Genetic potential of Sindhi cattle for A2 milk production

Abstract

ContextCow milk is consumed in many countries. However, its consumption can be associated with gastrointestinal disorders in humans. The genetic profile of β-casein is one of the factors responsible for these disorders and the A1 variant is a causal agent. The β-casein A1 leads to the formation of bioactive peptides, which trigger intestinal reactions. The same is not observed for the A2 allele. A2 milk is obtained from cows with the A2A2 genotype. The identification of breeds and selection of animals for A2 milk production is important for public health and animal production. The Sindhi cattle (Bos taurus indicus) possesses characteristics such as adaptation to hot climate, resistance to parasites and utilisation of low-quality forage that are important for rearing in the tropics. AimsThe objective of the present study was to genotype the single-nucleotide polymorphism (SNP) that forms A1 and A2 alleles of the β-casein in Sindhi cattle. MethodsIn total, 348 Sindhi animals were used. DNA was extracted from hair follicles and submitted to PCR-sequencing for genotyping. Key resultsAllele frequency for A2 was 0.94 and for A1 it was 0.06. Genotype frequencies were 0.90 (A2A2), 0.09 (A1A2) and 0.01 (A1A1). The frequency of the A2A2 genotype in Sindhi cattle was similar to or higher than those found in zebu breeds and higher than those reported for specialised taurine breeds. ConclusionsThis high frequency of the A2A2 genotype indicates a genetic potential of the breed for A2 milk production and easy, assisted selection (if that is the intention). ImplicationsThis information gives importance to the breed and permits to add value to dairy product derived from it. It may increase producer’s income through producing and marketing A2 milk.

Bovine beta casein polymorphism and environmental sustainability of cheese production: The case of Grana Padano PDO and mozzarella cheese

“…The difference between the A1 and A2 β-casein genetic variants is a single nucleotide polymorphism at position 8101 of the CSN2 gene, which changes the codon for the amino acid at position 67 from proline (Pro67: A2 β-casein) to histidine (His67: A1 β-casein) in the polypeptide chain (Schettini et al, 2020).…”

Bovine milk β‐casein: Structure, properties, isolation, and targeted application of isolated products

“…Structural and functional differences between A1 and A2 β‐casein variants and their digested peptides are closely associated with human health (Figure 3) (Bodnár et al., 2018; Kaskous, 2020; Pal et al., 2015). In fact, the minor difference between the two isoforms is the variation in the amino acid at the 67th position in the primary sequence of the protein chain (Kay et al., 2021; Schettini et al., 2020). A2 β‐casein has proline at this position, whereas A1 β‐casein has histidine (Caroli et al., 2016).…”

“…Structural and functional differences between A1 and A2 β-casein variants and their digested peptides are closely associated with human health (Figure 3) (Bodnár et al, 2018;Kaskous, 2020;Pal et al, 2015). In fact, the minor difference between the two isoforms is the variation in the amino acid at the 67th position in the primary sequence of the The N-terminal (1-60) contains a phosphoserine phthalate group, H. Arg-Glu-Leu-Glu-Glu-Leu-Asn-Val-Pro-Gly-Glu-IIe-Val-Glu-Ser-Leu-Ser-Ser-Ser-Glu-Glu-Ser-IIe-Thr-Arg-IIe-Asn-Lys-Lys-IIe-Glu-Lys-Phe-Gln-Ser-Glu-Glu-GLn-Gln-GLn-Thr-Glu-Asp-GLu-Leu-GLn-Asp-Lys-IIe-His-Pro-Phe-ALa-Gln-Thr-GLn-Ser-Leu-Val-Tyr-Pro-Phe-Pro-Gly-Pro-IIe-Pro-Asn-Ser-Leu-Pro-GLn-Asn-IIe-Pro-Pro-Leu-Thr-GLn-Thr-Pro-Val-Val-Val-Pro-Pro-Phe-Leu-Gln-Pro-Glu-Val-Met-Gly-Val-Ser-Lys-Val-Lys-Glu-Ala-Met-Ala-Pro-Lys-His-Lys-Glu-Met-Pro-Phe-Pro-Lys-Thr-Pro-Val-Glu-Pro-Phe-Thr-Glu-Ser-GIn-Ser-Leu-Thr-Leu-Thr-Asp-Val-Glu-Asn-Leu-His-Leu-Pro-Leu-Pro-Leu-Leu-GLn-Ser-Trp-Met-His-Gln-Pro-His-Gln-Pro-Leu-Pro-Pro-Thr-Val-Met-Phe-Pro-Pro-GLn-Ser-Val-Leu-Ser-Leu-Ser-Gln-Ser-Lys-Val-Leu-Pro-Val-Pro-Gln-Lys-Ala-Val-Pro-Tyr-Pro-GLn-Arg-Asp-Met-Pro-IIe-Gln-Ala-Phe-Leu-Leu-Tyr-Gln-Gln-Pro-Val-Leu-Gly-Pro-Val-Arg-Gly-Pro-Phe-Pro-IIe-IIe-Val.OH protein chain (Kay et al, 2021;Schettini et al, 2020). A2 βcasein has proline at this position, whereas A1 β-casein has histidine (Caroli et al, 2016).…”

Novel LNA probe-based assay for the A1 and A2 identification of β-casein gene in milk samples

“…The genotyping tests of beta-casein CNS2 gene in cattle herds have increased considerably over the last few years, since the demand for cattle with A2A2 genotypes has intensified due to the greater demand for milk and dairy products exclusively of A2 type. However, most of the research is strictly related to genotyping the animals ( Gustavsson et al, 2014 , Kamiński et al, 2006 , Keating et al, 2008 , Lien et al, 1999 , Rangel et al, 2017 , Royo et al, 2014 , Visker et al, 2010 , Ristanic et al, 2020 , Schettini et al, 2020 , Ivanković et al, 2021 , Ladyka, 2021 , Teixeira et al, 2021 ). The first study that was developed to genotype the CSN2 gene alleles directly in milk samples was accomplished by Giglioti et al, (2020) , that evaluated two methods: high-resolution melting (HRM) and rhAmp® SNP genotyping.…”