Longevity of Breeding Sows in Relation to Leg Weakness Symptoms at Six Months of Age

The objective of this study was to evaluate the influence of leg weakness symptoms measured early in life (at 6 months of age) on the longevity of the sows, i.e. the age at culling due to locomotory problems in a Danish pig herd. One hundred and eighty-seven gilts at 6 months of age were selected according to different leg weakness symptoms and were followed until culling and judged for leg weakness once in every gestation using a scale from 1 (normal) to 4 (severe changes). Age at culling, and the main and secondary reasons for culling were recorded. The influence of leg weakness symptoms on longevity was evaluated by survival analysis. Though only 12% of the gilts showed a stiff locomotion half of the sows had suffered from this and nearly one third had been distinctly lame at some time in their life. Buck-kneed forelegs, upright pasterns, legs turned out, standing under position and swaying hindquarters were associated with stiff locomotion or lameness, whereas weak pasterns on hind legs and splayed digits on forelegs were associated with brisk movement (freedom from locomotor problems). The following leg weakness symptoms at the gilt stage were found to have significant negative effects on longevity: buck-kneed forelegs, swaying hindquarters, and standing under position on hind legs.     

Housing of Pregnant Sows in Loose and Confined Systems–a Field Study. 2. Claw Lesions: Morphology,Prevalence, Location and Relation to Age

A field study of 36 Norwegian sow herds was conducted over a 12 month period, 18 herds had loose housing of pregnant sows and 18 herds had confined (stalled or tethered) dry sows. Fifteen of the loose housing herds had partly slatted concrete floors while 3 herds had other kinds of flooring. The types of claw lesions that were observed in these herds are described. The most prevalent lesions on both loose sows and confined sows were side wall cracks, heel lesions, cracks in the white line and overgrown heels. The lateral hind claws were the most frequent location for lesions and they were more severe than at other sites. These lesions tended to show a bilateral occurrence. More than 96% of slaughtered loose sows and 80% of slaughtered confined sows had at least 1 lesion on the lateral hind claws. The prevalence of claw lesions showed no obvious age pattern. However the prevalence seemed to be lower for the first litter sows and increased slightly thereafter, especially in the confined herds.     

Ground reaction forces in vertically ascending beetles and corresponding activity of the claw retractor muscle on smooth and rough substrates

We measured ground reaction forces in fore–aft and normal directions of single hind and front legs in vertically ascending Sagra femorata beetles (Coleoptera, Chrysomelidae) on a smooth and a rough substrate. Simultaneously, we performed electromyographic recordings (EMGs) of the hind leg claw retractor muscle that partly controls the attachment structures. On both substrates, hind legs produced upward- as well as downward-directed forces during one stance phase. Forces were equivalent in both directions. Front legs generated only upward-directed forces. The main function of hind legs in ascending beetles in the second half of the stance thus probably prevented the animals from tilting away from the substrate. The EMGs of hind legs showed an early spike during stance with large amplitude. It was mostly followed by few additional spikes with large amplitude and in some cases of spikes with smaller amplitude distributed throughout the stance phase. We found significantly more spikes on the rough substrate than on the smooth one. This is probably due to the more important role of pretarsal claws than tarsal hairy attachment pads on the rough substrate or to the reduced adhesive forces on the rough substrate that have to be compensated by additional muscle activity.     

