Estimated prevalence of the GYS-1 mutation in healthy Austrian Haflingers

The aim of this study was to determine the occurrence and frequency of a mutation in the gene coding for skeletal muscle glycogen synthase type 1 (GYS-1), which is the cause of equine polysaccharide storage myopathy (PSSM) type 1 in a population of 50 Haflingers. GYS-1 genotyping of 50 Haflingers was performed with a validated restriction fragment length polymorphism (RFLP) assay. The second aim was to compare resting and post-exercise muscle enzyme activities as well as parameters of glucose metabolism in blood between horses with and without the mutation. Nine of the 50 Haflingers were identified to be heterozygous for the mutation (HR). None was homozygous (HH). The estimated HR prevalence was 18 per cent in this herd. Mean aspartate aminotransferase (AST) activity at rest and mean creatine kinase and AST activity after exercise were significantly higher in HR compared with RR (homozygote normal) horses. No significant differences could be found in the other parameters.     

Gymnastic Training of Hippotherapy Horses Benefits Gait Quality When Ridden by Riders with Different Body Weights

The objective was to evaluate the effects of gymnastic training on stride characteristics of walk and trot in therapy horses carrying riders of different weights. Eighteen horses used for therapeutic riding 5 days/week were randomly divided into 2 groups. Nine horses performed gymnastic (GYM) exercises after therapeutic riding on 4 days/week for 3 months, 9 horses did no additional exercises (SED). On days 0 and 90, an inertial sensor mounted to the girth on the ventral midline was used to evaluate stride characteristics when horses were ridden at walk (1.3 m/second) and trot (3.0 m/second) by able-bodied riders representing rider: horse body weight ratios (BWRs) 15%, 20%, and 25%. On day 0, the measured variables did not differ significantly between sedentary (SED) and GYM groups, but on day 90, the following statistically significant results were found: GYM-trained horses had higher regularity for all BWRs at walk and 15% and 20% BWRs at trot. Higher stride symmetry was found in GYM-trained horses carrying 25% BWRs at walk and all rider weights at trot. Dorsoventral displacement was higher in GYM-trained horses when carrying 20% and 25% BWRs at walk and 25% BWRs at trot. Dorsoventral power was lower in SED-trained versus GYM-trained horses carrying 15% BWR at walk and 20% BWR at trot. A more regular and symmetrical stride with a larger range of dorsoventral trunk motion is likely to provide a better therapeutic riding experience.     

Epidemiological and genetic study of exertional rhabdomyolysis in a Warmblood horse family in Switzerland

Reasons for performing study: Exertional rhabdomyolysis (ER) and its familial basis in Warmblood horses is incompletely understood. Objectives: To describe the case details, clinical signs and management of ER‐affected Warmblood horses from a family with a high prevalence of ER, to determine if histopathological signs of polysaccharide storage myopathy (PSSM) and the glycogen synthase (GYS1) mutation are associated with ER in this family, and to investigate potential risk factors for development of ER. Methods: A family consisting of a sire with ER and 71 of his descendants was investigated. History of episodes of ER, husbandry, feeding and use was assessed by interviewing horse owners using a standardised questionnaire. All horses were genotyped for GYS1. In 10 ER‐affected horses, muscle histopathology was evaluated. Results: Signs of ER were reported in 39% of horses and 51% of the entire family possessed the GYS1 mutation. Horses possessing the GYS1 mutation had a 7.1‐times increased risk for developing ER compared to those with the normal genotype (95% confidence interval [CI] 2.37–21.23, P = 0.0005). All muscle samples from horses in the family with ER showed polysaccharide accumulation typical for PSSM, amylase‐resistant in 9/10 cases. There was evidence (odds ratio 5.6, CI 1.00–31.32, P = 0.05) that fat or oil feeding improved clinical signs of ER. No other effects of environmental factors associated with clinical signs of ER were identified. Conclusion and potential relevance: PSSM associated with the GYS1 mutation is one identifiable cause of ER in Warmblood horses. Signs of ER are not always manifest in GYS1 positive horses and there are also other causes for ER in Warmblood horses. Breeding animals with the GYS1 mutation results in a high prevalence of ER due to its dominant mode of inheritance.     

