Detection of a Nonoccluded Baculovirus in the Freshwater Crayfish Cherax quadricarinatus in North America

Abstract

A nonoccluded baculovirus was detected during a routine health examination of the tropical freshwater blue crayfish Cherax quadricarinatus reared in a farm in California, USA. The crayfish were progeny of captive-reared adults imported from Australia. There were no external or internal signs of disease in infected crayfish, but histological examination revealed eosinophilic to amphophilic intranuclear inclusions within the tubular epithelial cells of the hepatopancreas. The infected cells occurred throughout the hepatopancreas but never exceeded 10% of the cells constituting the tubule epithelium. Electron microscopy revealed numerous loosely enveloped, rod-shaped baculoviruses. The enveloped virions had a length of 292 ± 15 nm and a diameter of 102 ± 7 nm (mean ± SD). The cylindrical nucleocapsids often possessed squared ends and were 216 ± 13 nm in length by 47 ± 3 nm in width. There was no evidence of occlusion body formation similar to that known for certain other crustacean baculoviruses. The origin of the virus is uncertain, although a similar or identical agent has recently been detected among C. quadricarinatus in Australia.     

Fish population changes in the Sanyati Basin,Lake Kariba,Zimbabwe

Large-fish population changes in the Sanyati Basin of Lake Kariba between 1960 and 1975 are evaluated and discussed. The early lake population following closure of the dam wall in 1958 was similar to the pre-impoundment riverine population with Labeo spp., Distichodus spp., Clarias gariepinus and two characid species dominating gill-net catches. Exceptions were mormyrids, scarce in the new lake although abundant in the river, and Oreochromis mortimeri, scarce in the river but expanding rapidly in the lake. Productivity in the new lake in terms of ichthyomass relative to later years was high. In later years following closure several of the early abundant mostly potamodromous species declined rapidly (C. gariepinus, Labeo spp., Distichodus spp.,) and by 1975 they were unimportant. Mormyrids, cichlids and two silurid species increased significantly in catches as did the characin, Hydrocynus vittatus; the latter as a result of the expansion of the freshwater sardine population, from 1970. While early populations were essentially herbivorous later populations were largely insectivorous/molluscivorous. Concomitant with these changes new species appeared, while a few disappeared. Possible sources of origin of the new arrivals are discussed. Salient features of the entire evolutionary process are summarized, while some of the lessons leamt from Kariba, and a few recommendations arising from this, are listed in the conclusion.     

Determinations of the reproductive output of populations of a thalassinid prawn Upogebia africana (Ortmann) in the Swartkops estuary

Populations of large and ‘stunted’ (adult carapace lengths = 17,0–24,0 and 12,0–19,0 mm respectively) Upogebia africana were regularly and quantitatively sampled in the Swartkops estuary. At the site with ‘stunted’ prawns a well-defined spring (July to October) and summer (December to March) breeding cycle was recorded. The ‘stunted’ female prawns produced two broods of eggs per annum and the brood size ranged from about 305 to 2282 eggs depending on the size of the female. At the site with large prawns the spring and summer breeding cycles tended to merge, forming a longer breeding season, with the adult females apparently producing three broods of eggs per annum. The brood size of these females ranged from about 1304 to 4819 eggs. The calculated reproductive output (Pr) and reproductive biomass ratio (Pr/B) of the latter population were much greater than those of the ‘stunted’ prawns (1331 kJ m^?2 y^? and 0,53 v. 332 kJ m^?2 y^?1 and 0,26).     

The Birds of the Alien Acacia Thickets of the South Western Cape

The plough shell, Bullia rhodostoma (Mollusca: Gastropoda), has been studied on an open sandy beach where it is a common scavenger. Samples taken over a year indicate hatching of young individuals from December to February. They reach a length of about 10 mm after 1 year and 40 mm after 10 years. The von Bertalanffy growth equation is L_t = 47 (1 - e^{-0,19(t+0,23)}) and the annual mortality rate is 0,79. Mean decalcified dry biomass is 209 mg m^-2 and production by growth 189 mg m^-2 y^-1 giving a P/B of 0,9. Most production by adults (>15 mm shell length) goes into reproduction, particularly In the females which grow larger than the males. Production by reproduction is estimated to be about 135 mg m^-2 y^-1. Average calorific values are 19,04 kJ g^-1 dry tissue     