Lameness and Claw Lesions of the Norwegian Red Dairy Cattle Housed in Free Stalls in Relation to Environment,Parity and Stage of Lactation

Approximately 88% of Norwegian dairy cattle are housed in tie stalls. Free stall housing for all dairy cattle will be implemented within 20 years. This means that the majority of existing stalls will be rebuilt in the near future. Fifty-seven free stall herds of the Norwegian Red breed were randomly selected and 1547 cows and 403 heifers were trimmed by 13 claw trimmers during the late winter and spring of 2002. The claw trimmers had been taught diagnosing and recording of claw lesions. Environment, management- and feeding routines were also recorded. Fifty-three herds had concrete slatted alleys while 4 had solid concrete. Thirty-five herds had concrete as a stall base, while 17 had rubber mats, 2 had wood and 3 had deep litter straw beds. The prevalence of lameness was 1.6% in hind claws. Models for lameness and claw lesions were designed to estimate the influence of different risk factors and to account for the cluster effects within herd and claw trimmer. Detected risk factors for lameness were: parity three and above and narrow cubicles; for heel horn erosions: lactation stage around 5–7 months after calving and solid concrete alleys; for haemorrhages of the white line: lactation stage around 3–5 months after calving and solid concrete alleys; for haemorrhages of the sole: parity one, lactation stage around 5–7 months after calving and short cubicles, for white line fissures: slatted concrete alleys; for asymmetrical claws: parities two and above and for corkscrewed claws: solid concrete alleys. The prevalence of lameness in heifers was low, however 29% had one or more claw lesions. Heifers that were housed in pens or free stalls had more heel-horn erosions, haemorrhages of the sole and white-line fissures than heifers in tie stalls. As new free stalls are being built, it is important to optimise the conditions for claw health.     

Genetic trends of conformation traits and genetic correlations to osteochondrosis in boars

The objective of our study was to investigate the heritabilities and genetic correlations between traits from a linear exterior assessment system and osteochondrosis (OC) measured by computed tomography (CT), and in addition, to study the genetic trend in a population where the conformation traits have been included in the breeding goal. The data material consisted of phenotypes from a total of 4571 Norsvin Landrace test boars. At the end of the test period, all boars were subjected to a detailed exterior assessment system. Within 10 days of the assessment, the boars were CT scanned for measuring OC. The total score of osteochondrosis (OCT), used in this study, is the sum of phenotypes from the assessment on the medial and lateral condyles at the distal end of both the humerus and the femur of the right and the left leg of the boar based on images from CT. The exterior assessment traits included in the study were; ‘front leg knee’ (FKNE), ‘front leg pasterns’ (FPAS), ‘front leg stance’ (FSTA), ‘front leg twisted pasterns’ (FFLK), ‘hind leg stance’, ‘hind leg pasterns’ (HPAS), ‘hind leg standing under’ (HSTU), ‘hind leg small inner toe’, ‘dipped back’, ‘arched back’ (ARCH) and ‘waddling hindquarters’ (WADL). The estimation of (co)variance components and breeding values were performed using bivariate animal genetic models. Breeding values for HSTU, HPAS, FPAS, WADL and OCT traits were additional outputs from the same bivariate analyses. The lowest heritability was found for FFLK (h²_FFLK=0.05), whereas FPAS was estimated to have the highest heritability (h²_FPAS=0.36), and OCT demonstrating a heritability of 0.29. Significant genetic correlations were found between several traits; the strongest correlation was between FSTA and FFLK (0.94), which was followed by the correlation between FPAS and FKNE (0.69). The traits ARCH and FSTA had significant genetic correlations to OCT, whereas all other genetic correlations between OCT and the conformation traits were low and not significantly different from 0. Our study shows positive genetic trends for the conformation traits included in the breeding goal. In general, low genetic correlations between conformation traits and OC were observed in our study.     

To meet or not to meet welfare outcome thresholds: a case-control study in dairy cow herds