Glycogen synthase 1 (GYS1) mutation in diverse breeds with polysaccharide storage myopathy

Background: A missense mutation in the GYS1 gene was recently described in horses with polysaccharide storage myopathy (PSSM).
Objectives: The first objective was to determine the prevalence of the GYS1 mutation in horses with PSSM from diverse breeds. The second objective was to determine if the prevalence of the GYS1 mutation differed between horses diagnosed with PSSM based on grade 1 (typically amylase-sensitive) or grade 2 (typically amylase-resistant) polysaccharide.
Animals: Eight hundred and thirty-one PSSM horses from 36 breeds.
Procedures: Horses with PSSM diagnosed by histopathology of skeletal muscle biopsy samples were identified from the Neuromuscular Disease Laboratory database. Eight hundred and thirty-one cases had blood or tissue that was available for DNA isolation; these 831 cases were genotyped for the GYS1 mutation by restriction fragment length polymorphism.
Results: The PSSM mutation was identified in horses from 17 different breeds. The prevalence of the GYS1 mutation in PSSM horses was high in Draft- (87%) and Quarter Horse-related breeds (72%) and lower in Warmbloods (18%) and other light horse breeds (24%), when diagnosis was based on grade 2 diagnostic criteria. Overall, the PSSM mutation was present in 16% of grade 1 and 70% of grade 2 PSSM horses.
Conclusions and Clinical Importance: GYS1 mutation causes PSSM in diverse breeds and is the predominant form of PSSM in Draft- and Quarter Horse-related breeds. False-positive diagnosis, as well as the possibility of a second glycogenosis in horses with neuromuscular disease (type 2 PSSM), might explain the absence of the GYS1 mutation in horses diagnosed with excessive glycogen accumulation in muscle.     

The Interplay of Genetics,Exercise, and Nutrition in Polysaccharide Storage Myopathy

Polysaccharide storage myopathy (PSSM), identified in 1992 in a subset of horses with exertional rhabdomyolysis, is a glycogenosis characterized by amylase-resistant polysaccharide in a small number of skeletal muscle fibers along with 1.5 to 4 times normal muscle glycogen. Extensive biochemical and physiological analyses failed to identify defects in glycogenolysis and glycolysis. In 2008, a genome-wide association analysis detected a locus on equine chromosome 10 that was strongly associated with the PSSM in Quarter Horses. Glycogen synthase 1 (GYS1), which encodes the skeletal muscle isoform of glycogen synthase (GS), was a strong candidate gene for PSSM based on its location on equine chromosome 10. Sequencing of the GYS1 gene in PSSM and control Quarter Horses identified only one single base-pair change that resulted in an amino acid substitution in the GS enzyme. Mean GS activity was higher in PSSM than control muscle homogenates in both the presence and absence of the allosteric activator glucose 6-phosphate, suggesting that the GS enzyme in horses with PSSM is constitutively active. High-grain diets increase serum insulin concentrations which further act to stimulate GS activity. An restriction fragment length polymorphism assay for the GYS1 mutation showed that 10% of the Quarter Horse breed and a minimum of 20 other breeds have the GYS1 mutation. Muscle biopsies obtained after 20 minutes of aerobic exercise revealed much higher inosine monophosphate concentrations and lower adenosine monophosphate in whole muscle and single fibers from PSSM as compared with control horse muscle. Thus, the GYS1 mutation responsible for PSSM seems to cause an energy imbalance exacerbated by high-grain diets, which results in adenine nucleotide degradation in individual muscle fibers of horses with PSSM during submaximal exercise.     

