Natacha R. Róin¹, Nina A. Poulsen¹ and Lotte B. Larsen^{1
1 Department of Food Science, Aarhus University}

Abstract
The current investigation is part of a larger project, where variations in components are profiled in Danish dairy milk streams representing differences in production form, feeding strategy, breed, geography and season. Inherent natural variations in silo milk represent both opportunities and challenges e.g. an opportunity for improved utilization of the raw material and more differentiation into dairy products and ingredients or unwanted challenges in relation to process control and during e.g. up-concentration and fractionation. This is explored here for a number of components, including proteomic profiling of the major milk proteins and their isoforms, including, post translational modifications (PTMs) as well as enzymes and peptides relative to differential somatic cell count (DSCC). Preliminary results of the protein profile indicate differences in protein composition including variation in phosphorylation and glycosylation relative to both breed, feed and season. Peptide profiles will be determined by peptidomics using Q-ToF MS/MS to study proteolytic load also in relation to differences in DSCC.

Practical relevance
The mapping of Danish dairy milk is of great value for the dairy industry, as the composition of milk is relevant to ensure a stable and uniform production of dairy products but also when developing specialized products. Furthermore, milk proteins, PTMs and peptides are proven to impact processing qualities, whereas the possible interaction with DSCC is less explored, especially in silo milk.

Hasitha Priyashantha¹, Åse Lundh¹, Annika Höjer², Gun Bernes³, David Nilsson⁴, Mårten Hetta³, Karin Hallin Saedén², Anders H Gustafsson⁵, Monika Johansson^{1
1 Department of Molecular Sciences, Swedish University of Agricultural Sciences, Box 7015, SE-750 07 Uppsala, Sweden
2 Norrmejerier Ek. Förening, Mejerivägen 2, SE-906 22 Umeå, Sweden
3 Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
4 Växa Sverige, Ulls väg 26, SE-750 07 Uppsala,  Sweden
5 Computational Life Science Cluster, Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden}

Abstract
Dairy farms in Northern Sweden were characterized to investigate the effect of on-farm factors and season on the variation in milk quality. Based on principal component analyses (PCA), two major types of dairy farming systems were observed. Type-1: Larger farms with loose housing using automatic milking system or milking parlour with predominantly Swedish Holstein (SH) breed. Type-2: Farms with a lower number of cows in tie-stalls with breeds other than SH. PCA of variation in composition and properties of the milk samples showed a tendency for the formation of two clusters based on these farming systems. The interrelated effect of the milking system and breed is likely to contribute to this distribution. Type of farm influenced the gel strength, probably reflecting differences in milk composition. Total proteolysis and casein micelle size were mainly influenced by sampling month, with smaller micelles and slightly higher proteolysis in outdoor compared to the indoor period. Season associated differences in raw milk are not merely linked to the variation in the amount of grazing, suggesting the importance of holistic and comprehensive study designs.

Practical relevance
This study was part of a full-scale cheese making trial in Northern Sweden, with the overall aim to investigate the background of variation in raw milk quality, and its effect on cheese ripening. The results are of importance to gain further understanding of the impact of structural dairy farming intensification on raw milk quality and its coagulation properties and suitability for cheese making.

Anouk van Breukelen¹, Michael Aldridge¹, Chris Schrooten², Roel Veerkamp¹ and Yvette de Haas^{1
1 Animal Breeding and Genomics Group, Wageningen University & Research, The Netherlands
2 CRV, The Netherlands}

Abstract
The Dutch agricultural sector is facing the challenge to reduce methane emissions. In agriculture, most methane is produced by enteric fermentation of ruminants and emitted in the air through breathing and belching. The aim of our study was to investigate if we can use animal breeding techniques to reduce enteric methane emissions of dairy cows. Methane concentrations (ppm) were continuously recorded using gas analysers, called sniffers, in the feed bin of milking robots on 14 herds from March 2019 to September 2020. In total, data from 181,597 robot visits of 1,698 Holstein cows were recorded. Genetic parameters were estimated with a univariate animal model with repeated measurements. Preliminary results show that the heritability was highest for weekly mean emissions (0.23 ± 0.02). The genetic standard deviation for weekly mean emissions was 73 ppm, indicating that the genetic difference between the 1% highest and lowest emitting cows is 366 ppm. The results indicate that there is genetic variation in methane emissions between cows, and decreasing methane emissions by selection in dairy cows is a possibility in the near future.

