ALPHA S1 CASEIN Effects on Cheesemaking
The alpha s1-casein is a protein polymorphism of goat milk, and is one found in all dairy goat breeds.
The a s1-casein is a protein polymorphism of goat milk first described in Europe, in the French Alpine and Saanen breeds, in the early nineteen eighties.
These polymorphisms have been found to affect cheese-making due to differences in protein content, renneting properties (faster coagulation and firmer curd) and a possible connection in relation to cheese flavor. Researched conducted on homozygous individuals for the various alleles confirmed the effects of genotype on the casein content in milk by showing the cheese-making yield observed in milk produced by those animals with strong alleles was 7 per cent higher in comparison with those with medium alleles and 15 per cent higher than those with weak alleles. In addition, there have been studies that suggest that the genetic variation resulting in low or null levels could contribute to milk with a lesser antigenic burden and be of potential benefit to those with milk sensitivities.
Knowing the specific genetic polymorphism at goat casein loci on breeding stock would allow the breeder to set up breeding and selection programs targeted towards the improvement of cheese-making yield by selecting for high expression alleles, or selecting for animals with low levels which will be of benefit to those with milk or casein sensitivities.
Fortunately, Veterinary Genetics Laboratory at University of California, Davis, makes such testing possible in the United States. The test would detect low level variants for casein – E, F, and N. High level variants for casein – A or B, which represent several specific alleles. If you are interested in this testing for your does or buck you can approach ADGA.
However, the test is not designed to detect subvariants of A and B. The animal above (A/E), if a doe, would be expected to produce intermediate levels of the casein and pass on either the A or E to their offspring. The animal above, if a buck, would have daughters that would inherit either the A (high level) or E (lower level). The variant inherited from their dam would determine whether they were an intermediate or high level producer of casein.