Alpha-lactalbumin polymorphism in three breeds of Indian zebu cattle

Molecular characterization of bovine CSN1S2*B and extensive distribution of zebu-specific milk protein alleles in European cattle

The B allele of the bovine alpha (S2)-casein gene (CSN1S2) was characterized at the molecular level and the distribution of zebu-specific milk protein alleles was determined in 26 cattle breeds originating from 3 continents. The CSN1S2*B allele is characterized by a C --> T transition affecting nucleotide 17 of exon 3, which leads to a change in the eighth amino acid of the mature protein, from Ser to Phe (i.e., TCC --> TTC). DNA-based methods were developed to identify carriers of CSN1S2*B and the other alleles (CSN1S2*A, C, and D) at the same locus. CSN1S2*B and other zebu-specific milk protein alleles and casein haplotypes are widely distributed in European cattle breeds, particularly those of southeastern origin. Alleles CSN1S2*B and CSN3*H are important in searching for zebu imprints in European cattle breeds. Diversity estimates at the milk protein loci were highest in the zebus followed by southeastern European taurines. Anatolian Black had the highest number of zebu alleles among European taurines. Common, group, and intergroup haplotypes occurred in the breeds and demonstrated relationships that concurred with developmental histories, genetic makeup, and, in particular, exposed the extent of zebu influence on southeastern European cattle.

An evaluation of genetic diversity indices of the Red Bororo and White Fulani cattle breeds with different molecular markers and their implications for current and future improvement options

The genetic diversity of the Red Bororo and White Fulani cattle breeds of Cameroon and Nigeria was assessed with a panel of 32 markers. Estimates for the various indices of genetic diversity, total number of alleles (TNA), mean observed number of alleles (MNA), mean effective number of alleles (MNE), observed heterozygosity (Hob) and expected heterozygosity (Hex), were higher at microsatellite loci than at protein loci. Mean Hex values were above 71% at microsatellite loci in all the breeds and ranged from 37% to 41.6% at milk protein loci and from 40.9% to 45.6% at blood protein loci. The highest TNA and MNA of microsatellites were recorded for the Nigerian White Fulani. MNE of milk protein loci was highest in the Cameroonian Red Bororo, while TNA of blood protein loci was highest in the Cameroonian White Fulani. The high genetic diversity levels indicate the presence of the necessary ingredients for improvement breeding and conservation. Multi-locus estimates of within-population inbreeding (f), total inbreeding (F) and population differentiation (theta) of the breeds were significantly different from zero, except for theta of blood proteins. A high level of gene flow was found between the breeds (5.829). The phylogenetic relationship existing among the four breeds is greatly influenced by location. The high gene flow between the breeds may lead to a loss of genetic diversity through genetic uniformity and a reduction in opportunities for future breed development. We propose an improvement scheme with aims to prevent loss of genetic diversity, improve productivity and reduce uncontrolled genetic exchanges between breeds.