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Abstract

Objective—To assess the role of noncommercial pigs in the epidemiology of porcine reproductive and respiratory syndrome (PRRS) virus.

Design—Seroepidemiologic study and survey study.

Animals—661 pigs from which blood samples were collected at slaughter and 32 pigs from which blood samples were collected longitudinally.

Procedures—Spatial databases of commercial farms and 4-H participation were evaluated by use of commercial geographic information systems software. Information on disease knowledge and management methods of 4-H participants was obtained by mail survey and personal interview. Serum samples for antibody testing by PRRS ELISA were obtained from pigs at slaughter or at county fairs and on farms.

Results—Participation in 4-H swine programs was geographically associated with commercial swine production in Minnesota, and 39% of 4-H participants reared pigs at locations with commercial pigs. High seroprevalence at fairs (49%; range, 29% to 76%) and seroconversion after fairs indicated that PRRS virus exposure was common in pigs shown by 4-H participants and that transmission could occur at fairs.

Conclusions and Clinical Relevance—The small swine population shown by 4-H members (estimated 12,000 pigs) relative to the population of commercial swine in Minnesota (estimated 6.5 million pigs) suggested the former overall was likely of minor importance to PRRS virus epidemiology at present. However, the relative frailty of knowledge of biosecurity practices, evidence that PRRS virus exposure was frequent, common intentions to show pigs at multiple events, and often close interactions with commercial herds suggested that the 4-H community should be involved in regional efforts to control PRRS.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine effects of fecal sample storage and delayed secondary enrichment (DSE) on detection of Salmonella spp in swine feces.

Sample Population

Fecal samples obtained from 84 pigs in a commercial herd.

Procedure

Each fecal sample underwent 3 storage treatments: no storage (ie, processed on the day of collection), storage at 4 C for 6 days, and storage at −15 C for 14 days. After assigned storage treatments, all samples were enriched in Rappaport-Vassiladias (RV) broth (single enrichment) and plated on XLT4 agar. Delayed secondary enrichment was performed, using single enrichment broths that were stored for 4 days at room temperature.

Results

Of 504 cultures, 186 (36.9%) were Salmonella positive. A difference in proportions of samples with positive results was not found between same-day processing and storage at 4 C for 6 days. Compared with use of single enrichment for 24 hours (34% positive), use of DSE resulted in a greater proportion (40%; P < 0.001) of samples with positive results. Estimated relative sensitivities for the storage methods were 0.90, 0.85, and 0.71 for same-day processing, storage at 4 C for 6 days, and storage at −15 C for 14 days, respectively.

Conclusions

Where practical, processing of fecal samples on the day of collection is recommended, although storage at 4 C for several days does not result in marked loss of sensitivity. Improved detection associated with DSE warrants further investigation and optimization. (Am J Vet Res 1999;60:359–362)

Free access
in American Journal of Veterinary Research

Objective

To determine prevalence and risk factors for decubital ulcers of the shoulder in sows.

Design

Descriptive cross-sectional study.

Sample population

All females of breeding age in a large confinement swine facility.

Procedure

1,916 females were examined for lesions of the skin over the tuber of the spine of the scapula and for body condition scoring. Observational data were combined with sow data (parity, date of farrowing, litter size) contained in computerized records.

Results

Decubital ulcers were observed in 8.3% of females, predominantly lactating sows. Ulcer prevalence was strongly associated with time after farrowing. Lesions apparently healed rapidly after weaning. Ulcer prevalence was associated with low body condition scores, but was not associated with parity.

Implications

Decubital ulcers are a multifactorial condition. Housing on concrete floors per se did not result in ulcers. Prolonged recumbency during parturition, reduced activity in early lactation, periparturient illness, thin body condition, moist skin, and floor type are potential risk factors. (J Am Vet Med Assoc 1996;208:1058–1062)

