Branchial Ionic Flux Responses in Rainbow Trout to Chloramine-T after Acclimation to Different Levels of Water Hardness

Abstract

Whole-body unidirectional and net Na⁺ and Cl^– fluxes were determined in rainbow trout Oncorhynchus mykiss exposed to chloramine-T (9 mg/L) alone or in combination with 17 mmol NaCl/L (0.1 % weight per volume, w/v) after acclimation to either city of Ottawa tap water (TW: Na⁺ 0.121 ± 0.004 mmol/L; K⁺ 0.015 ± <0.001 mmol/L; Ca²⁺ 0.351 ± 0.004 mmol/L; Cl^– 0.141 ± 0.002 mmol/L) or artificial soft water (ASW: Na⁺ 0.043 ± 0.003 mmol/L; K⁺ 0.005 ± <0.001 mmol/L; Ca²⁺ 0.063 ± 0.002 mmol/L; Cl^– 0.026 ± 0.002 mmol/L). Preexposure fluxes revealed that ASW-acclimated fish had reduced rates of Na⁺ uptake and efflux compared with TW-acclimated fish. However, rates of Cl^– uptake among ASW-acclimated fish were comparable with those of TW-acclimated fish. Exposure to chloramine-T in TW resulted in significant increases in the Cl^– efflux, giving rise to a significant and negative net flux. Exposure of ASW-acclimated fish to chloramine-T caused a significant negative increase in the Na⁺ efflux and net flux but only a negative increase in the Cl^– net flux. The addition of 17 mmol NaCl/L (0.1% w/v) eliminated the negative net ionic fluxes, resulting in significant increases in influx. The combined use of chloramine-T with NaCl is a potential method of remediating ionic disturbances that may be caused by treating trout with chloramine-T.     

Retracted: Determination of some blood and seminal plasma ions in the beluga,Huso huso (Linnaeus, 1758)

Blood and seminal plasma ionic parameters are essential for monitoring health status, detecting illnesses, fish stock conservation and development of artificial propagation methods via extender improvement. In this study, comparison of blood and seminal plasma ionic parameters in beluga, Huso huso (30–45 kg, 1–2 m, n = 10), was made. The results obtained show that Na⁺ (82.54 ± 5.46), Cl^‐ (15.95 ± 0.72) and K⁺ (3.57 ± 0.15) were predominant ions in the seminal plasma (as mm ). Blood ionic values (as mm ) were determined for Na⁺ (110.2 ± 1.26), K⁺ (3.77 ± 0.081), Cl^? (60.12 ± 1.5), Ca²⁺ (2.05 ± 0.35) and Mg²⁺ (1.9 ± 0.16). Results of the comparison between ionic parameters of seminal and blood plasma indicated that the concentrations of all parameters of blood plasma with the exception of K⁺ were significantly (p < 0.05) higher than those of seminal plasma.     

Physiological Changes in the Red Drum after Long-Term Freshwater Acclimation

Abstract

The effect of long-term freshwater acclimation on the blood and plasma ion composition of Red Drum Sciaenops ocellatus was investigated with the goal of elucidating the necessity of ion remediation. Four replicates (n = 50) of freshwater-acclimated (FW) fish (1.6 ± 0.2 g) were raised in 25-m³ tanks supported by 140,000 L of recirculating water. Four replicates (n = 50) of seawater (SW) fish groups were placed in 40-m³ offshore cages at 32–35 psu. Blood was collected from 100 fish (FW = 578 ± 50 g; SW = 686 ± 45 g) of each group (FW, SW) after 8 months of rearing. During the grow-out phase, the survival of FW and SW fish was 57.5% and 92.2%, respectively. The water ion composition (mainly the Ca²⁺/K⁺ [43%] and Ca²⁺/Mg²⁺ ratios [1%]) explained 56.6% of the plasmatic ion variability in the fish groups. Freshwater exposure produced significant reductions in osmolality and in several plasma indicators (Na⁺, Cl^?, and Mg²⁺); the K⁺ levels from FW fish were the most compromised parameter. The water Ca²⁺/Na⁺ ratio had a greater influence (44%) on the plasma chemistry parameters, mainly glucose and creatinine. Freshwater-acclimated fish had a higher percentage of hematocrit, hemoglobin, and red blood cells than SW fish, but the water quality explained only 12.5% of the blood parameter variability between the FW and SW groups. The results support the conclusion that Red Drum tolerates salinity variations and can adopt a relatively stable condition for short periods; however, the data suggest that Red Drum have only a limited ability to withstand a hyposmotic environment for long periods due to their limited ability in maintaining K⁺ concentrations without external supplementation. Freshwater environments with high Ca²⁺/Na⁺, Ca²⁺/K⁺, and Ca²⁺/Mg²⁺ ratios appear to be a chronic stress factor that should be considered in future experiments.

