Research from the Faculty of Veterinary Medicine and Animal Science (FMVZ) at University of São Paulo reveals that supplementation with donkey milk reduced the release of cortisol, known as a stress hormone, and the inflammatory response in piglets during the weaning period.
The study, carried out in collaboration with the Federal University of Bahia (UFBA), suggests that donkey milk has potential use as a supplement for human babies, which will depend on further investigation. The results of the work also indicate that the production of this milk could eliminate the slaughter of donkeys for export of the skin, which has put the survival of the species at risk.
“The research was inspired by a study we completed in the Northeast where 70% of those interviewed, in the regions of Euclides da Cunha, in Bahia, and Santa Quitéria, in Ceará, commented on the use of donkey milk for therapeutic purposes,” they report to USP Journal Sharacely de Souza Farias, responsible for the research, and professor Adroaldo José Zanella, from FMVZ, supervisor of the work. “According to the latest data computed by the Brazilian Institute of Geography and Statistics (IBGE) in 2018, there were 822,255 donkeys in Brazil.”
According to the researchers, donkey milk is not sold in the country, however in countries such as Germany, France and Italy, it is used especially to care for premature babies.
“Donkey milk is highly valued for its similarity to human milk,” they point out. “As research indicates that weaning is a very stressful period for piglets, we studied the effect of supplementation during this period.”
In commercial farms, weaning takes place after four weeks of age, while in natural situations it takes place at up to 12 weeks.
In the experiment, the piglets were divided into three groups, which received donkey's milk, skimmed cow's milk and no supplements, three days before and three days after weaning.
“To evaluate the effectiveness of the supplementation on the immune, cognitive system and response to stress, the concentration of salivary cortisol was measured, which is a hormone linked to stress. In addition to behavioral tests that measure emotionality and cognition and isolation of piglets' immune system cells,” describe Sharacely Farias and Professor Zanella. “All measurements were taken before and after weaning. In immune system cells, we evaluated the expression of genes associated with the stress response and also the production of inflammatory cytokines.”
“The immune system represents a set of responses existing in animals and humans, which can act specifically or generally to protect against potential attacks by disease-causing agents, and stress makes them more vulnerable, affecting their entire development," the researchers said.
“Piglets are excellent model animals adopted in comparative studies with humans in relation to anatomy, physiology, neurodevelopment processes and immune response. A critical period of greater sensitivity to stressors and exposure to pathogens is weaning, which represents maternal separation and a change in diet.”
Results
Researchers found that donkey milk reduced the release of the stress hormone cortisol in pigs subjected to stressful situations.
“We also found, in pig immune system cells, that donkey milk can reduce the production of 1L1β genes, which is a pro-inflammatory cytokine [ protein ]. Exaggerated inflammatory responses can compromise several adaptive systems, with consequences for the development of animals,” they emphasize. “With this, we were able to verify that donkey milk mitigated the inflammatory response that the stress of weaning and the change of diet caused in the piglets, when compared to the treatment with skimmed bovine milk and the group that did not receive supplementation.”
“The results suggest that supplementation with donkey milk may be a strategy to reduce the damage associated with an early stressful event, reducing the release of cortisol and also reducing the expression of 1L1 Beta, which can trigger inflammatory responses,” highlight Sharacely de Souza Farias and Professor Zanella. “Therefore, supplementation with donkey milk could also serve premature babies, in addition to being used as a dietary supplement for children and the elderly. However, more research must be carried out.”
The researchers hope that proving the benefits that milk can bring to human health will change the outlook of the Brazilian population and government officials towards donkeys. “We understand that it is urgent to end slaughter to meet demand in China,” they warn.
“Around 70,000 animals are slaughtered every year to export their skin, from which collagen, or ejiao, used in traditional medicine is extracted, although its therapeutic properties are not scientifically proven. The slaughter places donkeys at risk of extinction, primarily due to the twelve-month gestation period and late sexual maturity of the species.”
“Our research group is part of the National Task Force for Donkeys, which, since 2015, has been working to improve the well-being and reframe the role of these animals in the northeastern and Brazilian economy and culture,” concludes the professor.
The research is described in Sharacely de Souza Farias' doctoral thesis at FMVZ, supervised by Zanella and co-supervised by professor Chiara Albano de Araujo Oliveira, from UFBA. Professor Guilherme Pugliesi and Priscilla Assis, from the Department of Animal Reproduction, collaborated in the study, in the work on gene expression in cells of the immune system, and Ana Carolina Dierings, Vinicius Cardoso Mufalo, Leandro Sabei, Arthur Nery da Silva and Marisol Parada Sarmiento, from the Center for Comparative Studies in Health, Sustainability and Wellbeing (CECSBE) at FMVZ. Researcher Claudio Vaz Di Mambro Ribeiro, from UFBA, helped with the statistical analysis of the experiment. Criatório Ximbó, in Laranjal Paulista (interior of São Paulo), supported the execution of the project.
22 May 2024
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