Variation in milk proteins across a contemporary group of Holstein cattle

Variation in milk proteins across a contemporary group of Holstein cattle

Summary

The goal of our project is to explore the possibility of improving genetic selection of milk proteins in dairy cattle through the examination of the variation in individual milk proteins such as casein, alpha lactalbumin and beta lactoglobulin. It is our hope that our study will reveal significant variation and yield an improved ability to make genetic progress by allowing breeders to select for individual milk proteins instead of crude protein. The ability to generate lines of cattle that excel in one protein fraction over another would result in a new level of efficiency on the industrial side of dairy as one of the major challenges in different areas of dairy processing is dealing with protein byproducts. The key components of our study consisted of obtaining three consecutive milk samples at two week intervals from a large herd of dairy cattle to reduce environmental influence on the variation in the protein fractions. The sampling took place at Sunnyside Farms in Scipio Center, NY. Due to the rotary style parlor in place at this location we were able to obtain samples from ~1200 cows over the course of our sampling period. In addition, we collected samples from 30 cows at calving and followed them throughout their lactations (~6 months) to examine how much the milk protein fractions change as a cow progresses through her lactation. The chemical fractionation processing began in October of 2015 and will continue through the spring of this year. While we have not yet performed data analysis on the physical weights of the milk proteins we have isolated, it appears as though basic chemical fraction procedures are sufficient to isolate the milk proteins we are interested in. Due to equipment malfunction and modifications to our procedure, we are slightly behind in our proposed timeline but hope to regain ground in the Spring of 2016.

Objectives/Performance Targets

 Objectives:

Determine the amount of variation in the individual milk proteins across a Holstein herd.

Performance targets:                 

1. Obtain samples – Completed. Our sample collections were accomplished and a sufficient number of cows were sampled.
2. Verify chemical fractionation procedures and modify as necessary – Completed.
3. Perform chemical fractionation on all samples obtained – In progress.
4. Determine variation in milk proteins – Planned.
5. Share results with key dairy industry leaders to utilize data to make the dairy industry more efficient – Planning in progress.

Accomplishments/Milestones

This year we accomplished our sample collection and confirmed that the chemical fractionation procedures outlined in our materials and methods are sufficient to allow us to isolate the unique protein fractions in order to determine if there is sufficient variation across the population. The timeliness and accuracy of our sample collection, utilizing the same technique and timing for each sampling, will reduce the amount of environmental influence on our results. Once we have determined the variation across the population we will work to educate dairymen about the possibility of this new selection criteria.

Impacts and Contributions/Outcomes

The rotary style parlor impacted our success in sampling – performing this type of data collection in a different type of parlor would impede the milkers and potentially influence the results. Thus far Erika (Project leader) has contributed with the bulk of the sampling with Tom assisting along with some student assistants. The outcome of our samplings was successful and all test samples were fractionated. At this time, Erika fractionates several batches a week. Once all samples have been fractionated, Tom will perform data analysis.

Collaborators: