Radiographic characterisation of spinal curvature development in farmed New Zealand Chinook salmon Oncorhynchus tshawytscha throughout seawater production.

Spinal anomalies are a recognised source of downgrading in finfish aquaculture, but identifying their cause(s) is difficult and often requires extensive knowledge of the underlying pathology. Late-onset spinal curvatures (lordosis, kyphosis, scoliosis) can affect up to 40% of farmed New Zealand Chinook (king) salmon (Oncorhynchus tshawytscha) at harvest, but little is known about their pathogenesis. Curvature development was radiographically documented in two related cohorts of commercially-farmed Chinook salmon throughout seawater production to determine (1) the timing of radiographic onset and relationships between (2) the curvature types, (3) the spinal regions in which they develop and (4) their associations with co-existing vertebral body anomalies (vertebral compression, fusion and vertical shift). Onset of curvature varied between individuals, but initially occurred eight months post-seawater transfer. There were strong associations between the three curvature types and the four recognised spinal regions: lordosis was predominantly observed in regions (R)1 and R3, kyphosis in R2 and R4, manifesting as a distinct pattern of alternating lordosis and kyphosis from head to tail. This was subsequently accompanied by scoliosis, which primarily manifested in spinal regions R2 and R3, where most of the anaerobic musculature is concentrated. Co-existing vertebral body anomalies, of which vertebral compression and vertical shift were most common, appeared to arise either independent of curvature development or as secondary effects. Our results suggest that spinal curvature in farmed New Zealand Chinook salmon constitutes a late-onset, rapidly-developing lordosis-kyphosis-scoliosis (LKS) curvature complex with a possible neuromuscular origin.

Imposed running exercise does not alter cell proliferation in the neurogenic niches of young lambs.

Neurogenesis, the process by which neurons are generated in the brain from progenitor cells, occurs in the subventricular zone (SVZ) and the subgranular zone (SGZ) in the adult human brain. Recently, rodent studies have demonstrated that exercise can increase neurogenesis in the SGZ; however, it is unclear if exercise also has this effect in more complex mammalian brains. The overarching aim of this study was to explore whether exercised-induced neurogenesis occurs in larger mammalian brains more representative of human brains and to explore the use of a model for exercising large animals such as sheep. For these studies, 6 male twin lambs had a structured exercise regime for 4 wk and 6 other twin male lambs were kept in an open field pen. All lambs were injected with bromodeoxyuridine (BrdU), a thymidine analog that is incorporated into the DNA of proliferating cells. Immunoperoxidase was used to visualize and quantify BrdU-positive cells in the SVZ and SGZ. Overall, no significant change in the number or distribution of BrdU-positive cells was observed in the lamb SVZ and SGZ with exercise or colabeling of BrdU with mature neuronal or glial markers in the exercised and nonexercised lamb SVZ and SGZ. Overall, this study provides a novel methodology to investigate the effects of imposed exercise on large animals and exercise-induced neurogenesis in animals with gyrencephalic brains.

Influence of Exercise and Intra-articular Site on Canals in Articular Calcified Cartilage of Equine Third Carpal Bones.

The third carpal bone (C3) responds to exercise by adaptive modeling of bone and articular calcified cartilage along the dorsal load path. Canals penetrating articular calcified cartilage, thought to contain vascular tissue, are reported in numerous species. Their significance remains unclear. Our objective was to determine if the number of canals was significantly different in strenuously exercised and control young horses and in a site of intermittent high loading compared to sites sustaining lower habitual loads. Volumetric bone mineral density in the radial facet of C3 of strenuously exercised and gently exercised (control) 19-month-old thoroughbred horses (n= 6/group) was determined by peripheral quantitative computed tomography. The hyaline cartilage was corroded to expose the surface of articular calcified cartilage. The number of canals penetrating the articular calcified cartilage surface in en face scanning electron microscopy images was compared in 4 regions. Volumetric bone mineral density of C3 was significantly greater (P= .004) in strenuously exercised horses. There were 2 morphologically distinct groups of canals and significantly fewer (P= .006) large canals in the dorsal than in the palmar aspect of C3 in control but not in exercised horses. Roughly circular depressions in the articular calcified cartilage surface around apparently forming canals were visible in some samples and have not been previously described in the literature. The canals may be evidence of chondroclastic activity reaching the interface of hyaline and calcified cartilage. Further work is needed to elucidate the relationships between presence of canals and the responses to exercise and to joint disease.