Received June 11, 2012; accepted March 17, 2013     

Effects of three infusion fluids with different sodium chloride contents on steady‐state serum concentrations of bromide in dogs

Potassium bromide overdose (bromism) in the management of canine epilepsy has been known. However, a protocol to reduce bromide concentrations rapidly has not been previously established. The effects of three infusion fluids with different chloride contents on the steady‐state serum concentrations of bromide in beagles were determined. After stabilization of the serum bromide concentrations, seven dogs were infused with saline (Na⁺ 154 mmol/L; Cl^? 154 mmol/L), lactated Ringer's (Na⁺ 131 mmol/L; Cl^? 110 mmol/L), or maintenance solutions (Na⁺ 35 mmol/L; Cl^? 35 mmol/L) at a rate of 2 or 10 ml kg^?1 hr^?1 for 5 hr. Serum and urine were collected hourly, and the bromide concentrations were measured. When saline and lactated Ringer's solutions were infused at a rate of 10 ml kg^?1 hr^?1 for 5 hr, serum bromide concentrations were decreased by 14.24% and urine bromide concentrations by 17.63%, respectively. Of all compositions of infusion fluids, only sodium and chloride contents were associated with the decreased serum concentrations and the increased renal clearance of bromide. In summary, saline and lactated Ringer's solutions reduced serum bromide concentrations in a sodium chloride‐dependent manner in dogs were found when infused at 10 ml kg^?1 hr^?1 for 5 hr.     

The effect of different dietary levels of sodium and chloride on performance and blood parameters in goslings (1–28 days of age)

A total of 702 1-day-old male Jiangnan White goslings were used to study the effects of varying levels of Na⁺ and Cl⁻ on their growth performance and blood parameters. In this experiment, goslings were randomly allotted to nine treatments, with six pens per treatment in a 3 × 3 factorial arrangement, and fed diets with three concentrations of added Na⁺ (0.10%, 0.15% and 0.20%) and three concentrations of added Cl⁻ (0.15%, 0.20% and 0.25%). The purpose of this experiment was to investigate the sensitivity of goslings to Na⁺ and Cl⁻ during brooding to determine the appropriate levels of Na⁺ and Cl⁻ in their feed. The results are as follows: (a) Different levels of Na⁺ and Cl⁻ in the diet, especially low Na⁺ and Cl⁻, significantly affected the body weight (BW), average daily gain (ADG) and feed/gain ratio (F/G) of the 28-day-old goslings (p < .05). But Na⁺ × Cl⁻ has no significant effect on water consumption (p > .05). (b) Serum concentrations of urea increased linearly with Na⁺ content (p < .05). Serum concentrations of creatinine (CR) and uric acid (UA) increased linearly with Cl⁻ content (p < .05). (c) Na⁺ × Cl⁻ has a significant impact on the serum sodium (Na) and chlorine (Cl; p < .05). The content of serum Na and Cl increased linearly with increasing levels of Na⁺ and Cl⁻. These results show that low levels of Na⁺ and Cl⁻ had significant adverse effects on the growth of 1- to 28-day-old goslings. The results of the experiment support a recommendation to supplement the diet of goslings with 0.20% Cl⁻ and not <0.15% Na⁺.     