Recently published thresholds allow classifying dairy cattle herds according to target, caution and alert ranges for welfare outcomes. Such normative thresholds provide one way to transparently assess production practices and are a straightforward communication tool with farmers. In an ordinal response case-control study, we investigated associations of animal, management and resource-related indicators with the risk of exceeding thresholds of prevalence for lameness, claw disorders, integument alterations and leg cleanliness. To this end, we used cumulative logistic regression models on 264 tethered and 392 loose-housed Austrian dairy herds. In tethered herds, the risk indicator average lactation milk yield was positively associated with the probability to exceed thresholds for integument alteration prevalence but negatively regarding leg cleanliness. Associations were also found for operation type regarding integument alterations (lower risk on organic vs conventional farms), for herd size regarding lameness (negative association) and dirty upper hind leg (positive association), and for percentage of fifth or higher parity cows in the herd regarding dirty lower hind leg (positive association). Stall type was identified as risk indicator regarding claw disorders (lower risk of long vs short stands). In loose housing systems, none of the analysed risk indicators was associated with the probability to exceed thresholds for total lameness and claw disorder prevalence. Negative associations with the probability to exceed caution or alert thresholds were identified for lifetime milk yield (dirty upper hind leg), lactation milk yield (dirty upper and lower hind leg), percentage of cows in the herd with a fat-protein-ratio <1 (integument alterations), and percentage of cows in the herd with a fat-protein-ratio >1.5 (dirty upper hind leg). Pasture access showed negative (severe lameness, integument alterations) and herd size positive associations (severe lameness) with the probability to exceed thresholds. Deep litter cubicles compared to raised cubicles with rubber mats showed a lower probability to exceed thresholds (integument alterations, dirty lower hind leg) as well as solid rubber compared to concrete slatted flooring in alleyways (integument alterations). Assessments carried out during the pasture period compared to during winter housing were associated with a lower risk of exceeding thresholds for leg cleanliness measures in both, tethered and loose-housed herds, and for integument alteration prevalence in tethered herds. In conclusion, no principal risk indicator was identified which consistently determined the probability of exceeding predefined thresholds of considered welfare outcomes. Nevertheless, outcome-specific factors show sufficient impact on the categorisation of farms according to prevalence ranges.     

Pincer-like claws in centipedes (Chilopoda): multiple evolutionary origin of similar form and serial pattern

In most Chilopoda, the walking legs end in a single-tip claw usually accompanied by short accessory spines. Instead, in all species of three small and only distantly related geophilomorph taxa (Diphyonyx, Neogeophilidae, Eucratonyx), the claws of an anterior set of leg pairs are unusually pincer-like. By integrating different microscopic techniques, including confocal laser scanning microscopy, we found that these modified claws are very similar in form, internal structure, and pattern of variation in shape along the trunk in all three taxa: the claws are distinctly swollen and bent, provided with peculiar bulges, and flanked by a conspicuous additional branch, either cylindrical or flattened, which overreaches the tip of the claw; instead, the internal cuticular features are not modified with respect to the condition in the other centipedes, claiming against the possibility of controlled abduction/adduction between claw and branch. Irrespective of the total number of leg pairs (63–129), the claws change gradually from pincer-like to usual shape invariantly in the range spanning between the 34 and the 45% of the total number of leg pairs. Despite these similarities, pincer-like claws originated independently in the three taxa, and by way of fundamentally different changes, either by the dramatic modification of the already existent anterior accessory spine (Diphyonyx, Neogeophilidae) or by the production of a novel cuticular projection (Eucratonyx). Moreover, their shared pattern of variation along the body was most probably constrained by already operating developmental processes controlling the longitudinal patterning of the trunk.     

The Effect of Claw Lesions and Claw Infections on Lameness in Loose Housing of Pregnant Sows

During a 12-month period lameness, claw lesions and claw infections were studied in 15 herds with loose housing of pregnant sows on partly slatted concrete floors. Of these herds, 12 herds had concrete slats and 3 herds had plastic slats. The mean prevalence proportion of lame sows in the herds was 13.1%. The risk of lameness increased with increasing claw lesion score and with the presence of claw infections. In the herds with concrete slats, the relative risk of lame sows was 2.4 times higher than in the herds with plastic slats. In the herds with poor floor hygiene, the relative risk of lameness was 2.8 times higher than in the herds with dry and clean floors. The mean prevalence proportion of sows with claw infections at the 3 separate examinations in the 15 herds was 3.8%. Claw infections were more prevalent in herds with dirty floors and in herds with little space per animal (<2m2). In the herds with concrete slats, the relative risk of claw infections was 2 times higher than in the herds with plastic slats.     