Different short-term mild exercise modalities lead to differential effects on body composition in healthy prepubertal male rats.

Physical activity has a vital role in regulating and improving bone strength. Responsiveness of bone mass to exercise is age dependent with the prepubertal period suggested to be the most effective stage for interventions. There is a paucity of data on the effects of exercise on bone architecture and body composition when studied within the prepubertal period. We examined the effect of two forms of low-impact exercise on prepubertal changes in body composition and bone architecture. Weanling male rats were assigned to control (CON), bipedal stance (BPS), or wheel exercise (WEX) groups for 15 days until the onset of puberty. Distance travelled via WEX was recorded, food intake measured, and body composition quantified. Trabecular and cortical microarchitecture of the femur were determined by microcomputed tomography. WEX led to a higher lean mass and reduced fat mass compared to CON. WEX animals had greater femoral cortical cross-sectional thickness and closed porosity compared to CON. The different exercise modalities had no effect on body weight or food intake, but WEX significantly altered body composition and femoral microarchitecture. These data suggest that short-term mild voluntary exercise in normal prepubertal rats can alter body composition dependent upon the exercise modality.

The effect of interruptions during training on the time to the first trial and race start in Thoroughbred racehorses.

Few studies have investigated the effect of having interruptions during training on future training and racing performance in Thoroughbred racehorses. The aim of this paper was to investigate the effect of having an interruption before the first trial on starting in a trial or a race. A prospective cohort study was used to record the training activity of a cohort of Thoroughbred racehorses, over two racing seasons. Fourteen racehorse trainers recorded information on the distances worked at canter and at fast speeds (<15s/200 m) and provided reasons for horses not training, or for having interruptions (break from training). Trial and racing results were obtained from the New Zealand Thoroughbred Racing online database. A Cox proportional hazards regression model was used to investigate two outcome measures of performance: (1) time to the first trial and (2) time to the first race. The type of interruption that had occurred before the first trial was the main exposure of interest, and was grouped into: no interruption, voluntary (no known condition or disease present) and involuntary interruptions (due to the presence of a condition or disease). A total of 160/200 (80%) horses started in at least one trial and 100/205 (48%) horses started in at least one race during the study period. The median time to starting in a trial or a race differed significantly (p<0.001) with the type of interruption. The hazard of starting in a trial was lower for horses experiencing voluntary and involuntary interruptions (p<0.001) but there was no association with starting in a race, after adjusting for confounding variables. As age at the start of training increased the hazard of starting in a trial decreased. Horses accumulating longer distances at 15s/200 m had a higher hazard of starting in a trial, whilst horses accumulating fewer events at high speed and fewer trials had a reduced hazard of starting in a race. There was significant clustering at the trainer level for both the outcomes investigated. Interruptions to training had an effect on the time to, and hazard of, a trial but not a race start. The timing of these interruptions may have implications for future racing success and career longevity.

The association of 2-year-old training milestones with career length and racing success in a sample of Thoroughbred horses in New Zealand.

