Total body and regional measurements of bone mineral content and bone mineral density in pigs by dual energy X-ray absorptiometry

Application Times, Placement Accuracy, and User Ratings of Commercially Available Manual and Battery-Powered Intraosseous Catheters in a High Bone Density Cadaveric Swine Model

INTRODUCTION

Intraosseous (IO) infusion, the pressurized injection of fluids into bone through a catheter, is a life-preserving resuscitative technique for treating trauma patients with severe hemorrhage. However, little is known regarding the application times, placement accuracy, and end-user ratings of battery-powered and manual IO access devices. This study was specifically designed to fill these knowledge gaps on six FDA-approved IO access devices.

MATERIALS AND METHODS

Three experienced U.S. Navy Emergency Medicine residents each placed commercially available 15-gauge IO catheters in cadaveric swine (Sus scrofa) proximal humeri and sternums in a randomized prospective experimental design. Devices included the battery-powered EZ-IO Rapid Infuser and the manual Jamshidi IO, PerSys NIO, SAM Manual IO, Tactical Advanced Lifesaving IO Needle (TALON), and PYNG First Access for Shock and Trauma 1 (30 trials per device, 10 per user, 210 total trials). Application times, placement accuracy in medullary (zone 1) and trabecular (zone 2) bone while avoiding cortical (zone 3) bone, and eight subjective user ratings were analyzed using ANOVA and nonparametric statistics at P < .05.

RESULTS

The EZ-IO demonstrated the fastest application times, high rates in avoiding zone 3, and the highest user ratings (P < .0001). The TALON conferred intermediate placement times, highest rates of avoiding zone 3, and second-highest user ratings. The SAM Manual IO and Jamshidi performed poorly, with mixed results for the PerSys NIO and PYNG First Access for Shock and Trauma 1.

CONCLUSIONS

The battery-powered EZ-IO performed best and remains the IO access device of choice. The present findings suggest that the TALON should be considered as a manual backup to the EZ-IO.

Determining Intraosseous Needle Placement Using Point-of-Care Ultrasound in a Swine (Sus scrofa) Model

OBJECTIVE

Intraosseous (IO) access is critical in resuscitation, providing rapid access when peripheral vascular attempts fail. Unfortunately, misplacement commonly occurs, leading to possible fluid extravasation and tissue necrosis. Current research exploring the utility of bedside ultrasound in confirming IO line placement is limited by small sample sizes of skeletally immature subjects or geriatric cadaveric models. The objective of this study was to investigate the potential value of ultrasound confirming IO needle placement in a live tissue model with bone densities approximated to the young adult medical or trauma patient.

MATERIALS AND METHODS

In this randomized, blinded prospective study, IO devices were placed into the bilateral humeri of 36 sedated adult swine (N = 72) with bone densities approximating that of a 20-39-year-old adult. Of the 72 lines, 53 were randomized to the IO space ("correct") and 19 into the subcutaneous tissue ("incorrect"). Four emergency physicians with variable ultrasound experience and blinded to needle location independently assessed correct or incorrect needle placements based on the presence of an intramedullary "flare" on color power Doppler (CPD) during a saline flush. Participants adjusted the ultrasound beam trajectory and recorded assessments up to three times, totaling 204 separate observations.

RESULTS

Overall, sensitivity for placement confirmation was 72% (95% CI: 64%-79%). Specificity was 79% (95% CI: 66%-89%). First assessment and final assessment results were similar. More experienced sonographers demonstrated greater success in identifying inaccurate placements with a specificity of 86% (95% CI: 63%-96%).

CONCLUSION

Within the context of this study, point-of-care ultrasound with CPD did not reliably confirm IO line placement. However, more accurate assessments of functional and malpositioned catheters were noted in sonographers with greater than 4 years of experience. Future study into experienced sonographers' use of CPD to confirm IO catheter placement is needed.

Dietary Phosphorus and Calcium Utilization in Growing Pigs: Requirements and Improvements

The sustainability of animal production relies on the judicious use of phosphorus (P). Phosphate, the mined source of agricultural phosphorus supplements, is a non-renewable resource, but phosphorus is essential for animal growth, health, and well-being. P must be provided by efficient and sustainable means that minimize the phosphorus footprint of livestock production by developing precise assessment of the bioavailability of dietary P using robust models. About 60% of the phosphorus in an animal's body occurs in bone at a fixed ratio with calcium (Ca) and the rest is found in muscle. The P and Ca requirements must be estimated together; they cannot be dissociated. While precise assessment of P and Ca requirements is important for animal well-being, it can also help to mitigate the environmental effects of pig farming. These strategies refer to multicriteria approaches of modeling, efficient use of the new generations of phytase, depletion and repletion strategies to prime the animal to be more efficient, and finally combining these strategies into a precision feeding model that provides daily tailored diets for individuals. The industry will need to use strategies such as these to ensure a sustainable plant–animal–soil system and an efficient P cycle.

Penetration of Energised Metal Fragments to Porcine Thoracic Tissues

Energised fragments from explosive devices have been the most common mechanism of injury to both military personnel and civilians in recent conflicts and terrorist attacks. Fragments that penetrate into the thoracic cavity are strongly associated with death due to the inherent vulnerability of the underlying structures. The aim of this study was to investigate the impact of fragment-simulating projectiles (FSPs) to tissues of the thorax in order to identify the thresholds of impact velocity for perforation through these tissues and the resultant residual velocity of the FSPs. A gas-gun system was used to launch 0.78-g cylindrical and 1.13-g spherical FSPs at intact porcine thoracic tissues from different impact locations. The sternum and rib bones were the most resistant to perforation, followed by the scapula and intercostal muscle. For both FSPs, residual velocity following perforation was linearly proportional to impact velocity. These findings can be used in the development of numerical tools for predicting the medical outcome of explosive events, which in turn can inform the design of public infrastructure, of personal protection, and of medical emergency response.