Mucosal and systemic T cell response in mice intragastrically infected with Neospora caninum tachyzoites

The murine model has been widely used to study the host immune response to Neospora caninum. However, in most studies, the intraperitoneal route was preferentially used to establish infection. Here, C57BL/6 mice were infected with N. caninum tachyzoites by the intragastric route, as it more closely resembles the natural route of infection through the gastrointestinal tract. The elicited T-cell mediated immune response was evaluated in the intestinal epithelium and mesenteric lymph nodes (MLN). Early upon the parasitic challenge, IL-12 production by conventional and plasmacytoid dendritic cells was increased in MLN. Accordingly, increased proportions and numbers of TCRαβ⁺CD8⁺IFN-γ⁺ lymphocytes were detected, not only in the intestinal epithelium and MLN, but also in the spleen of the infected mice. In this organ, IFN-γ-producing TCRαβ⁺CD4⁺ T cells were also found to increase in the infected mice, however later than CD8⁺ T cells. Interestingly, splenic and MLN CD4⁺CD25⁺ T cells sorted from infected mice presented a suppressive activity on in vitro T cell proliferation and cytokine production above that of control counterparts. These results altogether indicate that, by producing IFN-γ, TCRαβ⁺CD8⁺ cells contribute for local and systemic host protection in the earliest days upon infection established through the gastrointestinal tract. Nevertheless, they also provide substantial evidence for a parasite-driven reinforcement of T regulatory cell function which may contribute for parasite persistence in the host and might represent an additional barrier to overcome towards effective vaccination.     

Dietary Sodium and Chloride for Twenty-Nine-to Forty-Two-Day-Old Broiler Chickens at Constant Electrolyte Balance Under Subtropical Summer Conditions

The study was conducted to evaluate the response of broiler chicks to different dietary Na⁺ and Cl⁻ concentrations with similar dietary electrolyte balance of 250 mEq/kg during 29 to 42 d of age in a hot environment with average minimum and maximum temperatures of 32.4 and 36.6°C, respectively, and an average RH of 69.2%. Three levels of dietary Na⁺ (0.20, 0.25, and 0.30%) and 3 levels of dietary Cl⁻ (0.30, 0.40, and 0.50%) were used in 3 × 3 factorial arrangement in which BW at 28 d were used as covariate in the statistical analysis. A decreasing linear effect of dietary Na⁺ was observed on breast yield and lowering of abdominal fat, whereas increasing dietary Cl⁻ linearly increased litter moisture and decreased dressing weights. No significant effects of dietary Na⁺, Cl⁻, or Na⁺ × Cl⁻ were observed on feed intake, BW gain, feed:gain, rectal temperature, water:feed, or mortality. An improvement in litter condition, toe ash, blood parameters, and lowered abdominal fat yield was observed for the diet having 0.30% dietary Na⁺. The results of the present study suggest the dietary requirements of 0.20 to 0.25% Na⁺ and 0.30% Cl⁻ during the finisher phase (29 to 42 d) of broiler chicks when the ambient temperature ranged from 32 to 40°C.     

Study of Sperm Concentration,Seminal Plasma Composition and their Physiological Correlation in the Persian Sturgeon,Acipenser persicus

The objectives of the present study were to determine ionic and organic composition of seminal plasma, sperm concentration and their relationships in the Persian sturgeon (Acipenser persicus). In this regard, ionic content (Na⁺, K⁺, Cl^?, Ca²⁺ and Mg²⁺) and organic content (total protein, glucose, cholesterol and triglyceride) along with sperm concentration were measured in 17 specimens of the Persian sturgeon. The seminal plasma contained 59.53 ± 2.56 mm /l sodium, 9.1 ± 1.42 mm chloride, 4.72 ± 0.3 mm potassium, 1.45 ± 0.075 mm calcium and 0.7 ± 0.072 mm magnesium. The following organic contents were found: total protein 0.11 ± 0.02 g/dl, glucose 22.18 ± 4.16 mg/dl, cholesterol 6.67 ± 1.04 mg/dl and triglyceride 15.2 ± 0.65 mg/dl. The mean sperm concentration was estimated to be 1.6 ± 0.12 (×10⁹ sperm/ml). A significant relationship was found between sperm concentration and K⁺ of seminal plasma (r = 0.533, p < 0.05). Significant correlations were observed between ionic contents: Na⁺ vs Cl^? (r = ?0.854, p < 0.01) and Mg²⁺ vs K⁺ (?0.583, p < 0.05). Also, level of triglyceride was negatively correlated with Mg²⁺ (r = ?0.503, p < 0.05). Presented data could be considered as a complementary study for developing special extenders and protectant solutions for improving artificial fertilization in this valuable species.     

