Effect of hCG on Early Luteal Serum Progesterone Concentrations in PG600‐Treated Gilts

Gilt oestrus and ovulation responses to injection of a combination of equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG) (PG600) can be unpredictable, possibly reflecting inadequate circulating LH activity. The objective of this study was to determine the effect of PG600 followed by supplemental hCG on gilt ovarian responses. In experiment 1, 212 Hypor gilts (160 day of age) housed on two farms in Spain received intramuscular (i.m.) injections of PG600 (n = 47), or PG600 with an additional 200 IU hCG injected either concurrently (hCG‐0; n = 39), or at 24 h (hCG‐24; n = 41) or 48 h (hCG‐48; n = 45) after PG600. A further 40 gilts served as non‐injected controls. Ovulation responses were determined on the basis of initial blood progesterone concentrations being <1 ng/ml and achieving >5 ng / ml 10 d after the PG600 injection. The incidence of ovulating gilts having progesterone concentrations >30 ng/ml were recorded. During the study period, 10% of control gilts ovulated whereas 85–100% of hormone‐treated gilts ovulated. There were no significant differences among hormone groups for proportions of gilts ovulating. The proportions of gilts having circulating progesterone concentrations >30 ng/ml were increased (p ≤ 0.02) in all hCG treated groups compared with the PG600 group. In experiment 2, a total of 76 Hypor gilts at either 150 or 200 days of age were injected with PG600 (n = 18), 400 IU eCG followed by 200 IU hCG 24 h later (n = 20), PG600 followed by 100 IU hCG 24 h later (n = 17), or 400 IU eCG followed by 300 IU hCG 24 h later (n = 21). Blood samples were obtained 10 days later for progesterone assay. There were no effects of treatment or age on incidence of ovulation, but fewer 150‐day‐old gilts treated with PG600 or 400 IU eCG followed by 200 IU hCG had progesterone concentrations >30 ng / ml. We conclude that hCG treatment subsequent to PG600 treatment will generate a higher circulating progesterone concentration, although the effect is not evident in older, presumably peripubertal, gilts. The mechanism involved and implications for fertility remain to be determined.     

An approach to acorn production in Iberian dehesas

Acorn production is one of the most important products in silvopastoral systems in the Mediterranean region. In the present study we carried out two preliminary trials to analyze the distribution of production over time and the effect of pruning. The objective was to develop tools to manage this valuable resource within these systems. In the first part of the study, we analyzed the total acorn production of a holm oak stand, and its seasonal distribution (October–January) over two years (1997–1998 and 1998–1999) in five sites in the southwest of Spain. Mean total acorn production ranged from 590 to 830 kg ha⁻¹. There was considerable variation between the different sites and years studied, as was expected from studies on other oak species. A comparison was also made of acorn production, comparing annual acorn production between 40 pruned and 40 non-pruned trees, for the period 1994–1999. There was an interaction between ‘pruning treatment’ and ‘year’. Pruning, significantly decreased acorn production in all but two years when production was above the average, whereas production was not affected by pruning the three years that acorn yield was below the average. The study of acorn production and the analysis of the effect of pruning, needs to be studied over a longer time period.     