Unrecognized diversity in New Guinean crayfish species (Decapoda,Parastacidae): The evidence from molecular data

The phylogenetic relationships among imported ornamental crayfish belonging to the genus Cherax were inferred from a combined dataset of 3 mitochondrial genes (COI, 16S and 12S) and by comparison with available GenBank sequences of 14 Cherax species. Furthermore, the concordance of previously described species obtained from a wholesaler (Cherax boesemani, C. holthuisi and C. peknyi) with available GenBank sequences was verified based on COI with special respect to comparison with sequences assigned as Cherax species. Recently described species C. gherardiae, C. pulcher and C. subterigneus belong to the northern group of Cherax species. Comparison and analysis with other GenBank COI sequences show previously unreported diversity of New Guinean species, suggesting 5 putative new species. Surprisingly, species assigned to the subgenus Astaconephrops do not form a monophyletic clade; this subgenus should be reappraised relative to the purported typical morphological characteristic of the uncalcified patch on male chelae. Increasing importation of crayfish underscores the importance of accurate species identification. Use of basic molecular methods is a necessary requisite for documenting occurrence, abundance and population trends of target species. Consequently, it helps to support eventual conservation decision‐making by stakeholders.     

Thermoneutral zone and resting metabolic rate of broilers

1. Metabolic rate was determined once a week in broilers from a commercial source, from 1 to 63 d of age.

2. The equations relating minimal resting metabolic rate (oxygen consumption, ml/bird h,y) and body weight (W) were: males 45 to 497 g, y = 3.2 W^0.882 597 to 3000 g, y = 40.5 W^0.483; females 45 to 514 g, y = 2.52 W^0.881; 514 to 2500 g,y = 12.3 W^0.627.

3. The relationship between lower critical temperature (T_cl , °C,y) and age (d, x) may be described by the following equations: chicks 1 to 21 d, y = 34.2 ‐ 0.32 x; 14 to 63 d,y = 49.4 × ^?0194.

4. The relationship between T_cl and W may be described by one equation for both sexes between 100 and 3000 g, y = 62.15 W^?0.135..

5. The equations for T_cl and data for upper critical temperature (T_cu ) could be used to obtain maximal performance from broilers, with reduced costs, by providing a suitable environment related to age or body weight.     

Effects of freshwater crayfish on influenza A virus persistence in water

Several investigations have recently assessed the ability of some aquatic invertebrates to act as tools for avian influenza A virus (IAV) surveillance as well as their potential role(s) in IAV ecology. Because of this, as well as the high IAV seroprevalence rates noted in select mesocarnivores that commonly inhabit aquatic and semi‐aquatic habitats, we evaluated the effects that freshwater crayfish have on IAV in water at three dose levels and monitored for the presence of IAV in crayfish tissues (gill and green gland) and haemolymph at multiple time points. At relatively high, medium and low (approximately 10⁴, 10³ and 10² EID₅₀/ml, respectively) doses, mesocosms containing crayfish (Orconectes sp.) had less detectable IAV RNA present when final water samples were assayed (9 days post‐contact [DPC]). In general, containers without crayfish present had nearly three‐fold greater quantities of viral RNA at 9 DPC. A varying number of RNA positive samples were detected for the three crayfish sample types collected. Gill tissue produced the largest number of positive non‐water samples (n = 26), with the highest quantities detected from crayfish sampled on 1 and 4 DPC (10^3.5 EID₅₀ equivalent/ml). On a few occasions, gill (n = 8) and haemolymph samples (n = 1) produced higher quantities of viral RNA than their respective water samples or water samples collected 1–2 DPC earlier, but these differences were typically minor. Based upon water samples, statistical models indicated that the interaction of dose and crayfish exposure days explained most of the variation in these data. Future efforts should address if crayfish exposed to IAV‐laden water have the capacity to successfully transmit IAVs to mammals and birds which frequently prey upon them.     

