Genetic factors affecting the composition and quality of cow’s milk

Abstract

This chapter reviews the genetic factors affecting the composition and quality of cow's milk. It starts by discussing how different breeds of cattle can affect the composition of milk. The chapter then goes on to examine milk proteins, genetic variants and post-translational modifications. It then discusses milk coagulation and other functional properties, before highlighting the genetic influence of fatty acids on minor milk components. The chapter also discusses using mid-infrared spectroscopy for genetic parameter estimation, before concluding with a section on the possibilities for genetic improvement in relation to dairy milk.

Livestock species as emerging models for genomic imprinting

“…In addition, a report from the Food and Agriculture Organization of the United Nations (FAO) pinpoints the importance of animal milk in the diets of children in populations with very low fat intakes and limited access to other animal source foods ( https://www.fao.org/dairy-production-products/products/milk-composition/en/ ). Association genetics identified many genomic regions influencing different phenotypes of milk composition, showing in particular a major effect of the imprinted gene DGAT1 (Diacylglycerol O-Acyltransferase 1) and caseins on total yields of milk, protein and fat ( Poulsen and Larsen, 2021 ). In addition, other candidate genes mostly affecting milk fat and protein content were shown to play a role in secretory functions in the mammary gland as well as mammary gland development ( Cui et al, 2014 ).…”

What is the impact of amino acid mutations in the primary structure of caseins on the composition and functionality of milk and dairy products?

“…The total and ionic calcium contents were found to greatly influence the acid-induced gelation and rennet-induced coagulation of bovine milk ( Hallén et al, 2007 ; Poulsen et al, 2013 ; Poulsen and Larsen, 2021 ). In this regard, milk samples carrying β-casein A1 contained higher calcium amount, especially ionic calcium in A1/A2 milk compared to A2/A2 milk and smaller casein micelle sizes ( Daniloski et al, 2022d ; Day et al, 2015 ; Jensen et al, 2012a ; Poulsen et al, 2013 ).…”

“…Compared to other caseins, the genetic variants of κ-casein have been most discussed and related to acid gelation and rennet coagulation of bovine milk ( Bijl et al, 2014a ; Bonfatti et al, 2010 ; Poulsen and Larsen, 2021 ). Different studies have found that the genetic polymorphisms of κ-casein might substantially affect the rennet-induced coagulation characteristics; milks containing κ-casein B variant were represented with a higher amount of κ-casein and smaller casein micelles, decreased curd firming time, and increased whey protein expulsion compared with milks carrying κ-casein A ( Bisutti et al, 2022 ; Gambra et al, 2013 ).…”

“… Frederiksen et al (2011) actually related the composite A/B-A1/A2 (β-κ-casein) haplotype, considered as a sufficient factor for good milk coagulation properties, with a higher content of κ-casein in the gels. Thus, genetic selection of dairy cows for milk with good acid gelation or rennet coagulation abilities, should be highly considered, since they can potentially lead to an improvement in yoghurt and cheese production ( Poulsen and Larsen, 2021 ).…”

“…Although the impact of the genetic variants of all 4 caseins on physicochemical and functional properties of dairy products have been extensively studied and reviewed ( Gai et al, 2021 ; Mendes et al, 2019 ; NguyenSchwendel et al, 2018 ; Poulsen and Larsen, 2021 ), there is no consensus on the structure of casein micelle governed by the major milk proteins and their genetic variants. Therefore, greater scale and extensive data studies that would contain different levels of αs 1 -, αs 2 -, β-, and κ-caseins including their polymorphic variants, degree of κ-casein glycosylation, composite αs 1 -αs 2 -β-κ-casein variants are needed to further elaborate on the impact of these genetic variants on both milk and micellar casein.…”