Study of LGB gene polymorphisms of small ruminants reared in Eastern Europe

The objectives of the current research were: (i) to determine the allele and genotype frequencies of the LGB gene in the sheep and goat breeds reared in Eastern Europe; (ii) to implement a comparative study in order to evaluate the milk production potential and efficiency of the main sheep and goat dairy breeds reared in Romania; (iii) to test the genetic basis and feasibility of introducing the molecular-marker assisted selection for this trait into future breeding schemes designed for small ruminants. Totally 731 purebred unrelated sheep (Turcana: 111, Racka: 98, Tsigai: 79, Karakul of Botosani: 60, Transylvanian Merino: 77) and goats (Carpatina: 82, Banat's White: 73, Saanen: 74, French Alpine: 77) were sampled and genotyped for the earlier detected alleles. The frequencies of A (0.44-0.53) and B (0.42-0.51) alleles of LGB gene were generally equal, while the C allele incidence was significantly lower for all sheep breeds studied. A relatively low or missing incidence of the C allele and no BC genotype were detected in the studied sheep breeds. All studied sheep breeds were in Hardy-Weinberg equilibrium. Gene homozygosity was lower than gene heterozygosity, with the effective allele numbers ranging from 2.00 (Transylvanian Merino) to 2.23 (Tsigai). Two alleles (A and B) and two genotypes (AA and AB) were detected in the four goat breeds studied. Allele A was the most frequent allele found in all breeds (0.57-0.68), while AB genotype had the highest frequency. Gene homozygosity was higher than gene heterozygosity, while the effective allele numbers varied between 1.76 (Banat's White) and 1.96 (Carpatina). The frequency of alleles and genotypes was similar to that reported in other Eastern sheep and goat breeds, however polymorphism has not been studied yet among these breeds in such a high number in Romania. An association study between single nucleotide polymorphisms and milk production traits should follow.