Single Versus Double Anatomic Site Intraosseous Blood Transfusion in a Swine Model of Hemorrhagic Shock

BACKGROUND

Blood transfusion via single site intraosseous access is a critical modality when caring for a trauma victim that lacks intravascular access. Flow rates and potential clinical complications when utilizing two sites of intraosseous access are not well known.

MATERIALS AND METHODS

Anesthetized adult female Yorkshire swine (Sus scrofa; n = 48; 76.7 ± 1.75kg; range 66-90kg) were cannulated and then bled approximately 30% total blood volume. Swine were randomly assigned to treatment groups: single sited humerus, single sited sternum, dual sited humerus or dual sited humerus and sternum. Flow rates, hemolysis, physiologic measurements, biochemical variables, and pulmonary histologic inflammation and occlusion were contrasted between groups.

RESULTS

Dual sited intraosseous transfusion flow rates (128ml/min, 95% CI 123-132) were double the flow rates of single sites (65ml/min, 95% CI 60-70), P < .0001.Single sited humeral flow rates were greater than sternal flow rates, with respective averages of 74ml/min and 55ml/min, though not reaching statistical significance (P < 0.17). There was no significant elevation of plasma free hemoglobin in any group after transfusion as compared to baseline (P = 0.7). Groups did not significantly differ in vitals or biochemical variables. Most pulmonary specimens had some intraparenchymal fat embolism, however no animals had evidence of occlusive intra-arterial fat embolism.

CONCLUSIONS

Dual anatomic site, pressure bag driven, intraosseous blood transfusion approximately doubles flow rates without evidence of clinical complications or hemolysis. Further research using a survivability model is needed to characterize long-term complications from pressurized IO transfusions.

Pediatric Intraosseous Access Performed by Emergency Department Nurses Using Semiautomatic Devices: A Randomized Crossover Simulation Study

BACKGROUND

No study has examined the performance of emergency department (ED) nurses in establishing intraosseous access (IO) access. This study aimed to evaluate ED nurses' success rate in establishing pediatric IO access using semiautomatic devices.

METHODS

A randomized crossover simulation study was conducted. The success rates of ED nurses were compared with those of paramedics with similar years of experience. The study instruments were the new spring-loaded injector (NIO) and the battery power drill (EZ-IO). Uncooked piglets' bones were used as the study model. All attempts were filmed by a video camera. Successful placement was defined as the visualization of flow from the marrow cavity. Participants recorded their ranking of the "ease of use" of each device.

RESULTS

No differences in 1-attempt success rate was found between nurses and paramedics (27/34 [79.4%] vs 25/30 [83.3%], P = 0.68). Nurses and paramedics had similar success rates with the 2 semiautomatic IO devices (12/17 vs 12/15 with the spring-loaded injector, P = 0.69, and 15/17 vs 13/15 with the battery power drill, P = 0.9). The number of failed attempts and the causes for failure were equally distributed between nurses and paramedics. Median ease-of-use Likert-scale scores of the spring-loaded injector and the battery power drill were 4 (interquartile range [IQR] = 3-4) and 5 (IQR = 5-5) (P < 0.04) for the nurses and 5 (IQR = 4-5) and 5 (IQR = 4-5) (P = 0.44) for the paramedics, respectively.

CONCLUSIONS

Emergency department nurses and paramedics had a similarly high insertion success rates on a pediatric bone model. This pilot study suggests that ED nurses can successfully perform this procedure.

Intravenous and Intraosseous Blood Transfusion With Three Different Pediatric Pressure Transfusion Strategies in an Immature Swine (Sus scrofa) Model of Hemorrhagic Shock: A Pilot Study

INTRODUCTION

Exsanguination remains the leading cause of preventable death in military conflicts, and pediatric casualties are common. Transfusion is crucial to preserve life, but vascular access is challenging in children, so intraosseous (IO) access is often required. However, the optimal transfusion method is unclear. There was therefore the need for feasibility testing of a model for contrasting the efficacy of blood infusion devices via intravenous (IV) and IO access in immature swine with bone densities similar to children.

MATERIALS AND METHODS

Eighteen immature swine (21 ± 1 kg) were bled 31% of estimated blood volume and then received autologous blood delivered by pressure bag, push-pull (PP), or LifeFlow Rapid Infuser via IO (15-gauge IO needle placed in the humeral head) or IV (auricular 20-gauge), with monitoring for 60 minutes.

RESULTS

Flow rates for LifeFlow (172 ± 28 mL/kg) were 4-fold higher than pressure bag (44 ± 13 mL/kg, P < 0.001) and 80% higher than PP (95 ± 28 mL/kg, P < 0.02). However, higher hemolysis was evident in the IV LifeFlow condition, with 6-fold more plasma-free hemoglobin than other conditions (P < 0.0001).

CONCLUSIONS

IV LifeFlow conferred higher flows, but higher hemolysis in this pilot study demonstrates the feasibility of an immature swine model toward determining optimal methods for resuscitating children with hemorrhagic shock.