A glycogen synthase 1 mutation associated with equine polysaccharide storage myopathy and exertional rhabdomyolysis occurs in a variety of UK breeds

Reasons for performing study: A glycogen synthase (GYS1) mutation has been described in horses with histopathological evidence of polysaccharide storage myopathy (PSSM) in the USA. It is unknown whether the same mutation is present in horses from the UK. Objectives: To determine whether the GYS1 mutation occurs in UK horses with histopathological evidence of PSSM and exertional rhabdomyolysis. Hypothesis: The R309H GYS1 mutation is present in a variety of UK horse breeds and that the mutation is commonly associated with exertional rhabdomyolysis. Methods: DNA was extracted from 47 muscle or blood samples from UK horses with histories of exertional rhabdomyolysis in which muscle biopsy diagnosis had been pursued. The proportions of GYS1 mutation positive cases were compared among histopathologically defined groups. In addition, breeds that carried the GYS1 mutation were identified from a total of 37 grade 2 (amylase‐resistant) PSSM cases. Results: Of 47 horses with exertional rhabdomyolysis in which a muscle biopsy diagnosis was pursued, 10 (21%) carried the GYS1 mutation. The mutation was only found in horses with grade 2 PSSM (i.e. not in horses with normal, idiopathic myopathy or grade 1 PSSM biopsy samples). In total, the GYS1 mutation was found in 24/37 (65%) of grade 2 PSSM cases. A variety of breeds, including Quarter Horse, Appaloosa, Warmblood, Connemara‐cross, Cob, Polo Pony and Thoroughbred cross carried the mutation. Conclusions: The GYS1 mutation is an important cause of exertional rhabdomyolysis of UK horse breeds but does not account for all forms of PSSM. Potential relevance: Genotyping is recommended in cases of exertional rhabdomyolysis, prior to or in combination with, muscle biopsy. However a significant proportion of horses with histopathological evidence of PSSM and/or exertional rhabdomyolysis have different diseases.     

Presence of the glycogen synthase 1 (GYS1) mutation causing type 1 polysaccharide storage myopathy in continental European draught horse breeds

The purpose of this study was to determine which continental European draught horse breeds harbour a mutation in the glycogen synthase 1 gene (GYS1) that is known to be responsible for type 1 polysaccharide storage myopathy in quarter horses and North American draught horses. Of a non-random selection of continental European draught horses belonging to 13 breeds, 62 per cent (250 of 403) tested were found to carry the mutant allele. The horses were located in Belgium, France, Germany, The Netherlands, Spain and Sweden. The mutation was identified in animals from each of the breeds examined. In the breeds in which more than 15 animals were available for testing, the highest percentages of GYS1-positive horses were found in the Belgian trekpaard (92 per cent; 35 of 38 horses tested), Comtois (80 per cent; 70 of 88), Netherlands trekpaard (74 per cent; 17 of 23), Rheinisch-Deutsches kaltblut (68 per cent; 30 of 44) and Breton (64 per cent; 32 of 51).     

Polysaccharide storage myopathy – the story so far

Polysaccharide storage myopathy (PSSM) was first described in 1992 in Quarter Horses, Appaloosa and Paint‐related breeds with clinical signs of exertional rhabdomyolysis. The disease is characterised by the accumulation of excessive glycogen and diastase‐resistant amylopectin polysaccharide inclusions within skeletal muscle fibres. The discovery of a mutation in the glycogen synthase 1 (GYS1) gene in some, but not all, horses with the disease suggested that PSSM represents a group of diseases with similar pathology but different aetiologies and that the pathogenesis is more complex than initially thought. Type 1 PSSM (PSSM1) refers to horses with the GYS1 mutation and has subsequently been identified in a large number of breeds found in Europe and North America. Clinical presentations associated with PSSM1 can vary and increased muscle enzyme activity at rest or following exercise often accompanies PSSM1; however, such changes may not be present in all cases. A diagnosis of PSSM is made on the basis of histopathology or specifically PSSM1 is diagnosed by genotyping horses for the GYS1 mutation. Cases usually respond well to management changes, in particular a diet low in starch and high in fat when it is accompanied by regular exercise.     

