavior and postures of pigs during transport. The frequencies of standing, lying, sitting, standing-rearing on another pig, lying/huddling on top of another pig, total active and total inactive behaviors were recorded using 1-min scan samples during the entire duration of transport. Inside trailer temperature ranged from − 2.4 to 21.7 °C and inside trailer relative humidity ranged from 28.4 to 89.2% during transport. Cortisol, the neutrophil:lymphocyte (N:L) ratio, blood urea nitrogen, total bilirubin, total protein, albumin, aspartate aminotransferase, and creatine kinase were higher (p < 0.05) in pigs after transport regardless of space allowance. Skin lesions were more severe (p < 0.001) in pigs after transport regardless of space allowance. Pigs spent more (p < 0.001) time active during the first 75 min of transport compared with the last 30 min, regardless of space allowance. Pigs spent less (p < 0.01) time standing on another pig during transport at 0.07 m²/pig compared with pigs transported at 0.06 m²/pig. Higher cortisol concentrations and N:L ratio in weaned pigs after transport suggest that these pigs experienced stress, however space allowance did not appear to influence this response. Space allowances of 0.05, 0.06 or 0.07 m²/pig did not differentially influence pig well-being during a 112-min transport period as measured by changes in physiological measures.     

The correlation between Salmonella serology and isolation of Salmonella in Danish pigs at slaughter

In Denmark, a serological Salmonella surveillance programme in finishing pig herds has been in place since 1995. The programme was founded on data from experimental studies, which demonstrated a strong association between Salmonella serology and the prevalence of these bacteria. The current study was carried out in three Danish abattoirs to evaluate the correlation under field conditions. A total of 160 Danish finishing pig herds were included. Seven out of these were examined twice, yielding a total of 167 observations. The herds were selected according to their herd serology based on data from the national surveillance. From each herd, samples were taken from 10 finishers at slaughter. The prevalence of Salmonella bacteria was measured at four sites: (1) caecal-content; (2) carcass surface; (3) pharynx; and (4) caecal lymph nodes. A logistic regression model was constructed for each sampling site. Abattoir, sanitary slaughter and herd seroprevalence were used as explanatory variables. The results demonstrated that there was a strong association between herd serology and the prevalence of Salmonella bacteria measured at three of the sampling sites: caecal-content, pharynx, and carcass surface. For these sites, the odds for being culture-positive for Salmonella varied from 1.3 to 1.5 for each increase of 10% in herd serology (P < 0.0001). For caecal lymph nodes, however, no linear association was found.     

The prevalence of gastrointestinal helminth infections in pigs in Kenya

The prevalence of helminth infection, species spectrum and worm burdens in Kenyan pigs was examined. A total of 115 gastrointestinal tracts (GIT) from 61 growers and 54 adult pigs were examined between February 2005 and January 2006. Seventy eight (67.8%) had one or more helminth parasites, of which thirty six (31.3%) were mixed infection. Ten types of helminth parasites encountered in descending order of prevalence were, Oesophagostomum dentatum (39.1%), Trichuris suis (32.2%), Ascaris suum (28.7%), Oesophagostomum quadrispinulatum (14.8%), Trichostrongylus colubriformis (10.4%), Trichostrongylus axei (4.3%), Strongyloides ransomi (4.3%), Hyostrongylus rubidus (1.7%), Ascarops strongylina (1.7%) and Physocephalus sexalutus (0.9%). Oesophagostomum dentatum was the most prevalent species (51.9%) in the adult pigs, while Trichuris suis was the most prevalent species (44.3%) in growers. The highest worm counts were recorded in the out door production system. Oesophagostomum quadrispinulatum, Trichostrongylus colubriformis, Trichostrongylus axei, Hyostrongylus rubidus, Ascarops strongylina and Physocephalus sexalutus were recorded in Kenya for the first time. The high prevalence and wide spectrum observed in the present study suggests that helminth infection may be a constraint to economic pig production in the country and there is need to institute control measures.     

The capacity of inspection on farm and at the abattoir to predict post-mortem outcomes in slaughter pigs: A study at animal level

The aim of this study was to investigate associations between ear, tail, and skin lesions, hernias, bursitis, and rectal prolapses at the abattoir and meat inspection outcomes in slaughter pigs, including carcass condemnations and trimmings, carcass weight, and carcass quality. This was an observational study whereby pigs were managed according to routine practices in a single abattoir. Data were collected from 1816 pigs. The relationship between animal-based welfare and post-mortem outcomes was analyzed using generalized mixed models (Proc Glimmix). Our findings showed that tail lesions were associated with entire carcass condemnations and trimmings (P < 0.001), a reduction in carcass weight (P < 0.05), and a potential to impair carcass quality by reducing muscle pH (P < 0.05), especially in carcasses from male pigs (P < 0.05). Additionally, hernias were associated with viscera condemnation (P < 0.05) and a reduction in carcass weight (P  < 0.05). Therefore, our findings confirm that ante-mortem inspection could be useful to predict post-mortem outcomes in the same pigs, especially in cases of tail lesions and hernia, which might trigger attention of the veterinary inspector in charge of the post-mortem inspection.     