Influence of copper sulphate on the water and electrolyte balance of the freshwater snail Bulinus (Bulinus) tropicus

The water and electrolyte balance of Bulinus (Bulinus) tropicus, a freshwater pulmonate, was determined when subjected to different sublethal concentrations of copper sulphate. It was found that the lethal dose (LD₅₀), which is the dose lethal to 50% of the snails, is 1,0 ppm in water of pH 8,5. Increasing dosages disturb the ionic and water balance. Haemolymph concentrations of Na ⁺ , Ca²⁺ and Cl^- decrease markedly. The rates of ion influx and efflux for Ca²⁺ , Na ⁺ , Cl^- and ³H₂0, measured With their corresponding radioisotopes, were drastically changed. The results indicate that the physiological effects of copper are not limited to particular organs or tissues but probably occur throughout the snail body. The possible effect of copper sulphate on the in- tegumental exchange mechanisms for Ca²⁺, HCO3^-, Na⁺ , K⁺ and Cl^- are discussed.     

Spermatozoa Concentration,Seminal Plasma Composition and Their Physiological Relationship in the Endangered Stellate Sturgeon (Acipenser stellatus) and Russian Sturgeon (Acipenser gueldenstaedtii )

Comparative studies of ionic composition, osmolality, protein concentration and pH of seminal plasma along with spermatozoa concentrations were carried out in stellate sturgeon, Acipenser stellatus, and Russian sturgeon, Acipenser gueldenstaedtii. Analysis of A. gueldenstaedtii sperm showed significantly higher concentrations of Na⁺ (34.58 ± 4.61 mm ), Ca²⁺ (0.35 ± 0.12 mm ), Mg²⁺ (0.70 ± 0.25 mm ), Cl^? (13.50 ± 4.04 mm ) and proteins (0.60 ± 0.29 mg/ml) in the seminal plasma than did seminal plasma of A. stellatus: Na⁺ (20.08 ± 10.75 mm ), Ca²⁺ (0.28 ± 0.06 mm ), Mg²⁺ (0.29 ± 0.05 mm ), Cl^? (7.50 ± 3.00 mm ) and 0.30 ± 0.11 mg/ml proteins. Significantly higher concentration of K⁺ (5.42 ± 1.06 mm ) was observed in A. stellatus compared to A. gueldenstaedtii K⁺ (2.29 ± 0.50 mm ). Concentration of Na⁺ was positively correlated with osmolality (r = 0.819), levels of Cl^? (r = 0.922) and Mg²⁺ (r = 0.727) and pH (r = 0.848). The concentration of Mg²⁺ was positively correlated with protein concentration (r = 0.774), Na⁺ (r = 0.727), Cl^? (r = 0.872) and Ca²⁺ (r = 0.801). A positive relationship was also found between concentration of K⁺ and spermatozoa concentration (r = 0.709). Results revealed strong inter‐species differences in several parameters. The data should be useful for artificial fertilization and for cryopreservation of sturgeon sperm.     

Feed-induced Changes in the Transport of Butyrate,Sodium and Chloride Ions Across the Isolated Bovine Rumen Epithelium

A short-chain fatty acid (SCFA) burst feeding strategy to dry cows (periodically high SCFA concentration in the ruminal fluid) has been hypothesized to increase the ruminal surface area and absorptive capacity. The present paper deals with the effects of a SCFA burst feeding strategy on epithelial transport function in dry cows. The epithelial transport capacity for [¹⁴C]butyrate and Na⁺ across the rumen epithelium in vitro was significantly increased by the SCFA burst feeding strategy, compared with the controls. The transport of Cl^- was significantly increased by the SCFA burst feeding strategy at the high feeding level, but non-significantly decreased at the low feeding level. The increase in transport capacity could not be attributed to changes in epithelial resistance, to the concentration of Na⁺/K⁺-ATP-ase or to the epithelial surface area and structure (data on epithelial surface area and structure were published by Andersen et al., Report No. 23 from the National Institute of Animal Science, Denmark, 1994). The observed changes in transport must reflect a change in either composition of the cell membranes or processes that facilitate transport through the cell, including metabolic processes. The presented results support the existence of a saturable SCFA transport system in the epithelial cells and the results show that the capacity of this transport system can be the subject for feed-induced regulation.     

