Showing papers by "University of Veterinary Science published in 2013"

Cortisol release, heart rate and heart rate variability in the horse and its rider: Different responses to training and performance

Abstract: Although some information exists on the stress response of horses in equestrian sports, the horse-rider team is much less well understood. In this study, salivary cortisol concentrations, heart rate (HR) and heart rate variability (HRV), SDRR (standard deviation of beat-to-beat interval) and RMSSD (root mean square of successive beat-to-beat intervals) were analysed in horses and their riders (n=6 each) at a public performance and an identical rehearsal that was not open to the public. Cortisol concentrations increased in both horses and riders (P<0.001) but did not differ between performance and rehearsal. HR in horses and riders increased during the rehearsal and the public performance (P<0.001) but the increase in HR was more pronounced (P<0.01) in riders than in their horses during the public performance (from 91 ± 10 to 150 ± 15 beats/min) compared to the rehearsal (from 94 ± 10 to 118 ± 12 beats/min). The SDRR decreased significantly during the equestrian tasks in riders (P<0.001), but not in their horses. The RMSSD decreased in horses and riders (P<0.001) during rehearsal and performance, indicating a decrease in parasympathetic tone. The decrease in RMSSD in the riders was more pronounced (P<0.05) during the performance (from 32.6 ± 6.6 to 3.8 ± 0.3 ms) than during the rehearsal (from 27.5 ± 4.2 to 6.6 ± 0.6 ms). The study has shown that the presence of spectators caused more pronounced changes in cardiac activity in the riders than it did in their horses.

Cortisol release, heart rate and heart rate variability, and superficial body temperature, in horses lunged either with hyperflexion of the neck or with an extended head and neck position.

Abstract: Summary Bringing the head and neck of ridden horses into a position of hyperflexion is widely used in equestrian sports. In our study, the hypothesis was tested that hyperflexion is an acute stressor for horses. Salivary cortisol concentrations, heart rate, heart rate variability (HRV) and superficial body temperature were determined in horses (n = 16) lunged on two subsequent days. The head and neck of the horse was fixed with side reins in a position allowing forward extension on day A and fixed in hyperflexion on day B. The order of treatments alternated between horses. In response to lunging, cortisol concentration increased (day A from 0.73 ± 0.06 to 1.41 ± 0.13 ng/ml, p < 0.001; day B from 0.68 ± 0.07 to 1.38 ± 0.13 ng/ml, p < 0.001) but did not differ between days A and B. Beat-to-beat (RR) interval decreased in response to lunging on both days. HRV variables standard deviation of RR interval (SDRR) and RMSSD (root mean square of successive RR differences) decreased (p < 0.001) but did not differ between days. In the cranial region of the neck, the difference between maximum and minimum temperature was increased in hyperflexion (p < 0.01). In conclusion, physiological parameters do not indicate an acute stress response to hyperflexion of the head alone in horses lunged at moderate speed and not touched with the whip. However, if hyperflexion is combined with active intervention of a rider, a stressful experience for the horse cannot be excluded.

Effect of Semen Collection Methods on the Quality of Pre- and Post-thawed Bali Cattle (Bos javanicus) Spermatozoa

Abstract: Contents This study was conducted to evaluate the response of Bali bulls (Bos javanicus) to different semen collection methods and their effects on fresh and post-thawed semen quality. The collection methods employed were electro-ejaculation (EE), transrectal massage (RM) and RM followed by EE (RM + EE). A total of 25 untrained Bali bulls (age between 2 and 4 years old) were subjected to the different semen collection methods. Fresh semen samples from all the 25 bulls were evaluated for volume, pH, general motility, live/dead ratio and abnormality using the conventional method. For fresh and frozen samples collected by EE and RM from 10 bulls, computer-assisted semen analysis system was used for precise quantitative measurement of motility, velocity and forward progression. Accucell photometer was used to measure sperm concentration in all samples, regardless fresh and frozen. Semen samples were obtained 100% of the attempts using EE, 84% using RM and 96% using RM + EE. There were no differences among the collection methods for fresh semen quality characteristics, including motility, morphology and viability, but pH and volume were higher for EE than RM and RM + EE. Higher sperm concentration was observed in semen collected by RM than the other two methods. Different age groups (2–3 and >3–4 years old) of the bulls did not show significant differences in volume, pH, sperm concentration, percentages in motility, live/dead ratio and normal sperm morphology. The quality of semen for general and progressive motility, VAP, VSL and VCL and acrosomal integrity after thawing was higher for RM than EE. In conclusion, Bali bulls appeared to respond best to EE and the combination of RM + EE than RM, as a method of semen collection, with a shorter time of stimulation required. Differences in age of the Bali bulls did not affect the semen quality.

