Evaluation of ground reaction forces produced by chickens walking on a force plate

Overview of the various methods used to assess walking ability in broiler chickens

BACKGROUND

Walking ability is a highly important animal-based indicator of welfare in broilers that warrants monitoring across commercial production.

METHODS

A review of the technical and scientific literature on existing methods for assessing walking ability in broilers was conducted, and the reliability, validity and feasibility of the different methods were assessed when relevant information was available.

RESULTS

Visual gait scoring has high validity, minimal equipment needs and is relatively quick to perform; however, this method is subjective and requires extensive training. Due to this, more objective tests, such as the latency to lie test, have been developed, although more validation of these tests is required. Other identified methods, such as obstacle courses, the rotarod test and kinetic and kinematic approaches, require considerable amounts of equipment, making them impractical for use during on-farm inspections. Automated methods that rely on movement or activity data have potential for future development but currently lack the resolution of traditional gait scoring and require equipment such as cameras or accelerometers.

CONCLUSIONS

Objective, seemingly valid, repeatable and feasible options exist for the assessment of walking ability that would facilitate the monitoring of commercial broiler welfare; however, more validation of these methods is required, especially in commercial farm settings.

Comparison of methods of derivation of the yank-time signal from the vertical ground reaction force-time signal for identification of movement-related events

Temporal changes in ground reaction force magnitudes reflect movement strategy, and thus underlying muscle activation patterns, during movement tasks. Speculatively, these changes may be observed more readily when the force-time signal is differentiated, yielding the yank-time signal. However, the differentiation process, including the signal filtering used before or after differentiation, can significantly affect the signal-to-noise ratio (SNR) and likelihood of meaningful inference. The aim of the present study was to compare three methods of deriving the yank-time signal: Method 1 derived the yank-time signal using 2nd-order central differentiation subsequent to application of a 4th-order Butterworth filter; Method 2 included the same process as Method 1 but additionally filtered the yank-time data with a Savitzky-Golay smoothing filter; and Method 3 directly and simultaneously derived and smoothed the yank-time signal using a Savitzky-Golay digital differentiation filter. The current analyses revealed Method 2 had the best SNR, followed by Methods 3 and 1, but caused a small loss of signal amplitude. With regards to timing of inflection points in the yank-time data, no significant difference was observed. Therefore, Method 3 led to the best derivation of the yank-time signal due to its efficiency and preservation of signal characteristics and good SNR. Also, a strong association between the first maximum point of the yank-time signal and the start of the downward movement of the body's centre of mass during a countermovement jump, as identified by 3-D motion analysis, was observed. Thus, subtle events (e.g. start of downward movement) can be easily observed in the yank-time signal.

Analgesic Efficacy of Tramadol Compared With Meloxicam in Ducks (Cairina moschata domestica) Evaluated by Ground-Reactive Forces

The purpose of this study was to determine the efficacy of tramadol and meloxicam in an induced, temporary arthritis model in ducks as assessed by ground-reactive forces measured by a pressure-sensitive walkway (PSW) system. Twelve ducks (Cairina moschata domestica) were randomly separated into 3 equal groups of 4 birds each: water control, tramadol treatment, and meloxicam treatment. Baseline measurements were collected by having all ducks walk along a 3-m-long PSW in a custom-built corral before anesthesia and induction of arthritis. Arthritis was induced in all groups through injection, under anesthesia, of a 3% monosodium urate (MSU) solution into the intertarsal joint. One hour after MSU injection, birds were orally gavage fed 1 mL of tap water (control), tramadol (30 mg/kg), or meloxicam (1 mg/kg). After treatments, all ducks were reevaluated on the PSW at 1, 2, 3, 4, 8, and 24 hours post-MSU injection. The difference in maximum force was significantly greater in the control group than in both the tramadol- (P = .006) and meloxicam-treated (P = .03) individuals. Post hoc comparisons revealed differences between control and treated birds occurred only at the 3- and 4-hour time points after administration. No differences were found in the absolute difference in maximum force between tramadol- and meloxicam-treated birds at any time point (P > .05). Results of this study support the hypothesis that tramadol (30 mg/kg PO) and meloxicam (1 mg/kg PO) improve certain objective variables in an induced arthritis model in ducks. Our findings also support studies in other avian species that determined that both tramadol and meloxicam are effective analgesic drugs in some birds.

