Goats and Cattle Goats - milk yield

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Milk yield in goats - determination of kappa-casein genotype

The milk production is subject to many factors. It depends, for example, on feeding und stabling, but also on the variability of genetic markers having effect on the milk yield.

Casein is the main milk protein and is composed of several types of molecules that differ particularly by their structure. The main components are αs1- casein, αs2-casein, β-casein and κ-casein (Walstra,1999).

Kappa casein (κ-casein) plays an important role in the formation, stabilization and aggregation of the casein. The casein in milk aggregates into casein micelles. Ions and hydrophilic κ-casein are attached to the micelles. The ions and κ-casein protect the internal hydrophobic content made of molecules of αs1, αs2 and β-casein. In principle, milk is a suspension of casein micelles that are stabilized by calcium.

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Kappa-casein in dairy cattle

Studies dealing with research of CSN3 gene encoding κ-casein in cattle have proven the relationship between some alleles of kappa casein and milk yield, composition and milk quality. Cows of A/A-genotype produced 173 kg of milk more than cows of B/B-genotype.

Generally, the B-variant of κ-casein is associated with higher fat, protein and casein in milk and has a significant influence on cheese making properties of the milk in comparison to AA or BB variants (Gangaraj et al., 2008). The genotypes BB and AB are used in artificial insemination programs to obtain a greater increase of the frequency of these alleles in the dairy cattle (Otaviano et al. 2005).

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Kappa-casein in goats

A number of genetic studies have proven the high variability of CSN3 gene encoding the kappa-casein in goats. In domesticated goats, a total of 16  variations of CSN3 gene have been identified so far, of which 13 are protein variants and 3 are silent mutations in exon 4 (Prinzenberg et al., 2005). Kiplagat et. al, 2010 have found another two polymorphisms. There have been inferred 20 different haplotypes so far: A, B, B´, B´´, C, C´, D, E, F, G, H, I, J, K,  L, M, N, O, P, Q. According to nomenclature proposed by Prinzenberg et al., 2005 the new haplotypes are designated alphabetically and for the existing haplotypes  letters with an apostrophe are used.

The published studies emphasised that the analyzed goat breeds show differences in occurrence and frequency of alleles. The distribution of such alleles reflects the geographical origin of the goat breed (Moioli, 2007) and has been influenced either by selection pressure for milk production or, more likely, by genetic drift (Yahyaoui et al., 2003).

On the basis of isoelectric focusing (IEF, electromigration technique for the separation of proteins) of milk samples, the analysed genetic variations of kappa-casein have been divided in 2 groups after determination of isoelectric point (IP):

  • Group AIEF (IP = 5,29) includes genetic variations A, B, B´, B´´,C, C´, F, G, H, I, J, L
  • Group BIEF (IP = 5,66) corresponds to genetic variations D, E, Ka M (Chiatti at al. 2005, Prinzenberg et al. 2005, Caroli at al. 2006).

Based on the above studies, many benefits of the kappa-casein BIEF variant have been found that are involved, for example, in production of milk products. The advantages included for example increased cheese yield, faster curd formation and firmer curd structure, shorter coagulation time, greater heat stability and higher protein content in milk.

The genetic test makes the determination of the haplotype for kappa-casein in goats possible. On the basis of haplotype determination it is possible to concentrate the breed on the milk yield. It is important to choose the suitable breeding preferring the individuals belonging to the group of  kappa-casein BIEF variant.

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Reference:

Caroli A, Chiatti F, Chessa S, Rignanese D, Bolla P and Pagnacco G (2006). Focusing on the Goat Casein Complex. J. Dairy Sci. 89:3178-3187

Chiatti F, Caroli A, Chessa S, Bolla P, Pagnacco G (2005). Relationships between goat κ-casein (CSN3) polymorphism and milk composition. The role of Biotechnology.Villa Gualino, Turin, Italy.

Gangaraj DR, Shetty S, Govindaiah MG, Nagaraja CS, Byregowda SM and Jayashankar MR (2008). Molecular characterization of kappacasein gene in Buffaloes. Sci. Asia 34: 435-439.

Kiplagat SK, Agaba M, Kosgey IS, Okeyo M, Indetie D, Hanotte O and Limo MK (2010). Genetic polymorphism of kappa-casein gene in indigenous Eastern Africa goat populations.

International Journal of Genetics and Molecular Biology Vol. 2 (1), pp. 001-005

Kumar D, Gupta N, Ahlawat SPS, Satyanarayana R, Sunder S, Gupta SC (2006). Single strand confirmation polymorphism (SSCP) detection in exon I of the  - lactalbumin gene of Indian Jamunapri milk goats (Capra hircus). Genet. Mol. Bio. 29: 271-74.

Moioli B, D'Andrea M, Pilla F (2007). Candidate genes affecting sheep and goat milk quality. Small Rumin. Res. 68: 179-192.

Otaviano AR, Tonhati H, Sena JAD, Munoz MFC (2005). Kappa-casein gene study with molecular markers in female buffaloes (Bubalus bubalis). Genet. Mol. Bio. 28: 237-41.

Prinzenberg EM, Gutscher K, Chessa S, Caroli A, Erhardt G (2005). Caprine kappa-Casein (CSN3) Polymorphism: New Developments in Molecular Knowledge J. Dairy Sci. 88: 1490-1498.

Walstra P (1999). Casein sub-micelles: do they exist? Inter. Dairy J. 9:189-192.

Yahyaoui MH, Angiolillo A, Pilla F, Sanchez A, Folch JM (2003). Characterization and genotyping of the caprine kappa casein variants. J. Dairy Sci. 86: 2715-2720.

Usual turnaround time: 7 business days
1 test price: 57.00 $ without VAT
Price for 5+ tests: 52.00 $ without VAT