Phenotypic and genotypic characterisation of Pasteurella multocida isolated from pigs at slaughter in New Zealand

AIMS: To examine pigs at slaughter in New Zealand for the presence of Pasteurella multocida, and to determine for isolates, their biochemical profiles, somatic and capsular types, and the presence or absence of the HSB and toxA genes, associated with haemorrhagic septicaemia (HS) and progressive atrophic rhinitis (PAR), respectively.

METHODS: Swabs from 173 lungs, 158 palatine tonsils and 82 nasal passages of pigs at two abattoirs in New Zealand were cultured for P. multocida using conventional techniques, and isolated colonies were subjected to biochemical tests for identification of biovars. Somatic serotyping was conducted using an agar gel immunodiffusion (AGID) test. Polymerase chain reaction (PCR) assays were used to confirm phenotypic identification of colonies using species-specific primers, capsule type using serogroup-specific primers and multiplex PCR, and to test for the presence of HSB and toxA genes.

RESULTS: Pasteurella multocida was isolated from 11/173 (6.4%) lung, 32/158 (20.2%) palatine tonsil and 5/82 (6.1 %) nasal swab samples, a total of 48 isolates from 413 samples (11.6%). Isolation rates per farm ranged from 1–53% of tissue samples collected from pigs 5–6 months of age. On phenotypic characterisation, isolates were allocated to seven main biovars, viz 1, 2, 3, 5, 9, 12, and a dulcitol-negative variant of Biovar 8, the majority (30/48) being Biovar 3. Of the 42 isolates for which somatic serotyping was conducted, 10% were Serovar 1, 79% were Serovar 3, 2% were Serovar 6,1, 2% were Serovar 12, and 7% could not be typed. All 48 isolates were confirned as P. multocida using a species-specific PCR. In the capsular multiplex PCR, 92% of isolates were Capsular (Cap) type A, 2% were Cap D, and 6% could not be typed. None of the samples were positive for the HSB or toxA genes.

CONCLUSION: Serovars or capsular types of P. multocida associated with HS or PAR in pigs were not detected. Establishment of species-specific, capsular and toxin PCR assays allowed the rapid screening of isolates of P. multocida, while serotyping provided an additional tool for epidemiological and tracing purposes.     

Comparison of recording of pericarditis and lung disorders at routine meat inspection with findings at systematic health monitoring in Danish finisher pigs

Background

The use of secondary data is widespread in a range of surveillance and monitoring applications because of the low cost and high availability associated with this form of data. However, as they are often collected for quite unrelated purposes, they are not necessarily fit for the new purpose that is required of them. Routine meat inspection data were originally collected with the purpose of safeguarding food, but have been re-tasked to also include animal welfare assessment. The objective of the present study was to compare the recording of pericarditis, pleuritis and lungs with lesions at routine meat inspection (RMI) with those performed at systematic health monitoring (SHM) in Danish pigs at slaughter, in order to assess the usefulness of RMI for monitoring the prevalence of these diseases. Data originating from 165 Danish pig herds were collected in the period September 2011 to November 2013. From each herd, a batch consisting of all pigs slaughtered on a specific day from a specific farm were included as the RMI data, while lungs and hearts sampled from the batches were used for the SHM. The RMI data and SHM data included recordings related to a) chronic pericarditis, b) chronic pleuritis and c) lung lesions. The proportion of carcases with a specific disease recording was estimated for each batch of pigs, and linear regression was used to relate the RMI-proportion to the SHM-proportion for the conditions mentioned above.

Results

The coefficients of determination (R²) were estimated as R²_{,pericarditis} = 0.16; R²_,pleuritis = 0.67; R²_{,lungs with lesions} = 0.40. R²_{,pericarditis} changed to 0.42 when the regression analysis included inspection type at the abattoir (with purely visual inspection of the hearts versus traditional inspection including an incision into the heart).

Conclusions

Overall, the results suggest that the correlation between findings at RMI and SHM was moderate for pleuritis and lungs with lesions, but poor for pericarditis. The latter could partly be explained by the type of meat inspection conducted at the abattoir. We conclude that caution should be used whenever RMI data are used for purposes other than those for which they were originally intended.     