Tardigrades from Ecuador,with the Description of Two New Species: Mixibius ornatus n. sp. and Diphascon (Adropion) onorei n. sp. (Eutardigrada,Hypsibiidae)

Seven species are reported from Ecuador, South America, two of which, Mixibius ornatus and Diphascon (Adropion) onorei, are new to science. Mixibius ornatus n. sp. differs from Mixibius saracenus (Pilato 1973) and from M. fueginus Pilato & Binda 1997 by having a sculptured cuticle, broader claws, lunulae present, stylet supports inserted on the buccal tube in a more caudal position, and shorter placoids. Diphascon (A.) onorei n. sp. has an elongate pharyngeal bulb with small apophyses, three rod-shaped macroplacoids, a granular microplacoid, and septulum; claw bases enlarged, smooth (first three pairs of legs) or crenate (outer claws on the hind legs); a cuticular bar is present near the inner claws on the first three pairs of legs. Other species reported are Echiniscus aliquantillus Grigarick, Schuster & Nelson 1983; Minibiotus intermedius (Plate 1888); Macrobiotus coronatus De Barros 1942; Macrobiotus danielae Pilato, Binda, Napolitano & Moncada 2001, and Astatumen bartosi Weglarska 1959.     

Tight turns in stick insects

We investigated insects Carausius morosus walking whilst hanging upside down along a narrow 3 mm horizontal beam. At the end of the beam, the animal takes a 180° turn. This is a difficult situation because substrate area is small and moves relative to the body during the turn. We investigated how leg movements are organised during this turn. A non-contact of either front leg appears to indicate the end of the beam. However, a turn can only begin if the hind legs stand in an appropriate position relative to each other; the outer hind leg must not be placed posterior to the inner hind leg. When starting the turn, both front legs are lifted and usually held in a relatively stable position and then the inner middle leg performs a swing-and-search movement: The leg begins a swing, which is continued by a searching movement to the side and to the rear, and eventually grasps the beam. At the same time the body is turned usually being supported by the outer middle leg and both hind legs. Then front legs followed by the outer middle leg reach the beam. A scheme describing the turns based on a few simple behavioural elements is proposed.     

Relationship between dairy cows' hind leg activity and vacuum records during milking

In a number of dairy farms, a restlessness of hind legs of cows during milking can be observed for no apparent reason. Previous studies have associated the hind leg activity of cows with mental or physical discomfort. Aim of this study was to investigate whether the observed hind leg activity was influenced by the milking process. The analysis was performed for total milking period and also separately for the following milking periods: let-down, main milk flow and over-milking. The following variables were analyzed for their influence on dairy cows' hind leg activity: the vacuum level in the MPC and SMT, the length of the milking periods, the vacuum curve type, bimodal curves and the presence of teat-end hyperkeratosis. In turn, it was also investigated whether the cows' hyperkeratosis is influenced by milking duration, length of milking periods or by the vacuum level in the SMT. Measurements and observations were done in ten milking parlors, each visited twice. Four milking units per parlor were equipped with vacuum loggers (VaDia 2.0, BioControl AS, Norway). One observer recorded hind leg activity per up to four cows, using the following categories: (1) stepping (claw raised < 15 cm) and (2) kicking (claw raised > 15 cm). A powerful, purposive kick to milking unit/milker was classified as p-kick (3) initially. Due to a small number of p-kicks, they were added to the number of kickings for further analysis. The analyses showed that none of the milking process-related variables had a significant influence on the dairy cows' prevalence to show hind leg activity. Although the prevalence was not influenced, the type of hind leg activity was. The hind leg activity kicking was observed at significantly higher average mouthpiece chamber vacuum levels than steppings. Cows showing kickings had a higher degree of teat-end hyperkeratosis than those showing steppings. The degree of teat-end hyperkeratosis was related to the milking duration.     