Effects of Whole Body Vibration on the Horse: Actual Vibration,Muscle Activity,and Warm-up Effect

Whole body vibration (WBV) exercise has been introduced into human and recently also into equine training. Only a few studies about physical and physiological effects on horses are available. This study should clarify the actual physical vibration of a commercially available WBV plate itself and on the horse as well as the muscular activity in the limbs and back. Furthermore, the effects of WBV warm-up on clinical parameters and body surface temperatures were compared to standard warm-up exercises. Ten sound horses (vibration and muscle activity of six horses) were recorded while standing (control) and during 15 and 25 Hz (manufacturer information) vibration exercise. The vibration of plate, hoof, fetlock, withers, and sacrum was analyzed for frequency, peak-to-peak displacement, and peak acceleration. Activity of M. triceps, quadriceps, and longissimus dorsi was assessed using surface electromyography. Warm-up effects were compared between four different warm-up scenarios: standing (control), 10-minute vibration, 10-minute lunging (walk), and 12-minute lunging (walk and trot). Maximal body surface temperature of upper forelimb, thigh, and back was measured. Actual plate vibration frequency was 7 or 11 Hz with a maximum peak-to-peak displacement of 9 mm in longitudinal direction. WBV exercise induced no increase in electromyographic activity, clinical parameter, or body surface temperature. It was concluded that actual plate vibration was mainly longitudinal with a lower frequency than proposed and 10-minute exercise had no significant effect. Different vibration protocols and vibration acting in the vertical direction might enable more effective exercise in horses.     

Muscle glycogen depletion patterns during draught work in Standardbred horses

Muscle fibre recruitment was investigated during draught loaded exercise by studying glycogen depletion patterns from histochemical stains of muscle biopsies from the gluteus and semitendinosus muscles. Three Standardbred trotters performed several intervals of draught loaded exercise on a treadmill with 34 kp at a trot (7 m/sec) and with 34 and 80 kp, respectively at a walk (2m/sec). Exercise was continued until the horses were unwilling to continue. Glycogen depletion was seen in all three fibre types when trotting with 34 kp for 5 or 10 mins. When an equal weight resistance was pulled at a walk, glycogen depletion was first seen in type I fibres only, then followed by a small percentage of type IIA fibres after at least 1 h. When 80 kp was pulled at a walk both type I and IIA fibres showed glycogen depletion, and after at least 30 mins exercise a small percentage of type IIB fibres was also depleted. These results indicate that the muscle fibres are depleted, in order, from type I through IIA to IIB as the intensity or duration of draught work increases.     

The effect of induced forelimb lameness on thoracolumbar kinematics during treadmill locomotion

REASONS FOR PERFORMING STUDY: Lameness has often been suggested to result in altered movement of the back, but there are no detailed studies describing such a relationship in quantitative terms. OBJECTIVES: To quantify the effect of induced subtle forelimb lameness on thoracolumbar kinematics in the horse. METHODS: Kinematics of 6 riding horses was measured at walk and at trot on a treadmill before and after the induction of reversible forelimb lameness grade 2 (AAEP scale 1-5). Ground reaction forces (GRF) for individual limbs were calculated from kinematics. RESULTS: The horses significantly unloaded the painful limb by 11.5% at trot, while unloading at walk was not significant. The overall flexion-extension range of back motion decreased on average by 0.2 degrees at walk and increased by 3.3 degrees at trot (P<0.05). Changes in angular motion patterns of vertebral joints were noted only at trot, with an increase in flexion of 0.9 degrees at T10 (i.e. angle between T6, T10 and T13) during the stance phase of the sound diagonal and an increase in extension of the thoracolumbar area during stance of the lame diagonal (0.7degrees at T13, 0.8 degres at T17, 0.5 degres at L1, 0.4 degrees at L3 and 0.3 degrees at L5) (P<0.05). Lameness further caused a lateral bending of the cranial thoracic vertebral column towards the lame side (1.3 degrees at T10 and 0.9 degrees at T13) (P<0.05) during stance of the lame diagonal. CONCLUSIONS: Both range of motion and vertebral angular motion patterns are affected by subtle forelimb lameness. At walk, the effect is minimal, at trot the horses increased the vertebral range of motion and changed the pattern of thoracolumbar motion in the sagittal and horizontal planes, presumably in an attempt to move the centre of gravity away from the lame side and reduce the force on the affected limb. POTENTIAL RELEVANCE: Subtle forelimb lameness affects thoracolumbar kinematics. Future studies should aim at elucidating whether the altered movement patterns lead to back and/or neck dysfunction in the case of chronic lameness.     