The association of hoof lesions at claw trimming with test-day milk yield in Danish Holsteins

In a cross-sectional study, performed between October 2002 and April 2003 on 55 Danish dairy herds with 6161 predominantly Holstein Friesian cows the prevalence of 9 hoof lesions was determined.

All test-day yields (TDY) of kg energy corrected milk (ECM) in the lactation of diagnosis were recorded. For the purpose of including hoof lesions in a decision support model an attempt was made to aggregate the lesions into digital dermatitis (DD), other interdigital diseases (OID, infectious diseases other than DD) and hoof horn diseases (HHD, related to metabolic disorders and trauma). A division was made based on the stage of lactation in which the lesions were diagnosed; during the first 100 days in milk, between days 101 and 200 and between days 201 and 305. Associations between the presence of hoof lesions at trimming and milk production were analyzed by linear mixed modeling at the cow level, clustered within herd. The data of primiparous cows was analyzed separately from the multiparous cows.

Based on the associations between TDY and the individual lesions aggregated into HHD, this aggregation as initially planned could not be justified and was therefore not maintained. For OID the value of early diagnosis was apparent; an early diagnosis and early treatment (<101 DIM) was associated with either a positive value or a value less negative compared to a diagnosis and treatment in late lactation (201–305 DIM). This pattern was not as clearly present for the other lesions.     

The effect of dietary barley level on volatile fatty acid concentration and manure ammonia emissions in finishing pigs

An experiment was conducted to investigate the linear and quadratic effects of barley on volatile fatty acid (VFA) profile and manure ammonia emissions in pigs. Sixteen boars (66 kg) were assigned to one of four treatments (n = 4): (T1) 0 g/kg barley (control), (T2) 222 g/kg barley, (T3) 442 g/kg barley and (T4) 666 g/kg barley. Barley was substituted for wheat. The diets were formulated to contain similar concentrations of digestible energy and lysine, soya oil was adjusted to maintain net energy. Increasing barley levels caused a linear decrease in colonic (P < 0.01) and caecal pH (P < 0.001). Total caecal VFA and propionic acid were affected by dietary barley level (quadratic, P < 0.05). There was a linear decrease in the proportion of acetic acid (P < 0.001), isobutyric acid (P < 0.01), isovaleric acid (P < 0.05) with increasing levels of barley in both the caecum and colon. There was a linear increase in the proportion of propionic acid (P < 0.001) and butyric acid (P < 0.05) with increasing barley in the colon. Barley based diets had a lower ammonia emission from 96 to 240 h (P < 0.05) and from 0 to 240 h (P < 0.05) than the wheat based diet. In conclusion, a high level of barley is required to reduce offensive branch chained VFAs.     

Accuracy of two commercial enzyme-linked immunosorbent assays for the detection of antibodies to Salmonella spp. in slaughter pigs from Canada

Large discrepancies are usually found when different ELISAs for the diagnosis of pig salmonellosis are compared. Thus, our main goal was to estimate the diagnostic accuracy through Bayesian approaches of two commercial assays (Svanovir™ “test A” and HerdCheck™ “test B”) for the detection of antibodies to Salmonella spp. in slaughter pigs. Previously, we estimated the agreement between both tests and their relative sensitivity (Se) and specificity (Sp) with respect to bacteriology on caecal content and ileocaecal lymph nodes. Test A, at a cut-off OD% ≥20%, indicated higher prevalence than test B (OD% ≥10%) (14.6% vs. 8.6%). Relative Se with respect to overall bacteriology was low (≈30%) and similar for both tests, but the relative Sp was significantly lower for test A compared to B (88% vs. 95%). Both tests failed to detect some pigs infected with Salmonella serogroups B and C₁, which they were supposed to identify. In general, tests showed only fair-to-moderate agreement when they were compared (kappa: 0.41). In the Bayesian models, Se of test A varied between 63% and 77%, while Se of test B was 73%. Sp of A was always lower than that of test B (89% vs. 95%). The implications derived from the use of these imperfect serological tests will have to be accounted for in large-scale Salmonella-control programs.     

Welfare of layers housed in small furnished cages on Danish commercial farms: the condition of keel bone,feet, plumage and skin

1. An on-farm assessment of keel bone, feet, plumage and skin damage was conducted in layers in small furnished cages to evaluate welfare implications.

2. Thirteen farms participated, all housing Lohmann LSL layers in systems allowing 8 or 10 hens per cage.

3. Each flock was visited at three different ages: 32, 62 and 77 weeks. During each visit, 100 hens were examined for keel bone fractures and deviations, plumage damage, body wounds, foot pad lesions, bumble feet, missing toes and toe wounds.

