Date of Award
Master of Science (MS)
Dairy farmers in the Northeastern Unites States are paid based on the amount of fat and protein in their cows' milk, and improving fat and protein production is linked with improved financial sustainability for dairy farms. However, not all farmers are motivated to make changes to increase milk fat and protein production. Previous research has identified a positive correlation between a group of fatty acids, known as the de novo fatty acids, and the fat and protein content of bulk tank milk from commercial dairy farms. Therefore, the first objective of this research was to explore the relationship of farm management, the cow's diet, and lactation performance with de novo fatty acid content on Northeastern US dairy farms. Results from the first objective were communicated with dairy farmers; therefore, the second objective was to understand how to communicate with farmers to influence their behavior. We hypothesized that farms with high de novo fatty acids in bulk tank milk would manage and feed their cows to optimize rumen fermentation conditions.
The first (Chapter 2) and second (Chapter 3) studies were methodologically very similar. Farms were categorized as either high de novo (HDN) or low de novo (LDN) based on the concentration of de novo fatty acids in their bulk tank milk for the 6 months prior to the farm visit. Farms were then visited once in March or April, 2014 (Chapter 2) or between February and April, 2015 (Chapter 3) to assess management practices and collect samples of the cows' diet.
There were no differences in days in milk in Chapter 2 or Chapter 3. Yield of milk, fat, and true protein per cow were higher for HDN versus LDN farms in Chapter 2. In both chapters, HDN farms had higher milk fat and true protein content and higher de novo fatty acid yield per day. The HDN farms had lower freestall stocking density in Chapter 2 and provided more feedbunk space per cow in Chapter 3. Additionally, tiestall feeding frequency was higher for HDN than LDN farms. No differences were detected for dietary chemical composition, except ether extract was lower for HDN than LDN farms in both chapters.
Chapter 4 explored how to communicate the results of Chapter 2 and Chapter 3 through eleven qualitative, semi-structured interviews and insight from the 83 farm visits. Farmers identified the cooperative, expert consultants (nutritionist, veterinarian, and agronomists), financial advisers, print publications, and other farmers as principal sources of information. However, barriers to the transfer of information included family dynamics, lack of access to high speed internet, and difficulties evaluating divergent recommendations from experts. Several farmers expressed an incorrect perception of their farms' fat and protein production compared with cooperative averages which reduced their motivation to incorporate management changes. Recommendations to overcome these barriers include integrating management team meetings and facilitating informal discussion groups between farmers.
This research is correlational in nature, and future research is needed to verify a causal relationship between de novo fatty acids and milk fat and protein content. However, the results of this research can be used to help farmers increase their cows' milk fat and protein content, improve the transfer of knowledge to dairy farmers, and ultimately support the financial sustainability of dairy farms in the Northeastern US.
Number of Pages
Woolpert, Melissa Elizabeth, "Management Practices and Communication Strategies to Improve Milk Fat and Protein Content on Dairy Farms" (2016). Graduate College Dissertations and Theses. 594.