Growth Dependent Changes in Pressure Sensing Walkway Data for Turkeys

Genetic selection for rapidly growing turkeys has created an unfavorable consequence impacting the skeletal system resulting in long bone distortions. These distortions have resulted in locomotor problems, gait abnormalities, leg weakness, or lameness issues. These effects raise welfare concerns along with animal agriculture inefficiency in the form of lost product. The purpose was to determine baseline gait and force distribution in visibly unimpaired growing turkey hens. Hendrix commercial turkey hen poults (n = 100) were placed on pine wood shavings providing 0.78 m² per bird with ad libitum access to feed and water at the MSU Poultry Farm. Fifty hens were randomly selected at 5 weeks and identified with a leg band to ensure longitudinal data collection. The turkeys were walked across a pressure-sensing walkway (PSW, Tekscan, Boston, MA) and weighed at 5, 6, 8, and 10 weeks of age. PSW collected data on gait length, gait time, step force and step length, and the statistics were analyzed with SAS. Both temporospatial data, including step time and step length, and kinetic data, including peak downward force, and vertical impulse, were recorded. Body weight increased linearly with age (P < 0.001), demonstrating a typical growth pattern. Gait cycle time and peak vertical force (PVF) all displayed no difference between right and left sides, indicating that the hens had no detectable gait abnormalities. Gait velocity increased with age (P = 0.02) suggesting hens' growth impacted their gait velocity. The gait cycle time (P < 0.01) did not correspond with age. PVF increased linearly with age (P < 0.01) from 6 weeks (2.23 kg) to 10 weeks of age (5.91 kg). PVF/kg body weight (P < 0.01) increased from 6 weeks of age (96.9% BW) to 8 weeks of age (106%BW). Overall, the birds were not lame and some data was influenced by the hen's adjustment to the materials or stage of growth; in contrast, some temporospatial data did not coincide with age. The PSW could be used to detect locomotor issues in commercially produced turkey hens providing another tool for assessing well-being.

Influence of gait on bone strength in turkeys with leg defects

Leg problems have become more frequent in fast-growing turkeys. The objective of this study was to evaluate the effects of common leg defects on kinetic parameters of gait and biomechanical properties of bone. Nine hundred, day-old, male, Large White turkeys were raised in 48 floor pens. At 42 d of age, turkeys were divided into four categories of leg condition as determined by visual evaluation: Normal, Crooked toes, Shaky legs, and Valgus. Fifteen toms were selected from each group and trained to walk on a pressure sensitive walkway. Gait kinetic data were collected at 92, 115 and 144 d of age. At 145 d of age, turkeys were sacrificed and bones were collected and frozen until analysis. Morphological measurements of femur, tibia and tarsus-metatarsus were recorded. Bone mineral density (BMD) and content (BMC) were obtained using DEXA. Bone strength of tibias was evaluated using a four-point bending test and femurs with a torsion test. ANOVA was used to detect differences among groups, and Tukey's test used for mean separation. There were no differences in BW among different leg conditions. Gait parameters changed as turkeys aged, and age-group interactions were observed on peak vertical force (PVF), contact time, step length (SL) and bipedal cycle. No differences (P > 0.05) were detected in morphological measurements of femur or tibia. Relative asymmetry of femur length was lower (P < 0.05) in Normal and Valgus turkeys than in toms with Crooked toes. There were no differences (P > 0.05) among groups for femur BMD, BMC or strength. Tibia BMD and the area moment of inertia of turkeys with Crooked toes were lower (P < 0.05) than in toms with Valgus. With all four leg conditions, femur strength was positively correlated with PVF and negatively correlated with SL; BMD and BMC were correlated with tibia strength and gait kinetic parameters. In conclusion, only crooked toes caused consistent differences in gait patterns, bone properties and bone strength, but in general, gait kinetics was correlated with bone biomechanics in turkeys.

