Induced Maturation and Spawning of the Chinese Catfish Clarias fuscus

Chinese catfish ( Clarias fuscus ) were successfully spawned in Hawaii using human chorionic gonadotropin (HCG) at dosage rates of two and four international units (IU) per gram body weight. Fish not injected with HCG did not produce viable eggs. Successful spawns with HCG occurred between May and October. Hatch rates of up to 80% were obtained during June, July, and August for those fish given either a 2 or 4 IU per gram body weight injection of HCG. Fish spawned in either May or October yielded significantly higher hatch rates when injected with 4 rather than 2 IU per gram body weight. Fish held at elevated temperatures (28 to 30 C) prior to the normal spawning season developed significantly larger oocyte diameters, 60 days earlier than fish held under ambient temperature conditions (21.5 to 24 C). Photoperiod manipulation at ambient temperature conditions was associated with earlier oocyte maturation, but photoperiod effects were much less important than temperature.     

Prolongation of xylazine/ketamine induced recumbency time with temazepam in horses

Short term anaesthesia induced with xylazine and ketamine was compared to a combination of xylazine, ketamine and temazepam (a benzodiazepine) in six adult horses. Duration of recumbency was significantly prolonged when temazepam was administered with xylazine and ketamine. No significant differences in heart rate, respiratory rate, blood pressure or arterial pH, pCO2 and pO2 were seen between the xylazine and ketamine combination plus temazepam, and xylazine and ketamine combination only treated horses.     

Culture and Stimulation of Tammar Wallaby Lymphocytes

We describe the culture and stimulation of lymphocytes from the model marsupial, the tammar wallaby (Macropus eugenii). We also describe the capacity of tammar wallaby lymphocytes isolated from blood, spleen and lymph nodes to produce soluble immunomodulatory factors. Culture conditions were optimized for mitogen-driven stimulation using the plant lectin phytohaemagglutinin (PHA). Products secreted by stimulated cells were harvested and crudely fractionated before they were added back to freshly isolated lymphocytes. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay, both stimulatory and inhibitory bioactive factors were detected in serum-free supernatants harvested from mitogen-treated peripheral blood mononuclear cells. This paper describes the capacity of leukocytes of the tammar wallaby to respond to mitogenic stimulation and to produce soluble, low-molecular-weight bioactive molecules that possess cytokine-like activity.     

Can goats learn about foods through conditioned food aversions and preferences when multiple food options are simultaneously available?

The objective of this study was to determine the extent to which herbivores are able to use conditioned food aversions and preferences to learn about the nutritional and toxic properties of food plants, when food options are simultaneously available. Conditioned food aversions and preferences have been invoked as important mechanisms by which free-ranging herbivores optimize food selection by learning about the negative and positive consequences of consuming particular plant species through a series of encounters. In most previous tests of this hypothesis, access to individual test foods has been separated in time, giving animals the opportunity to associate particular foods with particular post-ingestive effects. We presented animals with a more complex scenario by offering test feeds simultaneously during the learning phase. Such a test is an important step in assessing the importance of conditioned food responses as mechanisms by which herbivores learn to select an optimal diet. We first assessed the ability of goats to learn about test foods and their post-ingestive effects, when different conifer species were offered on separate days during the learning phase and animals were dosed with compounds eliciting positive, negative, or neutral post-ingestive effects. We then investigated the ability of animals to learn to make appropriate choices when all potential test foods were simultaneously available during the learning phase. The results confirmed that goats can learn to associate particular foods with particular post-ingestive effects and adjust their diet selection accordingly. The success with which animals made such associations was greatly reduced when they were presented with test foods simultaneously during the learning phase. When test foods were simultaneously available, animals tended to select a mixed diet, thereby reducing their opportunity to learn about the post-ingestive effects of particular foods. The results suggest that caution is required in extrapolating results of artificial conditioning experiments to free-ranging herbivores. The results also suggest that reducing the risk of toxicity through selection of mixed diets is an important component of a successful foraging strategy.     