Comparative analysis of hatching rates and clutch sizes of Nile crocodile (Crocodylus niloticus) eggs collected on- and off-farm in Zimbabwe

The Nile crocodile (Crocodylus niloticus) is a large aquatic reptile predominant in the tropics in Africa and Zimbabwe in particular. Clutch sizes and hatching rates of Nile crocodile eggs collected from the wild and on-farm in Lowveld, Highveld and Kariba regions of Zimbabwe were evaluated. A total of 274 egg records for the period 2000 to 2008 from 39 farms were collected from the Crocodile Farmers Association of Zimbabwe. The effect of source of eggs was analysed using the non-parametric one way analysis of variance procedure of SAS Version 9.1.3. Wilcoxon signed rank test for independent samples was used to compare the mean hatching rates and clutch sizes for eggs collected from the different sources by region. The degree of association between clutch sizes and the hatching rates by source and region was determined using the Spearman’s rank correlation test. Source of eggs had no effect (P > 0.05) on hatching rates in all the regions but significantly influenced (P < 0.05) clutch sizes in Lowveld and Kariba. In these regions, clutch sizes in the wild were significantly (P < 0.05) higher than those on-farm. Correlation estimates between clutch size and hatching rates were weak and non-significant (P > 0.05) for the different sources of eggs in all regions. Full utilization of the wild resource would reduce challenges relating to shortage of captive breeders and high cost of rearing breeders and hence increase productivity.     

Pharmacokinetics of xylazine after 2-, 4-, and 6-hr durations of continuous rate infusions in horses

Intravenous (i.v.) bolus administration of xylazine (XYL) (0.5 mg/kg) immediately followed by a continuous rate infusion (CRI) of 1 mg kg⁻¹ hr⁻¹ for 2, 4, and 6 hr produced immediate sedation, which lasted throughout the duration of the CRI. Heart rate decreased and blood pressure increased significantly (p > .05) in all horses during the first 15 min of infusion, both returned to and then remained at baseline during the duration of the infusion. Compartmental models were used to investigate the pharmacokinetics of XYL administration. Plasma concentration–time curves following bolus and CRI were best described by a one-compartment model. No differences were found between pharmacokinetic estimates of the CRIs for the fractional elimination rate constant (K_e), half-life (t_1/2e), volume of distribution (V_d), and clearance (Cl). Median and range were 0.42 (0.15–0.97)/hr, 1.68 (0.87–4.52) hr, 5.85 (2.10–19.34) L/kg, and 28.7 (19.6–39.5) ml min⁻¹ kg⁻¹, respectively. Significant differences were seen for area under the curve ( ) (p < .0002) and maximum concentration (C_max) (p < .04). This indicates that with increasing duration of infusion, XYL may not accumulate in a clinically relevant way and hence no adjustments are required in a longer XYL CRI to maintain a constant level of sedation and a rapid recovery.     

Variance and covariance of hatchability and some of its components in the chickens

Samples of 20 hatching eggs from each of 2004 individual pedigreed pullets were incubated and hatchability recorded. Unhatched eggs were examined for evidence of embryo development and classified as infertile, early embryonic death (died 0–10 d) or late embryonic death (died 11–22 d). Variance analysis yielded a mean heritability value for hatch of all eggs of approximately 0.30. Heritability values for early and late embryo mortality were subject to larger errors but there was a tendency among the estimates of h ² ₈ for late embryo mortality to be higher than those for early embryo mortality.

The genetic correlations between hatchability and both early and late embryonic mortality were high and negative as was to be expected from part × whole correlations. However the genetic correlation between early and late embryonic mortality was also consistently positive indicating common genetic determination of these two independent traits.     