4. A deterioration with age of the condition of the plumage and keel bone was found (P < 0.001). At 77 weeks of age, 16% of the birds had poor plumage, and 43% of the birds had keel bone damage. In contrast, foot pad lesions were most prevalent at 32 weeks of age (13%), whereas the other foot injuries and body wounds remained at a relatively low level throughout the three ages examined.

5. Prevention of damage to the keel bone, plumage and foot pads should therefore be considered when aiming to improve welfare of laying hens housed in small furnished cages.     

The prevalence of macroscopic sarcocysts in New Zealand cattle at slaughter

A survey carried out to determine the prevalence of visible Sarcocystis spp. infection in 100 slaughtered cattle in a South Island abattoir revealed 64% infected. Although all ages, genders, breeds and export grades were infected, only host age had a statistically significant effect on the infection rate.

Infections were most common in the rectus abdominis and the psoas muscles (47% and 41% respectively). Most infections were light, with less than ten macrocysts seen, though infections of more than 50 macrocysts occurred.

The average macrocyst length was 4.1±0.10 mm (SE) (n = 233), the average cyst wall thickness 5.3 ±0,12 μm (SE) (n = 45).

It is thought that the actual prevalence of infection is higher than that recorded and reasons for this are discussed.     

Relationship to growth performance of pneumonia and atrophic rhinitis lesions detected in pigs at slaughter among four seasons.

A commercial swine herd was selected for study, because pigs at slaughter repeatedly had lung lesions consistent with enzootic pneumonia and had snout lesions typical of atrophic rhinitis. Pigs born during various seasons of the year were allotted to 4 investigations and were evaluated from birth to slaughter. Individual lungs and snouts were identified and collected at the slaughter plant and later examined for gross lesions of bronchopneumonia and atrophic rhinitis, respectively. Each lesion was scored, and the following comparisons were made within investigations: prevalence and mean scores for lung lesions; prevalence and mean grades for snout lesions; correlations between lung lesion scores and growth indicators; correlations between snout lesion grades and growth indicators; and correlations between lung lesion scores and snout grade scores. Included in the growth indicators were average daily gain during the growing phase, average daily gain during the finishing phase, average daily gain during growing and finishing phases, and days to attain 104.5 kg of body weight. Prevalence of lung or snout lesions, mean values for lung lesion scores, mean values for snout lesion grades, and mean values for the various growth indicators were tested for statistical differences among the 4 investigations. Prevalence of lung lesions was highest (96%) for winter-slaughtered and lowest (81%) for autumn-slaughtered pigs. Mean scores for lung lesions were 7% (summer), 5% (autumn), 9% (winter), and 16% (spring). Prevalence of snout lesions was highest (85%) for spring-slaughtered pigs and lowest (42%) for autumn-slaughtered pigs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of the two production programs ‘Naturafarm’ and ‘conventional’ on the prevalence of non-perforating abomasal lesions in Swiss veal calves at slaughter

Non-perforating abomasal lesions are a considerable problem affecting more than half the population of veal calves. The objective of the present study was to assess the prevalence of pyloric and fundic abomasal lesions in Swiss veal calves at slaughter and to compare the occurrence of non-perforating abomasal lesions between two different production programs (‘Naturafarm’ and ‘conventional’). ‘Conventional’-production settings met the minimal standards as defined by the Swiss animal welfare legislation, whereas ‘Naturafarm’ production complied with increased animal welfare requirements. In order to identify risk factors for the development of abomasal lesions, information on management, housing, and feeding was obtained by a questionnaire. A total of 125 abomasa were randomly selected in one large abattoir. They were examined macroscopically, and the occurence of lesions in either the fundic or pyloric region of the abomasum was recorded separately. Animals raised in the ‘conventional’-production setting revealed a significantly higher prevalence of lesions in the fundic part. Factors significantly affecting the prevalence of non-perforating lesions in the fundic part were the ‘conventional’-production environment, including missing access to an outside pen, missing access to water and straw as the only roughage, feeding by bucket and the liquid milk by-product Protofit in combination with the powder Sprayfit.     

