Significance of Intestinal Helminth Infection and Animal Sex for Mercury Concentrations in Two Rodent Species.

We compared the effects of animal gender, species, and intestinal helminth burden on mercury concentrations in rodents. Total mercury concentrations were determined in the liver and kidney tissues of 80 small rodents (44 yellow-necked mice, Apodemus flavicollis, and 36 bank voles, Myodes glareolus) captured in the Ore Mountains (northwest Bohemia, Czech Republic). Overall, 25/80 (32%) of animals were infected by intestinal helminths. The differences in mercury concentration between rodents infected and not infected with intestinal helminths were not statistically significant. Statistically significant differences in mercury concentrations were found only between voles and mice (that were not infected with intestinal helminths). This suggests the differences may be associated with host genetics. Apodemus flavicollis body tissues had significantly lower (P=0.01) mean Hg concentrations (0.032 mg/kg) than Myodes glareolus (0.279 mg/kg), provided that animals were not infected by intestinal helminths; if the animals were infected by intestinal helminths, the difference between both groups was insignificant. The effect of gender in this study was significant only for voles (without helminth infection); for mice (either with or without helminth infection) the differences between genders were not significant. Myodes glareolus males had significantly lower (P=0.03) Hg concentrations in liver and kidney tissues (0.050 mg/kg) than Myodes glareolus females (0.122 mg/kg). These results reveal the importance of considering species and gender when evaluating mercury concentrations.

Impact of Heat Stress on Selected Parameters of Robotic Milking.

The values of the temperature-humidity index and its influence on the performance parameters of dairy cows were monitored on four farms located in the southern part of the central Slovakia during a period of three years. The observed parameters included: the milk yield per cow per day, average milk speed and maximum milk speed. The thermal-humidity index was calculated based on a formula. The individual periods were divided according to the achieved THI. The results of dairy cows with a milk yield of 29 kg to 31 kg show that there is not a decrease in the milk yield per milking if the THI value is lower than 68. It was also found that there was a decrease in the milk yield per dairy cow in the robotic milking parlor for a THI value greater than 72. The influence of a THI value higher than 68 in these dairy cows results in a higher average milk speed, as well as a higher maximum milk speed. These two parameters are not yet in the main area of research interest. This study enriches the area with new knowledge, according to which dairy cows can show thermal stress by increasing the milk speed as well as the maximum milk speed.

Tenebrio molitor (Coleoptera: Tenebrionidae)-Optimization of Rearing Conditions to Obtain Desired Nutritional Values.

The present study dealt with the influence of temperature and feed on the nutritional value of Tenebrio molitor, especially on the content of crude protein, amino acids, fat, and fatty acid profile. Tenebrio molitor larvae were kept in 15, 20, and 25°C and fed with wheat bran, lentil flour, and mixture. The parameters were analyzed by international standard methods. Generally, with an increase of the lentils in the feed, the crude protein content increased. The changes in the temperature and the feed were most pronounced on the essential amino acids Val, Arg, and Leu. The highest average fat content was determined at 20°C in insects fed with wheat bran. The lowest fat content was determined at 15°C in bran-fed insects. The dependency of fat content on the temperature in feeding with lentil flour and a mixture of wheat bran and lentil flour was statistically insignificant (P > 0.05, Kruskal-Wallis, Mann-Whitney post hoc tests). The highest content of polyene fatty acids was achieved at a rearing temperature of 15°C and the bran diet. It was concluded that a higher proportion of protein diet could increase the content of crude protein in the insects. An increase in the temperature generally leads only to a slight increase in the content of nitrogenous substances. The influence of feed on this nutritional parameter is therefore much more significant than the effect of the rearing temperature. In general, it can be stated that the feed and the temperature also significantly affect the fat content.

Surprisingly low risk of overheating during digging in two subterranean rodents.

Capacities for and constraints of heat dissipation are considered to be important factors governing maximum intensity and duration of physical activity. Subterranean mammals are endurance diggers, but because of lack of air currents in their burrows, high relative humidity and other physical constraints, the capacity of common mammalian cooling mechanisms underground is very limited. We analyzed surface and body core temperature changes after digging in soft and hard substrates in two species of African mole-rats (Bathyergidae, Rodentia); the social giant mole-rat Fukomys mechowii and the solitary silvery mole-rat Heliophobius argenteocinereus. As expected, we observed an increase of body core temperature in both species after digging in both substrates. Surprisingly, and contrary to our expectations, we observed remarkable decrease of mole-rats' surface temperature immediately after the end of the digging trials. This decrease was greater in soft and moister soil than that in hard and drier soil. Our results suggest that mole-rats may effectively avoid overheating in burrows by effective cooling while digging, especially in wet soil. This indicates that burrowing in soils moistened by rains could be easier than previously thought contributing thus to mole-rats success in challenging environment of subterranean burrows.

Thermal profile of rabbits infected with Eimeria intestinalis.

In this study, infrared thermography (IRT) was assessed as a means of detecting the changes in body temperature in rabbit coccidiosis, as well as determining IRT used in imaging and measuring the regional changes in skin temperature that occur in the rabbits during this infection. Rabbits were inoculated with 5 x 10(4) or 1 x 10(5) oocysts of Eimeria intestinalis, respectively. The group of control animals remained non-inoculated throughout the study. All measured temperatures (rectal, ocular surface and auricle pavilion temperatures) dropped significantly (P<0.05) in rabbits infected with 1 x 10(5) oocysts. This group of rabbits also showed a medium negative correlation in rectal temperature (r=-0.49), ocular surface temperature (r=-0.49) and auricle pavilion temperature (r=-0.49) and a small negative correlation in live body weight gain (r=-0.22) depending on the number of days elapsed from the time of infection exposure.

Patterns of surface temperatures in two mole-rats (Bathyergidae) with different social systems as revealed by IR-thermography.

Furred subterranean mammals face the problem of dissipating heat to the environment because high humidity and absence of air flow in sealed belowground tunnels constrain heat loss from body by convection and evaporation. In order to detect body areas responsible for heat loss, surface temperatures in two species of African mole-rats were measured at different ambient air temperatures by infrared thermography. Fur characteristics were also evaluated. Thinner pelage of the ventrum, its moderate temperature and large size suggest that ventral side of the body is the main thermal avenue for heat loss in both species. Interspecific differences could be explained by different fur characteristics connected with social thermoregulation. Compared to the social Fukomys mechowii, the solitary Heliophobius argenteocinereus has denser and longer fur on most of its body; its surface temperature was thus lower than in F. mechowii at lowered ambient temperatures. On the other hand, the denser and longer hair cover in H. argenteocinereus impedes heat dissipation at highest ambient temperatures (and probably also during digging activity) resulting in increase of core body temperature. H. argenteocinereus seems to be more sensitive to overheating than F. mechowii. At lower air temperatures, the social species may uses huddling to combat hypothermia.