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The mercury-binding capacity of seleno-DL-methionine and selenium dioxide was assessed in male Wistar rats. Mercury was supplied as fish loaves made of northern pike or rainbow trout. We used a selenium concentration of 3.4 mg/kg fish, about sixfold compared to the equivalent quantity of mercury. Seleno-DL-methionine had a tendency to increase both methyl mercury and total mercury in blood, although it also seemed to reduce the proportion of methyl mercury of total mercury. Selenium dioxide lowered mercury levels by 24–29% both in the blood and in the liver of rats that were fed with northern pike.

In-cage reaction tests, the open field test and daily activity in the home cage were used to assess the effect of the internal design and location of cages on the behaviour of juvenile blue foxes (Alopex lagopus) during the growing season. The inclusion of nest boxes or resting platforms affected the behaviour of farmed blue foxes, but to a lesser extent than did the location of the animal in the cage row, i.e. the environment outside the cage itself. This study demonstrated that the actual environment in which the farm foxes live may be far larger than the cage interior itself, and that attempts to improve housing design should take into consideration the environment outside the cage to a greater extent than has heretofore been the case.

The preferences of juvenile farmed silver foxes (n = 14) and blue foxes (n = 12) for an empty cage (105L × 115W × 70H cm) and a cage of equal size with a wooden nest box were assessed in an 11-day preference test. The silver foxes spent a higher percentage of their time (86 ± 8%) in the nest box cage than the blue foxes (66 ± 21%). The silver foxes, but not the blue foxes, had a strong preference for the nest box roof as a resting site (44% of total daily time). Assuming that greater use indicates a greater need, silver foxes may benefit more from the nest boxes than blue foxes.

Rats were trained by daily running exercises for 7 weeks. In addition, one group of rats was trained under the influence of propranolol, while another group received daily injections of propranolol only. None of the treatments used had influence on the activities of myocardial enzymes: 3-hydroxyacyl-CoA dehydrogenase (HADH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), and citrate synthase (CS) which were assayed for estimating oxidative capacity, or lactate dehydrogenase (LDH) which was used as a measure of anaerobic capacity. Training without propranolol resulted in elevated activities of the oxidative enzymes in M. extensor digitorum and in M. soleus. The corresponding changes in the rat group trained with propranolol always were much smaller, despite an equal amount of training. Only the trend for lowered activity of LDH was observable in skeletal muscle of the rat groups trained both with and without propranolol. Long-term beta-blockade alone did not induce enzymatic changes. It is concluded that a functioning sympathetic nervous system is necessary for the adaptive responses of muscular metabolism to training. Blockade of the sympathetic influence during exercise periods also hampers the training-induced responses.

At weaning raccoon dogs were divided into two experimental groups: (1) Group 2, animals kept in pairs in standard cages, and (2) Group 4, four animals kept in each cage measuring four times larger than standard cages. At the same time the animals in each cage were ranked into different social classes according to their weaning body weight (social status 1=heaviest, 2=lightest). The parameters measured during the experiments were body weight, feed intake, character (tameness score), organ scaling and fur quality characteristics. The aim of the regime was to elucidate to which extent the productive performance of the animals could be predicted from the factors such as group size, litter, sex, social status and tameness score. The results showed that both experimental groups gained weight at the same mean rate, and no statistical differences existed between the mean weights of social groups either. Within each cage group, however, significant weight differences were found from mid-August onwards. Feed consumption, fur quality and tameness score were of the same order of magnitude in both groups. The differences in organ sizes were minimal and mainly non-significant. Tameness was weakly associated with the social status (body weight) of the animals with the most dominant animals having the least tameness score. Social status, tameness score, litter, sex and group together accounted for 53% of the total variation in final body weight. Social status was the only single factor having significant importance to the variation in body weight whereas the group size and cage condition emerged to be the least important factors.

Effects of dietary dilution, plane of energy intake and meal frequency on growth, body composition, organ sizes and fur quality parameters were studied on farmed raccoon dogs (Nyctereutes procyonoides Gray 1834) during the growing period (July-November). Meal frequencies were manipulated by two fasting arrangements: (1) animals without feed twice a week (Wednesday and Sunday), but other days fed ad libitum, (2) two-day ration offered every other day. Feed dilution was achieved by mixing low-energetic brewers' mash (25%; w/w) with basal feed. Both the diluted and the basal diets were offered as restricted or ad libitum portions. Live weight curves of the experimental groups were similar (p>0.05). Energetic efficiency of the animals was clearly better on mash than on basal diet. Daily feed spillage was highest in mash groups whereas feed remains in these groups were the lowest. No significant differences in the carcass content of ash, lean or fatty tissues between different feeding groups were found. With increasing age (and body weight) the amounts of carcass ash, protein, fat and energy increased. In adult animals, there were a positive correlation between carcass weight and carcass energy (r=0.87), fat (r=0.83) and protein (r=0.82). In general, no marked differences in fur quality parameters between different groups were found—the only exception being animals fasted twice a week whose mass and quality of fur was poorer (p<0.05) than that in other groups. The quality of fur was better in animals of longer and heavier pelts, i.e. in animals of big body size. The weights of visceral organs in various feeding groups did not differ significantly from each other. This supports earlier findings that no reliable conclusions can be drawn regarding the previous dietary history of the animals from their organ sizes. It is concluded that raccoon dogs naturally are accustomed to utilize effectively the energy of meals irrespective of their frequencies. Thus, restricted feeding in an attempt to avoid excessive fattening probably results in a simultaneous restriction in protein accumulation, and in a smaller pelt size.

