Associations Between Prolactin Gene And Microsatellite DNA Polymorphisms And Milk Production Traits Of Holstein Cattle In China

Selection of high quality catties is primary approach for increasing catties production performance and dairy farms economic benefit. Traditional judging of exterior and production performance have bigger limitation because of environmental factor influence and time, sex confinement, but selection of molecule genetic marker combining production trait for dairy genetic quality is high accuracy method to conquer these limitations.This experiment selects 130 Holstein dairy catties in the dairy farm belonging to Shi Jiazhuang Sanlu Group and the Honglida dairy farm in Rongcheng totally.Applied PCR-RFLP and microsatellite DNA polymorphism detection technique, Prolactin (bPRL) and four microsatellite loci Holstein cattle are analysed for DNA polymorphism. Effects of bPRL and microsatellite loci on milk performance were examined using least squares model.Frequency of variants in PRL were: PRL(A)0.7538, PRL(a)0.2462. For the genotype frequency of PRL, the genotype of AA is 0.5462, Aa is 0.4154, aa is 0.0385. The gene frequency and genotype frequency of PRL were analysed using chi-square test. The result showed that the Holstein dairy cattle lies in Hardy-Weinberg equilibrium state. The heterozygsity, number of effective alleles, and polymorphism information content were 0.3711, 1.5901, 0.3022, respectively. The PIC showed the medium polymorphism.This experiment made use of four microsatellite loci (ILSTS103, ILSTS96, CSSM66, BM6425 )analyzing dairy cattle construction and variation with inherit. The gene frequency and genotype frequency of four microsatellite loci were analysed using chi-square test. The result showed that the Holstein dairy cattle lies in Hardy-Weinberg equilibrium state. Through Chi-square independence test, the CSSM66 and BM6425 locating on the No. 14th chromosome together, is mutually independent on the heredity. The gene frequency and genotype frequency of four microsateliite loci were analysed using chi-square test. The result showed that the Holstein dairy cattle lies in Hardy-Weinberg state. The number of alleles, range of the polymorphism information content, number of effective alleles and the heterozygsity in the population .were 5 - 11, 0.78-0.88, 4.83~ 8.19 and 0.79~0.88. These resulted show that four microsatellite loci in Holstein cattlehave high polymorphism. So there was a large selection potential in dairy cattle population. Least squares analysis showed that herd, year, season of calving and parity had significant effects on milk yield(P<0.01), In addition,herd had significant effects on lactose percent. PRL and three microsatellite loci(ILSTS103, CSSM66, BM6425) had significant effect on milk yield (P<0.05 or P<0.01). In addition, ILSTS103, CSSM66 and BM6425 had significant effects on protein percent (P<0.05), and CSSM66 had significant effects on fat percent and drymatter percent (P<0.05) .ILSTS96 hadn't significant effect on milk prodution.