The Breeding and Genetics aspect of the American Dairy Science Association Virtual Meeting kicked off with a look into Milk Genetics. The Breeding and Genetics: Genetics of Milk symposium was chaired by Francisco Penagricano. It was divided into five sessions to include five presenters: Prof. Henk Bovenhuis of the Wageningen University of Research; Laurel Mastro, Staff Product Manager at Illumina; Derek Bickhart from the USDA ARS Dairy Forage Research Center; Jay Mattison at National DHI, Quality Certification Services; and Cees Jan Hollander, Global Farming Practices Manager at Danone Company.
Mr. Francisco started by introducing himself and after which he ushered in Professor Henk Bovenhuis. Prof. Henk took us through a lecture on genes that alter milk composition and their marketability.
According to him, there has been a steady increase in milk yield (kg) over the past seven decades with observable stability in milk fat since 1995, while milk protein has been indifferent over the years. Milk fat and protein measurement became of interest because of their relevance in butter and cheese production. However, these milk compositions vary based on several factors. For instance, milk fat was observed to differ between cattle and herd. Similarly, genetic differences affect the protein composition of the fat and mineral compositions except for selenium. Notable is the polymorphism observed in the Chromosome 14 containing DGAT1 gene in dairy cattle which causes low milk yield, increase fat, and reduced protein content. DAGT1 affects the manufacturing compositions of milk. Milk has six protein types. Mutation in these protein genes can result in a different protein type which is responsible for well-known milk protein variants. A popular example, A2 milk is produced by cows with the A2A2 genotype, and the European Food Safety Association reported in 2009 that there is no cause-effect relationship between A2 milk and diabetes. Professor Henk then summarized thus: Milk composition is affected by genes. It affects the nutrition and manufacturing properties of milk, and that selective breeding can be used for product differentiation.
The next presenter, Ms. Laurel Mastro, took to the stage with the topic, Genomic Testing for Milk Composition: Past, Present, and Future. She chose to lecture us from the vantage point of what is practical and meaningful to the commercial dairy producer. She began by stating the compositions of milk, which are: water, lactose, fat, protein, and mineral. Protein is 3.4% of milk composition, and Casein makes up 76-80%. There are four casein proteins: Alpha S1 Casein, Alpha S2 Casein, Kappa casein, and beta casein. For these proteins to be candidates of genomic testing, they should have economic significance with their location on the gene of interest known. They must also have observable genetic variation. With increasing genomic testing in dairy cattle, microarrays and some Single Nucleotide Polymorphisms can be used to look at milk protein content to find out what other information is out there. Of all the Casein protein types, only the Kappa Casein and Beta Casein could stand alone for genomic testing. Beta casein has a large variation, and people are willing to pay more for milk containing this variant. It is also grouped mostly in 2 – A1 and A2 due to limited reporting or understanding of other variants. Bioactive peptide beta-casomorhin7 (BCM7) produced from metabolism is higher for the A1 group than A2. BCM7 has been linked with negative health events. Kappa Casein, on the other hand, shows significant variability, and it is economically important in cheese production, however, cheese producers still don’t pay more for its applicability. In her final remark, Ms. Laurel concluded that genomic profiling will increase knowledge on milk protein. She recommended that additional casein variants should be studied as a single prolific sire can increase such rare variants in the population even within 2 years.
After a few questions and answers series, the next speaker, Mr. Derek Bickhart, began his presentation on The Effects of the Rumen Microbiome on Milk fat Composition. He stated that the overarching goal of milk fat content improvement is related to human health. More specifically, to tackle cardiovascular diseases. Defining Fatty acids as chains of carbons terminated with a carboxyl group, he went on to talk about their types and significance. Saturated fatty acid (SFA) has single bonds, while unsaturated fatty acid (UFA) contains double bonds. Derek agreed with professor Henk on research that also found significant genetic heritability for shorter fatty acids. According to him, the Rumen microbe alters raw components through 2 functions: Lipolysis and hydrogenation. Through these processes, healthy UFA in forage gets converted to SFA. The rumen contains all major microorganisms. Bacteria has the largest population and responsible for SFA production in the rumen. For genomic selection for improved milk fat content, phenotypes are needed. Also, short and long-chain fatty acids are influenced by the genotype and can be modified. Selection models must incorporate microbial effects. He rounded up his presentation, stating that to improve milk fat content, interdisciplinary research at the interface of genetics, microbiology, and nutrition is of the essence.
Jay Mattison’s presentation on Future Milk Composition and Market Opportunities Driven by the DHI System followed next. Following a cheerful greeting, Mr. Jay started his session by stating that milk composition and component start and end with the cow. He gave a brief history behind the development of the Kjeldahl and Babcock method in milk component measurements. Still, on the history lane, he mentioned Dairy Herd Improvement was founded in 1905. Years later, it got changed to Dairy Herd Information in 2000. The Quality Certification Service, a subsidiary, was founded in the 1980s to ensure compliance with guidelines and a uniform operating procedure across dairy farms. The QCS has 25 field services affiliates, 17000 field assistance or technicians, Milk calibration centers, 4 dairy processing centers, 42 Laboratories, and 22 offer Elisa screening. The QSC ensures that all instruments and procedures are monitored for accuracy in all milk components. In anticipation of the future, new technologies should be validated, and all correlations checked. He concluded that the dairy industry relies on genetics, genomics, etc. however, it is very data-driven. Data is critical to information delivery, management and decision-making.
Finally, the last speaker was Mr. Cees Jan Hollander, and he led us through the session on Dairy processor’s view on milk marketing and the rise of plant-based products-can genetics help? He inferred that consumer perception is pivotal in their company mission as they are the source of their business. Danone seeks to connect its company goal to consumer needs. Not only that, but they also stay rooted and connected to the farming community to foster a great working relationship between the farmers and the company. Danone hopes to embrace regenerative agriculture, which was defined as renewing systems that are broken, but keeping what is good. In a regenerative agricultural system, farmer empowerment, environmental balance, and animal welfare are secured. The final presenter ended with a quote from the company’s client, Joseph Maria, in Spain. “Trust is the basis of our relationship. and together we can work successfully towards regenerative agriculture”.
Bukola Adenuga is a recent Msc graduate in Animal Breeding and Genetics, University of Ibadan, Nigeria. She expects to proceed to a Ph.D. on precision breeding in dairy cattle.
Source: ADSA
(T5, D1)
