Polymorphism of β-lacto globulin gene in Barki and Damascus and their cross bred goats in relation to milk yield

Abstract

?-LG gene polymorphism at the DNA level has been analyzed by PCR-RFLP and reported two novel genetic variants of the ?-LG gene in Indian goats. However, no study has been reported in Barki Egyptian local goat breed, Damascus and their crossbred goats regarding ?-LG polymorphism at DNA level. The association of ?-LG polymorphism with milk yield has been reported in cows, sheep and Indian goats. However, this relation has not clarified yet in local or foreign goat breeds raised in Egypt. This study aimed to fingerprint ?-LG gene in the Barki, Damascus and their crossbred goats in an attempt to have clear image about genotypes of ?-LG gene in these breeds in relation to their milk yield. A total of 120 adult female does belonging to these three different genetic groups were analyzed by the PCR-RFLP method. The goats are raised by farmers in North West coast (Borg EL-Arab, Alexandria, Egypt) in which goats are living in natural habitats. The amplified product was observed as 426 bp and the restriction digestion with SacII revealed three genotypes, namely AA, AB and BB at the ?-LG locus. The frequencies of AA, AB and BB genotypes were 0.1, 0.8, 0.1; 0.85, 0.1, 0.05; 0.41, 0.51, 0.08 in the Barki and Damascus and their crossbred goats, respectively. The frequency of (AA)genotype was higher in Damascus breed than Barki and Damascus x Barki crossbred and according to reference milk production was associated with significantly higher milk production in this goat breed as compared by the two other goat breeds.Veza izmedju ?-LG polimorfizma i prinosa mleka je utvrdjena kod krava, ovaca i indijskih koza. Medjutim, ovaj odnos jos uvek nije objasnjen kod koza lokalnih ili stranih rasa koje se gaje u Egiptu. Ovo istrazivanje je imalo za cilj desifrovanje ?-LG gena koza rase barki, damask i njihovih meleza u pokusaju da se dobije jasna slika o genotipovima ?-LG gena kod ovih rasa u odnosu na prinos mleka, sto bi bilo korisno za poboljsanje produktivnosti lokalnih egipatskih rasa, kao sto je barki, u okviru odgajivackog programa gde bi se otkrili superiorni genotipovi egzoticnih rasa mogu ubrzani kroz optimalno ukrstanje sa lokalnim grlima sa minimalnim uticajima na osobine adaptacije lokalnih rasa. Ovo istrazivanje je izvedeno na 120 koza rase barki i damask, kao i njihovih meleza, barki (40), damask (40), 1/2 damask x 1/2 barki (40). ?-LG gen od eksona 7 do 3' slobodnog bocnog regiona je pojacan iz genomske DNK koriscenjem specificnih prajmera i nakon digestije sa SacII endonukleazom, homozigotni nosioci ?-LG gena su imali dve trake na 349 i 77 bp (BB), ne-nosioci su imali nepresecenu endonukleazu 426 bp traku (AA), dok su heterozigoti imali i 426, 349 i 77 bp trake (AB). Frekvencije AA, AB i BB genotipova su bile 0,1, 0,8, 0,1; 0,85, 0,1, 0,05; 0,41, 0,51, 0,08 kod rasa barki i damask i njihovih meleza, respektivno. Frekvencija (AA) genotipa je bila visa kod koza rase damask nego kod barki koza, i meleza damask x barki, a u vezi sa proizvodnjom mleka, ona je bila znacajno visa kod koza ove rase u poredjenju sa kozama druge dve rase.