Study on the Association Relationship Between the Polymorphism of MSTN Gene and Production Performance in Baicheng Fatty Chicken

In this study, the single nucleotide polymorphism(SNP) of MSTN gene and its correlation with the production performance was tested, and explored the molecular genetic marker of breeding in Baicheng fatty chicken. 96 Baicheng fatty chicken roosters were selected randomly and divided into 3 groups, there were 32 chicken in each group. The indexes of production performance were measured in 12, 18 and 24 weeks old and the SNP of MSTN gene was detected by PCR-RFLP method, and analyzed the relationship between gene polymorphism and production performance indexes.The results showed that 3 genotypes of AA,GA and GG were found in Baicheng fatty chicken, GA was the dominant genotype, and allele A was the dominant allele, the allele frequency was not in the Hardy-Weinberg equilibrium (P<0.05). At 12 weeks old,AA genotype was significantly higher than GA genotype in body weight, carcass weight,semi-eviscerated weight, eviscerated weight, breast muscle weight and leg muscle weight (P<0.05). At 18 weeks old,GA genotype was significantly higher than GG genotype in body weight, breast muscle weight and leg muscle weight (P<0.05). At 24 weeks old,AA genotype was extremely significantly higher in body weight, carcass weight and semi-eviscerated weight than GG genotype (P<0.01),and AA genotype was significantly higher in eviscerated weight and leg muscle weight than GG genotype (P<0.05). GA genotype was significantly higher in body weight, carcass weight,semi-eviscerated weight and leg muscle weight than GG genotype (P<0.05), there were no significant difference in the other indexes among different genotypes at different ages (P>0.05). MSTN gene polymorphism was closely related to the production performance indexes of Baicheng fatty chicken, it was speculated this gene could be used as one of the molecular genetic markers for the breeding of Baicheng fatty chicken.     

Polymorphisms in the promoter region of myostatin gene are associated with carcass traits in pigs

Higher average daily gain, more lean meat yield and less fat yield of porcine carcass increase selling profits for animal producers. Myostatin (MSTN), previously called GDF8, is a member of transforming growth factor‐β (TGF‐β) superfamily. It is a negative regulator for both embryonic development and adult homeostasis of skeletal muscle. In this study, the genotypes of the previously described SNPs MSTN g.435G>A and g.447A>G SNPs in 66 Duroc pigs, 33 Landrace pigs, 180 Duroc × Landrace (DL) pigs and 155 Duroc × Yorkshire × Landrace (DYL) pigs were determined by Taqman SNP Genotyping Assays. For Duroc and Landrace pigs, MSTN g.435GG/g.447AA individual had greater backfat thickness (p < 0.05) than g.435AA/g.447GG individual, whereas MSTN g.435AA/g.447GG had greater meat (p < 0.05) and meat percentage (p < 0.05) than g.435GA/g.447AG individual. For DL and DYL pigs, the MSTN g.435GG/g.447AA animals were greater in backfat at ultrasound 10th rib (p < 0.05) and carcass 10th rib (p < 0.01) than g.435AA/g.447GG individual. The MSTN g.435AA/g.447GG individual also had higher values than g.435GG/g.447AA for anterior‐end meat (p < 0.05), posterior‐end meat (p < 0.01), total meat weight (p < 0.01) and meat percentage (p < 0.01). This study confirmed evidence that MSTN g.435G>A and g.447A>G affected carcass traits in pigs. The effects of the mutated alleles were additive with the maximal effects resulting from two copies of the mutated allele. Selection for MSTN g.435A/g.447G allele is expected to increase muscle of limb and total meat production and decrease backfat thickness.     