A Novel Corn-Expressed Phytase Improves Daily Weight Gain, Protein Efficiency Ratio and Nutrients Digestibility and Alters Fecal Microbiota in Pigs Fed with Very Low Protein Diets

The objective of this study was to assess the effect of a novel corn-expressed phytase (CEP) on growth, nutrients digestibility, bone characteristics and fecal microbiota of pigs fed with very low-protein, -calcium (Ca) and -phosphorous (P) diets. Forty-eight barrows were subjected to 6 groups for 4 weeks: positive control-adequate protein (PC), negative control-reduced protein (NC), NC + low-dose CEP, i.e., 2000 FTU/kg (LD), NC + high-dose CEP, i.e., 4000 FTU/kg (HD), LD with 0.12% unit reduced Ca and 0.15% unit reduced available P (LDR), and HD with 0.12% unit reduced Ca and 0.15% unit reduced available P (HDR). Compared to NC, LD and HDR had a higher average daily gain (ADG) and gain:protein ratio (G:P), HD and HDR had greater apparent fecal digestibility of Ca and P and bone mineral density and LDR and HDR had lower serum osteocalcin. The feces of LD was enriched in Lachnospiraceae, while the HD had a higher abundance of Succinvibrio and LDR had a higher abundance of Bifidobacterium and Actinobacteria. In conclusion, supplementation of protein-restricted diets with a CEP decreased their negative effects on ADG and G:P ratio, increased the digestibility of Ca and P regardless of the levels of these minerals in the diet, improved bone characteristics and produced differential effects on fecal bacterial population.

"Sex" and body region effects on bone mineralization in male pigs

Lameness in pigs is one of the major reasons for culling and early losses in pigs. This can be linked to osteoporosis due to pathologic alterations in bone mineral density (BMD) or bone mineral content (BMC) and may also be linked to the sex. Dealing with the ban on piglet castration without anaesthesia in Germany 2021, we have three male “sex” types: entire boars (EB), immunocastrated boars (IB), and surgically castrated boars (SB). The hypothesis of the present study is that BMC or BMD varies between different male sex types. If sex has an effect on bone mineralization (BMC or BMD) and if this affects leg health, it could result in more lameness and problems during fattening in the negatively affected sex type. The present study evaluated bone mineralization (in terms of BMD and BMC) and body composition traits using dual-energy X-ray absorptiometry (DXA) three times during growth at 30, 50, and 90 kg live body weight. Nine body regions were analysed for bone mineral traits and compared for different male sex types and the fattening season. Significant differences were found regarding BMD (and BMC) among EB, IB, and SB for whole-body BMD (BMC). Additionally significant differences were found in the front and lower hind limbs, where SB showed a significantly higher BMD compared to EB, with IB in between. Additionally regional differences were detected among the groups. Further studies are needed to evaluate the effect of these differences in bone mineralization on leg health.

Identification of novel variants and candidate genes associated with porcine bone mineral density using genome-wide association study

Pig leg weakness not only causes huge economic losses for producers but also affects animal welfare. However, genes with large effects on pig leg weakness have not been identified and suitable methods to study porcine leg weakness are urgently needed. Bone mineral density (BMD) is an important indicator for determining leg soundness in pigs. Increasing pig BMD is likely to improve pig leg soundness. In this study, porcine BMD was measured using an ultrasound bone densitometer in a population with 212 Danish Landrace pigs and 537 Danish Yorkshires. After genotyping all the individuals using GeneSeek Porcine 50K SNP chip, genetic parameter estimation was performed to evaluate the heritability of BMD. Genome-wide association study and haplotype analysis were also performed to identify the variants and candidate genes associated with porcine BMD. The results showed that the heritability of BMD was 0.21 in Landrace and 0.31 in Yorkshire. Five single-nucleotide polymorphisms on chromosome 6 identified were associated with porcine BMD at suggestive significance level. Two candidate quantitative trait loci (74.47 to 75.33 Mb; 80.20 to 83.83 Mb) and three potential candidate genes (ZBTB40, CNR2, and Lin28a) of porcine BMD were detected in this study.

Safety of Pressurized Intraosseous Blood Infusion Strategies in a Swine Model of Hemorrhagic Shock

BACKGROUND

Current guidelines support intraosseous access for trauma resuscitation when intravenous access is not readily available. However, safety of intraosseous blood transfusions with varying degrees of infusion pressure has not been previously characterized.

MATERIALS AND METHODS

Adult female Yorkshire swine (Sus scrofa; n = 36; mean (M): 80 kg, 95% CI: 78-82 kg) were cannulated and then bled approximately 30% total blood volume. Swine were randomly assigned to proximal humerus intraosseous blood infusion with either Rapid Infuser, or Pressure Bag, or Push-Pull methods (n = 12 each). Flow rates, infusion pressures, vitals, biochemical variables, and pulmonary and renal tissue pathology were contrasted between groups.

RESULTS

Flow rates were greater for the Push-Pull strategy than Pressure Bag (96.5 mL/min versus 72.6 mL/min, P = 0.02) or Rapid Infuser (96.5 mL/min versus 60 mL/min, P = 0.002) strategies. The pressures generated during the Push-Pull transfusion (3058 mmHg) were greater than the other strategies (≤360 mmHg). After the observation period, plasma-free hemoglobin levels were higher in the Push-Pull strategy than in the Rapid Infuser (40 mg/dL versus 12 mg/dL, P = 0.02) or Pressure Bag (40 mg/dL versus 12 mg/dL, P = 0.01). Groups did not significantly differ in vitals, biochemical variables, or tissue pathology.