Soil carbon dioxide effluxes from different vegetation environments in semi-arid Eastern Cape,South Africa

Though important, CO₂ effluxes from non-agricultural ecosystems are poorly characterised. Given that thicket vegetation is prevalent in Eastern Cape, South Africa, we monitored soil CO₂ effluxes from an intact thicket, degraded thicket (DT) and grassland (G) over 10 months, as affected by temperature, moisture and penetration resistance (PR). High soil moisture (16%) reduced PR (4?kg cm^?2), which raised winter effluxes (1.2 µmol m^?2 s^?1), while low moisture (2%) resulted in hard dry soil (14?kg cm^?2) that suppressed spring effluxes (0.2 µmol m^?2 s^?1). There was good interaction between PR and moisture (r = ?0.53), with seasonal effluxes increasing with increasing moisture (r = 0.9, p = 0.0001) and decreasing PR (r = ?0.66, p = 0.02). Temperature effects were significant under unlimited moisture supply. Thus high summer temperature (40 °C) gave lower effluxes in DT and G (<1 µmol m^?2 s^?1) due to limited moisture (<10%), whereas high autumn temperature (48 °C) and good moisture (16%) accelerated CO₂ emissions (averaging 2 µmol m^?2 s^?1) from all covers. Although semi-arid ecosystems are limited by low moisture and sandy soils, they contribute to CO₂ emissions under high moisture and increasing temperature. Keywords: Eastern Cape, grassland, soil carbon dioxide effluxes, soil organic carbon, thicket     

Survivability of Infectious Hematopoietic Necrosis Virus in Fertilized Eggs of Masu and Chum Salmon

Abstract

The possibility of vertical transmission of infectious hematopoietic necrosis virus (IHNV) was studied with the eggs of masu (cherry) salmon Oncorhynchus masou and chum salmon O. keta. The surfaces of eggs and sperm were contaminated with IHNV (10^3.8-10^4.8 50% tissue culture infective dose [TCID50]/egg) and then the eggs were fertilized. Eggs just after fertilization and embryonated eggs also were infected by injection with IHNV (10^3.8 TCID50/egg) directly into the yolk. During incubation, eggs were held in running water at 10°C. Mortality of the eggs or hatched progeny was determined and isolation of IHNV on the surface or inside of the eggs was determined during the incubation period. No mortality occurred and no virus was detected in fertile eggs from contaminated gametes. For injected eggs, IHNV was not detected on the surface of masu and chum salmon eggs after 1 d of incubation. Infectivity of IHNV inside the eggs decreased gradually and could not be detected after 1 month of incubation. This rate of IHNV reduction in the fertilized egg was similar to that found in a mixture of IHNV and homogenized yolk contents. Several individual yolk components also showed anti-IHNV activity. When eyed eggs were injected with IHNV, the embryos of both masu and chum salmon became infected, and the concentration of virus increased rapidly and reached more than 10^6.5 TCID50/fish. The cumulative mortality of eggs injected at the eyed stage for both masu and chum salmon was 90%. The susceptibilities of hatched-out larvae of masu and chum salmon to IHNV were different; cumulative mortality was more than 90% in masu salmon and 20–30% in chum salmon artificially infected with the virus. We concluded that vertical transmission of IHNV is doubtful because the virus is apparently unable to survive in eggs before the eyed stage.     

