Functional performance of oak seedlings naturally regenerated across microhabitats of distinct overstorey canopy closure

The extent to which seedling recruitment is limited by summer drought in Mediterranean-type ecosystems depends on the light microsite, yet the relationship between light availability and water status, functional performance, and survival of seedlings in these systems is still unclear. Over a 3-year period, we studied the pattern of survival and functional performance of seedlings of Quercus petraea (Matt.) Liebl. and Quercus pyrenaica Willd. in a montane forest in central Spain, which is the southern edge of the natural range of Q. petraea. After a mast year of the two species, 72 plots were established in six microhabitats spanning a range of overstorey canopy closure: closed, partial and open canopies dominated by either Q. petraea or Q. pyrenaica adult trees. Seedlings of each species naturally emerged beneath the conspecific-dominated canopies. The second and third years of study were extremely dry. Three years after emergence, the greatest seedling survival occurred beneath the partial canopy of Q. pyrenaica trees (8%) and the lowest (0%) beneath the closed canopies of Q. pyrenaica and Q. petraea. Survival for Q. pyrenaica increased linearly with understorey light across the range of 10–35% Global Site Factor. Plant water deficit (estimated by leaf water potential) was high across microhabitats, and increased with light availability for Q. pyrenaica. Potential for photosynthesis (estimated by the electron transport rate of photosystem II) decreased with canopy closure; and potential for light harvesting (e.g. specific leaf area (SLA) and chlorophyll concentration) increased with closure. Extreme water deficit could be the main contributor to seedling death in the more open microhabitats, whereas light level was insufficient to maintain carbon balance under the water-stressful conditions existing beneath the closed tree canopies. Seedling establishment appears to be a limiting factor for the recruitment of both oaks within this forest in a wide range of microhabitats, especially for the more drought-sensitive Q. petraea. Moderate reductions of tree canopy cover can improve seedling establishment, but extreme summer droughts can prevent the success of any silvicultural practice made.     

Semen Characteristics in a Sub‐Fertile Arabian Stallion with Idiopathic Teratospermia

A 5‐year‐old Arabian stallion was managed for breeding with fresh/extended semen during a period of 8 months with a resulting per cycle pregnancy rate of 26.3%. The stallion was in good health and no abnormalities of the reproductive tract were observed. Evaluation of several ejaculates revealed that sperm production and semen quality were mostly unchanged during the period of evaluation, that sperm production was normal and that semen quality was extremely poor. The most prevalent sperm defects were abnormal heads and mid‐pieces. Most abnormal heads were microcephalic and/or tapered and considerable variation in sperm head dimensions within and among ejaculates was observed. A unique defect characterized by swollen/roughened mid‐piece caused by accumulation of cytoplasmic‐like material and abnormal mitochondrial sheath was observed. Nuclear vacuoles, acrosome defects, and teratoids were also prevalent and most sperm presented multiple abnormalities. The absence of any clear cause or any signs of testicular degeneration, combined with normal sperm production, and constant abnormal sperm production suggest an inherent, congenital disturbance of spermatogenesis as the cause of teratospermia in this case.     

Yersinia species isolated from sheep with enterocolitis

In 40 submissions to the Regional Veterinary Laboratory (RVL) Wagga Wagga from sheep in southern New South Wales from 1981 to 1989, 53 isolates of Yersinia sp were recovered from 45 sheep in 37 flocks. Of 53 isolates, 26 were identified as Y. pseudotuberculosis, 20 as Y. enterocolitica, 5 as Y. intermedia and 2 as Y. frederiksenii. Twelve isolates of Y. pseudotuberculosis tested in the slide agglutination test all belonged to serotype III. The 20 Y. enterocolitica isolates were categorised biochemically as biotype 5 strains and, of 6 isolates serotyped, all belonged to serogroup 2,3. Outbreaks of yersiniosis were most common in late winter and early spring and affected flocks often had experienced a change in husbandry. Infection with Yersinia sp was associated with diarrhoea, illthrift and mortality. At necropsy, congestion and occasionally thickening of the intestinal mucosa were observed in affected sheep. Gastrointestinal nematodiasis and coccidiosis often were concurrent findings. The characteristic histological lesion in sheep infected with Y. pseudotuberculosis was acute segmental suppurative erosive enterocolitis. There were no lesions consistently associated with Y. enterocolitica, Y. intermedia or Y. frederiksenii.     

