2023-06-15 12:23:35
Red deer don’t hibernate like some other mammals that have to deal with low temperatures and short days at high latitudes, but they reduce their metabolism if necessary. Researchers in Vienna have now shown that the level of the hormone melatonin is primarily responsible for this. With high doses of melatonin, the scientists sent the animals metabolically into the winter in early summer, as they report in the journal “Animals”.
The team led by study leader Walter Arnold from the Research Institute for Wildlife Ecology at the University of Veterinary Medicine (Vetmed) in Vienna carried out their investigations in a 45,000 square meter enclosure belonging to the institute. They equipped a total of 16 red deer cows (Cervus elaphus) with sensors that recorded heart rate, body temperature and the movement patterns of the animals between March 2017 and 2020, the researchers write in their work.
The aim of the study was to examine whether the seasonal physical changes in animals that do not hibernate follow the same signals as in hibernators. As is well known, the latter adjust their metabolism to the “photoperiod”, i.e. the change in the length of day and night over the course of the year. However, the availability of essential polyunsaturated fatty acids in food also has an influence on the reduction in body temperature and the shutting down of the metabolism.
On the one hand, the research team varied the amount of linoleic acid or linolenic acid present in the feed pellets that the animals ate. On the other hand, they changed the supply of melatonin released in dark phases. The hormone translates the information regarding the length of the day into a signal that the body can read.
When the scientists increased the melatonin level in early summer to three times the maximum value in winter, all measured characteristics in the animals switched towards winter mode: “We conclude from this that red deer reduce the energy expenditure for thermoregulation with short day lengths, a reaction , which is reinforced by a limited supply of food,” Arnold said in a Vetmed broadcast on Thursday. However, if the researchers only changed the fatty acid supply, the hinds showed only minor changes.
The new study shows for the first time that seasonal changes in non-hibernating mammals are driven by the same clocks as in animals that hibernate extensively. These processes are apparently “responsible for the timely preparation not only of hibernators, but also of many other species for the profound change in living conditions through the seasons,” says Arnold.
(S E R V I C E – https://doi.org/10.3390/ani13101600)
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