REASONS FOR PERFORMING STUDY: There is increasing evidence that exercise early in life has a positive effect on musculoskeletal health. At present, there is little whole population research investigating the effect of racing as 2-year-olds on future racing career. OBJECTIVES: To investigate the association between attaining training milestones as 2-year-olds with length of career and racing success in Thoroughbred horses in New Zealand. METHODS: Retrospective data were obtained of the 2001/02-born Thoroughbred foal crop. The 3 training milestones were: registered with a trainer, trialled and raced. The association of the training milestones with career length was measured using the outcomes: number of race starts and number of years raced, in a Cox regression model. Logistic regression models analysed the association of the training milestones with the outcomes: won or placed in a race. Linear regression was performed to assess the association of training milestones with total career earnings. RESULTS: Of 4683 horses in the population; 3152 horses were registered with a trainer, 2661 horses trialled and 2109 horses raced. Horses that raced as 2-year-olds had significantly (P<0.001) more race starts than those first raced as 3-year-olds or older, this was also true when the 2-year-old year data were omitted. Horses that raced as 2-year-olds had significantly (P<0.001) more years racing. Horses registered with a trainer, trialled or raced as 2-year-olds were more likely to have won or been placed in a race than those that achieved the milestones as 3-year-olds or older. Horses that first trialled and raced as 2-year-olds had greater total earnings than those that first trialled or raced at a later age. CONCLUSIONS AND POTENTIAL RELEVANCE: Two-year-old training milestones had a strong association with positive racing career outcomes. Horses in training or racing as 2-year-olds may have better musculoskeletal health throughout life than horses that are first in training or racing at a later age.

Voluntary exercise in pregnant rats improves post-lactation maternal bone parameters but does not affect offspring outcomes in early life.

OBJECTIVES: The objectives of this study were to examine the effects of voluntary exercise during pregnancy on maternal post-lactation bone parameters and offspring growth. METHODS: Pregnant Wistar rats were housed in conventional cages (control), or were housed in raised cages requiring them to rise to an erect, bipedal stance to obtain food/water, throughout pregnancy. Dual energy X-ray absorptiometry and peripheral quantitative computed tomography scans were performed pre-mating and post-weaning. Maternal stress was assessed by fecal corticosterone measurement. Offspring weights were assessed at postnatal days 1 and 25 (weaning). RESULTS: Changes in bone mineral over the pregnancy/lactation period were site-specific. Exercise did not affect loss of bone mineral from the lumbar spine, but did attenuate the loss of trabecular bone mineral from the tibial metaphysis and enhance the strength strain index and cross-sectional moment of inertia at the tibial diaphysis (P≤0.05) in dams in the exercised group. Fecal corticosterone did not differ between dam groups. There were no significant differences in offspring weight between the exercised and control group at either time point. CONCLUSIONS: Voluntary exercise in the pregnant rat can improve some post-lactation bone parameters and does not adversely affect early postnatal outcomes of the offspring.

Reproductive performance of Thoroughbred mares in the Waikato region of New Zealand: 2. Multivariable analyses and sources of variation at the mare, stallion and stud farm level.

AIM: The objective of this study was to utilise multivariable statistical methods appropriate for clustered data to identify mare-related explanatory variables that significantly affected the reproductive performance of Thoroughbred mares in the Waikato region of New Zealand. In addition, we aimed to determine the relative contribution of the mare, stallion and stud farm to reproductive performance. METHODS: A prospective cohort study was performed involving five stud farms in the Waikato region of New Zealand during three consecutive breeding seasons (2006-2008). A total of 1,482 individual mares contributed 2007 mare years and 3,402 oestrous cycles over the three breeding seasons. Reproductive performance was measured using three parameters; (a) first-cycle pregnancy rate (FCPR), (b) end-of-season pregnancy rate (SPR), and (c) the start-of-mating to conception interval. RESULTS: When controlled for the effects of serving stallion, stud farm and year of study the only significant mare-related variables included in the final models of FCPR, SPR and conception interval were the age of the mare and her reproductive status (classified as dry or foaling). Advancing mare age significantly reduced reproductive performance regardless of reproductive status and foaling mares had significantly poorer reproductive outcomes compared with dry mares when controlled for age. For each additional increase in year of age, the FCPR was reduced by a factor of 0.94 (95% CI=0.92-0.96) and the SPR was reduced by a factor of 0.91 (95% CI=0.88-0.93). Mares older than 14 years of age took longer to conceive after the start-of-mating compared with younger mares. The daily hazard of conception for mares 14 years and older was 0.64 (95% CI=0.47-0.83) times less than mares younger than 9 years of age. Determining the relative contribution of the mare, stallion and stud farm to the FCPR indicated that 95.9% of the variation was at the mare level, 4.1% was at the stallion level and 0% was at the stud farm level. For the SPR the variance components indicated that 92.5% of the variation was at the mare level, 6.7% was at the stallion level and 0.8% was at the stud farm level. CONCLUSIONS: The reproductive performance of Thoroughbred mares in the Waikato region of New Zealand is influenced by two main mare-related factors; the age of the mare and her reproductive status (dry or foaling). The majority of variation in reproductive performance was associated with mare-level factors and the contribution of the stallion and stud farm was relatively minor.

