Comparative water relations of three successional hardwood species in central Wisconsin

Water relations of co-occurring understory saplings of Quercus ellipsoidalis E.J. Hill, an early successional, xeric species, Populus tremuloides Michx., an early successional, mesic species, and Acer rubrum L., a late successional species that occurs on both wet and dry sites, were evaluated on four dates during the 1986 growing season. The understory was characterized by high soil water content, low irradiance and low vapor pressure deficit throughout the growing season. Stomatal conductance and calculated transpiration flux were lowest for A. rubrum and highest for P. tremuloides and Q. ellipsoidalis. Except early in the growing season, leaf water potentials were lower in P. tremuloides than in the other species. Populus tremuloides had the highest bulk modulus of elasticity, Q. ellipsoidalis the lowest. Over the growing season, Populus tremuloides and Q. ellipsoidalis, but not A. rubrum, exhibited a decrease in osmotic potential at both full and zero turgor. Of the three species, Populus tremuloides exhibited the sharpest decrease in leaf water potential and turgor pressure with decreasing relative water content.     

Risk factors influencing death prior to discharge in 302 dogs undergoing unilateral adrenalectomy for treatment of primary adrenal gland tumours

Adrenalectomies for canine adrenal tumours are associated with peri-operative morbidity and mortality. Objectives of this study included assessing the prognostic value of tumour- or surgery-related variables in predicting peri-operative mortality and overall survival in dogs undergoing adrenalectomies for primary adrenal tumours as well as pre-treatment with phenoxybenzamine on survival to discharge with pheochromocytomas specifically. A multi-institutional retrospective cohort study was performed across nine institutions. Electronic medical record searches identified 302 dogs which met the inclusion criteria. Data collected included dog-related, tumour-related, treatment-related, surgery-related, and outcome variables. Univariate and multivariable logistic regression and cox proportional hazards models were used to identify variables associated with death prior to discharge and tumour-related survival. Overall, 87% of dogs survived to discharge with a tumour-related survival time of 3.96 years. Post-operative complications were reported in 25%. Increased surgical time (p = 0.002) and pre-surgical medical treatment other than phenoxybenzamine (p = 0.024) were significantly associated with increased peri-operative mortality while ureteronephrectomy (p = 0.021), post-operative pancreatitis (p = 0.025), and post-operative aspiration pneumonia (p < 0.001) were significantly associated with decreased overall survival. Phenoxybenzamine pretreatment had no effect on peri-operative mortality. Thirty-seven of 45 (82%) dogs with pheochromocytomas not pretreated survived to discharge, and 50 of 59 (85%) dogs with pheochromocytomas pretreated with phenoxybenzamine survived to discharge (p = 0.730). This study provides information on risk factors for death prior to discharge and tumour-related survival that may help guide clinical management and owner expectations. In addition, the study findings challenge the previously reported benefit of phenoxybenzamine for pretreatment of dogs undergoing adrenalectomies for pheochromocytomas.     

Seasonal Effect on Zebu Embryo Quality as Determined by Their Degree of Apoptosis and Resistance to Cryopreservation

In order to optimize the production of embryos under tropical conditions and to test a possible seasonal effect on embryo quality, 40 Zebu cows were superovulated during the dry season (April to May) and during the rainy season (July to August). A total of 116 (average 2.7/cow) and 83 embryos (3.5 average/cow) were obtained during the respective seasons. After classification as good, fair or poor quality, embryos were tested based on their ultrastructural differences (n = 53 dry season 16 good, 20 fair and 17 poor and n = 61 rainy season 21 good, 20 fair and 20 poor) and their degree of apoptosis using the TUNEL technique (n = 30 during the dry season and n = 55 in the rainy season). Structural characteristics determining embryo quality varied between good and fair quality embryos. No difference, however, was observed between good, fair and poor quality embryos from the two seasons. The number of TUNEL-positive cells was different among embryos (p < 0.001), being lower in labelled cells of good quality embryos regardless of the season. Fewer apoptotic cells were observed in embryos assigned in all three quality levels during the rainy season (p < 0.001). Ultrastructural evaluations confirmed the results obtained by TUNEL. Cryopreserved embryos of good (n = 25 in each season) and fair quality (n = 11 dry season; n = 17 rainy season) showed a significant decrease of TUNEL-positive cells during the rainy season (p < 0.05). Results suggest that embryos collected in the dry season have more cellular damage in contrast; embryos cryopreserved in the rainy season appeared morphologically better equipped to result in a pregnancy following transfer.     

Assessment of the Intensity of Behavioural Traits and Ovulation between Synchronized and Non-synchronized Cows

Thirty cyclic, non-suckled Brahman cows were divided into three groups, all of which were synchronized sequentially with CIDR-B and observed continuously for 100 h to determine different behavioural oestrus signs. Twenty-four hours after implant withdrawal, all synchronized cows in the group, together with all other cows displaying oestrus, were subjected to intensive ultrasonographic observations (every 6 h for 120 h) to pinpoint the moment of ovulation. In the first group, oestrus and ovulation response was 60% (6/10), in the second 44% (4/9) showed oestrus and six ovulated, and in the third group oestrus and ovulation were 80% (8/10). Significant differences were observed between the second and third groups (p < 0.05). No differences were observed in the duration of oestrus, time when oestrus was displayed after implant withdrawal, time of ovulation and onset of oestrus, end of oestrus to ovulation, and intensity of oestrus on a point scale. The relationship between duration of oestrus and time of ovulation was r(2) = 0.16. Ovulation, on average, was 32.1 +/- 14.5 h after the onset of oestrus, 22.3 +/- 16.5 h after the end of oestrus, and 91.8 +/- 16.7 after implant withdrawal, although no significant differences were observed. One non-synchronized animal showed oestrous activity in the second group but failed to ovulate. In the third group, 8 animals showed oestrus, 4 with high concentrations of progesterone. Of the other four one ovulated. In conclusion, oestrous behaviour is not necessarily the best marker to predict the time when ovulation takes place due to variation in the length of the oestrous period and the possible integration of non-ovulatory animals into sexually active groups.     