Walking on smooth or rough ground: passive control of pretarsal attachment in ants

The hymenopteran tarsus is equipped with claws and a movable adhesive pad (arolium). Even though both organs are specialised for substrates of different roughness, they are moved by the same muscle, the claw flexor. Here we show that despite this seemingly unfavourable design, the use of arolium and claws can be adjusted according to surface roughness by mechanical control. Tendon pull experiments in ants (Oecophylla smaragdina) revealed that the claw flexor elicits rotary movements around several (pre-) tarsal joints. However, maximum angular change of claws, arolium and fifth tarsomere occurred at different pulling amplitudes, with arolium extension always being the last movement. This effect indicates that arolium use is regulated non-neuronally. Arolium unfolding can be suppressed on rough surfaces, when claw tips interlock and inhibit further contraction of the claw flexor or prevent legs from sliding towards the body. To test whether this hypothesised passive control operates in walking ants, we manipulated ants by clipping claw tips. Consistent with the proposed control mechanism, claw pruning resulted in stronger arolium extension on rough but not on smooth substrates. The control of attachment by the insect claw flexor system demonstrates how mechanical systems in the body periphery can simplify centralised, neuro-muscular feedback control.     

Regulation of sex-specific feeding behavior in fiddler crabs: physiological properties of chemoreceptor neurons in claws and legs of males and females

This study examined properties of chemoreceptor neurons in the claws and legs of the fiddler crabs Uca pugilator and U. pugnax. The primary goal was to establish the neural basis of previously observed greater female sensitivity to feeding stimulants, and secondarily to compare physiological properties of chemoreceptor neurons in these semi-terrestrial crustaceans with those of fully aquatic forms. Sensitivity of chemoreceptor neurons in claws and legs is sex-specific; individual neurons of females respond to lower stimulus concentrations than male chemoreceptor neurons, and equivalent concentrations elicit greater spiking in female vs male chemoreceptor neurons. Thus, the population of chemoreceptor neurons in females expresses lower thresholds and greater average sensitivity than in males. Greater sensitivity of claw neurons explains observations indicating that females continue to feed at food levels too low to stimulate males. Sensitivity differences in leg neurons of males vs females have no clear behavioral correlate, but suggest that females can orient to more dilute stimuli than males. Chemoreceptor neurons of fiddler crabs have low sensitivities and slow rates of adaptation compared to other crustaceans. Also, neurons in claws adapt less slowly than neurons in legs, which may reflect subtle differences in the chemical stimulus environment experienced by claws vs legs.     

Do nurse sows and foster litters have impaired animal welfare? Results from a cross-sectional study in sow herds

Increasing litter size has led to introduction of so-called nurse sows in several EU countries. A nurse sow is a sow receiving piglets after having weaned her own piglets and thereby experiencing an extended lactation. In order to analyse whether nurse sows have more welfare problems than non-nurse sows a cross-sectional study was conducted in 57 sow herds in Denmark. Clinical observations were made on nurse and non-nurse sows and their litters. The clinical observations were dichotomized and the effect of being a nurse sow was analysed based on eight parameters: thin (body condition score<2.5), swollen bursae on legs, dew claw wounds, vulva lesions, poor hygiene, poor skin condition, shoulder lesions and cuts and wounds on the udder. Explanatory variables included in the eight models were: nurse sow (yes=1/no=0), age of piglets (weeks old, 1 to 7), parity (1 to 8+) and all first order interactions between these three variables. The effect of using nurse sows on piglet welfare was analysed with five models. The outcomes were: huddling, poor hygiene, lameness, snout cuts and carpal abrasions. The explanatory variables included in the five models were: nurse sow (yes=1/no=0), age of piglets (weeks old, 1 to 7), parity (1 to 8+) and all first order interactions between these three variables. Herd identity was included as a random factor in all models. The nurse sows had a significantly higher risk of swollen bursae on legs (P=0.038) and udder wounds (P=0.001). No differences in risk of being thin or having shoulder lesions were found. Foster litters had significantly higher risk of being dirty (P=0.026) and getting carpal abrasions (P=0.024) than non-foster litters. There was a tendency for higher lameness in foster litters than in non-foster litters (P=0.052). The results show that nurse sows and their piglets to some extent experience more welfare problems than non-nurse sows with piglets at a similar age.     