CONCLUSIONS

Push-Pull conferred the highest flow rates, but with higher infusion pressures and evidence of intravascular hemolysis. Rapid Infuser and Pressure Bag infusions had no increase from baseline in plasma-free hemoglobin. Pressure Bag infusion was noted to confer an advantage in flow rates over Rapid Infuser. Intraosseous blood transfusion with pressure bags can safely bridge toward central access in the early phases of trauma resuscitation.

The Effect of Group Composition and Mineral Supplementation during Rearing on Measures of Cartilage Condition and Bone Mineral Density in Replacement Gilts

Lameness is a major cause of poor longevity and poor welfare in replacement gilts. The problem is exacerbated by inappropriate housing and diet during the rearing period. Replacement gilts are often reared with male finisher pigs destined for slaughter. If they are not castrated, they perform high levels of potentially injurious sexual and aggressive behaviour. Furthermore, finisher pig diets are not designed to meet the needs of developing gilts and may not supply the necessary minerals to support good limb health. The objective of this study was to evaluate the effect of supplementing the diet of replacement gilts with copper, zinc and manganese and separating them from males during the rearing period on locomotory ability, bone mineral density and cartilage lesion scores. A 2 × 2 factorial design experiment investigated the effect of female-only or mixed-sex rearing, with or without supplementary minerals (Copper, Zinc and Manganese). In total, 384 maternal line gilts were assigned to 32 pens of 12 and were locomotion scored during the rearing period. A sub-sample (n = 102) of gilts were culled at breeding age and the front right limb was removed at slaughter. Areal bone mineral density (aBMD) was measured using dual energy X-ray absorptiometry, after which the limb was dissected to score the condition of the cartilage. The addition of trace minerals to the diet resulted in increased aBMD in the humerus (P < 0.05) compared to the control diet. Rearing gilts in female-only groups reduced the number of cartilage lesions overall (P < 0.05), and on the humeral condyle (P < 0.05). Rearing replacement gilts in female-only groups and with mineral supplementation had benefits for limb health.

The minipig as a potential model for pedicle screw fixation: morphometry and mechanics

Background

While there are several different animal models for use in the characterization of spinal fixation, none have emerged as a definitive model for comparative studies in spinal fixation methods. The purpose of this study is to establish morphometric data of porcine vertebrae and to characterize the feasibility of pedicle screw fixation in porcine spines for potential comparative human study.

Methods

Four spines from 45 to 50 kg Hanford minipigs were cleaned of soft tissue and analyzed by computed tomography and dual-energy x-ray absorptiometry. Two 5 × 30-mm pedicle screws were placed in each vertebra and tested to failure using a combined moment-load protocol.

Results

Pedicle widths were measured from L6-T5. Widths ranged from 7.15 mm (T6) to 9.24 mm (T14). Posterior cortex to anterior cortex depth ranged from 25.9 to 32.6 mm. Mean bone mineral density was 1.0665 g/cm² (range 1.139–1.016). Force-to-failure demonstrated mean 1171.40 N (+ 115.34).

Conclusion

Our baseline morphometric and compositional data demonstrate that porcine vertebrae can serve as a useful model for comparative studies due to their similar pedicle widths and bone mineral density to the human vertebra. This biomechanical data could provide a baseline comparison for future studies. This study also suggests that the minipig could be a suitable model for comparative studies due to similarities in pedicle width and bone mineral density to the human vertebrae.

Bone mineralisation, mechanical properties and body phosphorus content in growing gilts as affected by protein or feed intake during depletion-repletion periods

The influence of feed or protein depletion-repletion on phosphorus balance, and bone characteristics was studied on 70 growing pigs from 90 to 168 d of age. During depletion period (90-118 d of age), C pigs were fed semi ad libitum (95% ad libitum intake) on control diet; FR pigs (feed-restricted group) consumed 40% less of control diet compared to C pigs; PR pigs (protein-restricted group) were fed semi ad libitum a low-protein diet containing 40% less protein than control diet. During repletion period (119-168 d of age), daily allowances for C pigs were equal of 95% ad libitum intake. Remaining pigs consumed a control diet at the same amount as C pigs. Pigs were slaughtered at 90 d of age ("zero" animals, n = 7), following seven animals from each group at d 118, 146 and 168  of age. At 118 d of age, phosphorus content in the body was lower (p < 0.001) in FR than C and PR pigs. Lower phosphorus deposition and utilisation was observed in FR animals. Humerus in FR pigs was lighter, had lower mineral content and density, but had greater stiffness than in PR and C pigs. During repletion period, FR pigs deposited more phosphorus and had better phosphorus utilisation than C and PR pigs. Humerus mineral density was greater in FR and PR than in C pigs. Humerus strength was the highest in PR pigs, and the lowest in FR pigs. Humerus stiffness was greater in PR than in C and FR pigs. In conclusion, during depletion period feed restriction affects bone growth more than protein restriction, and bone strength is less sensitive, than other bone characteristics, to feed restriction. Reductions in measured bone indices observed after lower feed intake can be fully compensated during the repletion period and resulted mainly from better utilisation of minerals.

