Preselection of finishing pigs on the farm as an aid for meat inspection.

The ability of pig suppliers to separate pigs with abnormalities from pigs without abnormalities at the end of the finishing period was investigated. Nineteen hundred and seventy-eight pigs, delivered by 22 pig suppliers, were involved in the experiment. The pigs were inspected on the farm by the pig supplier and, separately, by a veterinary expert. The animals were sent in 22 deliveries to one slaughterhouse. A veterinary meat inspector carried out the ante- and post-mortem inspections. The results of the inspections were compared. The measure of agreement, Cohen's Kappa (CK), indicated a poor (CK less than 0.40) to fair (0.40 less than CK less than 0.75) agreement among the results of the different inspection procedures, depending on the abnormality under investigation. There was a fair to good agreement for the abnormality 'tail lesion' among all inspections. Some findings of the live animal, such as 'straggler', were associated with a wide range of post-mortem abnormalities. It is concluded that preselection is possible and that the economic and practical feasibility of preselection should be investigated.     

Use of information from Pig finishing herds for meat inspection purposes

Summary

In a field trial on Integrated Quality Control of finishing pigs we evaluated information written on Quality Information Cards (QUIC) for meat inspection purposes. These cards were sent with 3747 shipments of pigs going from the finishing herd to the slaughterhouse. Pig suppliers answered five questions dealing with health problems and the use of drugs during the finishing period By comparing QUIC answers to recorded post‐mortem abnormalities, we found that the information on the QUIC had some, albeit low, predictive value with respect to the abnormalities ‘arthritis’, ‘condemned liver’ and lung lesions. Shipments without a QUIC or with a faulty QUIC were considered ‘suspect’ because higher levels of abnormalities were found in these shipments. These results indicate the potential use of a QUIC.     

Differences in calpain system,desmin degradation and water holding capacity between commercial Meishan and Duroc × Landrace × Yorkshire crossbred pork

The objective of this study was to examine the differences in calpain system, desmin degradation, pH values and water holding capacity (WHC) between muscles of commercial Meishan and Duroc × Landrace × Yorkshire crossbred pigs. Meishan pork presented better WHC evidenced by lower purge loss at days 1 and 3 and less centrifugation loss at day 1 post mortem (P < 0.05). pH values at 45 min post mortem in Meishan pork were significantly higher compared to crossbred pork (P < 0.05). Calpain‐1 messenger RNA (mRNA) expression was lower in Meishan pork compared to that from crossbred pork (P < 0.05). Additionally, calpain‐1 activity, the ratio of calpain‐1 to calpastatin activity and desmin degradation were lower in Meishan pork compared to those from crossbred pork samples (P < 0.05). The results indicate that the calpain system including mRNA expression and activity were different between commercial Meishan and crossbred pork resulting in difference in the degree of desmin degradation during post mortem aging. pH values at 45 min and 24 h post mortem rather than calpain activity and desmin degradation could explain the higher water holding capacity in commercial Meishan pork.     

Breeding record analysis in pig herds and its veterinary applications--2: Experiences with a large commercial unit.

A computer program was used to analyse data from a large commercial pig unit over two years to assess reproductive efficiency and the efficiency of weaner production. Monthly inspections of the farm and quarterly post mortem examinations of all dead pigs provided further information. The effects of controlled changes in management on production were assessed. Overall the number of piglets reared per sow per year was increased from 15-1 to 17-2 and the eight-week weights improved from a mean of 10-3 kg to 15-0 kg during the two year-study period.     

Oestrous Synchronization,Ovarian Superovulation and Intraspecific Transfers From a Closed Breeding Colony of Inbred SLA Miniature Pigs

