Correlations between bulk tank milk analysis with weather conditions in dairy farms under tropical environments

The consequences of climate change on agriculture have generated concern among researchers and decision-makers, especially regarding the effects it will have on this sector. The phenomenon is expected to affect the productivity of livestock systems, even more so in grazing livestock, where cattle and pastures are directly impacted by climatic variables. This study evaluated the climatic influence on bulk tank milk production and quality in 38 tropical dairy farms, using Pearson's partial correlation and canonical correlation analyses. Farm production level and milk quality traits were merged with meteorological information obtained from climatological stations distributed around the Valle del Cauca department, Colombia. According to farms' milk production levels, four evaluation groups (EG) were established for the analysis, and within each group, the available information between 2.0 and 8.5 years was included. Pearson's partial correlations among productive and climatic variables were scarce and low (r <+/- 0.10) within each EG. On the other hand, canonical correlation analyses between productive and climatic variable sets presented a linear increase since the establishment of EGs from 1 to 4 (r ranging from 0.39 to 0.59). The magnitude of canonical correlation coefficients depended on bulk tank dairy farm production levels, being the most productive systems the most susceptible, especially for meteorological variables related to temperature and relative humidity. As a consequence, dairy farms with higher performances must define mitigation strategies to reduce the weather effects. Multivariate correlations are recommended to evaluate the relationship between milk production, composition, and environmental variables in grazing dairy systems of tropical areas.