Polysaccharide storage myopathy in the M. longissimus lumborum of showjumpers and dressage horses with back pain

This study was designed to investigate whether horses with clinical signs of back pain due to suspected soft tissue injuries were affected by polysaccharide storage myopathy (PSSM). Diagnosis of PSSM in muscle biopsies obtained from the M. longissimus lumborum of 5 showjumpers and 4 dressage horses with a history of back pain is reported. M. longissimus lumborum biopsies of these horses were characterised histopathologically and in 3/9 cases also by electron microscopy. Observations were compared with M. gluteus biopsies of the same horses, and with M. gluteus biopsies obtained from 6 Standardbreds with recurrent exertional rhabdomyolysis and from 6 healthy trotters. M. longissimus biopsies from horses with back pain showed pathognomonic signs of PSSM, i.e. high glycogen and/or abnormal complex amylase-resistant polysaccharide deposits. Similar features were found in M. gluteus biopsies of the same horses. Sections of horses with rhabdomyolysis had increased PAS stain when compared with healthy horses, but did not show amylase-resistant material. Qualitative observations were corroborated by quantitative histochemistry (optical densities) of sections stained with PAS and amylase PAS. This study demonstrated the presence of PSSM in the M. longissimus of showjumpers and dressage horses with back pain and indicates that epaxial muscle biopsy is an option in diagnosing back problems in horses when clinical examination and imaging techniques do not provide a precise diagnosis.     

Effect of local analgesia on movement of the equine back

REASONS FOR PERFORMING STUDY: Diagnostic infiltration of local anaesthetic solution is commonly used in cases of equine back pain. Evaluation is subjective and it is not known how local analgesia of the back affects horses without clinical signs of back pain. OBJECTIVES: To evaluate the effect of infiltration of local anaesthetics on the movement of the back in horses without clinical signs of back pain, and to evaluate the usefulness of kinematic studies as an objective and quantitative tool in evaluating local analgesia in clinical practice. METHODS: The kinematics of the back in 10 clinically sound horses were measured on 2 occasions at walk and trot before and after injections with mepivacaine and sodium chloride around the interspinous spaces between T16 and L2. The kinematics were compared between the 2 occasions before injections and before and after each injection. RESULTS: The range of motion (ROM) for dorsoventral flexion-extension (FE) of the back was increased significantly in all measured segments other than T10 at walk, as was lateral bending (LB) at T10, L3 and L5 after injection of mepivacaine. For lateral excursion (LE), total movement increased at all measured segments. At trot the only affected segment was L3, where the injection with mepivacaine decreased the ROM for FE. After injection of sodium chloride the ROM for FE increased at T13 and T17 at walk. Lateral bending and LE were not affected at walk. At trot, LB increased at L3 and L5. CONCLUSIONS AND POTENTIAL RELEVANCE: Diagnostic infiltration of local anaesthetic solution affects the function of the back in clinically sound horses, which must be considered when interpreting the use of this clinical aid in assessing clinical cases of back dysfunction. Kinematics can qualitatively and quantitatively evaluate the effect of local analgesia of the back.     