Evaluation of Emamectin Benzoate for the Control of Experimentally Induced Infestations of Argulus sp. in Goldfish and Koi Carp

Abstract

The effect of 0.2% emamectin benzoate (SLICE; Intervet/ Schering-Plough Animal Health, Roseland, New Jersey) administered in top-dressed, pelleted commercial fish feed was evaluated for control of freshwater Argulus sp. in goldfish Carassius auratus and koi carp, a variant of common carp Cyprinus carpio, in freshwater aquaria at 24–25°C. Sixteen individually housed goldfish were each exposed to 37 Argulus. The number of fish lice attached to each fish at the start of the experiment was not determined; however, the total number of motile fish lice in each aquarium (on fish and in the water) was determined at the start and end of each experiment. Eight goldfish were fed the control diet (0 μg · kg fish biomass^?1 · d^?1) and eight were fed the medicated diet (50 μg · kg fish biomass^?1 · d^?1) for seven consecutive days. After treatment, fish louse infestation in controls was 20.5 ± 1.5 (mean ± SE) lice per fish. No Argulus were found on fish in the treated group. In a separate experiment, 10 individually housed koi were each exposed to 128 Argulus. Five koi were fed the control diet and five were fed a low-dose medicated diet (5 μg · kg fish biomass^?1 · d^?1) for 7 d. After treatment, fish louse infestation among the controls was 14.6 ± 3.8 lice per koi. No Argulus were found on koi in the treated group. Hence, a 7-d regimen of oral emamectin benzoate controlled experimental infestation of Argulus when administered to goldfish at 50 μg · kg fish biomass^?1 · d^?1 and to koi at 5 μg · kg fish biomass^?1 · d^?1.

Received March 24, 2010; accepted January 17, 2011     

Cellular composition of granulomatous lesions in gut-associated lymphoid tissues of goats during the first year after experimental infection with Mycobacterium avium subsp. paratuberculosis

Mycobacterium avium subsp. paratuberculosis (MAP) causes lesions in naturally and experimentally infected ruminants which greatly differ in severity, cellular composition and number of mycobacteria. Morphologically distinct lesions are already found during the clinically inapparent phase of infection. The complex local host response and number of MAP were characterized at the initial sites of lesions, organized gut-associated lymphoid tissue, in experimentally infected goats. Tissues were collected at 3, 6, 9 and 12 month post-inoculation (mpi) from goat kids that had orally received 10 times 10 mg of bacterial wet mass of MAP (JII-1961). The cellular composition of lesions in Peyer's patches in the jejunum and next to the ileocecal valve was evaluated in 21 MAP-inoculated goats, where lesions were compared with unaltered tissue of six control goats. CD68⁺, CD4⁺, CD8⁺, γδ T lymphocytes, B lymphocytes and plasma cells, MHC class II⁺ and CD25⁺ cells were demonstrated by immunohistochemistry in serial cryostat sections.At 3 mpi, extensive granulomatous infiltrates predominated, consisting of numerous epitheloid cells admixed with many CD4 and γδ T lymphocytes. Only single MAP were detected. This indicates a strong cellular immune reaction able to control MAP infection. γδ T lymphocytes were markedly increased in this type of lesion which may reflect their important role early in the pathogenesis of paratuberculosis. At 9 and 12 mpi, divergent lesions were observed which may reflect different outcomes of host–pathogen interactions. In five goats, minimal granulomatous lesions were surrounded by extensive lymphoplasmacytic infiltrates and no MAP were detected by immunohistochemistry. This was interpreted as effective host response that was able to eliminate MAP locally. In three goats, decreased numbers of lymphocytes, but extensive granulomatous infiltrates with numerous epitheloid cells containing increased numbers of mycobacteria were seen. This shift of the immune response resulted in uncontrolled mycobacterial multiplication. Focal and multifocal circumscribed granulomatous infiltrates of mainly epitheloid cells may represent sites of new infection, since they were observed in goats at all times after inoculation. Their presence in goats with minimal granulomatous lesions surrounded by extensive lymphoplasmacytic infiltrates may indicate that despite the local clearance, the infection may be perpetuated.The complex cellular immune reactions postulated for the pathogenesis of paratuberculosis were demonstrated at the local sites of infection. These early host–pathogen interactions are most likely essential for the eventual outcome of the MAP infection.     