Over representation of Burmese cats with diabetes mellitus

Objective To determine if Burmese cats in Queensland have an increased risk of diabetes mellitus.
Design A retrospective study of diabetic and nondiabetic cats that had blood submitted to a veterinary clinical laboratory over a 22 month study period.
Sample population 4402 cats
Procedure Cats were considered diabetic if blood glucose concentration was > 11 mmol/L and fructosamine was > 406 μmol/L or hydroxybutyrate was >1 mmol/L. Cats were grouped into Burmese and non-Burmese. Adjusted odds ratios of diabetes were calculated for breed, gender and age group amongst cats with blood glucose > 11 mmol/L.
Results Burmese cats comprised 20% of 45 diabetic cats of known breed, which was higher (P < 0.001) than among the normoglycemic reference population of 2203 cats (7% Burmese). There were more females among the diabetic Burmese (62%), but this did not differ (P > 0.05) from the Burmese reference population (45% females). In contrast, males seemed to predominate among diabetic non-Burmese (63%), although this also did not differ (P > 0.05) from the reference population (55%) or from diabetic Burmese (38% males). The majority (90%) of diabetic cats were older than 6 years, irrespective of breed (median age 12 years, interquartile range 10 to 13 years). This was higher (χ²= 8.13, P < 0.005) than among the normoglycaemic reference population, where 69% were older than 6 years.
Conclusions Burmese cats were significantly over represented among cats with diabetes mellitus. Irrespective of breed, the risk of diabetes in the study population increased with age.     

Immune response to Neospora caninum in naturally infected heifers and heifers vaccinated with inactivated antigen during the second trimester of gestation

The objective of this study was to compare the immune response to Neospora caninum in naturally infected heifers and heifers inoculated with a killed whole N. caninum tachyzoite preparation during the second trimester of gestation. Nine Holstein heifers were used in this study; three naturally infected heifers were born from seropositive dams, and six seronegative heifers were born from seronegative dams. Four seronegative heifers were subcutaneously vaccinated with a killed whole N. caninum tachyzoite preparation at weeks 13, 15 and 17 of gestation. A killed whole N. caninum tachyzoite preparation containing 45 mg of protein/5 ml dose was formulated with 70% of mineral oil adjuvant (13% consisting of Arlacel C, 85% Marcol 52 and 2% Tween-80). Similarly, two seronegative heifers (negative controls) were inoculated with mock-infected bovine monocytes in oil adjuvant. Humoral immune responses were tested by using an indirect fluorescent antibody test (IFAT) and an indirect enzyme-linked immunosorbent assay (ELISA) for detecting isotype specific antibodies. Cellular immune responses were assessed by lymphocyte proliferation test (LPT) and IFN-gamma production. N. caninum-specific antibody responses increased in immunized cattle by week 15 of gestation (mean reciprocal antibody titers 450+/-252), peaked at week 23 (mean 16,000+/-6400). Maximum antibody response in naturally infected heifers was observed at week 19 of gestation (mean: 3467+/-2810). Mean serum IFAT titers were significantly higher in immunized heifers compared with those in naturally infected heifers from weeks 17 to 25 (P < 0.05). Analysis of isotype specific antibodies in naturally infected heifers revealed a predominant IgG1 response in one heifer and a predominant IgG2 response in the other two. Similar titers of IgG1 and IgG2 occurred in immunized heifers. Control heifers remained seronegative throughout the study by IFAT and ELISA. Significant antigen-specific proliferation responses were only detected in naturally infected heifers in week 19 of gestation. Peripheral mononuclear blood cells (PMBC) from immunized animals produced IFN-gamma in similar concentrations to those of infected animals (P > 0.05). No abortion was seen in any experimental group; however, one calf from a vaccinated heifer died due to dystocia. All calves from vaccinated and control heifers were seronegative by IFAT at 6 months of age; in contrast, calves born from naturally infected heifers remained seropositive with titers > or = 200. Killed vaccine induced similar immune responses to those found in chronically, naturally infected cattle which did not abort; however, different immune pathways may be followed in vaccinated and natural infected heifers with differences in degree of protective immunity.     

