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

Abstract

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.     

Comparison of lameness outcomes in horses with acute or chronic digital lameness that underwent magnetic resonance imaging

ABSTRACT

Aims: To compare the outcome, in terms of lameness score or return to athletic function, of horses with acute vs. chronic digital lameness that underwent magnetic resonance imaging (MRI) of the distal limb and to compare the proportion of horses that received intra-articular therapy of the distal interphalangeal (DIP) joint and pattern of diagnostic analgesia in these groups.

Methods: This is a retrospective study of horses (n?=?95) with acute (≤12 weeks; n?=?46) or chronic (>12 weeks; n?=?49) digital lameness that underwent MRI of the distal limb from 2009–2016, at two equine referral centres in the USA. Criteria for inclusion in the study were that a majority of lameness localised distal to the fetlock, and that lameness assessments for ≥12 months following MRI could be obtained from the medical record or the owner could be interviewed regarding their horse's athletic function. Outcome was characterised by an improvement score where 2?=?return to work at a previous or higher level or lameness improved by one grade or more, 1?=?return to work at a lower level or lameness improved by less than one grade, and 0?=?did not return to work or lameness grade worsened. Whether horses had received intra-articular therapy of the DIP joint and the pattern of diagnostic analgesia prior to MRI was also obtained from medical records or by interviewing the owner.

Results: There was a difference (p?=?0.004) in the proportion of horses assigned to improvement scores of 0, 1 and 2 between horses with acute or chronic lameness. There was no evidence of a difference in the likelihood of having received intra-articular therapy of the DIP joint prior to MRI between horses with chronic or acute lameness (p = 0.085). Similarly, there was no evidence of a difference in the pattern of diagnostic analgesia prior to MRI between the two groups (p = 0.94). Eighty-two percent of owners of horses with acute and 62% of those with horses with chronic lameness had a positive opinion of the utility of MRI as a diagnostic modality.

Conclusion: In a population of horses with digital lameness undergoing MRI, a difference in the outcome, in terms of lameness score or return to athletic function was identified between horses with acute lameness compared to those with chronic lameness.

Clinical relevance: Horses with digital lameness that undergo MRI when the lameness is acute may have an improved prognosis due to accurate diagnosis and earlier application of appropriate therapy.     

Soluble proteins and isoesterases as taxonomic markers tested on nine wildSolanum species and eight Slovakian potato varieties

Summary Attempts have been made to differentiate 9Solanum species and 8 Slovakian cultivars ofS. tuberosum using soluble proteins, isoesterases and antigenic properties of tuber proteins. Soluble proteins were shown to possess the highest diagnostic value in discriminating between individual species and varieties.S. brevidens of the subsectionEstolonifera deviated from the rest of the species belonging to the subsectionPotatoe. The electrophoretic profiles and immunological responses of individual species only partially correlated with their taxonomic positions. The highest similarity was observed between the pairs of speciesS. bulbocastanum, S. stenotomum, S. maglia-S. phurea andS. gourlayi-S. vernei. It was possible to differentiate also between individual potato cultivars or between their groups according to both soluble protein and isoesterase patterns.     

Ontogeny of the cortisol stress response in yellow perch (Perca flavescens)

The ontogeny of the cortisol stress response in yellow perch (Perca flavescens) was documented by measuring resting and stress-induced whole-body cortisol levels in fish at several early development stages. In newly fertilized eggs resting cortisol levels averaged 41.0 ± 3.0 pg/embryo, and decreased to 8.0 ± 3.0 pg/embryo by day 6 where they remained constant until hatch on day 10. Acute stress challenge tests (30 sec cold shock) conducted on embryonic (days 6 and 8 post-fertilization) and larval (hatch and 2 days post-hatch) yellow perch revealed no differences in whole-body cortisol levels between stressed and unstressed individuals. In acute stress challenge tests (30 sec net confinement) conducted on post-hatch yellow perch, differences in cortisol levels between stressed (30 min post-stress) and unstressed fish were detected one week after hatching (12.3 ± 1.6 ng/g and 7.0 ± 1.3 ng/g, respectively). The magnitude of the stress response was greater in 2- to 5-week-old fish than in one-week-old fish. Changes in post-stress cortisol levels were closely associated with changes in interrenal morphology. Cumulatively, these results indicate that cortisol biosynthesis, integration and maturation of the hypothalamic-pituitary-interrenal (HPI) axis can be observed in yellow perch as early as one week after hatching. This revised version was published online in July 2006 with corrections to the Cover Date.     

IRIDIUM-192 BRACHYTHERAPY FOR EQUINE SARCOID, ONE AND TWO YEAR REMISSION RATES

This report presents the results of 12 adult horses with 16 sarcoids which received radiotherapy from iridium-192 interstitial implants. Fourteen of the 16 tumors (87.5%) were in remission for at least 12 months, and 13 (81.2%) were in remission for at least 24 months. Generally, normal tissue reactions were within acceptable limits. The results of this study further substantiate the beneficial nature of radioactive brachytherapy for equine sarcold.     

Blastocladia and aqualinderella: fermentative water molds with high carbon dioxide optima

The uniflagellate aquatic phycomycete Blastocladia ramosa appears to be a facultative anaerobe. Blastocladia pringsheimii requires traces of oxygen. Growth of both species is no greater or only slightly greater at normal atmospheric oxygen pressure than under 0.2 percent oxygen pressure, but their growth is enhanced by the addition of 5 or 20 percent carbon dioxide. The cells of both species lack typical cristate mitochondria and contain only traces of cytochrome. Blastocladia resembles the biflagellate Aqualinderella fermentans in adaptation to an environment poor in oxygen and rich in carbon dioxide.     

Moving visual scenes influence the apparent direction of gravity

When an observer views a wide-angled display rotating around his line of sight, he both feels his body tilted and sees a vertical straight edge tilted opposite to the moving stimulus. Displacement of the perceived vertical increases with stimulus speed to reach a maximum (averaging 15 degrees) at 30 degrees per second.