Effects of α_s1-casein (CSN1S1) and κ-casein (CSN3) genotypes on milk coagulation properties in Murciano-Granadina goats

Abstract

The effects of the caprine α s1-casein (CSN1S1) polymorphisms on milk quality and cheese yield have been widely studied in French and Italian goat breeds. Much less is known about the consequences of κ-casein (CSN3) genotype on the technological and coagulation properties of goat milk. In the current study, we have performed an association analysis between polymorphisms at the goat CSN1S1 and CSN3 genes and milk coagulation (rennet coagulation time, curdling rate and curd firmness) and technological (time to cutting of curd and cheese yield) properties. In this analysis, we have included 193 records from 74 Murciano-Granadina goats (with genotypes constituted by different combinations of alleles B, E and F of the gene CSN1S1 and alleles A and B of the gene CSN3) distributed in three herds, which were collected bimonthly during a whole lactation. Data analysis, using a linear mixed model for repeated observations, revealed significant associations between CSN1S1 genotypes and the rate of the curdling process. In this way, milk from EE goats had a significantly higher curdling rate than milk from BB individuals (P<0·05). Contrary to previous experiments performed in French breeds, cheese yield was not significantly different in BB, EE and EF goats. Moreover, we have shown that CSN3 genotype has a significant effect on the rennet coagulation time (BB>AB, P<0·05) but not on cheese yield. No interaction between the CSN1S1 and CSN3 genotypes was observed.

Associação de SNPs nos genes para κ-caseína e β-lactoglobulina com curvas de lactação em cabras leiteiras

“…Os resultados para κ-CSN3 foram similares aos relatados para as raças Barbari, Marwari, Beetal e Surti, que mostraram maior frequência do genótipo AA; para a raça Surti, o genótipo BB não foi encontrado (Kumar et al, 2009;Caravaca et al, 2011). No presente trabalho, o genótipo BB não foi encontrado para κ-CSN3.…”

“…O uso de informação molecular sobre os genes que afetam a produção animal permite avaliar o potencial genético de populações com pouca informação genealógica. Pesquisas identificaram a associação dos genes para κ-caseína e β-lactoglobulina com a variação fenotípica na produção e na qualidade do leite de caprinos e ovinos (Kumar et al, 2006;Caravaca et al, 2011;Dagnachew et al, 2011). Mais de 95% das proteínas no leite de ruminantes são codificadas por seis genes bem caracterizados, que codificam as proteínas α-lactalbumina, β-lactoglobulina, αs1, αs2, β e κ.…”

Genetic Factors that Regulate Milk Protein and Lipid Composition in Goats

“…These associations, however, may change depending on the breed under consideration. In this regard, Caravaca et al (2011) were unable to find significant differences between the cheese yields of milks from BB, EE and FF MurcianoGranadina goats, whilst EE milk had a significantly higher curdling rate than its BB counterpart. As mentioned above, these differences amongst studies might be explained by a complex mixture of biological and technical factors.…”

“…In silico analyses with the Polyphen software have shown that in most mammalian species, Ile119 is a highly conserved residue, suggesting that it might have an important functional role (Caravaca et al 2010). It is also worth to mention that associations between CSN3 genotype and rennet coagulation time (BB>AB) have been recently reported (Caravaca et al 2011). This finding is consistent with the key role of CSN3 in the initial phase of milk rennet coagulation, where 87-90% of CSN3 is enzymatically degraded before micellar aggregation takes place.…”

The Application of Genomic Technologies to Investigate the Inheritance of Economically Important Traits in Goats

“…Rheological properties of milk are also influenced by the CSN1S1 genotype; for example, milk from AA goats is associated with a firmer curd, a slower coagulation time, and increased cheese yield than that of FF goats in French [32,33] and Italian breeds [25], whilst in Spanish goats less conclusive results have been obtained [34]. From an organoleptic point of view, the AA cheese has a less pronounced goat flavor intensity than that of the FF one, maybe because of differences in fatty acid composition and lipolysis rate [26,33].…”