Uterine infection with bovine herpesvirus type 4 in dairy cows

Diseases of the reproductive tract are a frequent problem in dairy herds. Herpesviruses are uterine pathogens also involved in other clinical diseases; for example, bovine herpesvirus type 4 BoHV‐4 induces abortion, enteritis, metritis, pneumonia and vaginitis, but it can also be detected in healthy cows. The role of BoHV‐4 in the development of clinical endometritis (CE) or subclinical endometritis (SE) has not clearly been described. Therefore, the objective of this study was to describe the prevalence of uterine BoHV‐4 infection and its relationship with clinical, bacteriological and cytological findings in dairy cows 20–30 days after calving. The experiment was performed as a completely randomized block design, with farm (n = 10) as blocking criterion and with cow (n = 397) as the experimental unit. Logistic regression models were used to assess the effect of BoHV‐4 infection on CE, SE and reproductive performance. Proportion of cows infected with BoHV‐4 was 5.8% (n = 23/397). BoHV‐4 was isolated in 11.0% (n = 12/109), 4.8% (n = 4/84) and 3.6% (n = 7/194) of cows diagnosed as CE, SE or healthy, respectively. A logistic model revealed that BoHV‐4 infection showed a tendency to increase the risk for CE (AOR = 2.17; p = .10) but significantly reduced both, the odds for artificial insemination within 80 days post‐partum (dpp) (AOR = 0.37; p = .035) and for pregnancy within 200 dpp (AOR = 0.13; p = .004). Furthermore, BoHV‐4 infection increased the chance for intrauterine infection with Trueperella pyogenes (AOR = 5.55; p < .001) and vice versa (AOR = 5.79, p < .001). In conclusion, BoHV‐4 infection is associated with reduced chances for insemination and pregnancy by 200 dpp and showed a trend to be associated with increased risk for CE. Furthermore, BoHV‐4 and Trueperella pyogenes infections are strongly related.     

Patterns of Follicular Growth in Superovulated Sheep and Influence on Endocrine and Ovarian Response

Objectives of this study were to characterize patterns of follicular development in sheep superovulated with purified follicle stimulating hormone (FSH) (OVAGEN^TM, ICP, Auckland, New Zealand) and to determine its influence on preovulatory events (onset of the oestrus behaviour and timing of the preovulatory luteinizing hormone surge) and ovarian response (ovulation rate and embryo yield). Number and size of all ≥ 23 mm follicles from the first FSH injection to withdrawal of progestagen sponges was determined by transrectal ultrasonography just prior to every FSH injection in nine Manchega ewes superovulated with eight decreasing doses (ml) (1.5 × 3, 1.25 × 2 and 1 × 3) of OVAGEN injected twice daily from 60 h before to 24 h after the withdrawal of 40 mg fluorogestone acetate sponges. Oestrous detection and jugular blood sampling for LH radioimmunoassay were performed every 3 h from 14 to 53 h after sponge removal and ovulation rate and number of embryos were determined 4 days after progestagen withdrawal. Administration of OVAGEN induced a significant rise (p < 0.0005) in the number of follicles ≥ 4 mm in size because of an increased growth in size of follicles from the first FSH injection to sponge removal, an increase in the number of newly detected follicles from 12 to 36 h of the first FSH dose (p < 0.005) and a decrease in regression rate from 24 h (p < 0.001). The number of follicles 2–3 mm in size at first FSH dose (10.4 ± 1.5) was positively correlated with the number of ≥ 4 mm follicles at 0 h (19.0 ± 2.7, p < 0.01). A higher number of ≥ 4 mm follicles at 0 h was related with an earlier appearance of oestrus (31.5 ± 1.5 h, p = 0.08) and LH surge (45.0 ± 2.3 h, p < 0.005), and a higher ovulation rate (18.2 ± 3.8, p < 0.005). On the other hand, the rate of embryo recovery was decreased in ewes with earlier preovulatory LH peaks (p < 0.005), with a shorter interval between oestrus and LH peak (p < 0.05).     

Seroprevalence of equine herpesvirus 1 in Thoroughbred foals before and after weaning