Genetic contribution of the Arabian to the Italian Haflinger horse

SUMMARY: The genetic contributions of the Arabian horse and the Austrian and German Haflingers to the registered Italian Haflinger are analysed by studying proportionate founder genetic contribution and by simulating Mendelian segregation of the founder alleles at an hypothetical locus. The Arabian proportionate contribution from the early 1960s is stabilized around 0.044, the Austrian Haflinger from the 1970s is around 0.03 and German Haflinger is always less than 0.001. The extinction probability of the Arabian gene pool reaches 0.37 in the 1950s then decreases to 0.15 in the 1990s due to the registration of the progeny of Arabian stallions. The extinction probabilities of some founder alleles are very high because of early pedigree bottlenecks. Contribution génétique du cheval Arabe à l'Haflinger italien Les contributions génétique du cheval Arabe et des Haflinger autrichien et allemand aux chevaux Haflinger italiens inscrits est analysée. On a etudié la contribution respective des differents fondateurs et on a simulé les ségrégations mendéliennes à un hypothétique locus neutre. La contribution relative de l'Arabe est stable, aux environs de 0,044; la contribution relative de l'Haflinger autrichien est d'environ 0,03 depuis les années 70 et celle de l'Haflinger allemand est toujours inferieure à 0,001. La prbabilité d'extinction du pool gènique Arabe atteint 0,37 dans les années 50 et décroit ensuite jusqu'à 0,15 dans les années 90, due fait de l'enregistrement de la descendance d'étalons Arabe. Les probabilitiés d'extinction de certains alléles fondateurs est très élevée à cause de "goulots de bouteille" intervenant précocément dans les pedigrees. RESUMEN: Contribution genética del caballo arabe al caballo italiano Haflinger Las contribuciones genéticas del caballo arabe y de los Haflinger austriacos y alemanes al Haflinger italiano registrado son analizados estudiando la contribucion genética de los animales fundatores (en porcentage) y pur medio de simulacion de la segregacion menedeliana de los alelos fundatores en un locus hipotético. La contribution proporcional arabe del inicio de los anos sesanta se estabiliza alrededor de 0,044. La contribucion genética del Haflinger austriaco de los anos setanta es alrededor de 0.03 y la contribucion del Haflinger aleman es siempre menos de 0.001. Las probabilidades de extinction del pool genético arabe alcanza el 0.37 en los anos cincuenta, disminuyendo a 0.15 en los anos noventa debido a la inclusion de la progenie de los caballos arabes. Las probabilidades de extincion de algunos alelos fundadores son muy altas debido a cuellos de botella en el arbol genealogico iniciales. ZUSSAMENFASSUNG: Einfluss von Arabers auf Italienische Haflinger Der genetische Beitrag des Arabers, des oestereichischen und deutschen Haflingers am italienischen Haflinger ist anhand von Analysen des genetischen Beitrages, der auf die Stammvaeter zurueckzufuehren ist, untersucht worden. Zudem wurde eine Simulation der mendelschen Aufspaltung von Stammvaeterallelen an einem hypothetischen Locus durchgefuehrt. Seit den fruehen 60er Jahren hat sich der arabische Anteil bei etwa 4,4 % stabilisiert, der des ?sterreichishen Haflingers liegt seit den 70er Jahren bei 3 % und der des deutschen Haflingers bei weniger als 1 %. Die Verdraengungswahrscheinlichkeit des arabischen Genpools reichte von 37 % in den 50ern bis zu 15 % in den 90ern durch Registration der Nachkommenshaft von arabischen Hengsten. Aufgrund durch vergangener einseitiger Selektion (Stammbaumflaschenhaelse) ist die Verdraengungswahrscheinlichkeit der Stammvaeterallele sehr hoch.     

Influence of the load of a rider or of a region with increased stiffness on the equine back: a modelling study

REASONS FOR PERFORMING STUDY: Knowledge of load effects is crucial for the understanding of the aetiology and pathogenesis of equine back problems. OBJECTIVE: To investigate different load scenarios of the equine back, such as being ridden or increased muscle tone, using biomechanical simulations. METHODS: Kinetic and kinematic data of 15 sound horses and the electromyelograph of their long back muscles were recorded. A biomechanical simulation model was used for simulations under different biomechanical scenarios (ridden/unridden, localised increased stiffness) using ADAMS. RESULTS: The vertical forces acting through a rider were: walk 3.83 N/kg, trot 5.18 N/kg and gallop 5.60 N/kg. No significant changes in transversal forces were found between ridden and unridden horses. Profound changes were seen in the torques at the segment following a region of increased stiffness: in walk, lateral peak torques increased from 342 to 1723 Nm, and in trot from 393 to 1004 Nm, and dorsoventral from 386 to 3705 Nm (walk) and 458 to 4340 Nm (trot). CONCLUSIONS AND POTENTIAL RELEVANCE: The simulation shows that the stress of a rider is lower than that of pathological processes such as partial increased stiffness of the back. Study of revised models with improved anatomical realism might help to raise the plausibility of model results.     

Effects of submaximal exercise on adenine nucleotide concentrations in skeletal muscle fibers of horses with polysaccharide storage myopathy