Growth Rates in Thoroughbred Horses Raised in Florida

SummaryGrowth rates of thoroughbred horses are not as well defined as those of other farm animals, and only a few articles summarize growth of thoroughbred horses over a prolonged period. Body weight (BW), heart girth (HG), wither height (WH), body length (BL), and hip height (HH) of 128 thoroughbred horses (59 colts and 69 fillies) were recorded from birth to 15 months of age at 14- or 28-day intervals. Data were obtained from consecutive 20 foal crops. At birth (0 day), BW was 53.55 ± 5.20 kg (range, 39.04–67.19), HG was 0.82 ± 0.03 m (range, 0.75–0.90), WH was 1.02 ± 0.03 m (range, 0.93–1.10), BL was 0.74 ± 0.03 m (range, 0.67–0.82), and HH was 1.05 ± 0.03 m (range, 0.93–1.14). At weaning (112 ± 3 days), BW was 199.57 ± 13.58 kg (range, 163.44–234.26), HG was 1.29 ± 0.04 m (range, 1.19–1.37), WH was 1.27 ± 0.03 m (range, 1.21–1.35), BL was 1.17 ± 0.03 m (range, 1.08–1.30), and HH was 1.32 ± 0.03 m (range, 1.24–1.39). At 6 months (181 ± 4 days), BW was 237.16 ± 18.48 kg (range, 186.14–288.74), HG was 1.36 ± 0.04 m (range, 1.24–1.45), WH was 1.33 ± 0.03 m (range, 1.26–1.40), BL was 1.25 ± 0.03 m (range, 1.17–1.33), and HH was 1.38 ± 0.03 m (range, 1.28–1.44). At 12 months (361 ± 8 days), BW was 337.73 ± 26.61 kg (range, 267.86–394.98), HG was 1.56 ± 0.05 m (range, 1.41–1.66), WH was 1.45 ± 0.03 m (range, 1.36–1.55), BL was 1.42 ± 0.04 m (range, 1.31–1.51), and HH was 1.49 ± 0.03 m (range, 1.41–1.57). At 15 months (447 ± 8 days), BW was 392.48 ± 30.61 kg (range, 317.80–457.18), HG was 1.64 ± 0.05 m (range, 1.52–1.76), WH was 1.49 ± 0.03 m (range, 1.42–1.58), BL was 1.48 ± 0.04 m (range, 1.40–1.59), and HH was 1.53 ± 0.03 m (range, 1.46–1.62). Two regression equations (y₁ from birth to 112 days of age and y₂ from 113 to 450 days of age) were calculated. WT_kg is estimated by y₁ = 1.28x + 57.82 (R² = 0.94) and y₂ = 0.57x + 133.28 (R² = 0.86). HG_m is estimated by y_l = 0.0041x + 0.86 (R² = 0.90) and y₂ = 0.0011x + 1.16 (R² = 0.84). WH_m is estimated by y₁ = 0.0022x + 1.03 (R² = 0.85) and y₂ = 0.0006x + 1.22 (R² = 0.80). BL_m is estimated by y₁ = 0.0038x + 0.77 (R² = 0.92) and y₂ = 0.0009x + 1.09 (R² = 0.85). HH_m is estimated by y₁ = 0.0024x + 1.07 (R² = 0.87) and y₂ = 0.0006x + 1.27 (R² = 0.78).     

Nutritive evaluation of legume seeds for ruminant feeding

Chemical composition, rumen degradability and the effect of particle losses, and intestinal digestibility of protein by using in situ‐in vitro and in vitro techniques were stated for beans (Vicia faba), lupin (Lupinus albus), vetch (Vicia sativa) and bitter vetch (Vicia ervilia) and four diets including those legume seeds. In addition, the apparent digestibility of experimental diets was determined in goats. The legume seeds showed high protein content (206–319 g/kg dry matter). Effective degradability of protein for legumes and diets varied from 0.80 to 0.87 and 0.76 to 0.82, respectively, decreasing to 0.53–0.76 and 0.61–0.67, respectively, when particle loss was taken into account. Different intestinal digestibility values were obtained with both methodologies without significant relationship between them (y = 1.058–0.463x; R² = 0.068; RSD = 0.140; p = 0.53). There were no differences in the apparent nutrients and energy digestibility among diets (p > 0.05). These legumes can supply rapidly degradable protein for microbial protein synthesis and contribute to the pool of amino acids available for the synthesis of milk protein and for retention in the body.     

The pharmacokinetics of cefadroxil over a range of oral doses and animal ages in the foal