Morphological and Molecular Characterization of Explanatum Explanatum from Cattle and Buffaloes in Myanmar

Abstract: A robust molecular marker is needed for discrimination of amphistome species, because identification based on morphology alone requires specialized knowledge and techniques. In this study, we performed morphological and molecular characterization of Explanatum explanatum, a species that causes severe liver damage in definitive host species. Fifty-five adult amphistomes were collected from cattle and water buffaloes in Myanmar. Eighteen of the amphistomes, arbitrarily chosen, were morphologically identified as E. explanatum using sagittal sections. All of the 55 amphistome isolates had identical second internal transcribed spacer (ITS2) of ribosomal DNA sequences; these sequences differed at 7 nucleotide sites from those of the closest species, Paramphistomum leydeni. Our data indicate that the ITS2 sequence could be a useful molecular marker for epidemiological studies on E. explanatum.

Investigations on the endometrial response to intrauterine administration of N-acetylcysteine in oestrous mares

Abstract: Contents In mares, mating-induced persistent endometritis contributes to low fertility. The condition is in part related to delayed clearance of mucus accumulated within the uterine lumen. The objective of this study was to investigate the endometrial response of healthy mares to intrauterine (i.u.) treatment with N-acetylcysteine (NAC). Oestrous mares (n = 12) were randomly assigned to a treatment (TM) or control (C) group and received an i.u. infusion of 5% NAC and saline (total volume 140 ml), respectively. Endometrial biopsies were collected in five of the mares 24 h after treatment, in the remaining seven mares 72 h after treatment. Endometrial biopsies were evaluated for integrity of the luminal epithelium, number of polymorphonuclear neutrophils (PMN), staining for cyclooxygenase 2 (COX2), staining with Kiel 67 antigen (Ki-67), lectins and periodic acid-Schiff (PAS). The integrity of endometrial epithelial cells was not affected by treatment (no statistical differences between groups or times). At 24 h after treatment, the mean number of PMN in endometrial biopsies from NAC- and C-mares did not differ, but at 72 h after treatment, number of PMN was significantly higher (p < 0.05) in C (3.9 ± 0.6 PMN/field) compared with NAC-treated mares (2.3 ± 0.2 PMN/field). At 72 h after treatment, the intensity of staining for COX2 was significantly higher after saline than after NAC treatment (p < 0.05). In the epithelium, no differences in staining for the proliferation marker Ki-67 were seen with respect to time and treatment. Score for the lectin wheat germ agglutinin (WGA) was slightly higher in NAC-treated mares than in C-mares 72 h after treatment (p < 0.05). Score for PAS staining of mucus in deep uterine glands differed significantly between groups at 24 h after treatment (p < 0.05). The present study demonstrates that NAC does not adversely affect the endometrial function. Moreover, an anti-inflammatory effect on the equine endometrium was observed.

Readability and histological biocompatibility of microchip transponders in horses.

Abstract: Identification of horses by microchip transponder is mandatory within the European Union with only a few exceptions. In this study, the readability of such microchips in 428 horses with three different scanners (A, B and C) and the histological changes at the implantation site in 16 animals were assessed. Identification of microchips differed between scanners (P<0.001), and with 'side of neck' (P<0.001). Scanners A, B and C identified 93.5%, 89.7% and 100% of microchips, respectively, on the 'chip-bearing' side of the neck. From the contralateral side, scanners A, B and C identified 21.5%, 26.9% and 89.5% of transponders, respectively. Microchip readability was affected by age (P<0.001), but not by breed of horse. At necropsy, transponders were found in the subcutaneous fat (n=3), inter- or peri-muscular connective tissue (n=8), or musculature (n=5), where they were surrounded by a fibrous capsule ranging in thickness from 12.7 to 289.5 μm in 15 animals. In two animals, immature granulation tissue with attendant granulomatous inflammation, and a granulomatous myositis, surrounding the microchip were identified, respectively. Severe (n=1), moderate (n=1), and mild (n=3) lymphohistiocytic inflammation was noted within the fibrous capsule. Microchip transponders were found to be a highly reliable and biocompatible method of horse identification.

Expression of 11β-hydroxysteroid dehydrogenase type 1 and glucocorticoid receptors in reproductive tissue of male horses at different stages of sexual maturity.

