Effects of divergent selection for limb weakness on bone and muscle cross-sectional areas in Duroc swine

The relationship of muscle and bone structure to limb weakness was examined in 60 Duroc pigs from 3 lines divergently selected for thoracic limb weakness. The lines were designated high, control, or low, with the low line having inferior thoracic limb structure. At approximately 100 kg, 10 pigs of each line and gender were scored for thoracic limb structure and movement. Right and left thoracic limbs were collected at slaughter. A computerized morphometric image analysis system was used to determine cross-sectional areas of muscles, bones, and soft tissues at levels through the brachium, antebrachium, metacarpus, and digits. The statistical model that was used to analyze the data included the effects of line, sire, gender, and side (left vs right), with weight as a covariate. Total bone area was similar for all 3 lines of pigs at all cross-sectional levels, but significant differences in muscle and other soft tissue areas were observed, including significantly greater extensor area for the antebrachium (P less than 0.001) in low-line pigs than in control- and high-line pigs, smaller total area (P less than 0.05) of the metacarpus in low-line pigs than in control and high-line pigs, and less total area of the medial digit (P less than 0.01) in low-line pigs than in control- or high-line pigs. Total area of bone and soft tissue for each cross-sectional region was significantly greater (P less than 0.05) in boars than in gilts. Side differences also were observed in total cross-sectional areas of bone and soft tissue of the antebrachium, metacarpus, and digits.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of divergent selection for leg weakness on angularity of joints in Duroc swine

Sixty Duroc pigs, representing offspring of three lines from the fifth generation of divergent selection for leg weakness, were examined to determine correlated responses in joint angularity. The lines were low, control, and high, with the latter having superior front leg structure. At approximately 100 kg, 10 pigs of each sex and line were scored for front and rear leg structure and movement. The shoulder, elbow, carpal and hock joints were measured for resting angles and range of motion. The model to analyze the data included the effects of line, sire, sex and side and covariable for weight. High-line pigs had significantly smaller (P less than .05) resting angles of the elbow joint than did control- or low-line pigs. The low-line pigs, however, had significantly smaller resting angles at the carpal joint (P less than .01) and greater resting angles at the hock joint (P less than .05) than did control- or high-line pigs. The low-line pigs had fewer degrees extension at the elbow joint and fewer degrees flexion at the carpal joint than did control- or high-line pigs. High-line pigs had fewer degrees of flexion of the elbow joint than did control-or low-line pigs. Resting angles and range of motion for the elbow and carpal joints were less on the left side than on the right side. Males had greater degrees of extension and total degrees of movement at the elbow joint than did females. Selection for different degrees of leg weakness resulted in accompanying alterations in angularity of joints.     

Absence of strictly age-related resistance to Mycoplasma hyosynoviae infection in 6-week-old pigs

Mycoplasma hyosynoviae has never been reported to cause arthritis in pigs younger than 10 weeks of age. In order to investigate whether a strict age-related resistance exists, four 6-week-old pigs and four 13-week-old pigs, all immunologically na?ve with respect to M. hyosynoviae, were inoculated intranasally with the agent and autopsied at day 11 or 13 after infection. One uninoculated pig per age group was included as a negative control. Just as the 13-week-old pigs, the 6-week-old piglets were susceptible to blood, joint and tonsillar infection with M. hyosynoviae and developed clinical arthritis following inoculation with the agent. Thus, we found no evidence of an age-related resistance to the infection.     

Effect of dietary sodium bicarbonate on leg structure in Duroc swine that differ genetically for leg weakness

Two trials were conducted to evaluate the effect of dietary replacement of .30% sodium chloride (NaCl) with a sodium-equivalent amount of sodium bicarbonate (NaHCO3) on leg weakness in swine. Three lines of Duroc swine established by six generations of divergent selection for front leg structure were used. In the first trial, a total of 80 low-line (increased leg weakness), 75 high-line (decreased leg weakness), 80 control-line (intermediate leg weakness) and 80 high x low pigs were used. Pigs were assigned within litter to an experimental or control diet and tested from approximately 37 to 104 kg live weight. The experimental diet contained .43% NaHCO3, replacing .30% NaCl in the control diet. Pigs had ad libitum access to feed. In the second trial, 48 high- and 48 low-line pigs were fed the same diets from 29 to 104 kg. At the completion of each trial, pigs were scored for various leg traits. The model used for statistical analyses included the effects of replicate, genetic line, dietary treatment and the dietary treatment x genetic line interaction. Trials were analyzed separately. Results indicated that there was no significant improvement in clinical signs of leg weakness due to dietary supplementation with NaHCO3 for front leg structure and movement, rear leg movement or rear toe size. Rear hock angle was improved in Trial 1 (P less than .05) but was reduced in Trial 2 (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)     

Mycoplasma hyopneumoniae and Mycoplasma hyosynoviae Infection in Cases of Fibrinous Pericarditis in Slaughter Pigs

Pericarditis, acute or subacute, is found at post mortem meat inspection of baconers in about 0.02 to 0.04% of slaughtered pigs in Denmark. The pathological findings are usually restricted to the pericardial sac. The pericardial sac is filled with a fibrinous exudate, which may be blood stained. In some cases massive granulation tissue formation is seen underlying the fibrinous exudate. Other constantly occurring, but less aggravating lesions, are chronic catarrhal bronchopneumonia and increased volume of serosanguinous synovial fluid in the large joints of the limbs. Lesions usually seen as sequelae to septicaemia have not been observed. The lesions seem to be part of a pathological entity which may be involved in the pathogenesis of fibrinous pericarditis in baconers.     

