Lipid Composition of Teat Canal Keratin Collected Before and After Milking from Holstein and Jersey Cows

¹ Milk Secretion and Mastitis Laboratory, Livestock and Poultry Sciences Institute, USDA-Agricultural Research Service, Beltsville, Maryland 20705, and Animal Health Laboratory, University of Vermont, South Burlington 05403

In three experiments, keratin was collected from individual teats of 40 Holstein and 20 Jersey cows immediately before and after milking. In Experiments 1 and 2, keratin collected from teats of 20 Holstein cows before milking was compared with keratin collected after milking. In Experiment 3, keratin was collected from two teats of 20 Jersey and 20 Holstein cows before milking and compared to the other two teats of the same cows after milking. All three experiments yielded similar results. In Holsteins, keratin weight before milking was 1.6 times greater than keratin weight after milking (3.1 vs. 1.9 mg). In Jerseys, only small amounts of keratin were removed during milking (3.5 mg before vs. 3.1 mg after). In Holsteins and Jerseys, neutral lipid concentration was 1.6 times greater after milking than before, suggesting that when keratin was removed during milking, only moderate amounts of lipid were removed. In Holsteins, total lipid collected per teat was similar before or after milking (59.2 vs. 48.5 µg). Results demonstrate that keratin collected after milking had a different lipid composition than keratin collected before milking.

Key Words: keratin • lipids • milking

Submitted on June 13, 1990
Accepted on August 30, 1990