Bone mineralisation of weaned piglets fed a diet free of inorganic phosphorus and supplemented with phytase, as assessed by dual-energy X-ray absorptiometry

Sixteen female piglets (58 d of age, 16.8 ± 0.8 kg body weight [BW]) were assigned to two groups (n = 8) and received until day 100 of age (50.3 ± 1.2 kg BW) ad libitum either a diet with a standard (diet C) or low (diet L) total phosphorus (P) content (5.38 and 4.23 g/kg, respectively). Diet C was supplemented with mineral P (1.15 g/kg) and did not contain microbial phytase. Diet L did not contain any inorganic P but 750 FTU/kg of microbial phytase. Despite these treatments, both diets were composed with the same ingredients. Body mineralisation of each gilt was assessed by determining the bone mineral content (BMC), area bone mineral density (BMD) by the dual-energy X-ray absorptiometry (DXA) at days 58, 72, 86 and 100 of age. Feeding diet L caused a higher P digestibility (p = 0.008) measured from days 72 to 86 of age and at 100 days of age a higher BMC and BMD (p ≤ 0.01). Furthermore, the gilts of group L deposited more minerals in the body than control pigs (by 2.4 g/d, p = 0.008). It was found that BMD and BMC were positively correlated with body lean mass and digestible P intake. The results indicated that, even for very young pigs, the addition of microbial phytase instead of inorganic P increases the amount of digestible P covering the requirements of piglets for proper bone mineralisation. Furthermore, it was proved that the DXA method can be successfully applied to measure body fat and lean mass contents as well as bone mineralisation of growing pigs using the same animals.

Evaluation of carcass composition of intact boars using linear measurements from performance testing, dissection, dual energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI)

The objective of this study was to investigate non-invasive imaging methods to update the used regression equation for stationary tested boars. A total of 94 boars were examined. 20 boars were dissected to provide the reference LMP. Performance data (PD) from right carcasses were available from all groups. The left carcasses were studied by MRI & DXA. Based on the reference LMP and the MRI & DXA data, regression equations for LMP were developed. The estimates for LMP based on MRI & DXA data were used to calculate new regression equations for entire male carcass halves based on linear PD. Further 33 PD sets served as independent sample, which was included in a Monte Carlo simulation for imputing the missing reference LMPs (n=74) and discussing the accuracy of the results. The LMP regression equation based on the combined MRI & DXA data is as accurate as the former regression equation, but needs only three instead of seven variables.

In vivo body composition in autochthonous and conventional pig breeding groups by dual-energy X-ray absorptiometry and magnetic resonance imaging under special consideration of Cerdo Ibérico

The improvement of carcass quality is one of the main breeding goals in pig production. To select appropriate breeding animals, it is of major concern to exactly and reliably analyze the body composition in vivo. Therefore, the objective of the study was to examine whether the combination of dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI) offers the opportunity to reliably analyze quantitative and qualitative body composition characteristics of different pig breeding groups in vivo. In this study, a total of 77 pigs were studied by DXA and MRI at an average age of 154 days. The pigs originated from different autochthonous or conventional breeds or crossbreeds and were grouped into six breed types: Cerdo Ibérico (Ib); Duroc × Ib (Du_Ib); White Sow Lines (WSL, including German Landrace and German Large White); Hampshire/Pietrain (Pi_Ha, including Hampshire, Pietrain × Hampshire (PiHa) and Pietrain × PiHa); Pietrain/Duroc (Pi_Du, including Pietrain × Duroc (PiDu) and Pietrain × PiDu); crossbred WSL (PiDu_WSL, including Pietrain × WSL and PiDu × WSL). A whole-body scan was performed by DXA with a GE Lunar DPX-IQ in order to measure the amount and percentage of fat tissue (FM; %FM), lean tissue (LM; %LM) and bone mineral, whereas a Siemens Magnetom Open with a large body coil was used for MRI in the thorax region between 13th and 14th vertebrae in order to measure the area of the loin (LA) and the above back fat area (FA) of both body sides. A GLM procedure using SAS 9.2 was used to analyze the data. As expected, the native breed Ib followed by Du_Ib crossbreeds showed the highest %FM (27.2%, 25.0%) combined with the smallest LA (46.2 cm2, 73.6 cm2), whereas Ib had the lowest BW at an average age of 154 days. Pigs with Pi_Ha origin presented the least %FM (12.4%) and largest LA (99.5 cm2). The WSL and PiDu_WSL showed an intermediate body composition. Therefore, it could be concluded that DXA and MRI and especially their combination are very suitable methods to reliably identify differences in body composition and carcass traits among different pig lines in vivo.

THE EFFECT OF KNEE POSTURES AND CUSHIONS IN THE LOAD TRANSMISSION OF IMPACT LOADING - AN IN VITRO BIOMECHANICAL PORCINE MODEL

Degenerative osteoarthritis is the consequence of impact force applied to articular cartilage that results in surface fissuring. Soft cushions and flexed posture are two important factors to reduce the impact force; however, no quantitative information of how soft should the cushion be to prevent the injury and the mechanism of force attenuation of knee joint at neutral and flexed posture was not well documented yet. The objective of current study is hence to find the quantitative shock attenuation of knee joint using different stiffness of cushions when the knee is at neutral posture and flexed posture. A “drop-tower type” impact apparatus was used for testing. Nineteen fresh porcine knee joints were divided into two posture groups, i.e. neutral and flexed posture. All specimens were tested using stiff, medium, and soft cushions. The axial reaction force, anteroposterior shear force, and flexion bending moment were recorded for analysis. We found the flexed posture decreased the axial reaction force and anterior shear force but increased the flexion bending moment. The effect of stiffness of cushions on the mechanical response of knee joint during impact loading was significant for neutral posture but not for flexed posture.