Gait parameters in four strains of turkeys and correlations with bone strength

Locomotion problems in meat poultry have multifactorial etiology. A better understanding of normal gait and its influences on biomechanical aspects of leg bones among turkey genetic lines is important to prevent skeletal disorders and locomotion issues. The objective of this experiment was to determine the possible differences in gait kinetic and kinematic parameters of turkey strains and their effects on bone biomechanical properties. Four genetic lines, named A, B, C, and D, were obtained and raised in 48 floor pens with new pine shavings. Leg health issues were classified at 16 and 33 d of age. Fifteen turkeys from each strain with apparent normal legs and gait at 33 d of age were selected for gait analysis. These 15 turkeys were trained to walk on a pressure sensitive walkway and video was recorded to calculate articulation movements. These data also were analyzed to obtain kinetic and kinematic parameters of the gait cycle collected at 47, 84, 107, and 145 d of age. At 20 wk all turkeys were sacrificed, and legs were collected and frozen for analysis. Weights and morphologic measurements of the femur, tibia, and shank were recorded. Bone mineral density (BMD) and content (BMC) were obtained using DEXA. Femur and tibia strength were evaluated by a 4-point bending test and torsion test, respectively. Gait parameters changed as toms aged and some differences were observed among lines. Genetic lines differed on BMD, but not on BMC. Strain D had a higher BMD and smaller diaphyseal angle than strain C, characteristics that were correlated with stronger bones. Strain D also had the lowest incidence of leg problems while strain C had the highest. Furthermore, the D strain had a smaller vertical motion of the toe than strains C and B at 47 d and strain A at 145 d, indicating that the D strain had a more efficient gait. In summary, genetic strains differ significantly on gait parameters, which in turn impacts bone biomechanics.

Ontogeny of sex differences in the energetics and kinematics of terrestrial locomotion in leghorn chickens (Gallus gallus domesticus)

Sex differences in locomotor performance may precede the onset of sexual maturity and/or arise concomitantly with secondary sex characteristics. Here, we present the first study to quantify the terrestrial locomotor morphology, energetics and kinematics in a species, either side of sexual maturation. In domestic leghorn chickens (Gallus gallus domesticus) sexual maturation brings about permanent female gravidity and increased male hind limb muscle mass. We found that the sexes of a juvenile cohort of leghorns shared similar maximum sustainable speeds, while in a sexually mature cohort maximum sustainable speeds were greater by 67% (males) and 34% (females). Furthermore, relative to that in juveniles of the same sex, the absolute duration of leg swing was longer in mature males and shorter in mature females. Consequently, the proportion of a stride that each limb was in contact with the ground (duty factor) was higher in sexually mature females compared to males. Modulation of the duty factor with the development of secondary sex characteristics may act to minimize mechanical work in males; and minimise mechanical power and/or peak force in females. A greater incremental response of mass-specific metabolic power to speed in males compared to females was common to both age cohorts and, therefore, likely results from physiological sexual dimorphisms that precede sexual maturation.

Automatic detection of lameness in gestating group-housed sows using positioning and acceleration measurements

Lameness is an important issue in group-housed sows. Automatic detection systems are a beneficial diagnostic tool to support management. The aim of the present study was to evaluate data of a positioning system including acceleration measurements to detect lameness in group-housed sows. Data were acquired at the Futterkamp research farm from May 2012 until April 2013. In the gestation unit, 212 group-housed sows were equipped with an ear sensor to sample position and acceleration per sow and second. Three activity indices were calculated per sow and day: path length walked by a sow during the day (Path), number of squares (25×25 cm) visited during the day (Square) and variance of the acceleration measurement during the day (Acc). In addition, data on lameness treatments of the sows and a weekly lameness score were used as reference systems. To determine the influence of a lameness event, all indices were analysed in a linear random regression model. Test day, parity class and day before treatment had a significant influence on all activity indices (P<0.05). In healthy sows, indices Path and Square increased with increasing parity, whereas variance slightly decreased. The indices Path and Square showed a decreasing trend in a 14-day period before a lameness treatment and to a smaller extent before a lameness score of 2 (severe lameness). For the index acceleration, there was no obvious difference between the lame and non-lame periods. In conclusion, positioning and acceleration measurements with ear sensors can be used to describe the activity pattern of sows. However, improvements in sampling rate and analysis techniques should be made for a practical application as an automatic lameness detection system.