Preliminary Studies on the Concentration of Na+,K+-ATPase in Skeletal Muscle of Draught Cattle in Mozambique: Effect of Sex,Age and Training

The effect of training on the potential for work in draught cattle was assessed by measuring the Na⁺,K⁺-ATPase in the muscle cell membrane and the elevation in the concentration of K⁺ in plasma during exercise. Biopsies of the semitendinosus muscle and venous blood samples were taken from the cattle used for draught work in Mozambique. No differences were found in the plasma ion or Na⁺,K⁺-ATPase concentrations in samples taken from Nguni, Africander and Angoni breeds. There were no significant differences in plasma ions (Na⁺, K⁺ and Cl^–) or muscle Na⁺,K⁺-ATPase concentrations between the Angoni males and females, although the males showed an increase in Na⁺,K⁺-ATPase with age, while the females showed a decrease. The increase in males might be attributed to their higher level of activity in the herds than that of females. After a training period of 15 days, a significant increase in Na⁺,K⁺-ATPase concentration in semitendinosus muscle was found in Angoni cattle. In females, this was significant after 8 days of training (about 30%); in males after 15 days of training (about 16%). On day 15, there was a reduction in the elevation of plasma K⁺ during the 2 h of draught work, indicating an increased capacity of the Na⁺,K⁺ pumps to maintain the extracellular K⁺ concentration in working muscles and a possible delay in the moment of fatigue.     

Induction and Evaluation of Proliferative Gill Disease in Channel Catfish Fingerlings

Abstract

Proliferative gill disease (PGD) was first reported in channel catfish Ictalurus punctatus at commercial farms in 1981 and is caused by the myxozoan parasite Henneguya ictaluri. The disease affects the gills and is characterized by severe branchial inflammation, epithelial hyperplasia, lamellar fusion, and lysis of chondrocytes. Presumptive diagnosis is based on the presence of lytic areas in the cartilage of the primary lamellae on microscopic examination and is confirmed histologically by the presence of the organism. In these trials, PGD was induced by exposing channel catfish fingerlings to fresh or aged infectious water collected from a pond containing fish diagnosed with severe PGD. The severity of disease was graded by histological scoring and microscopic examination of wet mounts to determine the percentage of gill filaments containing chondrolytic lesions. Exposure of fish to infectious pond water was shown to produce pathological lesions consistent with PGD, and the percentage of gill filaments containing chondrolytic lesions was positively correlated with histological scoring of gill pathology. The number of trophozoite stages in the gills was shown to increase with the severity of the disease. In most cases, however, parasitic cells were not observed in tissue samples with chondrolytic lesions during the early stages of infection. These observations indicate that pathology and lysis of chondrocytes can occur prior to detection of the organism by histopathology. Exposing fish to infectious pond water that was aged for 1 d produced negligible gill pathology and implies that the infectivity of the H. ictaluri actinospore stage is short lived. Removing fish from the source of infection promoted repair of damaged gill tissue; within 14 d of fish transfer to clean water, gill pathology associated with the acute infection was negligible.     

Channel Catfish Response to Ultraviolet-B Radiation

Abstract

Fingerling channel catfish Ictalurus punctatus exposed to simulated ultraviolet-B radiation at an average daily dose of 2.9 J/cm² were quite sensitive to the radiation. After a 24-h exposure, thinning of the most dorsal epidermis frequently was accompanied by edema. Compared with epidermis of unexposed fish, mucous cells in exposed fish were less superficial and club cells were less numerous both dorsally and high on the lateral surface of the body. Sunburn cells with pyknotic nuclei were evident in the epidermis of exposed fish. Among fish exposed for 48 h, focal necrosis and sloughing of the outer epidermal layer were widespread. A methanol-extractable skin substance that is associated with resistance to sunburn in other fish species was not detected in channel catfish.     

Effects of dietary cation-anion balance on blood PH, acid base parameters, serum and urine mineral levels, and parathyroidhormone (PTH) in weanling horses.

This study demonstrated that the feeding of treatment diets with calculated dietary cation-anion balances (DCAB) of +370.43 (H) and -25.69 (L) did not have significant effects on blood pH, pCO₂, and HCO₃-. Serum Ca²⁺, P, Na⁺, and Cl^- as well as plasma PTH did not differ (P > .05) between the two treatment groups. Serum K⁺ was higher (P< .05) in horses fed diet H rather than diet L. The DCAB of the diet significantly affected urinary Ca²⁺, P, Na⁺, K⁺, and Cl^- excretion in the young growing horse. Urine Ca²⁺ and Cl- levels were higher (P < .01) in horses fed diet H versus diet L. Furthermore, levels of P, Na⁺, and K⁺ in the urine were higher (P < .01) in horses on diet H as opposed to diet L. Results of this study indicate that horses were able to maintain acid-base status regardless of diet. However, these data imply that growing horses consuming diets low in DCAB may be predisposed to abnormal bone mineralization due to the increase in calcium excretion which could lead to a weakening of the skeletal system.     