Association and expression study of MMP3, TGFβ1 and COL10A1 as candidate genes for leg weakness-related traits in pigs

The present study was aimed to determine the association between metalloproteinase 3 (MMP3), transforming growth factor beta 1 (TGFβ1) and collagen type X alpha I (COL10A1) gene polymorphisms with traits related to leg weakness in pigs. Three hundred Duroc × Pietrain cross breds (DuPi) and 299 pigs of a commercial population (CP) were used for the experiment. DuPi animals were examined for 10 different traits describing leg and feet structure, osteochondrosis (OC) scores and bone density status. Data of OC score at condylus medialis humeri, condylus medialis femoris and distal epiphysis ulna regions of CP were used for association analysis. Significant association (P < 0.05) was found for MMP3 SNP (g.158 C>T) with OC at head of femur and bone mineral density in the DuPi population. Association (P < 0.05) was found between SNP of TGFβ1 (g.180 G>A) with rear leg score and the principle component denoting both OC and feet and leg scores in the DuPi population. No association was found between COL10A1 (g.72 C>T) and leg weakness related traits. The associations of SNPs with OC traits could not be confirmed in the commercial population. Expression analysis of the three candidate genes was performed to compare between healthy and OC. TGFβ1 was found to be highly expressed (P < 0.05) in the OC compared to healthy cartilages, but no significant different expressions were observed for MMP3 and COL10A1 genes. The present finding suggested that TGFβ1 and MMP3 genes variants have an effect on some of the leg weakness related traits.

Quantitative trait loci analysis for leg weakness-related traits in a Duroc × Pietrain crossbred population

Background

Leg weakness issues are a great concern for the pig breeding industry, especially with regard to animal welfare. Traits associated with leg weakness are partly influenced by the genetic background of the animals but the genetic basis of these traits is not yet fully understood. The aim of this study was to identify quantitative trait loci (QTL) affecting leg weakness in pigs.

Methods

Three hundred and ten F₂ pigs from a Duroc × Pietrain resource population were genotyped using 82 genetic markers. Front and rear legs and feet scores were based on the standard scoring system. Osteochondrosis lesions were examined histologically at the head and the condylus medialis of the left femur and humerus. Bone mineral density, bone mineral content and bone mineral area were measured in the whole ulna and radius bones using dual energy X-ray absorptiometry. A line-cross model was applied to determine QTL regions associated with leg weakness using the QTL Express software.

Results

Eleven QTL affecting leg weakness were identified on eight autosomes. All QTL reached the 5% chromosome-wide significance level. Three QTL were associated with osteochondrosis on the humerus end, two with the fore feet score and two with the rear leg score. QTL on SSC2 and SSC3 influencing bone mineral content and bone mineral density, respectively, reached the 5% genome-wide significance level.

Conclusions

Our results confirm previous studies and provide information on new QTL associated with leg weakness in pigs. These results contribute towards a better understanding of the genetic background of leg weakness in pigs.

Physiological values and factors affecting the metacarpal bone density of healthy feedlot beef cattle as measured by dual-energy X-ray absorptiometry

The metacarpal bone mineral density of 136 healthy feedlot beef cattle of four different breeds (Charolaise, Limousine, Irish Crossbreed and Slovakian Crossbreed) raised and fed on standard conditions was measured by means of a dual-energy X-ray absorptiometry technique in an ex vivo study design. The average reference values (mean ± SD) of bone mineral density (BMD) for animals aged between 12 and 22 months and weighing between 236 and 546 kg have been reported and the effects of (i) breed, (ii) gender, (iii) age and (iv) body weight on bone mineral density have been considered. A significant difference (i) among different breeds and (ii) between genders resulted, whereas a high correlation between bone density and (iii) age and (iv) body weight was detected within the same breed and gender, with body weight being the most important factor affecting BMD. A modern new technological insight into the study of bovine bone physio-pathology is proposed.

Molecular characterization and methylation study of matrix gla protein in articular cartilage from pig with osteochondrosis

Osteochondrosis (OC) or leg weakness is an economically important disease of young fast growing pigs and is a concern of animal welfare. The etiology and pathogenesis of osteochondrosis is not fully understood yet, but any abnormalities in the formation of hypertrophic chondrocytes and disrupted blood supply to the growth cartilage are very important predisposing factors. Matrix gla protein (MGP) as a potential calcification inhibitor of extracellular matrix might contribute to the development of OC. Molecular characterization, polymorphisms analysis, methylation at promoter region and expression of MGP gene and protein were performed in both healthy and OC cartilage collected from a DurocxPietrain resource population. The porcine MGP gene consists of 4 exons and 3 introns. The full-length MGP cDNA isolated from articular cartilage consists of 606 bp with a 69-bp 5' UTR, a 312-bp open reading frame with a start codon, a 225-bp 3' UTR. Three single-nucleotide polymorphisms (SNP) were detected in the intron 1 (A-115G, C-1073T and C-1135A) and one in the 3'UTR (C-3767T). The relative abundance of MGP mRNA was lower (P<0.05) in OC compared with healthy cartilage. Moreover, the intensity of MGP band was lower (P<0.05) in OC group when quantified by western blot. Furthermore, one CpG region was identified in MGP promoter and DNA methylation of three CG sites were higher in OC compared with normal cartilage. This suggested that the high DNA methylation at specific CG sites in the MGP promoter might be involved in the down regulation of MGP in OC. Immunofluorescence of normal cartilage collected from pigs of different ages revealed that MGP signals were higher in younger pigs and decreased in the older pigs. The MGP protein was expressed more near to the cartilage canals. These results suggest that the MGP gene might be a potential candidate gene for the development of OC in pigs.

