The occurrence of noncoagulating milk and the association of bovine milk coagulation properties with genetic variants of the caseins in 3 Scandinavian dairy breeds

Abstract

Substantial variation in milk coagulation properties has been observed among dairy cows. Consequently, raw milk from individual cows and breeds exhibits distinct coagulation capacities that potentially affect the technological properties and milk processing into cheese. This variation is largely influenced by protein composition, which is in turn affected by underlying genetic polymorphisms in the major milk proteins. In this study, we conducted a large screening on 3 major Scandinavian breeds to resolve the variation in milk coagulation traits and the frequency of milk with impaired coagulation properties (noncoagulation). In total, individual coagulation properties were measured on morning milk collected from 1,299 Danish Holstein (DH), Danish Jersey (DJ), and Swedish Red (SR) cows. The 3 breeds demonstrated notable interbreed differences in coagulation properties, with DJ cows exhibiting superior coagulation compared with the other 2 breeds. In addition, milk samples from 2% of DH and 16% of SR cows were classified as noncoagulating. Furthermore, the cows were genotyped for major genetic variants in the αS1- (CSN1S1), β- (CSN2), and κ-casein (CSN3) genes, revealing distinct differences in variant frequencies among breeds. Allele I of CSN2, which had not formerly been screened in such a high number of cows in these Scandinavian breeds, showed a frequency around 7% in DH and DJ, but was not detected in SR. Genetic polymorphisms were significantly associated with curd firming rate and rennet coagulation time. Thus, CSN1S1 C, CSN2 B, and CSN3 B positively affected milk coagulation, whereas CSN2 A(2), in particular, had a negative effect. In addition to the influence of individual casein genes, the effects of CSN1S1-CSN2-CSN3 composite genotypes were also examined, and revealed strong associations in all breeds, which more or less reflected the single gene results. Overall, milk coagulation is under the influence of additive genetic variation. Optimal milk for future cheese production can be ensured by monitoring the frequency of unfavorable variants and thus preventing an increase in the number of cows producing milk with impaired coagulation. Selective breeding for variants associated with superior milk coagulation can potentially increase raw milk quality and cheese yield in all 3 Scandinavian breeds.

Bovine chromosomal regions affecting rheological traits in rennet-induced skim milk gels

“…However, conflicting results are found between studies. Some studies also reported effects of genetic variants of α S1 -CN on milk gelation properties (e.g., Lodes et al, 1996;Poulsen et al, 2013). The different CN do not only differ from each other regarding genetic variants, but also through different degree of phosphorylation and, in case of κ-CN, also glycosylation (Farrell et al, 2004).…”

“…It is well known that different milk protein genetic variants affect both milk composition and milk gelation properties, as reviewed by Caroli et al (2009) and Bittante et al (2012). Documented effect on milk gelation properties has been found on genetic variants of κ-and β-CN and of β-LG (Ikonen et al, 1999;Poulsen et al, 2013). However, conflicting results are found between studies.…”

Duplication polymorphisms in exon 4 of κ-casein gene in yak breeds/populations

“…However, the characteristics of yak κ-casein have not been well-documented. Yak milk shows good coagulation following the addition of chymosin, and no individual showed noncoagulating milk (Zheng YC, Liu WJ and Jin SY, unpublished data) as in bovine milk (Okigbo et al, 1985;Poulsen et al, 2013). This is an advantage of yak milk during cheese-making, although the related mechanism remains unclear.…”

“…Genetic variants of κ-casein have been extensively studied in cattle at the protein and DNA levels, and numerous alleles have been revealed (Barroso et al, 1998;Prinzenberg et al, 1999;Gallinat et al, 2013). The association between milk coagulation properties and κ-casein variants and other casein variants have been reported previously (Bonfatti et al, 2010;Poulsen et al, 2013), and the genotyping of κ-casein and other caseins are important for determining milk processing properties.…”

Dairy processing and cold storage affect the milk coagulation properties in relation to cheese production

“…It is clear that the majority of samples present not only good coagulation properties but also poor coagulating and even non-coagulating milk (Ikonen et al 2004;Frederiksen et al 2011a;Poulsen et al 2013). The reasons behind this variability can be many, as a variety of factors influence the milk coagulation properties, including lactation stage, somatic cell count, breed, and parity, and these factors influence the properties by manifestation of changes in the milk composition (Devold et al 2000;Ikonen et al 2004;Frederiksen et al 2011b).…”