Leukocytes (white blood cells) are an important part of the mammalian immune system preventing the invasion and colonisation by different pathogens. Many factors may affect the number of leukocytes in mammals, including the population density. The population density in the same species of felines may differ 100-300 times and the aim of this study was to estimate an effect of this factor on the leukocytes number and the ratio for two groups of domestic cats (Felis catus) with different population densities. We sampled 47 cats in the surroundings of Daursky State Nature Reserve, counted the number of leukocytes with a microscope immediately upon sampling and the leukocytes formula in the blood smears later in the laboratory. The population density of cats in the village and at herdsman stations differs approximately by 330 times. Domestic cats in the village (with a denser population) had a higher number of leukocytes and neutrophils, but the same number of lymphocytes and neutrophils/lymphocytes ratio. The number of eosinophils was also higher in village cats. Presumably, the higher number of leukocytes and neutrophils in a cat population with higher density is determined by the higher exchange rate of pathogens/symbionts between cats in the village than at the herdsman stations. These results may give some insight into understanding the changes in wild feline populations at different densities.
Hair can be a useful matrix to examine the hormonal status of an animal, although it is difficult to correlate the results to a specific time point. The aim of this study was to evaluate seasonal changes in cortisol and testosterone levels in the hair of four feline species (lynx, Lynx lynx, n = 8; Amur wildcat, Prionailurus bengalensis euptilurus, n = 8; caracal, Caracal caracal, n = 6 and domestic cat, Felis catus, n = 17) with different breeding strategies. Animals of both sexes were sampled over the year, once per season (every three months), and the concentrations of hair testosterone and cortisol were measured by EIA. Both hormones showed annual dynamic changes, which coincided with the reproductive seasonality of the studied species. Sexual differences in testosterone level were found only during the mating season (spring for lynx and Amur wildcats, spring–summer for domestic cats), when testosterone levels were higher in males than in females. Cortisol levels were higher in males than in females in domestic cats and Amur wildcat, but also only during the mating season. Seasonal increases in testosterone were observed in three seasonal breeders (lynx, Amur wildcat and domestic cat) but not in caracal, which had high testosterone levels over the whole year. In lynx and Amur wildcat, it decreased sharply in the summer. Cortisol levels increased during the mating period in domestic cat males and lynx of both sexes; in caracal, an increase in cortisol was related to the transfer of animals to smaller winter cages. Measurements of steroids in hair can provide a reliable method for evaluating the reproductive status and the activity of the hypothalamus–pituitary–adrenal axis in several felid species.
Procapra gutturosa (hereinafter – Mongolian gazelle) is one of the last large migratory mammal species in Asia, which population has declined considerably over the past century due to various anthropogenic factors. In Russia, the Mongolian gazelle inhabits the north of its natural range, which supposes suboptimal conditions for this species, and it is listed in the Red Data Book of the Russian Federation. The physiological status of its calves was studied in the Daursky State Nature Reserve in 2015–2021 by assessing their body mass and the presence of antibodies to several pathogens. It was found that the body mass of Mongolian gazelle calves averaged from 2.85 kg to 6.14 kg and varied depending on such factors as sex, age and year of data collection. It was also related to climatic conditions, especially during the last third of pregnancy. In addition, Mongolian gazelle individuals were identified, which are seropositive to foot-and-mouth disease and peste des petits ruminants, but not to pasteurellosis and brucellosis. The number of positive reactions to the pathogens varied from year to year. So, the highest number of seropositive individuals was detected in 2018, representing 63.3%. Being still connected with the main range, the Mongolian gazelle group in Russia (surroundings of the Daursky State Nature Reserve) is gradually increasing. The study of animals’ physiological condition makes it possible to predict changes in the status of this ungulate group.
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