Dietary chlortetracycline induces differential effects on the accuracy of quantitative computed tomography and dual energy X-ray absorptiometry in assessing vertebral bone mineral density in growing pigs

The effect of dietary chlortetracycline (CTC) on the bone mineral density (BMD) of growing pigs was assessed using quantitative computed tomography (qCT) and dual energy X-ray absorptiometry (DXA). Pigs of 28 and 84 days old were given either drug-free (n=48) or CTC-fortified (800 ppm) diets for 56 days. At day 28, eight control pigs were selected for qCT and DXA, and their second lumbar vertebrae were removed. Eight control and eight CTC-treated animals were selected at days 84 and 140, respectively, and six pigs from each of these groups were assessed at day 168. Several CTC-exposure variables had significant effects (P<0.05) on the relationships between qCT-, trabecular- and vertebral body-BMD (R2 increments of 0.03 and 0.01, respectively) and between DXA-, trabecular- and vertebral body-BMD (R2 increments of 0.40 and 0.10, respectively). The findings of this study demonstrate that the qCT method is more reliable than the DXA technique in monitoring tetracycline-induced changes in porcine vertebral BMD. The magnitude of the effect of the drug treatment on the DXA-BMD estimation was surprisingly high, suggesting that DXA should not be used to monitor such changes in growing pigs. In contrast, the marginal influence of drug treatment on the qCT-BMD assessment suggests that this methodology is useful in this context. Furthermore, the qCT method may also have applications in the investigation of the effect of other osteotropic substances or bone metabolism modulators on BMD.

Mature runt cow lumbar intradiscal pressures and motion segment biomechanics

BACKGROUND CONTEXT

The optimal animal model for in vivo testing of spinal implants, particularly total or partial disc replacement devices, has not yet been determined. Mechanical and morphological similarities of calf and human spines have been reported; however, limitations of the calf model include open growth plates and oversized vertebrae with growth. Mature runt cows (Corrientes breed) may avoid these limitations.

PURPOSE

This study compared vertebral morphology and biomechanical properties of human and runt cow lumbar motion segments.

STUDY DESIGN

In vivo disc pressure measurements were obtained in six mature runt cows at L4-L5. In vitro evaluation was performed on these same segments and repeated on 12 human motion segments.

METHODS

Disc pressures were measured in vivo in runt cow (Corrientes breed) L45 discs using a percutaneous transducer with the animal performing various activities. These motion segments were then harvested and morphologic and biomechanical evaluations (disc pressure in compression, flexibility tests to 7.5Nm) were performed on both cow and male human L23 and L45 segments.

RESULTS

The transverse lumbar disc dimensions were slightly smaller for (mixed gender) cow versus (male) humans, but were within the range of reported (mixed gender) human values. The mean+/-SD disc height was smaller for runt cow (7+/-1mm) versus human discs (13+/-2mm, p<.001). The vertebral bodies of the cow were approximately twice as tall as the human. In vitro testing revealed significantly greater disc pressure response to applied axial loading in the runt cow versus humans (1.27+/-0.18 vs. 0.84+/-0.15kPa/N, respectively) but similar overall stiffness (2.15+/-0.71 vs. 1.91+/-0.94kN/mm, respectively). Runt cow and human segment flexibility curves were similar with the following exceptions: runt cow stiffness was approximately 40% greater in torsion (p<.05), runt cow segment lateral bending motion was greater versus humans (range of motion by 30%, neutral zone by 100%; both p<.05), and flexion range of motion tended to be smaller in runt cow versus human specimens (by approximately 40%, p=NS). In vivo, the standing disc pressure in the runt cow was 0.80+/-0.24MPa.

CONCLUSIONS

Although no animal replicates the human motion segment, the runt cow lumbar spine had a number of biomechanical and morphological measurements within the range of human values. The closed physes and temporally stable morphology of the mature runt cow may make this model more suitable versus standard calf models for human intradiscal implant studies.

A genome-wide scan for quantitative trait loci affecting limb bone lengths and areal bone mineral density of the distal femur in a White Duroc x Erhualian F2 population

Background

Limb bone lengths and bone mineral density (BMD) have been used to assess the bone growth and the risk of bone fractures in pigs, respectively. It has been suggested that limb bone lengths and BMD are under genetic control. However, the knowledge about the genetic basis of the limb bone lengths and mineralisatinon is limited in pigs. The aim of this study was to identify quantitative trait loci (QTL) affecting limb bone lengths and BMD of the distal femur in a White Duroc × Erhualian resource population.

Results

Limb bone lengths and femoral bone mineral density (fBMD) were measured in a total of 1021 and 116 F₂ animals, respectively. There were strong positive correlations among the lengths of limb bones and medium positive correlations between the lengths of limb bones and fBMD. A whole-genome scan involving 183 microsatellite markers across the pig genome revealed 35 QTL for the limb bone lengths and 2 for femoral BMD. The most significant QTL for the lengths of five limb bones were mapped on two chromosomes affecting all 5 limb bones traits. One was detected around 57 cM on pig chromosome (SSC) 7 with the largest F-value of more than 26 and 95% confidence intervals of less than 5 cM, providing a crucial start point to identify the causal genes for these traits. The Erhualian alleles were associated with longer limb bones. The other was located on SSCX with a peak at 50–53 cM, whereas alleles from the White Duroc breed increased the bone length. Many QTL identified are homologous to the human genomic regions containing QTL for bone-related traits and a list of interesting candidate genes.

Conclusion

This study detected the QTL for the lengths of scapula, ulna, humerus and tibia and fBMD in the pig for the first time. Moreover, several new QTL for the pig femoral length were found. As correlated traits, QTL for the lengths of five limb bones were mainly located in the same genomic regions. The most promising QTL for the lengths of five limb bones on SSC7 merits further investigation.