The inbred SLA miniature pig is a unique animal model developed for organ transplantation studies and pre‐clinical experimental purposes. Reported oestrous synchronization and superovulation treatments were examined in two SLA haplotypes (AA and DD) to allow collection of embryos for both practical embryo transfer and experimental technologies from a closed breeding colony. Pre‐puberal miniature pigs were poor responders to oestrous synchronization treatments, while post‐puberal sows were equivalent to commercial sows. Following superovulation, the ovulation number (corpora .hemorrhagica) was higher (p < 0.05) in the cycling sows when compared with non‐cycling sows. Ovulations were equivalent to commercial pre‐puberal gilts and non‐cycling sows (p > 0.05). No difference in ovulation number between haplotypes was observed, which differs from the previous report (DD>AA). Collection of zygotes for pronuclear injection was the highest in the non‐cycling post‐puberal miniature pig group (p < 0.05), although significantly lower when compared with the commercial pig treatment groups (p < 0.05). The incidence of cystic endometrial hyperplasia in our colony was equivalent to rates observed in commercial pigs. Pronuclear visualization following centrifugation was the highest in the non‐cycling miniature sow group and approximates to about 25% of ovulations and about half the rate observed in the commercial pigs (50%). Miniature pig embryos transferred between SLA haplotypes and transfer of DD embryos to commercial pigs resulted in live births at a higher efficiency than previously reported. This study demonstrates the feasibility of undertaking assisted reproductive technologies in a closed breeding colony of inbred SLA miniature pigs without compromise to the breeding programmes.     

The comparison of energy metabolism and meat quality among three pig breeds

The objective of this study was to evaluate the effects of muscle‐fibre types and hormones on glycolytic potential and meat quality traits and their association with glycolytic‐related gene expression in three different altitude pig breeds. The pig breeds studied were the Tibetan pig (TP, high altitude), the Liang‐Shan pig (LSP, middle altitude) and the Duroc × (Landrace × Yorkshire) cross (DLY, flatland). The results indicated that TP and LSP had better meat quality than DLY (P < 0.01). The glycolytic potential (GP) increased in the order of TP < LSP < DLY and decreased with time post mortem. DLY had higher glucagon and epinephrine contents than LSP and TP (P < 0.01). The proportions of myosin heavy chain muscle fibers type I in the Longissimus dorsi increased in the order of DLY < TP < LSP, whereas the proportion of type IIb increased in the order of TP < LSP < DLY. The expression of gene PKM2 played an important role in the glycolysis rate of the different genotypes. Compared with the other two pig breeds, the high‐altitude breeds had better meat quality attributes, which may be due to the slow rate of glycolysis metabolism.     

Parameters of meat quality and stress resistance of pigsParamètres de la qualité de la viande et la résistance au stress chez le procParameter der Fleischbeschaffenbeit und der Stressresistenz beim Schwein

Selection criteria for the improvement of meat quality and stress resistance of the Swiss pig breeds are given. The parameters of meat quality and stress resistance were estimated on 2680 Large White and 1567 Landrace pigs from the Swiss Performance Testing Station. The results indicate the possibility of improving meat quality by selection. Estimations made on the warm carcass (pH1) and on the cold carcass (reflectance) are suitable in combination for characterising meat quality. The heritabilities of meat quality (pH1, reflectance) vary between 0.14 and 0.27. For Landrace, in contrast to Large White pigs, the creatine-kinase test (CK test) and the halothane test allow conclusions to be drawn in the live animal on stress resistance and meat quality post mortem. The heritability of the CK value in Landrace pigs is 0.73 ± 0.18, and in Large White pigs 0.37 ± 0.11.Our results led to the following organisation of selection on meat quality and stress resistance in Switzerland. Testing at the station (mainly full sib tests) includes meat quality measurements. Boar performance tests include the halothane and CK tests. In the field, the Swiss Performance Testing Station offers the halothane test as a service to breeders of nucleus Landrace herds. Preparations are being made to apply the CK test in the field.     

Risk of zoonotic transmission of swine influenza at the human–pig interface in Guangdong Province,China

