Climate warming may worsen the weather conditions in the future, and the incidence of extreme events such as high temperature and heat waves will continue to increase. What impact will this have on animals and even humans? The lactation period is an important stage for small mammals. Animals in the lactation have reached the maximum level of energy intake and consumption, and are particularly sensitive to changes in environmental temperature. Hence, what changes does temperature cause to small mammals, especially animals in the lactation?

High temperature significantly inhibits energy intake and reproductive output during lactation

Recently, the team led by Professor Zhao Zhijun at Wenzhou University discovered that high temperature and heat waves will significantly inhibit the energy intake and reproductive output of small mammals during lactation, and even the reproductive success rate. 

Prof. Zhao's team has long been committed to the study of the physiological and ecological characteristics of energy metabolism in small mammals, as well as the adaptation strategies and energetic adjustment mechanisms for climate change. The research team worked with Professor John Speakman (Institute of Genetics and Developmental Biology, Chinese Academy of Sciences) and Dr. Catherine Hambly (Aberdeen University of UK), and found that The energy intake and lactation (isotopic labeling technology) of experimental mice and black-lined hamsters decreased significantly with the increase of ambient temperature, and the lactation energy expenditure at high temperature (33°C) was lower than that at room temperature (21°C) respectively by 82% and 22%. The offspring mortality rate reached 20% and 13%, respectively. More importantly, compared with the non-lactating control group, lactating animals have a lower tolerance to high temperature, and the tolerance temperature is lower by 3-6°C. The results of the study show that although small mammals (compared to large animals) have higher thermal conductivity, they are also affected by high temperature and heat waves, which have a particularly serious impact on the reproduction output and even the success rate of reproduction during the lactation period.

The research results were published online on September 14, 2020 in Proceedings of the National Academy of Sciences of the United States of America (PNAS) (https://doi.org/10.1073/pnas.2008974117), a journal founded in 1914 whose IF in 2019 reaching 9.35. It is one of the most prestigious academic journals in the field of basic sciences. The papers included in PNAS cover biology, physics and social sciences.

Prof. Zhao’s team has also made a series of progress in the study of energy metabolism and fat regulation mechanisms during the reproduction, growth and development of small mammals. He has published more than 70 academic papers as the first author or corresponding author, of which more than 50 papers are SCI-indexed, with a cumulative impact factor of 118.5.