To evaluate the effect of foal age on the pharmacokinetics of cefadroxil, five foals were administered cefadroxil in a single intravenous dose (5 mg/kg) and a single oral dose (10 or 20 mg/kg) at ages of 0.5, 1, 2, 3 and 5 months. Pharmacokinetic parameters of terminal elimination rate constant (β_po), oral mean residence time (MRT_po), mean absorption time (MAT), rate constant for oral absorption (K_a), bioavailability F, peak serum concentrations(C_max) and time of peak concentration (t_max), were evaluated in a repeated measures analysis over dose. Across animal ages, parameters for the intravenous dose did not change significantly over animal age (P 0.05). Mean values ± SEM were: β_IV = 0.633 ± 0.038 h^?1; Cl = 0.316 ± 0.010 L/kg/h; V_c = 0.196 ± 0.008 L/kg; V_area = 0.526 ± 0.024 L/kg; V_SS =0.374 ± 0.014 L/kg; MRT_iv = 1.22 ± 0.07 h; K_el = 1.67 ± 0.08 ^h?1. Following oral administration, drug absorption became faster with age (P < 0.05), as reflected by MRT_po, MAT, K_a and t_max. However, oral bioavailability (±SE) declined significantly (P < 0.05) from 99.6 ± 3.69% at 0.5 months to 14.5 ± 1.40% at 5 months of age. To evaluate a dose effect on the pharmacokinetic parameters, a series of oral doses (5, 10, 20 and 40 mg/kg) were administered to these foals at 1 month of age. β_po (0.548 ± 0.023 h^?1) and F (68.26 ± 2.43%) were not affected significantly by the size of the dose. C_max was approximately doubled with each two-fold increase in dose: 3.15 ± 0.15, 5.84 ± 0.48, 12.17 ± 0.93 and 19.71 ± 2.19 μg/mL. Dose-dependent kinetics were observed in MRT_po, MAT, K_a and t_max.     

Changes in structure of the limiting membrane and in oxygen permeability of the chicken egg integument during incubation

1. Oxygen permeabilities (K_O2 ) of the shell and shell membranes of fertile and infertile chicken eggs were measured at 37.5 °C and a relative humidity of 0.60 throughout 14 d incubation, with turning. The K_O2 of the shell and membranes of infertile eggs was around 1.0 × 10^?7 cm³ O₂STP sec^?1 cm^?2 Torr^?1 (1 Torr = 133.322 Pa) throughout incubation. With fertile eggs, from which there was a linear loss of water during incubation, the K_O2 of the shell and shell membranes was about 1.0 × 10^?7 cm³ O₂STP sec^?1 cm^?2 Torr^?1 for the first four days of incubation. Thereafter the majority of shells and membranes had a K_o2 of about 1.0 × 10^?6 cm³ O₂STP sec^?1 cm^?2 Torr^?1.

2. A diminution of the Na⁺ and K⁺ content of the shell membranes of fertile eggs was not associated with changes in the dimensions of the glyco‐protein mantle on the cores of the individual fibres of the membranes. There was, however, a progressive deterioration in the limiting membrane of fertile but not of infertile eggs.

3. It was concluded that changes in the O₂ resistance of the integument of fertile eggs were not a product of change in either of the shell membranes but of damage caused to the limiting membrane by the chorioallantois.     

The Biology of Alestes Imberi Peters (Pisces:Characidae) in Lake McIlwaine,Rhodesia

The population of Alestes imberi in Lake Mcllwaine increased greatly in late 1974, but the species is of little economic importance in the lake. The breeding season is short and coincides with the main river floods. Females are larger than males and fecundity is extremely high. Like other ,4/M/W species it is a very versatile feeder, and utilizes mainly insect alates from April to November, and chironomid larvae and pupae from December to March. It is able to takeadvantage of periodic insect emergences and to utilize some plant material. Zooplankton and fish are not important food items. Condition factors appear to be related to spawning. Growth rates could only be assessed indirectly but appear to be more rapid in Lake Mcllwaine than in Lake Kariba.     

Intravenous anaesthesia using detomidine, ketamine and guaiphenesin for laparotomy in pregnant pony mares

