Glutathione S-transferase (GST) and cortisol levels vs. microbiology of the digestive system of sheep during lambing.

Background: During parturition, animals exhibit variation in hormone levels, homeostasis disturbance and dysfunction of the immune system as a result of stress. Glutathione S-transferase (GST) is responsible for the occurrence of oxidative stress in the cells. Cortisol is known as the stress hormone, but it is also involved in the metabolism of proteins, carbohydrates and metabolism processes led by adipose tissue. The aim of the this study was to determine how the levels of GST and cortisol change depending on the parity. Additionally, the influence of lambing on the microbiological composition of the digestive system and placenta in Olkuska sheep was investigated.

Methods: Eighteen ewes were selected for the experiment - primiparas (n = 9) and multiparas (n = 9), they were kept in the same environmental conditions, had the same diet and did not show any disease symptoms. Fecal samples were collected individually from each ewe (n = 18) and then bacterial DNA isolation was made, then qPCR analysis for Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria phyla and Lactobacillaceae family bacteria levels was performed. These samples were also used to analyze cortisol levels by ELISA test. In addition, placenta fragments were collected during delivery, and then the GST level from the tissue was tested.

Results: The analysis of the results showed a higher level of cortisol in primiparous sheep than in multiparous ones, as in the case of glutathione transferase. There were differences between both studied groups in the microbiological composition of the digestive system. In primiparous sheep, the levels of the tested microorganisms were significantly lower than in multiparous ones. A similar relationship occurred in the study of the placental microbiome.

Conclusion: The results show that sheep microbiome, cortisol and GST levels are different in primiparas and multiparas. The study conducted may constitute an introduction to further analyzes that would help positively affect the welfare and homeostasis of the female organism.