A cross‐sectional survey was conducted from 2015 to 2018 to assess the risk of zoonotic influenza to humans at the human–pig interface in Guangdong Province, south China. One hundred and fifty‐three pig farmers, 21 pig traders and 16 pig trade workers were recruited using convenience sampling and surveyed at local pig farms, live pig markets and slaughterhouses, respectively. Questionnaires were administered to collect information on the biosecurity and trading practices adopted and their knowledge and beliefs about swine influenza (SI). Most (12 of 16) trade workers said they would enter piggeries to collect pigs and only six of 11 said they were always asked to go through an on‐farm disinfection procedure before entry. Only 33.7% of the interviewees believed that SI could infect humans, although pig farmers were more likely to believe this than traders and trade workers (p < .01). Several unsafe practices were reported by interviewees. ‘Having vaccination against seasonal flu’ (OR = 3.05, 95% CI: 1.19–8.93), ‘Believe that SI can cause death in pigs’ (no/yes: OR = 8.69, 95% CI: 2.71–36.57; not sure/yes: OR = 4.46, 95% CI: 1.63–14.63) and ‘Keep on working when getting mild flu symptoms’ (OR = 3.80, 95% CI: 1.38–11.46) were significantly and positively correlated to ‘lacking awareness of the zoonotic risk of SI’. ‘Lacking awareness of the zoonotic risk of SI’ (OR = 3.19, 95% CI: 1.67–6.21), ‘Keep on working when getting mild flu symptoms’ (OR = 3.59, 95% CI: 1.57–8.63) and ‘Don't know SI as a pig disease’ (OR = 3.48, 95% CI: 1.02–16.45) were significantly and positively correlated to ‘not using personal protective equipment when contacting pigs’. The findings of this study would benefit risk mitigation against potential pandemic SI threats in the human–pig interface in China.     

Predictability of post mortem abnormalities in shipments of slaughter pigs as an aid for meat inspection

This paper reports on the predictability of post mortem abnormalities in individual deliveries of pigs, shipped from the fattening herd to the slaughterhouse. The percentage of pigs in a delivery having post mortem abnormalities was expressed in a Meat Inspection Index. This index is based on data about relevant abnormalities, weighted on the specific significance of each for meat inspection. It was investigated whether Meat Inspection Indices of previous deliveries of pigs could be used for prediction of indices of future deliveries. Results suggest that the Meat Inspection Index cannot be used in such a predictive capacity, partly because of great variation among individual shipments. However, a Meat Inspection Index could play a role in signalling farms that are likely to deliver pigs with a higher level of abnormalities. More attention could then be paid to animals coming from these herds.     

Effect of Dietary Magnesium on Post Mortem Phosphocreatine Utilization in Skeletal Muscle of Swine: A Non-Invasive Study Using 31P-NMR Spectroscopy

The effect of dietary magnesium on the post mortem PCr (phosphocreatine) decay in muscle of heterozygote malignant hyperthermia pigs was studied after in vivo exposure to a combination of halothane and succinylcholine. The pigs were anaesthetized with halothane and succinylcholine was injected in the ear vein. Immediately after initiation of the depolarizing neuromuscular blocking effect of succinylcholine the animals were captive-bolt stunned. The PCr decay, reflecting ATP turnover, was followed in situ by ³¹P-NMR spectroscopy in the biceps femoris muscle for the subsequent 40-70 min post mortem. In 3 of the 4 experiments, the Mg-fed pig had a significantly reduced rate of PCr hydrolysis compared to the control animal. The mechanism of this magnesium effect is unknown.     

Antibiotic resistant Escherichia coli in southeastern Australian pig herds and implications for surveillance

To investigate public health implications of antibiotics to control post‐weaning scours, we surveyed 22 commercial pig herds in southeastern Australia. Fifty faecal samples per herd were collected from pre‐ and post‐weaned piglets. Presumptive Escherichia coli isolates were confirmed by MALDI‐TOF MS. Isolates (n = 325) were screened for susceptibility to 19 veterinary antibiotics using MIC broth microdilution. All 325 E. coli isolates underwent further testing against 27 antibiotics used in human medicine and were screened for ETEC adhesin and enterotoxin genes (F4 (K88), F5 (K99), F6 (987P), F18, F41, STa, STb, Stx2e and LT) by multiplex PCR. Isolates identified as phenotypically resistant to third‐generation cephalosporin (3GC) and aminoglycoside antibiotics were screened by multiplex PCR/reverse line blot to detect common β‐lactam and aminoglycosides resistance genes, confirmed by sequencing. Twenty (6.1%) of the E. coli isolates were resistant to 3GC antibiotics and 24 (7.4%) to the aminoglycoside antibiotic gentamicin. Genetic analysis revealed six different extended spectrum β‐lactamase (ESBL) genes (blaCTX‐M‐1, ‐14, ‐15, ‐27, blaSHV‐12 and blaCMY‐2‐like genes), four of which have not been previously reported in Australian pigs. Critically, the prevalence of 3GC resistance was higher in non‐pathogenic (non‐ETEC) isolates and those from clinically normal (non‐diarrhoeal) samples. This highlights the importance of non‐ETECE. coli as reservoirs of antimicrobial resistance genes in piglet pens. Antimicrobial resistance surveillance in pig production focused on diagnostic specimens from clinically‐affected animals might be potentially misleading. We recommend that surveillance for emerging antimicrobial resistance such as to 3GC antibiotics should include clinically healthy pigs.     

