Quantitative determination of fatty acids in the University of Vermont\u27s CREAM herd followed over the course of six months

Holstein and Jersey cows were used to determine how the fatty acid profile of their milk differed with regard to breed of cow and season over the course of six months. Milk was collected from each cow monthly between November 2011 and April 2012 and analyzed for components and fatty acid composition. Data were analyzed using linear mixed models with a repeated measures design with breed, month, and breed × month as the main effects. Holstein cows produced more milk than Jersey cows (79.98 vs. 50.48 lbs), and significant differences were seen between both breeds (P\u3c0.001) and months (P=0.014) of the study. Jersey cows produced more fat (5.20 vs. 3.91%, P\u3c0.001) and protein in their milk (3.83 vs. 3.12%, P\u3c0.001) when compared to Holstein cows. Jersey cows produced more saturated fatty acids than Holstein cows (72.9% vs. 70.7%, breed P=0.004, month P\u3c0.001). Vaccenic acid was produced in similar levels by both breeds, but Holsteins produced slightly higher levels (0.92%) than Jerseys (0.81%, breed P=0.0016, month P\u3c0.001). Holstein cows produced higher levels of conjugated linoleic acids in their milk (0.49%) when compared to Jersey cows (0.41%, P\u3c0.001). Holstein cows produced higher levels of linoleic acid (1.60% vs. 1.43%, P\u3c0.001, month P=0.005) when compared to Jersey cows. Linolenic acid levels produced by both breeds were similar for Holstein (0.31%) and Jersey cows (0.29%, month P=0.007). From the analysis of concentrations of both selected fatty acids as well as groups of major fatty acids, there is evidence that the fatty acid profile of milk differs with respect to both breed of cow, as well as month of the year