Analysis of the toxic potential of Palicourea corymbifera (Müll. Arg.) Standl. in laboratory animals

Palicourea species may produce bovine toxicity. Palicourea corymbifera grows in terra firme forests within the Amazon rain forest and in Tropical America, particularly in spots that gave place to gazing areas. The lyophilized extract done with the aerial organs of P. corymbifera were analyzed in male and female mice. Results revealed a significant toxicity: LD50 was 1.10 (1.04-1.15)g/kg for male mice, and 1.05 (1.00-1.10)g/kg for female mice. Locomotion was affected as well as there were reflexes linked to environmental stimuli in addition to changes in posture. Progressive central nervous system stimulus signs such as trembling and convulsions were detected, the latter followed by the animal's death. Macroscopic histopathological exams performed on the liver, kidneys and lungs of mice submitted to necropsy did not indicate the existence of lesions. General activity of animals, measured in an open field, was reduced as a result of the administration of the extract. Duration of locomotion and rearing frequency were reduced, in opposition to an increase in the duration of immobility. Thin layer chromatography analysis showed that monofluoroacetic acid is present in the lyophilized extract, but other qualitative techniques as gas chromatography/mass spectrometry and 19F nuclear magnetic resonance showed that the MFAA was not present in the extract, and that the toxicity is related to other compound, although the toxic profile is very similar to that of MFAA. P. corymbifera was shown to be significantly toxic to laboratory animals and investigation of the possible toxic substance shall be done.     

Studies on vitamin E and selenium deficiency in young pigs. III. Effect on kinetics of erythrocyte production and destruction.

The effect of vitamin E and/or selenium deficiency on the kinetics of erythrocyte production and destruction has been investigated in swine. The plasma iron turnover rate, 59Fe incorporation into newly formed red cells as well as the 51Cr apparent red cell half-life, were not found to be significantly affected by either vitamin E deficiency, selenium deficiency or deficiency of both, as compared to replete animals. The results of this study suggest that vitamin E is not a limiting factor for normal erythropoiesis in young growing pigs. Erythropoiesis appeared, however, to be slightly decreased in selenium deficient pigs and will need to be further investigated.     

Serum adipokine concentrations in dogs with diabetes mellitus: a pilot study

This study was conducted to determine whether serum adipokine concentrations differed between healthy dogs and dogs with diabetes mellitus (DM). To accomplish this, 19 dogs with newly diagnosed DM were compared to 20 otherwise healthy dogs. The serum concentrations of visfatin, leptin, IL-1β, IL-6, IL-18, and TNF-α were significantly higher in diabetic dogs than in healthy dogs, whereas the serum adiponectin concentrations were lower in diabetic dogs. However, there were no significant differences in the IL-10 and resistin levels between groups. The serum leptin concentrations in diabetic dogs with and without concurrent disorders differed significantly. Treatment with insulin induced a significant decrease in IL-6 in diabetic dogs without concurrent disorders. These results show that the clinical diabetic state of dogs could modulate the circulating visfatin and adiponectin concentrations directly, while upregulation of leptin was probably a result of concurrent disorders rather than an effect of persistent hyperglycemia as a result of DM.     

Association between the genetic similarity of the open reading frame 5 sequence of Porcine reproductive and respiratory syndrome virus and the similarity in clinical signs of Porcine reproductive and respiratory syndrome in Ontario swine herds

A study of Ontario swine farms positive for Porcine reproductive and respiratory syndrome virus (PRRSV) tested the association between genetic similarity of the virus and similarity of clinical signs reported by the herd owner. Herds were included if a positive result of polymerase chain reaction for PRRSV at the Animal Health Laboratory at the University of Guelph, Guelph, Ontario, was found between September 2004 and August 2007. Nucleotide-sequence similarity and clinical similarity, as determined from a telephone survey, were calculated for all pairs of herds. The Mantel test indicated that clinical similarity and sequence similarity were weakly correlated for most clinical signs. The generalized additive model indicated that virus homology with 2 vaccine viruses affected the association between sequence similarity and clinical similarity. When the data for herds with vaccine-like virus were removed from the dataset there was a significant association between virus similarity and similarity of the reported presence of abortion, stillbirth, preweaning mortality, and sow/boar mortality. Ownership similarity was also found to be associated with virus similarity and with similarity of the reported presence of sows being off-feed, nursery respiratory disease, nursery mortality, finisher respiratory disease, and finisher mortality. These results indicate that clinical signs of PRRS are associated with PRRSV genotype and that herd ownership is associated with both of these.