Haematology and blood‐chemistry for predicting abscesses and other abnormalities in slaughtered pigs

Summary

Blood values of slaughtered pigs were determined in an attempt to relate the blood profile with the prevalence of abscesses. To this end 319 pigs were selected and grouped into classes on the basis of pathological ante‐ and post‐mortem findings. The classes thus distinguished were (i) no pathology, (ii) pleurisy or pneumonia and (iii) abscesses occurring singly, metastasised or in combination with other abnormalities.

By stepwise discriminant analysis it was established that the blood variables ln(fibrinogen) and albumin were particularly suitable for the detection of abscesses in slaughtered pigs. In this way a correct classification of 89.3% of affected pigs is possible. The numbers of false‐positives and false‐negatives were 19.3% and 10.7%, respectively.

For meat‐inspection purposes application of blood analyses is promising. For application in meat‐inspection practice rapid on‐line methods need to be devised.     

Changes of microbial spoilage,lipid‐protein oxidation and physicochemical properties during post mortem refrigerated storage of goat meat

Examined was the effect of post mortem refrigerated storage on microbial spoilage, lipid‐protein oxidation and physicochemical traits of goat meat. Seven Boer bucks were slaughtered, eviscerated and aged for 24 h. The Longissimus lumborum (LL) and Semitendinosus (ST) muscles were excised and subjected to 13 days post mortem refrigerated storage. The pH, lipid and protein oxidation, tenderness, color and drip loss were determined in LL while microbiological analysis was performed on ST. Bacterial counts generally increased with increasing aging time and the limit for fresh meat was reached at day 14 post mortem. Significant differences were observed in malondialdehyde (MDA) content at day 7 of storage. The thiol concentration significantly reduced as aging time increased. The band intensities of myosin heavy chain (MHC) and troponin‐T significantly decreased as storage progressed, while actin remained relatively stable. After 14 days of aging, tenderness showed significant improvement while muscle pH and drip loss reduced with increase in storage time. Samples aged for 14 days had higher lightness (P < 0.05) and lower (P < 0.05) yellowness and redness. Post mortem refrigerated storage influenced oxidative and microbial stability and physico‐chemical properties of goat meat.     

Serological evidence of hepatitis E virus infection in pigs and jaundice among pig handlers in Bangladesh

Hepatitis E virus (HEV) is the most common cause of viral hepatitis in humans. Pigs may act as a reservoir of HEV, and pig handlers were frequently identified with a higher prevalence of antibodies to HEV. The objectives of this study were to identify evidence of HEV infection in pigs and compare the history of jaundice between pig handlers and people not exposed to pigs and pork. Blood and faecal samples were collected from 100 pigs derived from three slaughterhouses in the Gazipur district of Bangladesh from January to June, 2011. We also interviewed 200 pig handlers and 250 non‐exposed people who did not eat pork or handled pigs in the past 2 years. We tested the pig sera for HEV‐specific antibodies using a competitive ELISA and pig faecal samples for HEV RNA using real‐time RT‐PCR. Of 100 pig sera, 82% (n = 82) had detectable antibody against HEV. Of the 200 pig handlers, 28% (56/200) demonstrated jaundice within the past 2 years, whereas only 17% (43/250) of controls had a history of jaundice (p < .05). Compared to non‐exposed people, those who slaughtered pigs (31% versus 15%, p < .001), reared pigs (37% versus 20%, p < .001), butchered pigs (35% versus 19%, p < .001) or involved in pork transportation (28% versus 13%, p < .001) were more likely to be affected with jaundice in the preceding 2 years. In multivariate logistic regression analysis, exposure to pigs (odds ratio [OR]: 2.2, 95% CI: 1.2–3.9) and age (OR: 0.97, 95% CI: 0.95–0.99) was significantly associated with jaundice in the past 2 years. Pigs in Bangladesh demonstrated evidence of HEV infection, and a history of jaundice was significantly more frequent in pig handlers. Identifying and genotyping HEV in pigs and pig handlers may provide further evidence of the pig's role in zoonotic HEV transmission in Bangladesh.     