Rats were treated by daily swimming or running exercises for 7 weeks. One group of rats was also trained under the influence of propranolol, while another group received daily propranolol injections only.

Rats were trained by daily swimming or running exercises with and without daily propranolol injections. Both training methods resulted in cardiac enlargement, but only swimming exercise caused hypertrophy of the brown adipose tissue. These changes were antagonized by beta blockade. The size of the adrenals reflected the stress of the treatments, but other known stress parameters, such as the size of the thymus or sexual organs dit not. Only swimming training without beta blockade sensitized the rats to the calorigenic action of noradrenaline. The cooling rate of the rats in water, when taking into account the insulative capacity of the body, was decreased in swimming-trained as well as in propranolol-treated rats but increased in running-trained rats. The latter two changes may be due to circulatory alterations, while the delayed body cooling in swimming-trained rats probably results from increased heat production capacity. Training-induced resting bradycardia and enhanced tachycardic response to isoprenaline were observable only in the animal groups trained without beta blockade. The pressor response to noradrenaline tended to be higher in the trained groups and the propranolol-treated group than in the controls and was smaller in the animal groups trained under the influence of beta blockade. On the other hand, the hypotonic response to isoprenaline was smaller in the propranolol-treated and running-trained animals. The results emphasize the importance of the sympathetic nervous system in the adaptation of an organism to physical training.

1.Slow and fast contractions, as well as the corresponding excitatory junction potentials (ejp's) were recorded from the closer muscle (adductor of the dactylopodite) of the third walking legs, subjected to temperatures ranging from +6 °C to +32 °C. In addition, the effect of temperature on resting potential and resting tension was studied, and in several preparations we investigated the effect of temperature on the efficacy of the inhibitory axon. The experimental animals had been acclimated at 12 °C.2.The membrane potential was found to increase with temperature. In the lower temperature range (e.g., between 6°C and 14–18 °C) the slope was usually steeper; the maximal rate of change was 2 mV/°C.3.The amplitude of facilitated slow ejp's (10/s) changes only insignificantly over the temperature span from 6 °C to about 22 °C and declines at higher temperatures. Fast ejp's have maximal amplitudes at 20 °C and decline at lower and higher temperatures, the decline being insignificant, however, below 14 °C.4.Facilitation rate also changes little with temperature; a significant increase occurs near 30 °C in the case of fast ejp's, and between 15 °C and 20 °C in the case of slow ejp's. Above 28 °C, facilitation of slow ejp's declines.5.As the temperature is lowered, many muscles develop a contracture which may reach 10% of maximal tension at 6 °C. These temperature-induced contractures can be abolished by stimulation of the inhibitory axon.6.The effectiveness of the inhibitory axon in reducing the contraction caused by the slow motor axon increases with decreasing temperature.7.The time course of the decay of both slow and fast ejp's increases with falling temperature, particularly in the temperature range below 12 °C.8.At a given frequency (1–30/s), both slow and fast contractions increased with falling temperature over the entire temperature range tested. This increased efficiency of the neuro-muscular system is attributed to the depolarization and the prolonged time course of the ejp's.

Crayfish, Astacus leptodactylus, were acclimated to 12°C and to 25°C. Nerve muscle preparations (closer muscle of walking legs) were subjected to temperatures ranging from 6 to 32°C. The resting membrane potential of muscle fibres was found to increase with temperature in a linear manner, but with a change in slope at around 17° in cold-acclimated preparations, and around 24°C in warm-acclimated ones. Temperature acclimation shifted the temperature range of maximal amplitudes of fast and slow e.j.p.s toward the acclimation temperature. Optimal facilitation of slow e.j.p.s also occurred near the respective acclimation temperature. E.j.p. decay time is nearly independent of temperature in the upper temperature range but increases steeply when the temperature falls below a critical range around 17°C in preparations from cold-acclimated animals, and around 22°C after acclimation to 25°C. Peak depolarizations reached by summating facilitated e.j.p.s are conspicuously independent of temperature over a wide range (slow and fast e.j.p.s of cold-acclimated preparations, fast e.j.p.s of warm-acclimated ones) which extends to higher temperatures after warm acclimation in the case of fast e.j.p.s. In warm-acclimated preparations the peak depolarization of slow e.j.p.s first falls then rises and falls again as the temperature increases from 8 to 32°C. Tension development elicited by stimulation of the slow axon at a given frequency reaches maximal values at the lower end of the temperature range in cold-acclimated preparations. The maximum is shifted towards 20°C after warm acclimation. Fast contractions decline with temperature; possible acclimation effects are masked by the great lability of fast contractions in warm-acclimated preparations. It is suggested that changes in the composition of membrane lipids may be responsible for the effects of acclimation on the electrical parameters and their characteristic temperature dependence.