Reproductive performance of Thoroughbred mares in the Waikato region of New Zealand: 1. Descriptive analyses.

AIM: To describe the reproductive performance of a population of Thoroughbred mares on stud farms in the Waikato region of New Zealand. METHODS: A prospective cohort study was performed involving five stud farms in the Waikato region of New Zealand during three consecutive breeding seasons (2006-2008). A total of 1,482 individual mares contributed 2007 mare years and 3,402 oestrous cycles over the three breeding seasons. Mares were served by 87 individual stallions. RESULTS: The mean first-cycle pregnancy rate (FCPR) was 53.6%, the end-of-season pregnancy rate (SPR) was 85.3% and the foaling rate was 80.2%. There were significant differences amongst farms for FCPR (range 47.3-68.2%; p<0.01), SPR (range 81.4-92.6%; p<0.001) and foaling rate (range 77.8-90.1%; p<0.001). There were significant differences amongst stallions in their FCPR (range 38-74%; p<0.001) and SPR (range 72-97%; p<0.001).The proportion of pregnancies lost between day 14-16 and day 42 of gestation was 5.5% and the proportion of pregnancies lost between day 42 and term was 3.0%. Mares older than 14 years of age and barren mares had the highest pregnancy loss rates. Of all pregnancies diagnosed at 14-16 days, 12.9% were multiple pregnancies. The length of the breeding season was relatively short with 87.3% of services occurring in the 91-day period between 1 September and 30 November. CONCLUSIONS: The reproductive performance of Thoroughbred mares in the Waikato region of New Zealand was similar to that reported from other major Thoroughbred breeding countries. Although the per-cycle pregnancy rates in this study were lower than those reported in some studies, the foaling rate was similar to previous reports and this was achieved during a relatively short breeding season.

Risk factors for interruptions to training occurring before the first trial start of 2-year-old Thoroughbred racehorses.

AIM: To quantify the time from the start of training to the first interruption and to identify horse and training risk factors for voluntary interruptions and interruptions due to musculoskeletal injury occurring before the first trial. METHODS: A prospective cohort study was used to collect data on the training activity of 2-year-old racehorses, from 14 trainers in the Northern and Central Districts of New Zealand, over two racing seasons (2008/09 and 2009/10). Daily training data were recorded for each horse, including, distances worked at canter (>15 seconds/200 m), three measures of high-speed exercise (15, 13, and <12 seconds/200 m) and reasons why horses were not working. Competing risks survival analysis was used to investigate associations between risk factors and voluntary interruptions (no known condition or disease present), or interruptions due to musculoskeletal injury occurring before the first official trial. RESULTS: A total of 205 horses spent 11,051 training days at risk of an interruption before the first trial. There were 134/205 (65.4%) cases of interruptions, of which 115/134 (85.8%) were voluntary interruptions and 19/134 (14.2%) were due to musculoskeletal injury. In the final multivariable models, the risk of voluntary interruptions decreased with increasing age at the start of training, and increased with the number of days off during training, but was not associated with gender. Females had a decreased risk of interruptions due to musculoskeletal injury compared with males. There was no association between the number of high-speed events and either voluntary interruptions or interruptions due to musculoskeletal injury. CONCLUSIONS AND CLINICAL RELEVANCE: The study highlighted horse and training risk factors associated with two types of interruptions occurring during training. Identification of modifiable risk factors may help to reduce the proportion of horses experiencing an interruption before the first trial start, reducing the number of lost training days and the associated cost.

Bone volume and regional density of the central tarsal bone detected using computed tomography in a cross-sectional study of adult racing greyhounds.