Position-dependent sensitivity and density of taste receptors on the locust leg underlies behavioural effectiveness of chemosensory stimulation

Chemical stimulation of contact chemoreceptors located on the legs of locusts evokes withdrawal movements of the leg. The likelihood of withdrawal depends on the site of stimulation, in addition to the identity and concentration of the chemical stimulus. A significantly higher percentage of locusts exhibit leg avoidance movements in response to stimulation of distal parts of the leg with any given chemical stimulus compared to proximal sites. Moreover, the percentage of locusts exhibiting avoidance movements is correlated with the density and sensitivity of chemoreceptors on different sites of an individual leg. The effectiveness of chemical stimulation also differs between the fore and hind legs, with NaCl evoking a higher probability of leg withdrawal movements on the foreleg. Moreover, sucrose was less effective than NaCl at evoking withdrawal movements of the foreleg, particularly at low concentrations. The gradients in behavioural responses can be partially attributed to differences in the responsiveness and density of the contact chemoreceptors. These results may reflect the different specialization of individual legs, with the forelegs particularly involved in food selection.     

Prevalence of lameness and claw lesions during different stages in thereproductive cycle of sows and the impact on reproduction results

Lameness in sows is an emerging disease condition with major effects on animal welfare and economics. Yet the direct impact on reproduction results remains unclear. The present field study investigated the impact of lameness and claw lesions throughout the reproductive cycle on (re)production results of sows. In five farms, a total of 491 group-housed sows were followed up for a period of one reproductive cycle. Sows were assessed for lameness every time they were moved to another area in the farm. Claw lesions were scored at the beginning and at the end of the cycle. Reproduction results included the number of live-born piglets, stillborn piglets, mummified fetuses and crushed piglets, weaning-to-oestrus interval and the presence of sows not showing oestrus post weaning, returning to service and aborting. Sows that left the group were recorded and the reason was noted. A mean prevalence of lameness of 5.9% was found, although it depended on the time in the productive cycle. The highest percentage of lame sows (8.1%) was found when sows were moved from the post-weaning to the gestation stable. No significant associations were found between lameness and reproduction parameters with the exception of the effect on mummified foetuses. Wall cracks, white line lesions, heel lesions and skin lesions did have an effect on farrowing performance. Of all sows, 22% left the group throughout the study, and almost half of these sows were removed from the farm. Lameness was the second most important reason for culling. Sows culled because of lameness were significantly younger compared with sows culled for other reasons (parity: 2.6 ± 1.3 v. 4.0 ± 1.8). In conclusion, the present results indicate that lameness mainly affects farm productivity indirectly through its effect on sow longevity, whereas claw lesions directly affect some reproductive parameters. The high percentage of lame sows in the insemination stable indicate that risk factor studies should not only focus on the gestation stable, but also on housing conditions in the insemination stable.     

