Assessing the impact of climatic conditions and feeding systems on the quality of raw bovine milk in Spain.

The dairy industry faces significant challenges from climate change, requiring a deeper understanding of how climatic factors influence raw milk composition and quality. The aim of this study was to evaluate the impact of climatic variables, such as temperature, solar radiation, and carbon dioxide levels, on raw milk parameters, including somatic cell count, protein percentage, fat, and total bacterial count. Selectivity ratio and Spearman rank correlation analyses identified key associations. This study analysed data from 53 farms in northern Spain (2014-2019), using two feeding systems: Total Mixed Ration and Hand Feeding. Temperature and solar radiation negatively correlated with fat (r = -0.68, P < 0.05), protein (r = -0.71, P < 0.05), and dry lean percentages (r = -0.65, P < 0.05), while average temperature positively correlated with somatic cell count (r = 0.70, P < 0.05). Total bacterial count showed a negative correlation with carbon dioxide levels (r = -0.66, P < 0.05). Among the climatic variables, solar radiation and carbon dioxide were highlighted as the most influential factors through selectivity ratio analysis. Additionally, Total Mixed Ration feeding systems appeared to support better metabolic adaptation, underscoring the importance of balanced diets in mitigating climate-induced stress. These findings emphasise the need for improved farm management practices to address climate change impacts on milk quality.