AIMS: To determine whether left-to-right asymmetry of the central tarsal bone (CTB) of racing greyhounds was detectable using computed tomography (CT) in live dogs; to quantify the asymmetry in terms of average bone volume, volumetric bone mineral density (vBMD), and dorsal cortical shape, and to determine if age, gender, bodyweight, number of starts or history of tarsal injury were significant covariates. METHODS: One trainer supplied 11 male and seven female, unrelated, skeletally mature, actively racing greyhounds, including dogs with a history of tarsal injury diagnosed by the trainer and/or track veterinarian (n=8), and dogs without a history of tarsal injury (n=10). Using CT, standardised parameters of the CTB were measured including volume and average vBMD of the left and right CTB, vBMD of regions within the CTB, and bone shape. RESULTS: There was no difference in the volumes of the left and right CTB and no association with number of racing starts. Volume of CTB in dogs with a history of tarsal injury was greater than in dogs with no history of injury (p<0.001). Mean vBMD of the right was greater than the left CTB (p=0.004), and was independent of history of injury, gender, bodyweight, and number of starts. Males with a history of injury weighed more than those with no history of injury (p=0.004). The region of greatest difference in vBMD between right and left limbs was the centrodorsomedial aspect of the CTB. Middle plantar ligament enthesiopathies and fractures of tarsal bones other than the central tarsal bone were identified in dogs with and without a history of tarsal injury. CONCLUSIONS: Significant left-to-right asymmetry of the CTB in racing greyhounds was detected using CT. Contrary to previous suggestions, the asymmetry was not associated with the number of racing starts. We propose that the majority of the adaptive modelling of the CTB occurred rapidly following the onset of counter-clockwise training, with little further modelling throughout the racing career of the dog, however further investigation is warranted. CLINICAL RELEVANCE: This study described a technique using CT for imaging the CTB in live dogs, which opens the way for a longitudinal study of bone modelling of the CTB in response to training and racing in a counter-clockwise direction.

Exercise in Thoroughbred yearlings during sales preparation: a cohort study.

REASONS FOR PERFORMING STUDY: There is increasing evidence suggesting that early exercise in Thoroughbred racehorses may be beneficial to the development of the musculoskeletal system. At present, information on the exercise programmes and health problems of individual yearlings during a sales preparation is scant. OBJECTIVES: To describe the exercise and health problems of Thoroughbred yearlings during preparation for sales, and to identify variations in exercise between and within farms. METHODS: A prospective cohort study was used to collect exercise and health information from 18 farms across New Zealand. Daily exercise records for individual horses were recorded during the studfarms' preparation for the annual national yearling sales in January 2009. RESULTS: Data were collected from 319 yearlings, of which 283 (88.7%) were exercised (hand walking, mechanical walker and lungeing) during their preparations. Sales preparation lasted a median of 69 days (interquartile range 61-78) and differed significantly between farms (P<0.001). The median exercise time performed differed significantly by gender (P<0.001), farm (P<0.001) and month of the preparation (P<0.001), but not by type of sale (P = 0.14) or category of sales price (P = 0.12). Within certain farms, daily exercise differed between horses as did total exercise by gender and the number of days spent in the sales preparation. Lameness was the most common condition affecting yearlings and the overall incidence rate of lameness was 0.08 per 100 horse days (95% confidence interval 0.05-0.13). Incidence rates of lameness varied significantly between farms (P = 0.02), but not by age (P = 0.77), sales type (P = 0.58) or month of the preparation (P = 0.53). CONCLUSIONS AND POTENTIAL RELEVANCE: Yearling exercise programmes varied between and within farms. Since exercise is already being tailored for each individual horse, there may be an opportunity to allow for modifications to sales preparation with the future career in mind.

The reproductive performance of Thoroughbred mares treated with intravaginal progesterone at the start of the breeding season.

