EFEITOS DO SOMBREAMENTO ARTIFICIAL SOBRE PARÂMETROS PRODUTIVOS, FISIOLÓGICOS DE VACAS MESTIÇAS HOLANDÊS X GIR SOB ESTRESSE POR CALOR

Abstract

Dairy cattle production in Brazil faces challenges related to the tropical climate and the predominantly extensive production systems, demanding strategies that enhance productivity without increasing operational costs. In this context, artificial shading may mitigate the effects of heat stress, particularly in crossbred cows raised on pasture. This study evaluated the effects of artificial shading on milk yield and composition, as well as physiological parameters such as respiratory rate and rectal temperature, in Holstein × Gyr crossbred cows managed under pasture conditions with and without access to shade. The experiment was conducted at the Dairy Cattle Sector of the UFMS Experimental Farm, Terenos/MS, from March to July 2024, using ten cows allocated in five 2 × 2 Latin squares. Each experimental period consisted of 14 days of adaptation and 15 days of data collection, totaling 116 days. Cows were milked once daily at 08:00 h, and individual milk yield was recorded on days 17, 18, and 19. A single milk sample per cow was collected on day 29 for analysis of fat, protein, lactose, and total solids. Rectal temperature was measured from days 20 to 25 at 06:00, 09:00, 12:00, 15:00, 18:00, and 21:00. Data were analyzed using ANOVA, with significance declared at p < 0.05. Artificial shading did not significantly affect (p > 0.05) milk production or composition, nor rectal temperature; however, it reduced respiratory rate, indicating improved thermal comfort. It is concluded that artificial shading enhances the welfare of crossbred dairy cows on pasture, even without altering productive performance.