Determining the relationship between trans-10 fatty acid intermediates and milk fat percent in Jersey Cows
Open Access
- Author:
- Brody, Shoshana
- Area of Honors:
- Animal Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Kevin John Harvatine, Thesis Supervisor
Chad Daniel Dechow, Thesis Honors Advisor - Keywords:
- milk fat depression
milk fat
fatty acid
Jersey cows - Abstract:
- In the current dairy market, the value of milk is largely determined by its fat and protein content. Milk fat percent can vary among breeds, individual cows, and diets. The Jersey breed has become increasingly popular in the United States due to its high milk fat content. One of the factors that can influence milk fat content and, hence, the profit seen by producers, is diet-induced milk fat depression. Milk fat depression (MFD) is a condition that causes up to a 50% decrease in milk fat concentration, while milk production by weight remains the same. The biological pathway leading to MFD is caused by dietary or environmental changes that stress the rumen microbes. Under these stress conditions, an alternative, and slower bio-hydrogenation pathway is used by the bacteria, which increases production of trans-10, cis-12 conjugated linoleic acid (CLA) intermediates. Previous work has developed a model that can predict milk fat percent from trans-10 C18:1 in Holsteins. Currently, little information about MFD is available for Jerseys. The ability to use milk trans-10 C18:1 content to predict milk fat percent in Jerseys would allow us to compare the data to Holsteins and diagnose bio-hydrogenation induced MFD in Jersey herds. For this study, over 450 samples of Jersey milk were obtained from four dairy farms in Pennsylvania and analyzed for milk fatty acid content. The objective of this project was to measure the presence of trans-10 intermediates in milk from Jersey herds as an indicator of MFD. We hypothesized that an exponential relationship between milk fat and milk trans-10 C18:1 concentration would be observed in Jerseys, similar to that of Holsteins. We found little indication of MFD while fat concentration still varied widely. There are likely other factors that influence milk fat concentration in Jerseys more than MFD. In this study, we were not able to establish a relationship between low fat content in milk and trans-10 C18:1 as an indicator of trans-10, cis-12 CLA.