Is the Production of Embryos in Small‐Scale Farming an Economically Feasible Enterprise?

The present assay attempts to evaluate the feasibility of using embryo transfer in small community farmers by in vivo study and by modelling the results obtained. From the total of 59 donor cows, 62.7% responded to treatment, with a significant difference (p = 0.002) in the percentage of the response between breeds, being 90.5% (19/21) in Holstein and 47.4% (18/38) in Brahman. A total of 283 embryos were graded as transferable, while 141 as non‐transferable, without difference in the percentage of transferable embryo by breed (p = 0.18). The mean of transferable embryos graded as class I and II was not different between Holstein and Brahman (p = 0.96 and p = 0.92, respectively); besides, no differences were observed in the other grades (non‐transferable). The highest difference in costs, regardless of its quality by breed, was seen in the lower levels of probable fertility of the embryo transferred, even reaching several hundred dollars. When modelling the expected costs for embryo produced and transferred, values can reach nearly $2000.00 when the probable fertility is only 10%. However, when the probable fertility was 60%, embryo cost was close to $300.00. This technology seems to be viable on average or high‐scale systems, having a superovulatory response between 60 and 80% with 4–6 transferrable embryos. Yet, in small‐scale farming, due to the reduced number of donors and/or recipients, the costs surpass the economical feasibility of the technique.     

Relationship of Progesterone,Bovine Pregnancy-Associated Glycoprotein-1 and Nitric Oxide with Late Embryonic and Early Fetal Mortalities in Dairy Cows

The aim of the present study was to determine the relationship of progesterone (P4), bovine pregnancy-associated glycoprotein-1 (bPAG-1) and nitric oxide (NO) levels with late embryonic (LEM; day 28 to day 42) and early fetal mortalities (EFM; > day 42 to day 56) in dairy cows. Transrectal ultrasonography (6–8 MHz) was performed in 100 Holstein-Friesian cows at days 28, 42 and 56 after artificial insemination (AI; day 0) to diagnose pregnancy and to monitor the fate of the embryo. After ultrasound scanning of each cow, a milk sample was collected for assessment of P4 by an ELISA test and a blood sample was collected for assessment of bPAG-1, by using a double-antibody radioimmunoassay, and serum NO metabolites (nitrate + nitrite). Based on ultrasonographic examinations and bPAG-1-RIA, 41 of 100 inseminated cows were confirmed pregnant at day 28 after AI. Nine cows suffered of LEM, and 6 cows suffered of EFM and the overall pregnancy loss rate was 36.6% (15/41) between days 28 and 56 of pregnancy. By logistic regression analysis, there were no significant relationships between the level of P4 and bPAG-1 at day 28 after AI and the occurrence of LEM and EFM. Also, there were no significant relationships between the levels of P4 and bPAG-1 at day 42 and the occurrence of EFM. On the other hand, a significant relationship (P<0.05) was found between NO level at day 28 and the occurrence of LEM. In conclusion, measurement of the serum NO concentration at day 28 of pregnancy might help to predict the outcome of pregnancy by day 42 in dairy cows but further studies are needed to confirm this.     

Hyoscine‐N‐butylbromide premedication on cardiovascular variables of horses sedated with medetomidine

ObjectiveTo evaluate the effects of intravenous (IV) or intramuscular (IM) hyoscine premedication on physiologic variables following IV administration of medetomidine in horses.Study designRandomized, crossover experimental study.AnimalsEight healthy crossbred horses weighing 330 ± 39 kg and aged 7 ± 4 years.MethodsBaseline measurements of heart rate (HR), cardiac index (CI), respiratory rate, systemic vascular resistance (SVR), percentage of patients with second degree atrioventricular (2^oAV) block, mean arterial pressure (MAP), pH, and arterial partial pressures of carbon dioxide (PaCO₂) and oxygen (PaO₂) were obtained 5 minutes before administration of IV hyoscine (0.14 mg kg^?1; group HIV), IM hyoscine (0.3 mg kg^?1; group HIM), or an equal volume of physiologic saline IV (group C). Five minutes later, medetomidine (7.5 μg kg^?1) was administered IV and measurements were recorded at various time points for 130 minutes.ResultsMedetomidine induced bradycardia, 2^oAV blocks and increased SVR immediately after administration, without significant changes in CI or MAP in C. Hyoscine administration induced tachycardia and hypertension, and decreased the percentage of 2^oAV blocks induced by medetomidine. Peak HR and MAP were higher in HIV than HIM at 88 ± 18 beats minute^?1 and 241 ± 37 mmHg versus 65 ± 16 beats minute^?1 and 192 ± 38 mmHg, respectively. CI was increased significantly in HIV (p ≤ 0.05). Respiratory rate decreased significantly in all groups during the recording period. pH, PaCO₂ and PaO₂ were not significantly changed by administration of medetomidine with or without hyoscine.Conclusion and clinical relevanceHyoscine administered IV or IM before medetomidine in horses resulted in tachycardia and hypertension under the conditions of this study. The significance of these changes, and responses to other dose rates, requires further investigation.