高温期日粮电解质与铬对肥育猪生长与代谢的影响

将来源相同、体重相近的 (72kg) 杜长大肥育猪 32头 ,公母各半 ,随机分为 4个处理 ,每处理设 2个重复 (各组间差异不显著 ) ,每组公母各 2头 ,在试验日粮中分别添加碳酸氢钠、氯化钾、烟酸铬 ,研究日粮电解质与铬对持续高温期肥育猪生长性能与生化反应的影响。研究结果表明 ,持续高温期肥育猪采食含电解质日粮后 :(1 )日增重显著增加 (p <0 0 5) ;料肉比变化不显著 (p>0 0 5) ,试验组平均体重为1 0 0kg,平均日增重为 91 0g,分别比对照组高 5 %、7% ;(2 )血液葡萄糖、总蛋白、球蛋白、白蛋白含量普遍升高 ,但只有血清球蛋白水平变化差异显著 (p<0 0 5) ,肌酸激酶、尿素氮含量普遍降低(p >0 0 5) ;(3)Na+ 含量显著升高 (p<0 0 5) ,Cl- 明显降低 (p <0 0 5) ;血清K+ 的浓度变化不是很明显 ,但试验组K+ 平均浓度高于对照组     

Changes in haematological and clinicochemical profiles in blood of apparently healthy slaughter pigs, collected at the farm and at slaughter, in relation to the severity of pathological-anatomical lesions.

Differences in haematological and clinicochemical profiles of blood of apparently healthy slaughter pigs collected at the farm and at slaughter were investigated in relation to the severity of pathological-anatomical lesions. For this purpose blood-samples of castrated male pigs were collected once at seven different farms and from the same pigs one to three days later at the slaughterhouse. In general, as far as the investigated blood variables are concerned, there were distinct and significant differences in the mean values between farm and slaughter blood-samples. As a rule the mean values of the investigated blood variables were higher in the slaughter blood than in the farm blood. The effects are most pronounced for leucocyte concentration and for the activity of the enzymes creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and gamma-glutamyltransferase (gamma-GT). For the blood variables albumin, lymphocytes and magnesium there were significant, but not so strong interactions between the sites of blood-sampling and the groups, which were classified according to the severity of pathological-anatomical lesions. Despite the fact that there were significant differences in the mean values of blood profiles of the slaughter pigs between the sites of blood sampling, this effect was only manifest as a difference in the level of the values of the blood variables. This means that clinicochemical and haematological profiles from groups of pigs at slaughter reflect the herd's health status at the farm and can be used when monitoring it.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increasing feed withdrawal and lairage times prior to slaughter decreases the gastrointestinal tract weight but favours the growth of cecal Enterobacteriaceae in pigs

The objective of this study was to evaluate the influence of different feed withdrawal and lairage times prior to slaughter on the gastrointestinal tract (GIT) weight and on the fermentation pattern and numbers of Enterobacteriaceae in the cecum of pigs. A total of 72 finishing pigs (6 pens, 12 animals each) were included in the study and were sent to the slaughterhouse on three consecutive days. On each day pigs from two pens were deprived of feed for either 2 or 12 h before leaving the farm. Pigs from each of the two pens were divided in sub-groups (4 pigs each) on the moment of loading onto the truck and followed the same distribution at the slaughterhouse. Once there, each sub-group corresponding to the same feed withdrawal time was held in different holding pens for 0, 5 or 10 h before slaughter. The weight of the gastro-intestinal tract (GIT) was determined and cecal content was collected to evaluate pH, short chain fatty acids (SCFA) and ammonia (NH₃) concentrations as well as lactobacilli and Enterobacteriaceae numbers. Total GIT weight decreased as feed withdrawal (P < 0.0001) and lairage time (P < 0.001) increased within a range between 6.69 and 4.59 kg. Cecal pH increased with feed withdrawal (P < 0.0001) and lairage time (P = 0.0001) (ranging from 5.79 to 6.79) in parallel to a decrease in the total SCFA concentration (P < 0.005) (from 211 to 100 mM). The percentages of acetic and propionic acid were not modified by the experimental treatments but significant decreases were registered in the percentage of butyric acid with the increased times of both withdrawal (P < 0.0001) and lairage (P < 0.005). The percentage of valeric and branched SCFA and also NH₃ concentration showed an increase with withdrawal (P < 0.005, P < 0.0001 and P < 0.005 respectively) and lairage (P < 0.005, P < 0.0001 and P < 0.001 respectively). Lactobacilli numbers decreased as lairage time increased (from 9.97 to 8.63 log 16S rRNA gene copies/g FM; P < 0.05) and Enterobacteriaceae numbers increased with both, feed withdrawal (P < 0.05) and lairage (P < 0.05) (ranging from 8.53 to 9.95 log 16S rRNA gene copies/g FM).The previous to slaughter increase in feed withdrawal and lairage times decreased the GIT weight but involved changes in the gut microbial ecosystem caused through changes in the fermentation pattern that lead to the increase of Enterobacteriaceae numbers. This increase could represent a higher risk of carcass contamination by the enteropathogens of this group such as Salmonella. However this potential risk should be further investigated.