Abstract: Glucocorticoids (GCs) as mediators of the stress response may affect Leydig cell function by inhibiting either luteinizing hormone receptor expression or testosterone biosynthesis The isozymes 11β-hydroxysteroid dehydrogenase (11βHSD) 1 and 11βHSD2 control the intracellular cortisol levels Little is known about the effects of stress on fertility in the equine The objective of the present study was to determine the presence and cellular localization of glucocorticoid receptors (GCR) and glucocorticoid-metabolizing enzymes (11βHSD1 and 11βHSD2) in equine epididymal and testicular tissue with special regard to sexual maturation Testicular and epididymal tissue was collected from 21 healthy stallions, and four age groups were designed: pre-pubertal, young, mature and older horses Immunohistochemistry (IHC) analysis and quantitative real-time PCR (qRT-PCR) were used Pre-pubertal horses showed higher testicular gene expression of 11βHSD1, 11βHSD2 and GCR than horses of all other groups (p < 005) A positive intranuclear immunoreaction for GCR was seen in epithelial cells of caput, corpus and cauda epididymidis and in Leydig cells Significant differences (p < 005) between age groups occurred The number of Leydig cells staining positive for GCR was highest in immature stallions (p < 005) The enzyme 11βHSD1 was localized in epithelial cells of the caput and corpus epididymidis and in Leydig cells As determined by enzyme assay, nicotinamide adenine dinucleotide (NAD)-dependant dehydrogenase (oxidation) activity was not detected in testicular tissue from immature stallions but in all other age groups (n = 3 per group) Results of this study suggest a contribution of GCs to maturation of male reproductive tissue in horses In mature stallions, expression of 11βHSD enzymes and the oxidative 11βHSD activity in Leydig cells and epididymal basal and principal cells suggest a protective role on these tissues contributing to physiological intracellular glucocorticoid concentrations

Readability of branding symbols in horses and histomorphological alterations at the branding site.

Abstract: Identification of horses has traditionally been facilitated by hot iron branding, but the extent by which branding symbols and numbers can be identified has not been investigated. The local pathological changes induced by branding are also unknown. This study analysed the readability of branding symbols and histomorphological alterations at the branding sites. A total of 248 horses in an equestrian championship were available for identification of symbols and numbers. A further 28 horses, euthanased for other reasons, provided histological examination of the branding site. All except one horse had evidence of histological changes at the brand site, including epidermal hyperplasia, increase of dermal collagenous fibrous tissue and loss of adnexal structures. In two foals, an ulcerative to necrotizing dermatitis was observed and interpreted as a complication of recent branding lesions. Despite the fact that hot iron branding caused lesions compatible with third degree thermal injury, it did not allow unambiguous identification of a large proportion of older horses. While the breed-specific symbol was consistently identified by three independent investigators in 84% of the horses, the double-digit branding number was read correctly by all three investigators in less than 40%. In conclusion, hot iron branding in horses causes lesions compatible with third degree thermal injury but does not always allow identification of horses.

Cooled storage of canine semen: in vitro effects of different concentrations of an antibiotic combination on growth of mollicutes.

Abstract: Contents The aim of this study was to examine effects of an antibiotic combination at different concentrations on growth of mycoplasma and ureaplasma during cooled storage of canine semen (n = 20). Semen aliquots were diluted with Tris–citric acid–fructose–egg yolk extender containing either 1.0 g/l streptomycin and 0.6 g/l benzylpenicillin (control) or a combination of gentamycin, tylosin, lincomycin and spectinomycin (GTLS-1: 0.25, 0.05, 0.15 and 0.3; GTLS-2: 0.5, 0.1, 0.3 and 0.6; GTLS-3: 1.0, 0.2, 0.6 and 1.2 g/l). Samples were assessed for motility and membrane integrity by computer-assisted sperm analysis immediately after dilution and at 24, 48 and 72 h of cooled storage. Morphologically, normal spermatozoa were determined, and bacterial culture was performed at 24 and 72 h. Mycoplasma spp. were detected in 14 of 20 ejaculates (70%) with severe growth in 12 samples. A reduction but not total elimination of mycoplasma growth occurred in all GTLS extenders with the most pronounced reduction in group GTLS-3 (control vs GTLS-1 and GTLS-2 p < 0.05, control vs GTLS-3 p < 0.001). Ureaplasmas were detected in four ejaculates, and growth was reduced to the same extent in GTLS and control extender. Progressive motility in all groups, total motility in groups GTLS 1–3 and percentage of membrane-intact spermatozoa in groups GTLS 2 and 3 decreased slightly (p < 0.05) over time. In conclusion, dilution of canine semen with GTLS extender has no major detrimental effects on spermatozoa during cooled storage. It reduced the growth but did not totally eliminate mycoplasmas and ureaplasmas from cooled-stored dog semen.