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.

Kinematic analysis quantifies gait abnormalities associated with lameness in broiler chickens and identifies evolutionary gait differences

This is the first time that gait characteristics of broiler (meat) chickens have been compared with their progenitor, jungle fowl, and the first kinematic study to report a link between broiler gait parameters and defined lameness scores. A commercial motion-capturing system recorded three-dimensional temporospatial information during walking. The hypothesis was that the gait characteristics of non-lame broilers (n = 10) would be intermediate to those of lame broilers (n = 12) and jungle fowl (n = 10, tested at two ages: immature and adult). Data analysed using multi-level models, to define an extensive range of baseline gait parameters, revealed inter-group similarities and differences. Natural selection is likely to have made jungle fowl walking gait highly efficient. Modern broiler chickens possess an unbalanced body conformation due to intense genetic selection for additional breast muscle (pectoral hypertrophy) and whole body mass. Together with rapid growth, this promotes compensatory gait adaptations to minimise energy expenditure and triggers high lameness prevalence within commercial flocks; lameness creating further disruption to the gait cycle and being an important welfare issue. Clear differences were observed between the two lines (short stance phase, little double-support, low leg lift, and little back displacement in adult jungle fowl; much double-support, high leg lift, and substantial vertical back movement in sound broilers) presumably related to mass and body conformation. Similarities included stride length and duration. Additional modifications were also identified in lame broilers (short stride length and duration, substantial lateral back movement, reduced velocity) presumably linked to musculo-skeletal abnormalities. Reduced walking velocity suggests an attempt to minimise skeletal stress and/or discomfort, while a shorter stride length and time, together with longer stance and double-support phases, are associated with instability. We envisage a key future role for this highly quantitative methodology in pain assessment (associated with broiler lameness) including experimental examination of therapeutic agent efficacy.

The evolutionary continuum of limb function from early theropods to birds

The bipedal stance and gait of theropod dinosaurs evolved gradually along the lineage leading to birds and at some point(s), flight evolved. How and when did these changes occur? We review the evidence from neontology and paleontology, including pectoral and pelvic limb functional morphology, fossil footprints/trackways and biomechanical models and simulations. We emphasise that many false dichotomies or categories have been applied to theropod form and function, and sometimes, these impede research progress. For example, dichotomisation of locomotor function into 'non-avian' and 'avian' modes is only a conceptual crutch; the evidence supports a continuous transition. Simplification of pelvic limb function into cursorial/non-cursorial morphologies or flexed/columnar poses has outlived its utility. For the pectoral limbs, even the classic predatory strike vs. flight wing-stroke distinction and separation of theropods into non-flying and flying--or terrestrial and arboreal--categories may be missing important subtleties. Distinguishing locomotor function between taxa, even with quantitative approaches, will always be fraught with ambiguity, making it difficult to find real differences if that ambiguity is properly acknowledged. There must be an 'interpretive asymptote' for reconstructing dinosaur limb function that available methods and evidence cannot overcome. We may be close to that limit, but how far can it be stretched with improved methods and evidence, if at all? The way forward is a combination of techniques that emphasises integration of neontological and paleontological evidence and quantitative assessment of limb function cautiously applied with validated techniques and sensitivity analysis of unknown variables.

A force plate study of avian gait

OBJECTIVE

To test the force plate as a gait analysis system for broilers and to determine how the ground reaction force (GRF) patterns change in these birds with growth and administration of analgesia.