The objective of this study was to investigate the effects of intravaginal progesterone on the reproductive performance of transitional Thoroughbred mares on commercial stud farms. Two hundred twenty-seven (227) non-lactating transitional Thoroughbred mares aged between 4 and 18 y (mean 9.4 ± 3.2 y) located on three stud farms in the Waikato region of New Zealand were used in the study performed during four consecutive breeding seasons (2007-10). Mares were age-matched in pairs and either treated with an intravaginal progesterone releasing device (Cue-Mare, 1.72 g progesterone, 10% w/w) for up to 10 d (Treated; n = 126) or left untreated (Control; n = 101). In both groups, 1,667 iu of hCG was given IV when an ovarian follicle ≥35 mm was detected (in conjunction with estrous behavior) and each mare was bred by natural service. Treated mares were served earlier in the breeding season (mean ± SD interval to first service was 13.9 ± 3.0 vs 26.7 ± 13.2 d for Treated and Control groups, respectively; P < 0.001). In the Treated and Control groups, 95.2 and 42.6% of mares were served within the first 21 d of the season (P < 0.001). Treated mares conceived earlier in the breeding season (mean number of days to conception 37.5 ± 14.2 vs 50.8 ± 21.3 d, P = 0.01). There was no difference between groups in the first service pregnancy rates (53.9 and 50.5% for Treated and Control mares, P = 0.89). Treatment with an intravaginal device increased the number of mares conceiving by the end of the breeding season (91.3 vs 82.3% for Treated and Control groups, P = 0.04). Therefore, this treatment protocol appeared to offer a convenient, economical and reliable method for managing transitional mares on commercial Thoroughbred stud farms.

The relationship of training milestones with racing success in a population of Standardbred horses in New Zealand.

AIM: To investigate the association between attainment of training milestones by 2-year-old horses with racing outcomes in a population of Standardbred racehorses in New Zealand. METHODS: Retrospective records of the 2001/2002-born Standardbred foals were obtained. The three training milestones used were: registered with a trainer, entered in a trial, and competed in a race. The racing outcomes were length of career in years raced and number of race starts, and total earnings. Cox regression analysis was used to assess the association between attainment of the three milestones by 2-year-olds and the number of race starts and years raced. Logistic regression models were used to determine the association between attainment of the milestones by 2-year-olds and the outcomes won and placed in a race. Linear regression was used to model the association between attainment of the milestones by 2-year-olds and annual earnings and total earnings (transformed using Ln (earnings+NZ$100)). RESULTS: Of 3,032 horses in the population, 1,018 (33.6%) registered with a trainer, 609 (20.1%) trialled, and 272 (9.0%) raced as 2-year-olds. Horses that first raced as 2-year-olds had a longer racing career and more race starts than those that that did not race as 2-year-olds (p<0.001); this was also true when starts in the 2-year-olds were omitted from analyses. Horses that were registered with a trainer, trialled or raced as 2-year-olds were more likely to have won or placed in a race than those that did not achieve the milestones as 2-year-olds (p<0.001). Linear regression showed horses that trialled and raced as 2-year-olds had greater total earnings than those that did not, and male horses had a greater total earnings than female horses. CONCLUSION: Only one third the Standardbred racehorses born in 2001/2002 registered with a trainer as 2-year-olds, but the results of this study indicate that horses that began training, trialling, or racing as 2-year-olds had longer and more successful careers than those that did not achieve the milestones as 2-year-olds. Further investigation is required to quantify the management practices of these horses to determine the factors that may be associated with a successful racing career.

Assessment of bone response to conditioning exercise in the radius and tibia of young thoroughbred horses using pQCT.

OBJECTIVES: To assess the effect of conditioning exercise on bone parameters at multiple sites in the radius and tibia of young Thoroughbred horses. METHODS: The left and right radius and tibia were obtained from twelve horses, six of which had received conditioning exercise and six which formed the control group. Each bone was scanned at 5% intervals along its entire length using pQCT. RESULTS: Bone strength, bone area and periosteal circumference were significantly greater for the group of conditioned horses in both the radius and tibia. Volumetric bone mineral density was lower while bone mineral content, endocortical circumference and polar moment of inertia were higher in the conditioned group of horses but the significance of these differences varied between the two bones. Cortical thickness was not significantly different between the groups in either bone. CONCLUSIONS: Conditioning exercise stimulated a significant increase in the strength of both bones that could be attributed mainly to an increase in bone size, rather than differences in bone mineral content or density. The radius and tibia exhibited differences in the significance of changes in several bone parameters suggesting that not all bones respond in an identical fashion to imposed exercise.