Free access
in Journal of the American Veterinary Medical Association

Summary

Seasonal variation oj reproductive performance of female swine was analyzed by use of a data base that included farrowing records from 42 commercial swine herds. Farrowing rates of sows bred during December or January were higher (P < 0.001) than those bred in July or August (79.2 vs 74.1%). The percentage of sows with irregular (prolonged) return-toestrus intervals after mating in December or January (2.63%) was lower (P < 0.01) than those mated in July or August (4.65%). Sows mated in November through January had greater total number of pigs born per litter (11.66 vs 11.19 pigs per litter), more pigs born alive per litter (10.39 vs 9.84 pigs per litter), and greater litter birth weights (15.20 vs 14.28 kg) than sows mated in June through August (P < 0.001). Adjusted 21-day litter weights were lower (P < 0.001) for litters from sows farrowing in July or August (52.04 kg) than sows farrowing in all other months (55.13 kg) except June and September. Sows that had their litters weaned in June through August had longer (P < 0.001) weaning-to-estrus intervals (7.95 days) than sows that had their litters weaned in November through January (6.84 days). The effects of season varied across parities. Primiparous sows had the greatest seasonal variability in weaning-to-estrus interval, whereas multiparous sows had the greatest seasonal variability in total number of pigs born per litter and pigs born alive per litter.

Free access
in Journal of the American Veterinary Medical Association

Objective

To evaluate agreement between trained veterinarians and a reference inspector when recording gross lesions of lungs, livers, and nasal turbinates of pigs.

Design

Prospective study.

Sample Population

10 veterinarians in workshop 1 and 11 veterinarians in workshop 2.

Procedure

Analysis of data obtained from 2 workshops in which veterinarians evaluated fresh tissues (30 lungs and 30 livers) and 100 slides of nasal turbinates previously evaluated by the reference inspector. Veterinarians independently recorded observations of gross lesions. Agreement was evaluated by percentage agreement, kappa or weighted kappa, and sensitivity and specificity, where relevant.

Results

Agreement between veterinarians and the reference inspector was excellent for detecting consolidation of lung lobes typical of enzootic pneumonia (κ = 0.81 and 0.87 for workshops 1 and 2, respectively) and white spots on livers (κ = 0.76 and 0.78). Estimates of the extent of consolidation as a proportion of lung volume also agreed closely with reference values. Agreement was closer for veterinarians who had undergone repeated training and evaluation. Agreement was good for detecting nasal turbinate atrophy (weighted κ = 0.63 and 0.68) and was poorest for detecting lesions of pleuritis (κ = 0.39 and 0.44).

Clinical Implications

For most of the lesions evaluated, acceptable levels of agreement with reference scores were achieved after training of veterinarians to use standardized methods to record gross lesions. Standardization of veterinarians’ recordings of gross lesions should improve the reliability and usefulness of data collected by inspection of slaughtered pigs. (J Am Vet Med Assoc 1996;209:823–826)

Free access
in Journal of the American Veterinary Medical Association

Objective

To determine attitudes of participating veterinarians toward a standardized slaughter-monitoring program for swine.

Design

Survey by mail questionnaire.

Sample Population

30 of 35 veterinarians in Minnesota who had participated in the program in 1993.

Procedure

Survey was conducted regarding a slaughter-monitoring program. Respondents answered questions related to professional experience, use of slaughter inspections, methods, advantages and disadvantages of the program, effects on clients and business, labor requirements, referral of inspections, confidence in identifying lesions, and usefulness of reports for on-farm decision making.

Results

27 respondents expressed overall satisfaction with the program. Perceived advantages of the program included use of standardized methods, quality of reports, inspection of more types of lesions, and accumulation of data. Disadvantages predominantly related to increased time commitments for veterinarians. Data considered most useful for on-farm decision making were white spots on livers, nasal turbinate atrophy, and lesions indicative of papular dermatitis and enzootic pneumonia. Respondents perceived positive effects of participating in this program In the areas of recruitment of clients, frequency of visits to clients, recommendations made to clients, satisfaction of client needs, and generation of revenue.

Clinical Implications

A standardized slaughter-monitoring program designed to provide improved information from slaughter inspections may be beneficial to the businesses of participating veterinarians. (J Am Vet Med Assoc 1996;209:123–126)

Free access
in Journal of the American Veterinary Medical Association

Abstract

A rapid subjective method for estimating the extent of gross pneumonia lesions in slaughtered pigs was compared with dissection of lungs in 51 slaughtered pigs. After standardization for prevalence in the regional industry, regression analysis indicated that the subjective method was highly predictive of the extent of pneumonic lesions (R 2 · = 0.88). Part of the error with the subjective method was attributed to approximations used for the relative proportions of lung lobes, which result in overestimation of the affected tissue by approximately 20%. Retrospective analysis of data from a slaughter monitoring program revealed strong associations (R 2, 0.54 to 0.91) between prevalence, mean, median, and maximal lung scores in groups of pigs. Maximal lung score was biased by sample size, but prevalence and mean or median lung scores could be used to describe pneumonia severity in groups of pigs. Our results indicate that error in measurement of the extent of pneumonic tissue in slaughtered pigs is unimportant if the time of onset, clinical severity, and duration of disease are not quantified.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether withholding feed from pigs prior to slaughter had any effects on meat quality, percentage of pigs with Salmonella spp in cecal contents during slaughter, or percentage of pigs with lacerations of the gastrointestinal tract during slaughter.

