Utjecaj DGAT1 genetskih varijanti na količinu i kvalitetu mlijeka holstein, simentalske i smeđe pasmine goveda u Hrvatskoj

The aim of this study was to determine allele frequency at the diacylglycerol-O-transferase 1 gene (DGAT1) K232A polymorphic site and effect of allelic variants K and A on milk production traits of Holstein (dairy), Simmental and Brown Swiss (dual purpose) cattle breeds in Croatia. The DNA was extracted from hair of 371 cows, while coding region of DGAT1p.K232A was amplified using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Dominant frequency of K allele was determined in all three analysed breeds: Holstein (0.775), Simmental (0.616) and Brown Swiss (0.651). The most Holstein cows were homozygotus for KK variant (0.637), while dominant genotype in other two breeds was KA (Simmental 0.647; Brown Swiss 0.644). Positive effect of KK genotype on milk yield was detected in Holstein and Brown Swiss breeds, while in Simmental breed was negative (-220.8 kg; -463.6 kg) in regard to KA and AA genotype. Milk of cows with KK genotype in Holstein breed, KA in Simmental and AA in Brown Swiss were found as the most favourable in terms of fat content. Cows of AA genotype in all the three analysed breeds have had higher milk protein content. Statistical analysis was performed using the GLM procedure, including genotype and breed effects as independent variables. The effects of DGAT1genotypes on milk quantity and quality were not significant (P>0.05).Cilj ovog istraživanja bio je utvrditi frekvenciju alela diacilglicerol-0-transferase 1 gena (DGAT1) K232A polimorfnog mjesta i utjecaja alelnih varijanti K i A na količinu i kvalitetu mlijeka tri pasmine krava, mliječnog i dvojnog tipa proizvodnje u Hrvatskoj. Istraživanje je uključivalo 371 jedinku holstein, simentalske i smeđe pasmine krava. DNA je izolirana iz dlake, kodogena regija DGAT1p.K232A gena umnožena je korištenjem PCR-RFLP metode. Dominantna frekvencija alela K utvrđena je kod sve tri istraživane pasmine: holstein (0,775), simentalske (0,616) i smeđe pasmine (0,651). Većina krava holstein pasmine bila je homozgotna za KK varijantu (0,637), dok je dominantan genotip za druge dvije pasmine bio KA (simentalska 0,647; smeđa pasmina 0,644). Pozitivan utjecaj KK genotipa na proizvodnju mlijeka zabilježen je populacijama u holstein i smeđe pasmine, dok je u simentalskoj populaciji bio negativan (-220,8 kg; -463,6 kg) u odnosu na KA i AA genotipove. Mlijeko krava KK genotipa holstein, KA genotipa simentalske i AA genotipa u smeđe pasmine imalo je veći sadržaj mliječne masti. Krave AA genotipa u sve tri istraživane pasmine proizvodile su mlijeko s većim sadržajem proteina. Statistička analiza provedena je uz pomoć GLM procedure, uvažavajući genotip i pasminu kao neovisne varijable. Utjecaj DGAT1 genotipova na istraživane kvantitativne i kvalitativne osobine mlijeka nisu bile signifikantne (P>0,05)

Effect of β-lactoglobulin, κ-casein and αs1-casein polymorphic allelic variant on milk production traits in Croatian population of Holstein, Simmental and Brown cattle breed

Cilj ovoga rada bio je istražiti utjecaj polimorfnih varijanti β-laktoglobulina, κ-kazeina i αs1-kazeina na ukupnu proizvodnju mlijeka te prosječni udio mliječne masti i bjelančevina u mlijeku holstein, simentalske i smeđe pasmine goveda u Hrvatskoj tijekom prve tri laktacije. Premda su uočeni određeni utjecaji polimorfnih varijanti β-laktoglobulina, κ-kazeina i αs1-kazeina na visinu proizvodnje mlijeka istraženih pasmina goveda, razlike nisu bile značajne. Istraživanjem su utvrđeni utjecaji polimorfnih varijanti β-laktoglobulina, κ-kazeina i αs1-kazeina na prosječni udio mliječne masti u mlijeku istraženih pasmina goveda, no uočene razlike također nisu bile značajne. Utvrđene razlike u udjelu bjelančevina u kravljem mlijeku s različitim polimorfnim varijantama β-laktoglobulina, κ-kazeina i αs1-kazeina nisu bile značajne, osim u slučaju BC genotipa αs1-kazeina koji je pokazao pozitivan utjecaj (P<0,05) na udio bjelančevina u mlijeku krava holstein pasmine.The object of the present study was to analyse effect of polymorphic allelic variants of β-lactoglobulin, κ-casein and αs1-casein on total milk yield, fat and protein content in milk of Holstein, Simmental and Brown cattle breeds in Croatia during the first three standard lactations. Although the certain effects of polymorphic variants of β-lactoglobulin, κ-casein and αs1-casein on the level of milk yield in analyzed breeds of cattle are observed, those effects were not significant. The effect of polymorphic variants of β-lactoglobulin, κ-casein and αs1-casein on average fat content in milk of analyzed breeds has noticed, although differences were not significant. Differences in protein content in milk with different polymorphic variants of β-lactoglobulin, κ-casein and αs1-casein were not significant, except in case of BC genotype of αs1-casein, which was significant (P<0.05) on protein content in the milk of Holstein breed