Comparison of owner-reported health problems with veterinary assessment of geriatric horses in the United Kingdom

Reasons for performing study: Previous studies suggest that owners underestimate or incorrectly recognise or report health problems in geriatric horses. However, few studies have directly compared owner‐reported and veterinary assessed disease. Objectives: To compare the findings of veterinary clinical examination of geriatric horses with owner‐reported clinical signs and disease. Methods: A total of 200 horses aged ≥15 years were randomly selected to receive a veterinary examination, from responses to a cross‐sectional postal questionnaire survey. Veterinary examinations were performed within 2 months of questionnaire return, and agreement between owner‐reported data and veterinary clinical findings was assessed. Results: Owners under‐reported many clinical signs and disease conditions detected on veterinary clinical examination. For example, dental abnormalities (detected in 95.4% of horses, reported by 24.5% of owners); cardiac murmurs (detected in 20% of horses, reported by 0.5% of owners); lameness (present in 50% of horses, reported by 23% of owners) and hoof abnormalities (detected in 80% of horses, reported by 27% of owners). Agreement between owner‐reported and veterinary assessed respiratory disease (Kappa 0.02–0.2), body condition score (Kappa 0.24) and coat abnormalities (Kappa 0.42) was poor, fair and moderate, respectively. Range of motion (ROM) of the tarsal and metacarpophalangeal joints was lower in horses with owner‐reported osteoarthritis (P = 0.005 and <0.001, respectively). Conclusions and potential relevance: The low prevalence and relatively poor agreement of owner‐reported disease compared to that detected on veterinary examination suggests inaccurate or under‐recognition, or inaccurate reporting of health problems by owners of geriatric horses, which could lead to a delay in presentation for veterinary treatment. Increased veterinary involvement and improved owner education in the care of geriatric horses should facilitate earlier identification of disease, particularly that which is not readily detectable by owners, and aid management of health and welfare problems.     

Influence of Post‐Mortem Sperm Recovery Method and Extender on Unstored and Refrigerated Rooster Sperm Variables

Many post‐mortem sperm collection techniques have been described for mammalian species, but their use in birds is scarce. This paper compares the efficacy of two post‐mortem sperm retrieval techniques ‐ the flushing and float‐out methods ‐ in the collection of rooster sperm, in conjunction with the use of two extenders, i.e., L&R‐84 medium and Lake 7.1 medium. To determine whether the protective effects of these extenders against refrigeration are different for post‐mortem and ejaculated sperm, pooled ejaculated samples (procured via the massage technique) were also diluted in the above extenders. Post‐mortem and ejaculated sperm variables were assessed immediately at room temperature (0 h), and after refrigeration at 5°C for 24 and 48 h. The flushing method retrieved more sperm than the float‐out method (596.5 ± 75.4 million sperm vs 341.0 ± 87.6 million sperm; p < 0.05); indeed, the number retrieved by the former method was similar to that obtained by massage‐induced ejaculation (630.3 ± 78.2 million sperm). For sperm collected by all methods, the L&R‐84 medium provided an advantage in terms of sperm motility variables at 0 h. In the refrigerated sperm samples, however, the Lake 7.1 medium was associated with higher percentages of viable sperm, and had a greater protective effect (p < 0.05) with respect to most motility variables. In conclusion, the flushing method is recommended for collecting sperm from dead birds. If this sperm needs to be refrigerated at 5°C until analysis, Lake 7.1 medium is recommended as an extender.     

Performance and nutrient digestibility in growing pigs fed wheat dried distillers’ grain with solubles‐containing diets supplemented with phytase and multi‐carbohydrase