Using classification trees to detect induced sow lameness with a transient model

Feet and legs issues are some of the main causes for sow removal in the US swine industry. More timely lameness detection among breeding herd females will allow better treatment decisions and outcomes. Producers will be able to treat lame females before the problem becomes too severe and cull females while they still have salvage value. The objective of this study was to compare the predictive abilities and accuracies of weight distribution and gait measures relative to each other and to a visual lameness detection method when detecting induced lameness among multiparous sows. Developing an objective lameness diagnosis algorithm will benefit animals, producers and scientists in timely and effective identification of lame individuals as well as aid producers in their efforts to decrease herd lameness by selecting animals that are less prone to become lame. In the early stages of lameness, weight distribution and gait are impacted. Lameness was chemically induced for a short time period in 24 multiparous sows and their weight distribution and walking gait were measured in the days following lameness induction. A linear mixed model was used to determine differences between measurements collected from day to day. Using a classification tree analysis, it was determined that the mean weight being placed on each leg was the most predictive measurement when determining whether the leg was sound or lame. The classification tree’s predictive ability decreased as the number of days post-lameness induction increased. The weight distribution measurements had a greater predictive ability compared with the gait measurements. The error rates associated with the weight distribution trees were 29.2% and 31.3% at 6 days post-lameness induction for front and rear injected feet, respectively. For the gait classification trees, the error rates were 60.9% and 29.8% at 6 days post-lameness induction for front and rear injected feet, respectively. More timely lameness detection can improve sow lifetime productivity as well as animal welfare.     

Kinematics and motor activity during tethered walking and turning in the cockroach, <Emphasis Type="Italic">Blaberus discoidalis</Emphasis>

When insects turn from walking straight, their legs have to follow different motor patterns. In order to examine such pattern change precisely, we stimulated single antenna of an insect, thereby initiating its turning behavior, tethered over a lightly oiled glass plate. The resulting behavior included asymmetrical movements of prothoracic and mesothoracic legs. The mesothoracic leg on the inside of the turn (in the apparent direction of turning) extended the coxa-trochanter and femur-tibia joints during swing rather than during stance as in walking, while the outside mesothoracic leg kept a slow walking pattern. Electromyograms in mesothoracic legs revealed consistent changes in the motor neuron activity controlling extension of the coxa-trochanter and femur-tibia joints. In tethered walking, depressor trochanter activity consistently preceded slow extensor tibia activity. This pattern was reversed in the inside mesothoracic leg during turning. Also for turning, extensor and depressor motor neurons of the inside legs were activated in swing phase instead of stance. Turning was also examined in free ranging animals. Although more variable, some trials resembled the pattern generated by tethered animals. The distinct inter-joint and inter-leg coordination between tethered turning and walking, therefore, provides a good model to further study the neural control of changing locomotion patterns.     

Experimental taphonomy of velvet worms (Onychophora) and implications for the Cambrian "explosion,disparity and decimation" model

Experimental preservation of velvet worms (phylum Onychophora), a very rare but evolutionarily important group that has existed for more than 500 million years, showed that the absence of bucal parts, adhesive-expelling organs, gonopore, eyes, legs, claws, annulation and papillation in fossils may not represent absence in the living animals. In fossils, leg thickness and claw orientation can be unreliable. The experiments indicate that not only absence, but even presence of certain structures can simply be the result of tissue decomposition. Computer-aided photorealistic reconstructions of fossi onychophorans are presented. We recommend future researchers to conduct taphonomy experiments specially before analysing unusual fossils.     

Does homozygosity contribute to the asymmetry of common white leg markings in the Arabian horse?

Common white and facial markings have a multifactorial mode of inheritance inEquus caballus and result from the absence of melanocytes in the unpigmented areas. Directional asymmetry and fluctuating asymmetry apparently account for the total asymmetry of common white leg markings. Using computerized records obtained from the Arabian Horse Registry of America, Inc., and the International Arabian Horse Association, studies were carried out to determine if homozygosity increases the total asymmetry in common white leg markings by presumably promoting fluctuating asymmetry. The results were as follows: (1) Arabian horses that are symmetrical and asymmetrical for common white leg markings have similar distributions of inbreeding coefficients; (2) Arabian and half-Arabian horses have similar concordance values, in general, for specific white markings in both their forelegs and hind legs. It is concluded that homozygosity does not contribute to the total asymmetry of common white leg markings in the Arabian horse.