Combined nanoindentation testing and scanning electron microscopy of bone and articular calcified cartilage in an equine fracture predilection site.

Condylar fracture of the third metacarpal bone (Mc3) is the commonest cause of racetrack fatality in Thoroughbred horses. Linear defects involving hyaline articular cartilage, articular calcified cartilage (ACC) and subchondral bone (SCB) have been associated with the fracture initiation site, which lies in the sagittal grooves of the Mc3 condyle. We discovered areas of thickened and abnormally-mineralised ACC in the sagittal grooves of several normal 18-month-old horses, at the same site that linear defects and condylar fracture occur in older Thoroughbreds and questioned whether this tissue had altered mechanical properties. We embedded bone slices in PMMA, prepared flat surfaces normal to the articular surface and studied ACC and SCB using combined quantitative backscattered electron scanning electron microscopy (qBSE) and nanoindentation testing: this allowed correlation of mineralisation density and tissue stiffness (E) at the micron scale. We studied both normal and affected grooves, and also normal condylar regions. Large arrays of indentations could be visualised as 2-dimensional maps of E with a limit to resolution of indentation spacing, which is much larger than qBSE pixel spacing. ACC was more highly mineralised but less stiff in early linear defects than in control regions, while subchondral bone was more highly mineralised and stiffer in specimens with early linear defects than those without. Thus both ACC and SCB mineralisation may be abnormal in a class of early linear defect in 18-month-old Thoroughbred horses, and this may possibly contribute to later fracture of the Mc3 condyle.

Comparing muscle temperature during static and dynamic squatting with and without whole-body vibration.

The aim of this study was to investigate the influence of shallow dynamic squatting (DS) versus static squatting (SS) with or without concurrent side-to-side alternating whole-body vibration (WBV) on vastus lateralis temperature and cardiovascular stress as indicated by heart rate (HR). Ten participants (five men, five women) participated in four interventions [DS with WBV (DS+), DS without WBV (DS-), SS with WBV (SS+), SS without WBV (SS-)] 48 h apart, in a randomized order. The interventions were preceded by a approximately 20-min rest period, consisted of 10 mins with or without WBV (26 or 0 Hz) with SS (40 degrees of knee flexion) or DS (55 degrees of knee flexion, at a cadence of 50 bpm) where SS+ and DS- were metabolically matched. Muscle (T(m)), core (T(c)), skin temperature (T(sk)), HR and VO(2) were recorded during each intervention. For T(m), there was a time (P<0.01) and WBV (P<0.01) effect but no squat effect was evident, and there was time xWBV interaction effect (P<0.01). In all four interventions, the work load was too low to cause cardiovascular stress. Instead normal, moderate physiological effects of exercise on autonomic control were observed as indicated by HR; there were no significant increases in T(sk) or T(c). There appears to be no benefit in performing an unloaded, shallow DS+ at a tempo of 50 bpm as T(m,) HR, VO(2) are likely to be increased by the same amount and rate without WBV. However, combining SS with WBV could be advantageous to rapidly increasing soft tissue temperature prior to performing rehabilitation exercises when dynamic exercise cannot be performed.

Tasks considered by veterinarians to cause them musculoskeletal discomfort, and suggested solutions.