Practical relevance
Animal breeding offers potential to reduce enteric emissions in a way that is cost-effective, cumulative, permanent, and accessible to dairy farmers. The study showed that enteric methane emissions has a heritable component. We are constructing a larger dataset to investigate relationships between methane and other common breeding goal traits, which is needed to add methane to breeding programs.    

Camilla Preece¹ and Paraskevi Paximada^{1
1 Harper Adams University, UK}

Abstract
Macro and micro-nutrients in milk influence Cheddar production, sensory and functionality of the cheese produced. The effect of breed on milk composition and coagulation properties have been previously investigated, although the effect of breed on the final Cheddar cheese produced has not. This study involved cheddar produced from four Dairy Cattle breeds (Jersey, Holstein Friesian, Ayrshire and Dairy Shorthorn) in the United Kingdom, where farming methods were comparable. Both milk and cheese components were tested using analytical testing methods, compared against each other and breed group to identify any differences. Significant difference between breeds (p>0.05) was identified in milk fat, protein values and cheese fat and protein values.  Among the correlations identified between milk and cheese components, cheese fat and protein had a significant (p=0.018) moderately strong negative correlation. Sensory evaluation (TBA) and functionality of the cheese was also analysed, breed did not have a significant effect on functionality. The current results indicate breed has an impact on components, however, the impact on sensory and functionality of the Cheddar could be minimal.

Practical relevance
The breeds chosen have not been widely investigated in the UK, nor has the effect on the outcome of the actual cheese produced been investigated. This study investigates not only composition but the functionality and sensory of the Cheddar, as Cheddar is the most commonly eaten cheese in the UK. The outcome of the research provides insight into the topic and opportunity for further investigation.

Naomi Arita-Merino^1,2, Hein van Valenberg² and Elke Scholten^{1
1 Physics and Physical Chemistry of Foods, Wageningen University, Wageningen, the Netherlands
2 Dairy Science and Technology, Food Quality and Design, Wageningen University, Wageningen, the Netherlands}

Abstract
Milk fat (MF) composition can be drastically affected by genetic and environmental factors. This is often observed when alternative feeding sources are used, a practice commonly driven by sustainability or productivity goals. It is known that these variations affect crystallization, but there is limited knowledge on the effect of specific components on crystal polymorphism. We investigated possible relationships between the amount of a given polymorphic phase formed and the concentration of triacylglycerols (TAG) and fatty acids (FA). We selected MF samples with diverse FA and TAG profiles, representative of different sources of variation, such as genetic variation, seasonal variation and different feeding regimes (e.g. palm, algae and linseed oils supplementation). We studied the crystallization of these samples using wide angle X-ray diffraction (WAXD) to quantify the formation of different crystalline phases (i.e. polymorphs α, β and two β’). Results showed correlations between specific TAG and FA groups and different polymorphic phases.

Practical relevance
The plasticity and melting of butter and cheese are examples of properties that are greatly affected by the complex crystalline polymorphism and phase behavior of milk fat, which in turn, are determined by its composition. The correlations found in this study can help to predict changes in crystallization behavior due to TAG and FA variation, regardless of the variation source.

Gayani M.S. Lokuge¹, Lotte Bach Larsen¹, Morten Maigaard², Lars Wiking¹ and Nina Aagaard Poulsen^{1
1 Department of Food Science, Aarhus University, Denmark
2 Department Animal Science, Aarhus University, Denmark}

Abstract
The ability of nitrate and 3-nitro-oxy-propanol (3-NOP) to reduce methane (CH4) production in ruminants is accompanied by increased loss of hydrogen from the rumen. The addition of these methane-reducing additives alone or in combination with fat would lower CH4 emission, but may also affect milk composition and functionality through the modifications of rumen fermentation. The present study is an experimental animal trial determining the effects of supplementing feed with fat, nitrate and 3-NOP on milk composition and functionality. Forty-eight lactating Holstein cows were blocked according to parity and days in milk and allocated to 8 different rations (2 levels of fat (cracked rapeseed), +/- nitrate, +/- 3-NOP) over 6 periods of 21 days each, according to the incomplete Latin square design. The overall milk composition including citrate and urea was measured using Milkoscan. The fatty acid and protein compositions were determined by GC-FID and LC-MS, respectively. Furthermore, the suitability of milk in dairy products is being evaluated by means of determining a number of physical and technological properties relative to specific feed additives and their potential interactions.

Practical relevance
In terms of sustainability, the production of environment-friendly milk with improved nutritional and functional properties receives more attention. Supplementing feed with nitrate, 3-NOP, or fat are all clearly promising strategies to reduce CH4 emission. Importantly, the addition of these compounds secures the milk quality and functionality to satisfy the milk producers and consumers.