Effect of supplementing wheat dried distillers’ grain with solubles (DDGS)‐containing diet with enzymes on nutrient utilization by growing pigs was evaluated in two experiments. In Experiment 1, 60 pigs weighing ~30 kg were fed five diets that included a corn‐based diet (Control), Control with 10% wheat DDGS (DDGS‐PC), DDGS‐PC without inorganic P source (DDGS‐NC), and DDGS‐NC plus phytase alone or with multi‐carbohydrase for 4 weeks to determine average daily gain (ADG), average daily feed intake (ADFI) and gain‐to‐feed ratio (G:F). In Experiment 2, 30 barrows weighing 22 kg were fed five diets fed in Experiment 1 to determine nutrient digestibility and retention. Pigs fed DDGS‐PC and Control diets had similar ADG and G:F. The ADG and G:F for DDGS‐PC diet were higher (P < 0.05) than those for DDGS‐NC diet. Phytase improved (P < 0.05) ADG, G:F, total tract P digestibility and P retention by 6.6, 8.7, 86.0 and 85.5%, respectively. Addition of multi‐carbohydrase to phytase‐supplemented diet did not affected growth performance, but reduced (P < 0.05) P retention. In conclusion, inclusion of 10% wheat DDGS in growing pig diet may not affect growth performance of growing pigs. Phytase supplementation to wheat DDGS‐containing diet can eliminate the need for inorganic P supplement in pig diets.     

The effect of fly maggot in pig feeding diets on growth performance and gut microbial balance in Ningxiang pigs

Fly maggot meal has been regarded as one of the substitutes of fish meal and soybean meal in pig feed. However, its effects on pig growth performance and faecal micro-organism remain unclear. The purpose of this study was to investigate the effect of dietary fly maggot meal on fattening performance, plasma indices related to gut hormones, immunity and faecal microbial communities composition of finishing pigs. A total of 40 Ningxiang fattening pigs were randomly allocated to two dietary treatments and pigs in each group were arranged by control group (CK) diet or 8% maggot meal group (MMG) diet for 45 days respectively. Growth performance, indices of gut hormones and immunity in plasma were evaluated. Microbiota composition in faeces was determined using 16S rDNA Amplicon Sequencing. The results showed that dietary MMG did not affect gut hormones and immune proteins in the trial compared with CK group (p > .05). However, dietary MMG significantly increased average daily gain (ADG). The population of the Firmicutes in MMG treatment was increased, while the percentage of the Bacteroidetes was decreased (p < .05). In particular, the number of Clostridiales related to hydrolyzed sugar and protein were increased (p < .05). It can inhibit the growth of harmful intestinal bacteria, promote the proliferation of beneficial bacteria and effectively improve the ability of digestion and absorption of nutrients. In conclusion, a diet containing 8% MMG changed the proportion of intestinal micro-organisms in finishing pigs, especially the higher richness of Firmicutes, and promoted the fattening ability of pigs to a certain extent. These changes should benefit finishing pig production during fattening period.     

Feeding brittle culm1 whole crop rice replacing wheat by-products to growing-finishing pigs

Abstract

The effect of feeding brittle culm1 whole crop rice (WCR) replacing wheat by-products on performance, digestibility and carcass quality was evaluated in growing-finishing pigs. Fifty-four pigs (Duroc) were randomly assigned to three dietary treatments: WCR at levels of 0 (control), 10 or 20%, respectively. Pigs were fed from about 29 to 85 kg. A digestion trial was conducted with all pigs at about 60 kg live weight. When the feeding trial was completed, six pigs from each treatment were slaughtered to determine carcass quality. In the growing period, pigs receiving the 10 or 20% WCR diet were not significantly different in daily feed intake, daily weight gain and feed conversion from the control pigs (p>0.05). In the finishing period, daily feed intake and daily weight gain of pigs fed the 20% WCR diet were significantly lower than control pigs or 10% WCR diet (p<0.05). However, the feed conversion was not significantly different among the pigs on three different diets. No significant (p>0.05) difference was shown in the apparent nutrient digestibility with the WCR substituting for wheat by-products. The dressing percentage and mean backfat thickness tended to be lower in pigs fed the 10 or 20% WCR diet than in control pigs. The meat from pigs on the 20% WCR diet showed a higher pH value at 24 h post mortem, and higher protein and lower fat content in longissimus muscles than control pigs (p<0.05). This study indicated that WCR could be an alternative feed source to replace wheat by-products in growing-finishing pig diets, but a high proportion of the WCR may result in an adverse effect on the performance traits.     

Back muscle necrosis of pigs.

The clinical signs and pathological features of back muscle necrosis (BMN) in four pigs from three English pig herds were similar to those recorded in pigs from mainland Europe. The observations made support the view that BMN is a special manifestation of the porcine stress syndrome. Diagnosis of acute BMN can be made clinically supported by the analysis of plasma creatine phosphokinase activity and can be confirmed post mortem by macroscopic and microscopic observation on the back muscles.