Milk yield in Saanen goats: relationships between stress, expression of genes related to milk synthesis, antioxidant enzymes and heat shock proteins in the mammary gland

• Grant number: 21/14724-7
• Support Opportunities: Regular Research Grants
• Start date: May 01, 2022
• End date: April 30, 2024
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Production
• Principal Investigator: João Alberto Negrão
• Grantee: João Alberto Negrão
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil

Abstract

Dairy animals are subjected to management and environmental challenges considered stressful that can decrease milk yield, however the effect of stress in apoptosis rate in mammary cells and lactation persistence is unknown. For this reason, understanding the effect of heat stress on molecular pathways related to milk synthesis, oxidation process, proliferation and apoptosis rate in mammary gland are important tools to assess the effect of stress on lactation persistence. In the present study, to evaluate the effect of stress on lactation, 40 lactating Saanen goats will be subjected to treatments: 1) heat stress (sun exposure), or 2) control (thermoneutral). In this context, this project proposes to study in vivo the effect of heat stress on gene expression in the mammary gland and milk production of Saanen goats during lactation (Experiment I); and to study in vitro the effect of cell culture temperature (36, 38, 40 or 42oC) on the expression of genes related to the synthesis of milk constituents, antioxidant enzymes and heat shock proteins by the mammary epithelial cells of Goats Saanen (Experiment II). In vivo study will be measured: cortisol release, cell proliferation and apoptosis, expression of key genes related to milk synthesis, antioxidant enzymes and heat shock proteins in mammary gland, as well as milk yield and milk quality to evaluate the effect of heat stress in Saanen goats. In vitro study will be measured: lactose, casein and lactalbumin in culture medium, and the expression of key genes related to the synthesis of milk, antioxidant enzymes, proliferation and apoptosis in mammary epithelial cells to evaluate the effect of cell culture temperature (36, 38, 40 or 42oC) on mammary epithelial cells of the Saanen goats. The data obtained in this study will be important to assess the effect of heat stress on the molecular pathways that regulate cell proliferation and apoptosis rates, as well as their effects on milk production and lactation persistence in animals raised under conditions tropical and subtropical. (AU)