Evaluation of salivary proteins as potential biomarkers of milk production in hot climates

Abstract

Evaluation of salivary proteins as potential biomarkers of milk production in hot climates Ana CAPM Geraldo1, Cristina Conceição 1,2, Liliana Cachucho2, Flávio Silva2, Catarina Matos2, Elsa Lamy1, Fernando Capela e Silva 1,3, and Alfredo Pereira 1,2 1 Institute of Mediterranean Agricultural and Environmental Sciences, University of Evora, Portugal; 2 Department of Zootechnics, University of Évora, Portugal; 3 Department of Biology, University of Evora, Portugal ecsl@uevora.pt

Dairy cattle are particularly sensitive to high temperatures, lowering milk output as well as milk quality (fat, solid, lactose and protein). Given the trend of global warming, the joint selection for productivity and adaptability is an objective, i.e. greater heat loss without lowering the metabolism. So, to search and validate the xistence of non"invasive biomarkers that could allow selection of the animals best adapted is crucial to achieve such an objective. The interest of saliva as a source of biomarkers starts to increase in animal production. Salivary ortisol has been used in some studies, but it presents some limitations for thermal stress, which can be circumvent by salivary proteins. The hypothesis that cows presenting high potential for milk production under adverse thermal conditions also present differences in salivary protein profiles comparatively to the ones less productive, is actually being tested at ICAAM"University of Évora, Portugal, by our research team. The experiment was design to identify salivary proteins whose expression levels can be related to the potential for milk production under unfavourable thermal conditions. Twelve animals (6 high and 6 low milk potential production) were analysed for salivary protein composition at three different acclimation time points: first, during summer, under hot temperatures; second, under thermoneutrality; and third, during winter, under low temperatures. Whole saliva was collected directly from cow mouth, using cotton rolls (salivettes). At each time point, collection was performed in two different days, to avoid bias due to particular variations due to environment. One and two"dimensional electrophoresis are being performed to compare salivary proteomes from animals with different milk production potential, and to assess how differences between these groups are maintained through the different acclimation periods.