Showing papers by "University of Veterinary Science published in 2012"

Physiological and behavioural responses of young horses to hot iron branding and microchip implantation.

Abstract: Branding is the traditional and well-established method used to mark horses, but recently microchip transponders for implantation have become available. In this study, behaviour, physiological stress vari- ables and skin temperature in foals were determined in response to hot-iron branding (n = 7) and micro- chip implantation (n = 7). Salivary cortisol concentrations increased in response to branding (1.8 ± 0.2 ng/mL) and microchip implantation (1.4 ± 0.1 ng/mL), but cortisol release over time did not differ. In response to both manipu- lations there was a transient increase in heart rate (P < 0.001) and heart rate variability (P < 0.01). Brand- ing and microchip implantation induced a comparable aversive behaviour (branding, score 3.86 ± 0.85; microchip, score 4.00 ± 0.82). Both techniques thus caused similar physiological and behavioural changes indicative of stress. Acutely, implantation of a microchip was as stressful as branding in foals. Branding caused a necrotising skin burn lasting at least 7 days. Moreover branding, but not microchip implantation (P < 0.001), was accompanied by a generalized increase in skin temperature which was comparable to low degree post-burn hypermetabolism in humans.

Gene Expression of ACTH, Glucocorticoid Receptors, 11βHSD Enzymes, LH‐, FSH‐, GH Receptors and Aromatase in Equine Epididymal and Testicular Tissue

Abstract: Contents Glucocorticoids (GCs) are important mediators of the stress response and have been implicated in the function and regulation of testicular functions in different species. In many tissues, intracellular glucocorticoid activity is controlled by either or both of the two known isoforms of 11β-hydroxysteroid dehydrogenase (11βHSD) type 1 and 2, which interconvert active and inactive GCs. Little is known about the effects of stress on fertility in the equine species. The main objective of the present study was to investigate the expression of receptors for GCs and adrenocorticotropic hormone [ACTH, melanocortin 2 receptor (MC2R)] as well 11βHSD1 and 11βHSD2 in male equine epididymal and testicular tissue. In addition, expression of aromatase P-450 and receptors for luteinizing hormone (LHR), follicle stimulating hormone (FSHR) and growth hormone (GHR) was studied. Reverse transcriptase PCR and quantitative real-time PCR were performed in tissue from the epididymis (caput and cauda) and testes collected from nine healthy mature stallions (age 4–10 years). mRNA for ACTH and GC receptors as well as 11βHSD1 and -2 were found in epididymal and testicular tissue. Expression of the genes studied was always positive in testicular tissue, while it was inconsistent in epididymal tissue. Quantitative gene expression in relation to β-actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was significantly correlated (R = 0.403, p < 0.001). Quantitative PCR in relation to β-actin revealed significant differences in the gene expression of 11βHSD1, 11βHSD2, LHR, FSHR, MC2R and aromatase between tissue collected from caput epididymidis, cauda epididymidis and testicular parenchyma (p < 0.05). With GAPDH, differences between tissues were significant for 11βHSD1, 11βHSD2 and MC2R (p < 0.05) In addition, high concentrations of mRNA of aromatase and receptors of LH and FSH were found in testicular tissue, while a pronounced expression of GH receptor was present in epididymal tissue. The results support the hypothesis of an interaction between the pituitary-adrenal axis and testicular function in the stallion.

Effects of oral supplementation with β-carotene on concentrations of β-carotene, vitamin A and α-tocopherol in plasma, colostrum and milk of mares and plasma of their foals and on fertility in mares.

Abstract: Summary In this study, effects of oral β-carotene supplementation to mares (β-carotene group: 1000 mg/day, n = 15; control group: n = 15) from 2 weeks before foaling until 6 weeks thereafter on concentrations of β-carotene, vitamin A and α-tocopherol in plasma, colostrum and milk and plasma of their foals were determined. In addition, effects on fertility were studied. Beta-carotene concentrations increased in plasma and colostrum of β-carotene-supplemented mares compared to control mares (p < 0.05). In mares of both groups, β-carotene concentrations were higher in colostrum than in milk (p < 0.05). In foals, β-carotene concentrations increased with colostrum uptake and were higher in foals born to supplemented mares (p < 0.05; control group: 0.0003 ± 0.0002 μg/ml on day 0, 0.008 ± 0.0023 μg/ml on day 1; β-carotene group: 0.0005 ± 0.0003 μg/ml on day 0, 0.048 ± 0.018 μg/ml on day 1). Concentrations of vitamin A and α-tocopherol were higher in colostrum than in milk (p < 0.05) but did not differ between groups. Concentration of α-tocopherol in plasma of mares decreased over time and in foals, increased markedly within 4 days after birth. All but one mare (control group) showed oestrus within 2 weeks post-partum. Occurrence of oestrus did not differ between groups. More mares of the control group (7/7 vs. 5/12 in the β-carotene group) became pregnant after being bred in first post-partum oestrus (p < 0.05). In conclusion, β-carotene supplementation to mares increased β-carotene concentrations in plasma, colostrum and milk of mares and plasma of their foals but had no positive effects on fertility.

Increasing expression of oxytocin and vasopressin receptors in the equine conceptus between Days 10 and 16 of pregnancy

Abstract: Oxytocin (OT) and arginine vasopressin (AVP) have been detected in the yolk sac of the pre-attachment equine conceptus. Therefore, we have assessed the presence of OT and AVP receptors in equine conceptuses between Days 10 and 16 of pregnancy by qualitative PCR, quantitative PCR and immunohistochemistry. Expression of OT receptor and of the AVP receptors V1aR and V2R could be verified after sequencing the RT-PCR products of the expected length. The size of conceptuses used for quantitative PCR significantly increased with day of pregnancy (P<0.01) as did their quantitative expression of OTR (P<0.01). Immunohistochemistry of OTR resulted in weak trophectodermal abundance on Day 10, increasing at Day 12. On Day 14, staining intensity increased in individual cells of the trophectoderm while it decreased in other cells; this trend became more apparent on Day 16. The endoderm of the trophoblast and surrounding subtrophoblastic compartments always showed moderate staining for OTR. On Day 10 immunoreactive V2R protein was localised in the trophectodermal apical membrane; on Day 12 it was also present in the basal membrane and weakly in the cytoplasm. On Day 14 only individual trophectodermal cells showed positive supranuclear cytoplasmic areas or V2R, whereas on Day 16 about one-third of the trophectodermal cells were stained entirely and intensely positive. These results suggest an involvement of OT and AVP action in the development and expansion of the early equine conceptus.