Buša je hrvatska autohtona pasmina goveda manjeg tjelesnog okvira, dobre prilagodljivosti i skromne proizvodnosti. Nedovoljna konkurentnost u proizvodnji mlijeka i mesa razlog su potiskivanja ove pasmine na rub biološkog opstanka. Dugoročna održivost pasmine moguća je isključivo kroz njenu ponovnu gospodarsku reafirmaciju. Skroman mliječni potencijal može gospodarski biti kompenziran proizvodnjom mlijeka dodanih tržišnih bonusa. Zapažena povezanost polimorfnih A2/A1 genetskih varijanti beta-kazeina mlijeka sa zdravljem potrošača, gastrointestinalnim i imunološkim smetnjama zadnjih desetljeća pobuđuje interes šire javnosti. Razlika navedenih varijanti beta-kazeina je na 67 poziciji aminokiselinskog proteinskog slijeda i to u zamjeni histidina prolinom. Ranija istraživanja uglavnom navode da je A2 varijanta beta-kazeina izvorna, te da ima povoljniji učinak na zdravlje potrošača. Cilj istraživanja bio je utvrditi zastupljenost alelnih varijanti i genotipova beta-kazeina u populaciji buše. Genotipizacija je provedena na 20 jedinki uz uporabu restrikcijske endonukleaze DdeI. Utvrđena je nazočnost sva tri genotipa u populaciji buše. Zastupljenost A2 alelne varijante beta kazeina je dominantna (67,5%) što čini povoljnu osnovu za profiliranje određenih stada buše prema proizvodnji A2 mlijeka. Osobitu pozornost treba posvetiti riziku od gubitka genetske raznolikosti, budući da preferiranje određenih genetskih varijanti u malim populacijama može narušiti njihovu genetsku varijabilnost.

Busa is a Croatian indigenous breed of small body frame, good adaptability and modest productivity. Insufficient competitiveness in production of milk and meat is the reason for pushing this breed to the brink of biological extinction. The long-term viability of the breed is possible only through its economic re-affirmation. The modest milk potential can be economically offset by the production of milk with added market bonuses. Observed association between polymorphic A2/A1 genetic variants of beta-casein milk with consumer health, gastrointestinal and immune disorders in recent decades has sparked interest in general public. Difference between these beta-casein variants is at 67 position of the amino acid protein sequence in the replacement of histidine by proline. Earlier research has generally stated that the A2 variant of beta-casein is original and more beneficial on consumer health. Aim of this study was to determine the presence of allelic variants and genotypes of beta-casein in the Busa population. Genotyping was performed on 20 individuals using DdeI restriction endonuclease. All three genotypes were determined. Presence of the A2 allelic variant of beta-casein is dominant (67.5%), which provides a favorable basis for profiling certain herds of bushes according to A2 milk production. Particular attention should be paid to the risk of loss of genetic diversity, since preference for certain genetic variants in small populations may impair their genetic variability.