Mycoplasma hyosynoviae in joints with arthritis in abattoir baconers.

The occurrence of Mycoplasma hyosynoviae in synovial fluid of baconers with chronic arthritis was studied at an abattoir. Cultural examination of synovial fluid samples from diseased tarsal joints of 50 animals from 42 herds yielded M. hyosynoviae in 10 cases from 8 herds. Streptococci were found in 6 cases from 6 other herds. M. hyosynoviae antigen was found in 1 of 47 of the samples, and antibody to the mycoplasma was found in 14 of 40 of the samples by ELISA test. The presence of M. hyosynoviae in a joint was usually accompanied by the corresponding antibody. In joints with streptococcal infection antibody to M. hyosynoviae could not be found.     

A biological network describing infection with Mycoplasma hyopneumoniae in swine herds

We have made a biological model based on a Bayesian network for risk factors for infection with Mycoplasma hyopneumoniae (Mycoplasma) in slaughter pigs; prevalence of infection is based on veterinary examinations. The model is a probabilistic/stochastic determination based on the inherent biological uncertainty of the severity of infection with Mycoplasma and the derived stochastic effects on productivity for the herd. The conditional probabilities in the Bayesian network are based on published studies and expert opinions. We used the model to calculate how the risk factors and our evidence about the herd influenced our view on the severity of Mycoplasma, and how our view changed when we had more veterinary evidence. We also show how one can use the model to deal with conflicting examinations.     

Factors affecting longevity in maternal Duroc swine lines

A competing risks approach was used to evaluate the influence of several pre-farrowing factors on risk of culling due to different causes in Duroc swine, these having low fertility, low productivity, lameness and mortality. Culling due to low fertility increased for average daily gains during the growth test lower than 585 g/day, whereas culling due to low productivity and mortality increased with low levels of backfat thickness at the end of the growth test. Lesser loin depths at first farrowing reduced culling due to low productivity but increased culling due to lameness. Furthermore, a higher average daily gain from the end of the growth test to first mating increased culling by all causes. A complementary analysis was carried out to evaluate the influence of these factors on risk of culling without taking into account the specific reason of failure. In this second analysis, the factors were included as time-dependent covariates whose relative importance changed throughout the sows' productive life. Expected survival functions and replacement rates have been calculated in different hypothetical situations in order to determine the optimal animal body type at first farrowing to maximise longevity, which under our production conditions is independent of average daily gain from birth until the end of the growth test, but from the end of the growth test to first mating average daily gain should not be over 485 g/day; backfat thickness should be more than 16 mm at the end of the growth test and maintain this level until the first parturition without exceeding 19 mm; loin depth should be kept below 45 mm at first farrowing.     

Chronological Development of Mycoplasma hyorhinis and Mycoplasma hyosynoviae Infections in Cultures of a Swine Synovial Cell Strain

The sequential development of Mycroplasma hyorhinis and Mycoplasma hyosynoviae was observed in cultures of a swine synovial fluid cell strain. An early transitory filamentous phase was observed with M. hyorhinis infection followed by the development of cell-associated, relatively large, round structures and some ring forms. Infection with M. hyorhinis was characterized by a generalized distribution of the organism and a severe cytopathic effect.

Infection with M. hyosynoviae was represented by the development of circumscribed foci of small pleomorphic structures and a milder effect on the cells. At a high multiplicity of infection, this organism became associated with the cytoplasmic membranes of the cells.

     

SLA与经济性状关系

作者概述了猪白细胞抗原与生产性能、繁殖性能以及抗病性能等诸多经济性状间的关系，为猪白细胞抗原作为一种遗传标记在猪育种生产上的应用提供了理论依据。     

FTO基因多态性与杜洛克公猪生长性状的关联研究

旨在分析肥胖相关基因(FTO)多态性位点(g.400CG与c.46-139AT)与杜洛克猪群的生长性状的关联性,为该位点的分子标记辅助选择提供理论依据。试验采集了广东某猪场374头杜洛克猪核心群公猪的DNA样本,并测定杜洛克公猪的生长性状,用高分辨率熔解曲线(HRM)技术检测基因型,并进行标记-性状关联分析。结果表明:FTO基因g.400CG和c.46-139AT位点多态性分别与杜洛克公猪100 kg背膘厚、瘦肉率、饲料转化率、体高、体长等性状存在显著相关。g.400CG位点CC基因型个体平均背膘厚显著低于CG与GG型,瘦肉率显著高于后两者,GG型个体的饲料转化率显著低于CC型与CG型个体(P0.05);c.46-139AT位点AT基因型在体长和体高上均显著高于AA型和TT型(P0.05),存在明显的杂合子效应。g.400CG位点CC基因型是优势基因型,可用于背膘薄、瘦肉率高的新品系的选育,而GG型具有更高的饲料化率,有一定的潜在价值;c.46-139AT位点在体长和体高方面存在杂合效应,可为选育种工作提供参考。     

Relationship between blood iron parameters and trichinellosis in swine

Reduced levels of total iron binding capacity and unsaturated iron binding capacity were observed in the blood of trichinous and iron-injected trichinous pigs. No change was observed in their serum iron and saturation concentration levels. Also, reduced iron concentration levels were observed in the livers of trichinous pigs, while increased iron concentration levels were observed in the spleens of trichinous pigs and the livers and spleens of iron-injected pigs. No difference was found with regard to weight gains, number of larvae per gram of tissues, or histologic characteristics of 'nurse cells'.