Reduced-size microchips for identification of horses: response to implantation and readability during a six-month period

Abstract: In this study, readability of reduced-size microchips in horses and the response to implantation were analysed. It was hypothesised that small microchips can be implanted stress-free but are less readable than larger microchips. Adult mares (n=40) were implanted with a reduced-size microchip (10.9×1.6 mm) at the left side of the neck (size of conventional microchips 11.4×2.2 mm). Microchips were identified with three different scanners (A, B, C) immediately, and at 6, 12 and 28 weeks after implantation. Twelve out of the 40 mares were submitted to microchip implantation and control treatments and cortisol, heart rate and heart rate variability (HRV) were determined. From the chip-bearing side of the neck, microchips were identified with all scanners in all horses at all times. From the contralateral side, correct readings were always 100 per cent with scanner C and with scanners A and B ranged between 60 and 100 per cent. Heart rate and HRV variable sd of beat-to-beat interval increased slightly (P<0.01) at microchip implantation and control treatment, but cortisol concentration did not increase. In conclusion, reduced-size microchips are highly reliable for identification of horses. Compared with conventional microchips, the reduction in size did not impair readability. Microchip implantation is no pronounced stressor for horses.

Development of leucaena mimosine-degrading bacteria in the rumen of sheep in Myanmar

Abstract: Myanmar has an agricultural base, and about 70% of people reside in rural areas. They depend for survival on agriculture and small-scale crop production, with ruminant livestock consuming fibrous agricultural residues. For optimal ruminant production, concentrates are needed as supplements to these residues. As concentrates are expensive, researchers are testing alternative protein sources like legumes, including foliage from leguminous trees such as leucaena (Leucaena leucocephala). Leucaena is the most widely used leguminous tree as a ruminant feed because it is rich in protein (~ 22%) and contains easily digestible fiber (23% neutral detergent fiber, 16.6% acid detergent fiber; Ni Ni Maw 2004). Khin Htay Myint (2005) noted that 25% of leucaena in the ration tended to increase nitrogen retention without decreasing dry matter and organic matter digestibilities. However, leucaena leaves contain a toxic non-protein amino acid, called mimosine. Research workers have endeavored to reduce mimosine toxicity in animals fed leucaena in Myanmar (Aung Aung 2007; Wink Phyo Thu 2010) and one avenue of research was the development of mimosine-degrading bacteria in the rumen of sheep fed leucaena. In this paper we describe an experiment tracing the development of mimosine-degrading bacteria in the rumen of sheep.

Applicability of a New Cell Culture Device for Cooled‐Storage of Stallion Semen

Abstract: Contents A new device for storage and shipping of cell cultures – the Petaka G3 cell management device – was tested for its applicability for cooled-storage of equine semen. Semen from three stallions was processed with EquiPro extender either without antibiotics (three ejaculates per stallion) or with gentamicin (250 mg / l; three ejaculates per stallion). Semen was either stored at five (anaerobic conditions) or 15°C (aerobic conditions) in syringes or cell culture devices. Total and progressive motility, as well as membrane integrity of spermatozoa, were evaluated from days 1 to 7 after collection with computer-assisted semen analysis. In experiment 1 (extender without antibiotics), total motility, progressive motility and viability of spermatozoa significantly decreased over time (p < 0.05). The decrease was significantly faster at 15°C than at 5°C (p < 0.05). In the presence of gentamicin (experiment 2), this difference was no longer present. It can be concluded that cooled-storage of equine semen in sophisticated devices for cell culture is not advantageous to syringes for successful maintenance of semen longevity.

Development, isolation and characterization of a new non-virulent mimosine-degrading Klebsiella pneumoniae strain from the rumen liquor of German steers by using IBT-Göttinger bioreactor

Abstract: The tropical legume Leucaena leucocephala (leucaena) has many uses, including: a potential source of firewood and timber; for soil erosion control (Dijkman 1950); to provide shade; to enhance soil fertility; and as a nutritious forage for animal feed (Ruskin 1977). It is widely used as forage for cattle in tropical agriculture (Shelton 1998). In Myanmar, leucaena is used as a protein source in urea-molasses multi-nutrient blocks for ruminants (Ni Ni Maw et al. 2004). However, the use of leucaena as ruminant feed is not without problems, because it contains mimosine, a toxic anti-nutritional factor limiting its use as animal feed. Jones (1981) reported the absence of toxicity when leucaena was fed to goats and cattle in Hawaii and Indonesia. According to the low dihydroxypyridine (DHP) in urine of those animals, it was assumed that they could degrade mimosine and DHP. Hawaiian goats, but not Australian goats, could degrade 3,4-DHP ruminally (Jones and Megarrity1983). Inoculation of susceptible animals with rumen liquor containing mimosinedegrading bacteria protected against DHP toxicity in ruminants (Jones and Lowry 1984). For maintaining mimosine-degrading bacteria, the donor animals should be fed on leucaena continuously and it is expensive to maintain their veterinary care. Hence, we tried to develop mimosine-degrading ruminal bacteria using a fermenter, intending to produce a source of inoculum for the routine control of leucaena toxicosis in ruminants.