Objective To characterize intravenous anaesthesia with detomidine, ketamine and guaiphenesin in pregnant ponies. Animals Twelve pony mares, at 260–320 days gestation undergoing abdominal surgery to implant fetal and maternal vascular catheters. Materials and methods Pre‐anaesthetic medication with intravenous (IV) acepromazine (30 µg kg^?1), butorphanol (20 µg kg^?1) and detomidine (10 µg kg^?1) preceded induction of anaesthesia with detomidine (10 µg kg^?1) and ketamine (2 mg kg^?1) IV Maternal arterial blood pressure was measured directly throughout anaesthesia and arterial blood samples were taken at 20‐minute intervals for measurement of blood gases and plasma concentrations of cortisol, glucose and lactate. Anaesthesia was maintained with an IV infusion of detomidine (0.04 mg mL^?1), ketamine (4 mg mL^?1) and guaiphenesin (100 mg mL^?1) (DKG) for 140 minutes. Oxygen was supplied by intermittent positive pressure ventilation (IPPV) adjusted to maintain PaCO₂ between 5.0 and 6.0 kPa (38 and 45 mm Hg), while PaO₂ was kept close to 20.0 kPa (150 mm Hg) by adding nitrous oxide. Simultaneous fetal and maternal blood samples were withdrawn at 90 minutes. Recovery quality was assessed. Results DKG was infused at 0.67 ± 0.17 mL kg^?1 hour^?1 for 1 hour then reduced, reaching 0.28 ± 0.14 mL kg^?1 hour^?1 at 140 minutes. Arterial blood gas values and pH remained within intended limits. During anaesthesia there was no change in heart rate, but arterial blood pressure decreased by 10%. Plasma glucose and lactate increased (10‐fold and 2‐fold, respectively) and cortisol decreased by 50% during anaesthesia. Fetal umbilical venous pH, PO₂ and PCO₂ were 7.34 ± 0.06, 5.8 ± 0.9 kPa (44 ± 7 mm Hg) and 6.7 ± 0.8 kPa (50 ± 6 mm Hg); and fetal arterial pH, PO₂ and PCO₂ were 7.29 ± 0.06, 4.0 ± 0.7 kPa (30 ± 5 mm Hg) and 7.8 ± 1.7 kPa (59 ± 13 mm Hg), respectively. Surgical conditions were good but four ponies required a single additional dose of ketamine. Ponies took 60 ± 28 minutes to stand and recovery was good. Conclusions and clinical relevance Anaesthesia produced with DKG was smooth while cardiovascular function in mare and fetus was well preserved. This indicates that DKG infusion is suitable for maintenance of anaesthesia in pregnant equidae.     

Effectiveness of Egg Immersion in Aqueous Solutions of Thiamine and Thiamine Analogs for Reducing Early Mortality Syndrome

Abstract

Protocols used for therapeutic thiamine treatments in salmonine early mortality syndrome (EMS) were investigated in lake trout Salvelinus namaycush and coho salmon Oncorhynchus kisutch to assess their efficacy. At least 500 mg of thiamine HCl/L added to egg baths was required to produce a sustained elevation of thiamine content in lake trout eggs. Thiamine uptake from egg baths was not influenced by a pH ranging from 5.5 to 7.5 or by a water hardness between 2 and 200 mg CaCO₃/L. There was poorer thiamine uptake when initial thiamine levels were low, suggesting that current treatment regimes may not be as effective when thiamine levels are severely depressed and that higher treatment doses are necessary. Exposure of eggs to the more lipid-soluble thiamine analog allithiamine (1,000 mg/L) during water hardening increased egg thiamine levels by 1.5–2.5 nmol/g and was completely effective at reversing EMS. Another more lipid-soluble thiamine analog, benfotiamine (100 mg/L), reduced EMS but did not produce detectable increases in egg thiamine content. Although benfotiamine may be more effective than thiamine at mitigating EMS, it is more expensive than thiamine HCl or allithiamine. In addition, there still needs to be a more thorough examination of dose–response relationships. We conclude that allithiamine is an alternative to the use of thiamine in egg baths as a therapeutic treatment for salmonid EMS.     

Biology of Hymenosoma Orbiculare Desm in Lake Sibaya

Hymenosoma orbiculare, (Crustacea: Brachyura: Hymenosomatidae) a crab common in estuaries in south- and south east Africa occurs in freshwater in Lake Sibaya at depths down to 40 m. This is the only known freshwater record of this species. The population density in the lake is fairly uniform declining in shallow and very deep water with an a11erage- of 2,5 m^-2 (134 Jm^-2). The proportion of females in the population increases with depth. Females carry fewer eggs than estuarine populations and breeding appears to occur throughout the year. Both zoeae and adults differ morphologically from estuarine populations. These differences in breeding, biology and morphology raise the possibility that the Lake Sibaya population is specifically distinct from estuarine populations and this is discussed in relation to other instances of hymenosomatid invasion of freshwater habitats.