Design—Split-plot design.

Animals—873 pigs.

Procedures—At the finishing barn, pigs were assigned to 30 pens. Feed withdrawal times were assigned to pens at random, and pigs in each pen were marketed in 3 groups. The first marketing group consisted of the 10 heaviest pigs in each pen, the second consisted of the next 10 heaviest pigs, and the third consisted of all remaining pigs.

Results—Withdrawing feed improved the redness score assigned to the meat but did not have any other significant effects on carcass composition or meat quality. The percentage of pigs with Salmonella spp in the cecal contents decreased from the first (73%) to the second (64%) to the third (52%) marketing group. However, isolation of Salmonella spp from cecal contents was not associated with feed withdrawal time or with pen prevalence of Salmonella shedding during the 2 months prior to slaughter. Feed withdrawal time and marketing group did not have any significant effects on overall prevalence of gastrointestinal tract lacerations.

Conclusions and Clinical Relevance—Results suggest that withdrawal of feed from pigs prior to slaughter does not increase the prevalence of Salmonella colonization or the risk of carcass contamination associated with gastrointestinal tract lacerations during slaughter but only slightly enhances meat quality. (J Am Vet Med Assoc 2002;220:497–502)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether withdrawing feed from pigs prior to slaughter had any effects on prevalence or severity of gastric ulcers.

Design—Split-plot design.

Animals—873 pigs.

Procedures—At the finishing barn, pigs were assigned to 30 pens. Feed withdrawal times (0, 12, or 24 hours) were assigned to pens at random, and pigs in each pen were marketed in 3 groups over a period of 4 weeks. The first marketing group consisted of the 10 heaviest pigs in each pen, the second consisted of the next 10 heaviest, and the third consisted of all remaining pigs. Feed was withheld from all pigs in each pen prior to removal of each marketing group. Thus, feed was withheld once, twice, or 3 times for pigs in the first, second, and third marketing groups, respectively.

Results—Feed withdrawal time was not significantly associated with ulcer score at the time of slaughter. Ulcer scores and prevalence of chronic damage were higher in the third marketing group, regardless of feed withdrawal time. Prevalence of severe damage, prevalence of chronic damage, and prevalence of esophageal constriction increased as carcass weight decreased. No pigs died of gastric ulceration.

Conclusion and Clinical Relevance—Results suggest that withdrawal of feed from pigs prior to slaughter does not increase damage to the stomach and that repeated feed withdrawal does not result in fatal gastric ulceration. (J Am Vet Med Assoc 2002;220:503–506)

Full access
in Journal of the American Veterinary Medical Association

Objective

To determine the prevalence and serotypes of Salmonella organisms in feces of pigs raised in a modern, multiple-site production system.

Design

Cross-sectional study of prevalence.

Sample Population

Swine housed on 7 farms (1 gilt development farm, 2 breeding farms, 1 nursery farm, and 3 finishing farms) that formed a multiple-site production system.

Procedure

Fecal samples were obtained from 792 pigs (96 to 202/farm) and submitted for bacteriologic culture of Salmonella organisms.

Results

Salmonellae were isolated from pigs on all 7 farms and from 95 of 792 (12%) fecal samples. Prevalence ranged from 3.4% at the gilt development farm to 18 and 22% at the breeding farms. Serotypes identified were Salmonella derby, S typhimurium var. Copenhagen, S heidelberg, S typhimurium, S mbandaka, S worthington, and S tennessee. No single serotype was not isolated from all the farms of the production system and the most prevalent serotypes at the 3 finishing farms (S typhimurium or S typhimurium var. Copenhagen) were not isolated from the breeding or nursery farms.

Clinical Implications

Upstream infection (pigs infected before arriving at finishing farms) appears to be an unimportant source of Salmonella infection of finished hogs in multiple-site systems. High prevalence of Salmonella shedding in breeding animals suggests that food products derived from culled breeding livestock may be an important source of foodborne disease. (J Am Vet Med Assoc 1998;212:1925–1929)

Free access
in Journal of the American Veterinary Medical Association