OBJECTIVE: To determine whether disruption of adenine triphosphate (ATP) regeneration and subsequent adenine nucleotide degradation are potential mechanisms for rhabdomyolysis in horses with polysaccharide storage myopathy (PSSM) performing submaximal exercise. ANIMALS: 7 horses with PSSM and 4 control horses. PROCEDURES: Horses with PSSM performed 2-minute intervals of a walk and trot exercise on a treadmill until muscle cramping developed. Control horses exercised similarly for 20 minutes. Serum creatine kinase (CK) activity was measured 4 hours after exercise. Citrate synthase (CS), 3-OH-acylCoA dehydrogenase, and lactate dehydrogenase activities prior to exercise and glucose-6-phosphate (G-6-P) and lactate concentrations before and after exercise were measured in gluteal muscle specimens. Adenine triphosphate, diphosphate (ADP), monophosphate (AMP), and inosine monophosphate (IMP) concentrations were measured before and after exercise in whole muscle, single muscle fibers, and pooled single muscle fibers. RESULTS: Serum CK activity ranged from 255 to 22,265 U/L in horses with PSSM and 133 to 278 U/L in control horses. Muscle CS activity was lower in horses with PSSM, compared with control horses. Muscle G-6-P lactate, ATP, ADP, and AMP concentrations in whole muscle did not change with exercise in any horses. Concentration of IMP increased with exercise in whole muscle, pooled muscle fibers, and single muscle fibers in horses with PSSM. Large variations in ATP and IMP concentrations were observed within single muscle fibers. CONCLUSIONS AND CLINICAL RELEVANCE: Increased IMP concentration without depletion of ATP in individual muscle fibers of horses with PSSM during submaximal exercise indicates an energy imbalance that may contribute to the development of exercise intolerance and rhabdomyolysis.     

拜城油鸡肌肉生长抑制素基因多态性与生产性能的相关性研究

试验旨在研究肌肉生长抑制素（myostatin,MSTN）基因在拜城油鸡中的多态性及其与生产性能的关系,探寻可用于拜城油鸡选育的分子遗传标记。选取96只6周龄的拜城油鸡公鸡,随机分为3组,每组32只,分别在12、18和24周龄时对其生产性能指标进行测定,同时采用PCR-RFLP方法检测MSTN基因的多态性,分析MSTN基因多态性与拜城油鸡生产性能的关系。结果显示,在拜城油鸡公鸡中MSTN基因存在多态性,检测到3种基因型:AA、GA、GG,GA为优势基因型,等位基因A为优势等位基因,不符合哈代－温伯格平衡定律（P<0.05）。在12周龄时,AA基因型个体的体重、屠体重、半净膛重、全净膛重、胸肌重和腿肌重均显著高于GA基因型个体（P<0.05）;在18周龄时,GA基因型个体的体重、胸肌重和腿肌重均显著高于GG基因型个体（P<0.05）;在24周龄时,AA基因型个体的体重、屠体重和半净膛重均极显著高于GG基因型个体（P<0.01）,全净膛重和腿肌重显著高于GG基因型个体（P<0.05）,GA基因型个体的体重、屠体重、半净膛重和腿肌重均显著高于GG基因型个体（P<0.05）,其余指标在不同周龄不同基因型个体间差异不显著（P>0.05）。MSTN基因多态性与拜城油鸡部分生产性能指标密切相关,推测该基因可以作为拜城油鸡选育的分子遗传标记之一。     

Influence of Equine Conformation on Rider Oscillation and Evaluation of Horses for Therapeutic Riding

To obtain basic knowledge about selecting horses for therapeutic riding, the influence of equine conformation on rider oscillation and relationships between these factors and the evaluation on horses as the therapeutic riding were studied. Thirty-five riding horses were used. Equine conformation was estimated by 24 indices. Rider oscillation was measured by an accelerometer fixed at the rider’s waist. The spatial position of the oscillation was estimated by a double integration of the acceleration. Horses were evaluated for therapeutic riding by a Riding for the Disabled Association instructor as a rider. Evaluations were on a scale of 1 to 5, with 5 being the highest score for 27 items. Horses were classified into 4 groups: the short and narrow (SN), short and wide (SW), tall and narrow (TN), and tall and wide (TW). The frequencies of rider oscillation both at walk and trot were higher (P<0.01), and the vertical (P<0.01) and longitudinal (P<0.05) amplitudes at trot were smaller, on short horses than on tall horses. The vertical amplitude at walk was smaller (P<0.05) and the lateral amplitude at trot was larger (P<0.01) on wide horses than on narrow horses. Short horses could be used for the rider who requires side walkers. Wide horses could be used for relieving muscular tension and for the rider who could not maintain good balance on the horse. Short and wide horses should be suitable for therapeutic riding.