GoatMilkSCC: High somatic cell numbers in goat milk – influence on product quality

In this project, we will research the type of cells present in the milk, and how these cells affect the quality of goat milk and goat's milk products.

prosjekt

About/Aims

Background

The project is important to obtain knowledge and understanding of how the number of cells affect the milk quality, the technological properties of the milk and further the product quality of goat milk products.

We often experience that the number of somatic cells in the milk increases when goats are let out at pasture and at oestrus, also in goats with no signs of clinical mastitis. High cell numbers reduce the payment that farmers receive for the milk, and reduced payout as a result of high cell numbers during the grazing period can lead to reduced use of rangeland pastures. These pastures are an important feed resource during the summer months, with many positive side effects. Furthermore, the project aims to contribute to the development of new and innovative products of goat's milk.

The Norwegian dairy industry observe that the somatic cell count (SCC) often increases when dairy goats are let out on rangeland pasture and during oestrus. However, in goats, a high SCC is also observed in milk without signs of clinical mastitis. There is limited knowledge on how the content and type of SCC in goat milk varies between individual goats and over the course of lactation, and on how they are influenced by pasture. Moreover, the effects of the SCC on product quality remain largely unknown. Therefore, knowledge of how, and to what extent SCC affects milk- and product quality especially during the pasture period, is of great importance for the future of the Norwegian goat milk production.

The novelty of the project is the combination/integration of high-resolution characterization of the somatic cell types by flow cytometry and goat milk composition (chemical and microbial) and goat milk processing aimed towards the production of increased value dairy products from goat milk. Goat milk SCC aims at securing a sustainable goat milk production from healthy goats by providing novel insights on reasons for high number of somatic cell counts (SCC) in Norwegian goat milk and its influence on the yield and quality of goat milk products.

Objective

To secure a sustainable goat milk production from healthy goats by providing novel insights on reasons for high number of somatic cell counts (SCC) in Norwegian goat milk especially during summer rangeland pasture, stress and oestrus and its influence on the yield and quality of goat milk products.

The project should:

Develop strategies to improve udder health (reduce SCC milk) especially during rangeland pasture.
Ensure that the methods and results achieved in the project are implemented to ensure optimal milk quality throughout lactation
Clarify how the SCC levels (and different types of SCC) are affected by farm management

The project is divided into 5 work packages and the key questions within each package are:

WP1. Reveal the biological background for variation and elevation of SCC in goat milk

How does SCC vary under different conditions? (Early late lactation, release to pasture etc.)
Which cell types comprise SCC and what does each of these cellular fractions contribute in terms of production-related enzymes, and inflammatory and stress factors?
Does elevated SCC and cell type composition correlate with inflammation status or stress markers in the milk?

WP2. Reveal the link between milk composition, microbiota and SCC

Does the SCC influence the chemical composition of goat milk?
Is high SCC a reliable marker of proteolytic enzyme activity and casein degradation?
Does the goat milk microbiota influence SCC or vice versa?
What is the connection between microbial udder infections and SCC?

WP3. Influence of SCC on cheese making and cheese ripening

How does the SCC and cell types in goat milk influence rennet coagulation and cheese yield?
Does storage of raw milk with high cell numbers influence rennet coagulation and cheese yield?
Does high and low SCC and types of cells in goat milk influence cheese making and ripening?
Which possibilities does low SCC goat milk give for new cheese varieties from goat milk?

WP4. The Swiss experience – how does SCC develop during mountain pasture in Switzerland

Does the SCC develop similarly in goat milk dependent of lactation stage, oestrus and grazing in Norway and Switzerland?
Do conditions during the mountain/rangeland grazing cause high SCC regardless of species?
What can be learned from Switzerland with regards to processing of goat milk?

WP5. Knowledge transfer and implementation

The dairy industry is actively taking part in the project→ active transfer → ensure implementation
Do the results obtained in this project comply with existing dataset from the Norwegian animal recording system?
How can the methods and results obtained with regards to SCC be implemented to ensure an optimal milk quality throughout the whole lactation?
How are levels of SCC and different types of somatic cells influenced by farm management?

More about the project

GoatMilkSCC should give us more knowledge about the type of cells found in goat's milk, why the cells increase in number, and how this affects milk quality, cheesemaking properties and the quality of cheeses made from goat's milk. In the project, we will develop a flowcytometric method to map the types of cells found in goat's milk, and we will investigate how cell numbers vary between different individuals, by grazing, eusterus, etc.

Furthermore, we will investigate how SCC affect the composition of milk, cheese yield and cheese yield. Both milk from individual goats and tank milk from different herds should be examined. A number of professionals with expertise in veterinary medicine, immunology, microbiology, milk quality, and dairy technology, as well as professionals from TINE and NSG will be involved in the project. The project also has relevance and transfer value for cell numbers in cow's milk.

News/Findings

Reviews

Researchers

Participating NMBU researchers