MATERIALS AND METHODS

Thirty-three male Ross 308 chicks were raised on either an ad libitum or restricted-feeding regime, and subsequently treated with carprofen or a placebo. Vertical, craniocaudal and mediolateral GRFs were measured as the birds walked across a standard force plate.

RESULTS

The data were easy to collect, and peak vertical forces of an equivalent percentage of bodyweight as seen in human walking were identified. Mediolateral forces were 2-3 times greater than those demonstrated in other species. GRF patterns showed significant changes during growth, but analgesia did not have a significant effect on the speed of walking, or GRF patterns.

CONCLUSIONS AND CLINICAL RELEVANCE

The force plate is a suitable research tool for recording GRFs from avian bipeds. The large mediolateral forces identify a particularly inefficient aspect of avian gait; however, the role of pain remains to be determined.

Association between subjective lameness grade and kinetic gait parameters in horses with experimentally induced forelimb lameness

OBJECTIVE

To evaluate the association between subjective lameness grades and kinetic gait parameters and assess the variability in kinetic parameters in horses with experimentally induced forelimb lameness.

ANIMALS

32 horses.

PROCEDURES

Forelimb lameness was induced in each horse via injection of lipopolysaccharide into 1 metacarpophalangeal joint (40 experimental trials). Subjective lameness grading and 13 kinetic gait parameters (force plate analysis) were assessed before (baseline) and at 12, 18, and 24 hours after lipopolysaccharide injection. While horses were trotting, kinetic gait analysis was performed for 8 valid repetitions at each time point. Repeated-measures analyses were performed with 8 repetitions for each kinetic parameter as the outcome, and lameness grades, time points after lipopolysaccharide injection, and repetition order as explanatory variables. Sensitivity and specificity of kinetic parameters for classification of horses as sound or lame (in relation to subjective lameness scores) were calculated. Between- and within-horse variabilities of the 13 kinetic parameters were assessed by calculation of coefficients of variation.

RESULTS

Subjective lameness grades were significantly associated with most of the kinetic parameters. Vertical force peak and impulse had the lowest between- and within-horse coefficients of variation and the highest correlations with subjective lameness grade. Vertical force peak had the highest sensitivity and specificity for lameness classification. Vertical force peak and impulse were significantly decreased even in horses with mild or unobservable lameness.

CONCLUSIONS AND CLINICAL RELEVANCE

Among the kinetic gait parameters, vertical force peak and impulse had the best potential to reflect lameness severity and identify subclinical forelimb gait abnormalities.

Accuracy and Optimization of Force Platform Gait Analysis in Labradors with Cranial Cruciate Disease Evaluated at a Walking Gait

OBJECTIVE

To determine the combination of ground reaction forces (GRFs) that best discriminates between lame and non-lame dogs. To compare the sensitivity of force platform gait analysis and visual observation at detecting gait abnormalities in Labradors after surgery for rupture of the cranial cruciate ligament (CCL).

ANIMALS

All dogs were adult Labrador Retrievers: 17 free of orthopedic and neurologic abnormalities, 100 with unilateral CCL rupture, and 131 studied 6 months after surgery for unilateral CCL injury, 15 with observable lameness.

PROCEDURE

Dogs were walked over a force platform with GRF recorded during the stance phase. Analytic properties of force platform gait analysis were calculated for several combinations of forces. The probability of visual observation detecting a gait abnormality was compared with that of force platform gait analysis.

RESULTS

We determined that a combination of peak vertical force (PVF) and falling slope were optimal for discriminating sound and lame Labradors. After surgery, many dogs (75%) with no observable lameness failed to achieve GRFs consistent with sound Labradors.

CONCLUSION

A force platform is an accurate method of assessing lameness in Labradors with CCL rupture and is more sensitive than visual observation. Assessing lameness with a combination of GRFs is better than using univariate GRFs.

CLINICAL RELEVANCE

Therapies for stifle lameness can be accurately and objectively evaluated using 2 vertical ground reaction forces obtained from a force platform.