CASE STUDY: Comparison of fatty acid content in homogenized and nonhomogenized milk from Holstein and Jersey cows

The objective of this study was to investigate fatty acid concentrations of homogenized and nonhomogenized milk from Jersey and Holstein cows. Twenty-two lactating Holstein (n = 11) and Jersey (n = 11) cows were fed the same ration twice daily. Feed offered was adjusted daily according to the amount of orts from the previous day. Body weight and measurements, blood, and ruminal samples were collected weekly, as were feed and orts samples. Ruminal fluid was collected from 6 Holstein and 6 Jersey cows weekly (n = 42). Milk weights were collected daily, and samples were taken at 0300 and 1500 h and pooled by week. No differences were observed in fatty acid concentrations in feed, refusals, or rumen fluid. Fatty acids C16, C18, and C18:1 were found in the greatest concentrations in all types of milk. In this study, these 3 fatty acids made up approximately 60% of the total fatty acids in milk across breeds and treatments. Fatty acid C16 was greater in milk than were other fatty acids, and there was a trend for greater C16 in milk from Jersey cows than in milk from Holstein cows (30.6 vs. 28.5%; P < 0.06). Fatty acid C12 was greater in milk from Jersey cows than in that from Holstein cows (8.04 vs. 7.42%; P < 0.04). Milk from Holstein cows had greater proportions of C16:1 (1.81 vs. 1.24, respectively; P < 0.03), C18:1 (20.7 vs. 17.1, respectively; P < 0.01), and C18:3 (2.39 vs. 0.09, respectively; P < 0.01) than did milk from Jersey cows. Homogenized milk had greater proportions of C10 (P < 0.04) but lower proportions of C18:1 (P < 0.01) compared with nonhomogenized milk. There appear to be more differences in fatty acid types in milk between different breeds of cows than as a result of processing.