Composition of seminal plasma and ovarian fluid in Ide Leuciscus idus and Northern pike Esox lucius

Seminal plasma (SP) and ovarian fluid (OF) plays an important role as storage media to prevent the activation of gametes both in vivo and under artificial conditions. The objectives of this study were to quantify gamete biochemistry and explore correlations among quantitative characteristics of SP, OF and sperm performance traits of Ide Leuciscus idus and Northern pike Esox lucius. Generally, Na⁺, K⁺ and Cl^? were found to be the most dominating ions, although concentrations of K⁺ were higher in SP, while Na⁺ and Cl^? concentrations were higher in OF for both species. Several significant correlations among the biochemical properties such as total protein, glucose, osmolality, cholesterol, K⁺, Ca²⁺, Cl^? and Mg²⁺ were observed for SP and OF. Total protein content of Ide SP was positively correlated with sperm activity traits (r ≥ .89, p ≤ .05), while K⁺ concentration was negatively correlated with sperm traits (r ≥ ?.89, p ≤ .05). Moreover, Ca²⁺ concentration in Northern pike SP was positively correlated with the percentage of sperm motility (r = . 98, p < .01). In conclusion, these results can be used to better understand the biochemistry of SP and OF, improve methods for short‐ and long‐term storage of gametes and standardize fertilization protocols.     

Effects of reducing dietary ([Na + K − [Cl + SO4]) on bone in dairy cows at parturition

The effects of feeding diets with different milliequivalents (mEq) of dietary ([Na⁺ + K⁺] − [Cl⁻ + SO₄⁼]) to dairy cows during the last seven weeks of pregnancy on bone morphology at parturition were studied. Nine monozygotic twin pairs of pregnant cows (five pairs of parity 1 or 2 and four pairs of parity 3 or more) were allocated to two diets which were formulated to provide either −4 mEq (anion diet) or +572·5 mEq (cation diet) of ([Na⁺ + K⁺] − [Cl⁻ + SO₄⁼]) kg⁻¹ dietary dry matter. Bone biopsies were taken from the tuber coxae between three and eight hours after parturition. The plasma concentrations of calcium and inorganic phosphorus, the total plasma alkaline phosphatase activity and the urinary hydroxyproline:creatinine ratio were not significantly affected by diet during the experimental period. In low parity (2 or less) cows the percentage trabecular bone volume, the percentage osteoclast surface and the mean number of osteoclasts per microscopic field (identified by Goldner staining) were lower on the anion diet than on the cation diet (P<0-02). In the high parity cows, the percentage osteoid volume (P<0·05) and the ratio of percentage osteoid volume to percentage osteoid surface (P<0·001) were greater in the cows fed the anion diet than in the cows fed the cation diet. The results show that reducing the mEq of dietary ([Na⁺ + K⁺] − [Cl⁻ + SO₄⁼]) to −4 mEq kg⁻¹ dietary dry matter affected some of the parameters of bone formation but did not enhance bone resorption.     

Goldfish, <Emphasis Type="Italic">Carassius auratus</Emphasis>, as an infection model for studying the pathogenesis of <Emphasis Type="Italic">Edwardsiella piscicida</Emphasis>

This study demonstrates the feasibility of using goldfish as an infection model to investigate the pathogenesis of Edwardsiella piscicida. Goldfish were found to be susceptible to acute E. piscicida-induced disease and died in a dose-dependent manner. E. piscicida was further shown to replicate rapidly in the head kidneys and livers of infected goldfish from 1 d post-injection, and bacteria numbers were significantly decreased 5 d post-injection. Immune responses were successfully induced in goldfish injected with E. piscicida strains and 60% of goldfish inoculated with an attenuated E. piscicida strain were found to survive subsequent injection with a pathogenic strain. The results of differential leukocyte count experiments suggested that leukocytes were immediately recruited as an innate immune response against the infection. Thus, this well-characterized goldfish species is a suitable infection model for studying E. piscicida pathogenesis, and might be applicable to research on other fish diseases.