Effects of tongue volume reduction on craniofacial growth: A longitudinal study on orofacial skeletons and dental arches

The interaction between tongue size/volume and craniofacial skeletal growth is essential for understanding the mechanism of specific types of malocclusion and objectively measuring outcomes of various surgical and/or orthodontic treatments. Currently available information on this interaction is limited. This study was designed to examine how tongue body volume reduction affects craniofacial skeleton and dental arch formation during the rapid growth period in five 12-week-old Yucatan minipig sibling pairs. One of each pair received a standardized reduction glossectomy to reduce tongue volume by 15-17% (reduction group), and the other had the reduction glossectomy incisions without tissue removal (sham group). Before surgery, five stainless steel screws were implanted into standardized craniofacial skeletal locations. A series of cephalograms, lateral and axial, were obtained longitudinally at 1 week preoperative, and 2 and 4 weeks postoperative. These images were traced using superimposition, and linear and angular variables were measured digitally. Upon euthanasia, direct osteometric measurements were obtained from harvested skulls. Five en-bloc bone pieces were further cut for bone mineral examination by dual photon/energy X-ray absorptiometry (DEXA). The results indicate that: (1) while daily food consumption and weekly body weight were not significantly affected, tongue volume reduction showed an overall negative effect on the linear expansion of craniofacial skeletons; (2) premaxilla and mandibular symphysis lengths, and anterior dental arch width were significantly less in reduction than sham animals at 2 and/or 4 weeks after the surgery; (3) both premaxilla/maxilla and mandible bone mineral density and content were lower in reduction than sham animals, significantly lower in anterior mandible; (4) craniofacial skeletal and dental arch size were significantly smaller in reduction than sham animals, being most significant in the mandibular anterior length and ramus height, the anterior dental arch and midface width. These results suggest that reducing tongue body volume in young animals slows craniofacial skeletal growth and anterior dental arch expansion during rapid growth. The mandible, in particular its symphysis portion, and the anterior dental arch width are most affected. These effects may in part contribute to the decrease of functional loads in the anterior mouth by a volume-reduced tongue.

Measures of Bone Mineral Content in Mature Dairy Cows

The objectives of this investigation were to assess the relationship between chemical measures and imaging estimates (radiographic photometry and dual-energy x-ray absorptiometry) of bone mineral content in dairy cows and to evaluate the effects of parity, stage of lactation, and site of measurement (fused third and fourth metacarpal bone vs. caudal vertebrae 14 and 15) on bone mineral content. In a preliminary study, the caudal vertebrae were excised from 33 cows following slaughter. Samples were analyzed by radiographic photometry and then analyzed for mineral content chemically. In a second experiment, the caudal vertebrae and right front metacarpal (sample pairs) were excised from 107 Holstein cull cows following slaughter. Parity and days in milk (DIM) of the donor animals were obtained for 43 pairs of samples. Samples were grouped by parity (1, 2, 3, and >or=4) stage of lactation (Stage 1: <90 DIM, Stage 2: 90 to 150 DIM, Stage 3: 151 to 250 DIM, and Stage 4: >250 DIM). Samples were analyzed by radiographic photometry and dual-energy x-ray absorptiometry and then analyzed for mineral content chemically. In both experiments, the relationship between mineral content estimated via the imaging techniques and mineral content measured chemically was poor, likely because of the relative maturity of animals in the sample set and lack of variation in mineral content. Ash content was higher in the metacarpal than in the caudal vertebrae, as were concentrations of Mg (expressed as a proportion of bone ash). No effects of stage of lactation were observed on bone mineral in the caudal vertebrae, but in the metacarpal, P content (proportion of total mineral) was highest in second lactation cows. Total bone mineral content (ash) was not affected by parity in the metacarpal or caudal vertebra, but Ca and P content of the metacarpal increased with parity. Noninvasive imaging techniques are not sufficiently sensitive to detect changes in mineral content or composition of mature cows, and only modest changes in bone mineral were observed with stage of lactation and parity.

Validation of Bone Mass and Body Composition Measurements in Small Subjects with Pencil Beam Dual Energy X-Ray Absorptiometry

OBJECTIVE

To validate the most widely reported dual energy X-ray absorptiometry (DXA) technique for the measurement of bone mass and body composition in human infants with a piglet model.

METHODS

Duplicate scans were obtained in 13 piglets (1950g to 21100g) using a whole body densitometer (Hologic QDR 2000 plus, Hologic Inc., Waltham, MA) operated in the pencil-beam mode on a two platform (aluminum platform overlying a foam table pad) system. DXA measurements that included total weight, bone mineral content, fat and lean mass were compared with carcass weight and chemical analysis for ash and calcium content, fat and lean mass.

RESULTS

Measurements from duplicate DXA scans were nearly perfectly correlated (r = 0.98 to 1.00). DXA measurements were strongly predictive of scale weight and chemical composition for all piglets (adjusted r(2) = 0.93 to 1.00, intraclass reliability coefficients = 0.943 to 0.999, p < 0.001 for all comparisons) although DXA bone mineral content consistently underestimated carcass ash and calcium content. Measured values from heavier piglets were not significantly different from values predicted from the lighter piglets' data. Slopes from regression based on lighter versus heavier piglets were not significantly different except for the bone mineral content with carcass ash or calcium content.

CONCLUSION

Our study validated the use of pencil beam DXA and its ability to determine relative changes in bone mass and body composition measurements over a much greater range of body weight than previous reports although its use as a direct indicator of nutrient requirement may be limited.