Suppression of testicular function using two dose rates of a reversible water soluble gonadotrophin releasing hormone (GnRH) vaccine in colts

Objective: To investigate the effect of two dose rates (200 and 400 ng) of a gonadotrophin releasing hormone (GnRH) vaccine on testicular function. Design: A vaccination dose rate experiment. Procedure: Two injections were administered 4 weeks apart to six colts in each treatment group. To maintain immunosuppression until the end of the breeding season, a third injection was given if antibody titres fell below 1000. Results: Effective antibody titres were present for 12 to 27 weeks. Testosterone concentrations decreased from 2.22 to 0.31 nmol/L 6 weeks after primary vaccination. Androstenedione concentrations decreased from 1.78 to 0.28 nmol/L 5 weeks after vaccination. Testosterone and androstenedione concentrations above 0.69 and 0.87 nmol/L were attained 31 to 43 weeks after vaccination. Mean scrotal widths and lengths decreased over 29 weeks from 9.2 cm and 9.7 cm to 6.7 cm and 7.6 cm. At surgical castration these dimensions were 10.1 cm and 11.0 cm. Mean semen characteristics before vaccination and after recovery were: gel-free volume 16.5 and 13.5 mL, sperm concentration 295.5 times 10⁶ 315.6 times 10⁶/mL, total sperm per ejaculate 4041 times 10⁶ 4657 times 10⁶ live normal spermatozoa 32% and 60%. Histologically, the testes showed active spermatogenesis. The mean testicular parenchyma weights for the 200 and 400 mg groups were 129.0 g and 109.8 g. Daily sperm production per testis and per gram of testis for the 200 and 400 mg groups were 3.7 times 10⁸ 2.8 times 10⁶ 2.3 times 10⁸ 2.0 times 10⁶. Conclusions: Both dose rates suppressed testicular function. Data showed that the vaccine effects were reversible. Individual immune response was less varied in the 200 mg group. Further work is necessary to achieve a less variable response in the immunosuppression of testicular function.     

Kinematic characteristics of Andalusian, Arabian and Anglo-Arabian horses: a comparative study

The aim of this study was to compare the kinematic trot characteristics of three different breeds of horse: Andalusian (AN, n = 15), Arabian (AR, n = 7) and Anglo-Arabian (AA, n = 5) using standard computer-assisted videography (25 Hz). Linear, temporal and angular parameters in fore- and hind limbs were analysed in six randomly selected strides per horse. Normalised angle-time diagrams along the complete stride were obtained for all joints angles in each breed and specific kinematic characteristics were detected graphically. AA horses displayed longer swing durations in both limbs ans a shorter angular range of motion (ARM) in scapula and pelvis inclination and in shoulder, hip and forelimb retraction-protraction angles. At lift off, stifle and tarsal joint angles were more flexed. In general, only small differences were observed in AR horse kinematics when compared with the other 2 breeds. AN horses presented negative overtracking length, which was positive in AR and AA. In AN horses the elbow and carpal joints were more flexed at the moment of maximal elevation, elbow and fore-fetlock joints also exhibited a larger ARM due to a smaller angle at maximal flexion. In the hind limbs, tarsal, hind fetlock and retraction-protraction angles presented a larger ARM in AN horses due to greater maximal flexion in the tarsal and hind fetlock joints. Fore- and hind fetlocks were also more flexed in horses from this breed. In conclusion, differences between kinematic variables at the trot were observed in the three breeds studied here, mainly in forelimb joints. The most outstanding feature was the greater forelimb flexion recorded in AN horses than in the other breeds which is consistent with the elevated movements in this breed. In AA horses, the ARM of proximal joints involved in retraction protraction in both fore- and hind limbs was smaller. All the differences observed highlighted the idiosyncratic nature of the trot in each breed; this may influence the functional capacity of each breed.     

Feasibility of pooled-sample testing for the detection of porcine reproductive and respiratory syndrome virus antibodies on serum samples by ELISA

Surveillance of porcine reproductive and respiratory syndrome (PRRS) in negative sow farms is usually performed by testing for the presence of antibodies against PRRS virus in serum with a commercial ELISA test. The objective of this study was to evaluate the feasibility of pooling serum samples for detection of PRRS virus antibodies by ELISA. The effect of pool size on the sensitivity and specificity of the ELISA test was evaluated by testing true positive samples and false positive samples, respectively, diluted in negative sera. The effect of three different cut-off values for the interpretation of the diagnostic test (0.4, 0.3 and 0.2) was evaluated as well. Furthermore, the obtained sensitivity and specificity estimates were used to calculate the herd sensitivity and herd specificity of surveillance protocols in different scenarios. The results showed that pooling serum samples to detect PRRSV antibodies resulted in a decrease in sensitivity and an increase in specificity, compared to testing individual samples, while the reduction of the s/p cut-off value recommended by the manufacturer (0.4) had the opposite effect. We describe an approach that can increase the herd sensitivity of a surveillance protocol for breeding herds, while maintaining high herd specificity and low testing costs. This can be achieved by sampling a larger number of animals and running the samples in pools. Therefore, the conventional monitoring protocols based on ELISA on individual samples can be improved by using pooled-sample testing.