Objective To investigate the seroprevalence of equine herpesvirus 1 in foals around weaning and after weaning on two large Thoroughbred farms using a type-specific enzyme-linked immunosorbent assay to determine exposure to infection.
Design A longitudinal population study in groups of Thoroughbred weanling foals.
Study population Two hundred weanling Thoroughbred foals from a population of about 380 foals were enrolled on two adjacent stud farms in the Hunter Valley of New South Wales. Foals on both farms were weaned from February to May 1995 into randomly selected groups of 10 to 15 foals. Farms were selected because of their willingness to cooperate in the survey and because their detailed records of foals and their movements. They were representative of well-managed large Thoroughbred stud farms in New South Wales. Both studs had upper respiratory tract disease among weanling foals around weaning each year although the sero-prevalence of viral respiratory disease on either farm was not known before the study.
Procedure Serum was collected from foals within each group at fortnightly intervals from 9th February until 1st June 1995, and at a single follow-up period in August 1995. Each sample was tested in triplicate using an antibody-detection ELISA which is type-specific for EHV-1 and EHV-4 antibodies.
Results and conclusions There was serological evidence of EHV-1 infection both before and after weaning. The prevalence of EHV-1 antibody in the sample population increased during the study and individual cases of EHV-1 infection were identified. The increase was caused both by the seroconversion of foals within the groups and by the recruitment into the study of foals with pre-existing EHV-1 antibody. Evidence of EHV-1 infection in Thoroughbred foals after weaning has not been reported previously in Australia and this has implications for vaccination regimens.     

Formation of molecular chlorine from the photolysis of ozone and aqueous sea-salt particles

Halogen atoms from the reactions of sea-salt particles may play a significant role in the marine boundary layer. Reactions of sodium chloride, the major component of sea-salt particles, with nitrogen oxides generate chlorine atom precursors. However, recent studies suggest there is an additional source of chlorine in the marine troposphere. This study shows that molecular chlorine is generated from the photolysis of ozone in the presence of sea-salt particles above their deliquescence point; this process may also occur in the ocean surface layer. Given the global distribution of ozone, this process may provide a global source of chlorine.     

Activated coagulation times in normal cats and dogs using MAX-ACTTM tubes

Objective  To establish reference values for activated coagulation time (ACT) in normal cats and dogs, by visual assessment of clot formation using the MAX-ACT^TM tube.
Subjects  We recruited 43 cats and 50 dogs for the study; 11 cats and 4 dogs were excluded from the statistical analysis because of abnormalities on clinical examination or laboratory testing including anaemia, prolonged prothrombin time (PT) or activated partial thromboplastin time (APTT), or insufficient plasma volume for comprehensive laboratory coagulation testing.
Procedure  Blood samples were collected via direct venipuncture for MAX-ACT, packed cell volume/total solids, manual platelet estimation and PT/APTT measurement. Blood (0.5 mL) was mixed gently in the MAX-ACT tube at 37°C for 30 s, then assessed for clot formation every 5 to 10 s by tipping the tube gently on its side and monitoring for magnet movement. The endpoint was defined as the magnet lodging in the clot. The technique was tested with 10 dogs by collecting two blood samples from the same needle insertion and running a MAX-ACT on each simultaneously.
Results  In normal cats the mean MAX-ACT was 66 s (range 55–85 s). In normal dogs the mean was 71 s (range 55–80 s). There was no statistical difference between the first and second samples collected from the same needle insertion.
Conclusions and Clinical Relevance  In both cats and dogs, a MAX-ACT result >85 s should be considered abnormal and further coagulation testing should be performed. Additionally, failure to discard the first few drops of the sample does not appear to significantly affect results.     

Temperature and surface-ocean water balance of the mid-holocene tropical western pacific

Skeletal Sr/Ca and 18O/16O ratios in corals from the Great Barrier Reef, Australia, indicate that the tropical ocean surface approximately 5350 years ago was 1 degrees C warmer and enriched in 18O by 0.5 per mil relative to modern seawater. The results suggest that the temperature increase enhanced the evaporative enrichment of 18O in seawater. Transport of part of the additional atmospheric water vapor to extratropical latitudes may have sustained the 18O/16O anomaly. The reduced glacial-Holocene shift in seawater 18O/16O ratio produced by the mid-Holocene 18O enrichment may help to reconcile the different temperature histories for the last deglaciation given by coral Sr/Ca thermometry and foraminiferal oxygen-isotope records.