Impact of Changing Climactic Conditions on Bulk Tank Milk Fatty Acid Production and its Relationship with Milk Composition

Recent advancements in the analysis of fatty acid groups using NIR technology developed revealed correlations between de novo fatty acids (FA) and total milk fat and protein production, however this work focused on northeastern U. S. Holstein herds.The objectives of this project were to evaluate the impacts of management practices, environmental conditions and breed on milk FA composition in the Southeast.Ten herds (6 Jersey, JE, 3 Holstein, HO, 1 mixed) were sampled weekly for milk FA (de novo, DNFA; mixed origin, MOFA; and preformed, PRFA).A positive relationship was observed between milk fat%, protein% and DNFA in JE herds (r = 0.7473 and 0.6474, R2 = 0.5571 and 0.6474, P < 0.0001).Herd management assessments were conducted quarterly, and temperature humidity index (THI) was collected throughout the study.Data were analyzed using PROC CORR and REG of SAS Fatty acid content was not affected by herd management factors assessed.HO herds produced less milk during elevated average THI while JE herds produced more milk.Milk fat and protein were greater in low minimum THI for both breeds.De novo FA was greater during low minimum THI.This indicates that milk FA, particularly DNFA, could be used as predictors of disorders or stressors to the cow.