Animal and Farm Factors Affecting the Fatty Acid Profile and Amyloid A Concentration of Milk on Quebec Dairy Farms

Relationships between farm and animal factors and the fatty acid (FA) profile and milk amyloid A (MAA) content of milk were determined in 336 Holstein dairy cows on 24 Quebec farms using multiple regression. Cows with a somatic cell count (SCC) above 200,000, and farms feeding palm oil were excluded. Independent factors of the regression models included days in milk (DIM), parity, yield, fat and protein contents of milk, SCC, and the dietary contents of neutral detergent fibre (NDF) and crude fat (CFAT). Non- significant variables with P-values >0.25 were stepwise removed. Models with high fits were those of total short chain FA, medium chain FA, odd- and branched-chain FA (OBCFA), and saturated long chain FA with R2 of 0.33, 0.36, 0.34, and 0.41, respectively. The fat and protein contents and yield of milk did not affect the milk FA profile. Higher NDF increased the milk fat proportions of short chain FA and OBCFA and decreased those of monounsaturated (MUFA) and polyunsaturated FA (PUFA). Higher CFAT reduced this proportion of short chain FA but increased those of MUFA and PUFA. Increasing DIM reduced this proportion of short chain FA and increased that of medium chain FA. Higher SCC increased MAA.