AIM: To describe veterinarians' perceptions of the causes of, and reasons for, work-related musculoskeletal discomfort (MSD), and to summarise their suggestions for ways to reduce the risk of MSD. METHODS: A cross-sectional study administered online asked 2,112 veterinarians registered in New Zealand to indicate, using free-handed text, the three tasks that "will most likely lead to musculoskeletal aches and pains (MSD)", reasons "why are these tasks likely to be the most risky?", and "any solutions that you apply or know of ". RESULTS: Complete questionnaires were returned by 828 veterinarians, a response rate of 39%. The tasks considered by veterinarians most likely to lead to MSD were lifting, surgery, rectal palpations, and animal handling. The main reasons why tasks were perceived to be most likely to lead to MSD were awkward posture, repetitive activities, and physical activity. The solutions suggested by veterinarians included provision of appropriate assistance and/or adequate staff, attention to correct manual handling techniques, provision of facilities to allow work to be carried out at a comfortable height, and regular rotation of jobs. Of the 39 solution categories, 16 (41%) could be categorised as those requiring a change in design of the work environment, and 15 (38%) involved training. CONCLUSIONS: The results of this study indicate that veterinarians perceive the causes of work-related MSD to be related to physical rather than psychosocial factors. We propose that the findings reported in this study provide a useful starting point for the application of a participatory ergonomics approach for addressing the problem of MSD amongst veterinarians in New Zealand.

Dam and granddam feeding during pregnancy in sheep affects milk supply in offspring and reproductive performance in grand-offspring.

In temperate climates, the cost of providing feed is greater in winter than in other seasons, causing ewes to be fed restricted rations during some periods of pregnancy. Epidemiological information indicates that undernutrition of the fetus may affect its health and performance in later life (i.e., fetal programming), and these effects may be passed between generations. The primary focus of the results presented in this paper is to examine the effects of feeding levels during pregnancy on a variety of traits from offspring at the fetal stage to 3.5 yr of age and also traits in the grand-offspring. Two studies are reported in which ewes were fed restricted diets during pregnancy, with a variety of fetal traits, offspring traits up to 3.5 yr of age, or grand-offspring traits up to 8 mo of age being measured. Study 2 also considered differences in dam size (heavy vs. light). In study 1, several fetal mammary gland measures indicated that milking ability may be enhanced in offspring from dams fed ad libitum during pregnancy. However, study 2 showed that mammary mass was greater in fetuses from dams fed at maintenance during pregnancy and that contemporaries of these fetuses produced greater protein and lactose yields in their first lactation. In the second lactation, the advantages in protein and lactose yields did not reoccur and ewes from ad libitum-fed dams produced greater fat yield. In study 2, grand-offspring whose granddams were fed at maintenance levels during pregnancy were lighter at birth in both the first and second parturitions than those whose granddams were fed ad libitum during pregnancy. First-parity grand-offspring whose granddams were fed maintenance levels during pregnancy achieved heavier BW by 40 to 50 d of age in the first lactation, which reflected the greater protein and lactose yields; however, no BW differences were present in second-parity lambs at the same age. A smaller proportion of first-parity ewe grand-offspring from heavy granddams that were fed ad libitum during pregnancy reached puberty at approximately 8 mo of age relative to the other granddam size and feeding groups. These results indicate that dam nutrition can affect the yield and composition of milk in their offspring and the BW and reproductive capability of their grand-offspring. Molecular and physiological mechanisms for these changes are being sought.

Changes in mineralised tissue at the site of origin of condylar fracture are present before athletic training in Thoroughbred horses.

AIM: To show that changes are present at the site of origin of metacarpal condylar fracture in young Thoroughbred horses before they enter race training. METHOD: Bone slices, 2 mm thick, in three mediolateral planes through the centre of rotation of the metacarpo-phalangeal joint (MCPJ) of both distal third metacarpal bones (Mc3) of 12 Thoroughbred horses aged 17 months, were imaged using point-projection digital X-ray imaging (muXR). RESULTS: In some horses, linear or ovoid radiolucency was found in articular calcified cartilage (ACC) and subchondral bone of the palmaro-distal aspect of the sagittal groove, exactly at the site of more advanced stages of condylar fatigue fracture. An incidental finding was ovoid radiolucency in the apex of the dorso-distal aspect of the sagittal ridge, with or without fragmentation or disturbance of the subchondral mineralised tissue line, resembling equine osteochondrosis. CONCLUSIONS AND CLINICAL RELEVANCE: The findings imply that the aetiology of condylar fatigue fracture in young Thoroughbred horses includes abnormality in development of the bone and joint that is present before athletic activity occurs.