The objective of this study was to determine the association of single nucleotide polymorphisms (SNPs) in selected candidate genes with fattening performance traits in a commercial cattle herd. Fifteen SNPs in 12 candidate genes (LEP, FABP4, DGAT1, TG, IGF1, IGF1R, MYF5, LGB, CAPN1, CAST, GHR, and OLR1) were evaluated in 296 purebred Holstein–Friesian bulls using PCR-RFLP (polymerase chain reaction – restriction fragment length polymorphism). Associations between each segregating SNP and genetic merit for fattening performance were quantified using linear mixed models. Traits included in the study were fattening period, final weight, dry matter intake, feed conversion rate, and average daily weight gain. Apart from the general determination of the above-mentioned traits, each trait was evaluated based on the fattening periods between five selected target body weights (W1 = 100 kg, W2 = 200 kg, W3 = 300 kg, W4 = 400 kg, W5 = 450 kg). All markers with the exception of CAPN1 530, IGF1R, TG, and DGAT1 were associated with at least one of the traits. Furthermore, novel associations were observed for LEP × GHR, IGF1 × LEP, FABP4 3691 × FABP4 2834, and FAP4 3533 × LEP interactions. The results of this study confirm some previously reported associations. Moreover, novel associations have been identified, which may be incorporated into breeding programs to improve fattening performance.

the aim of this study was to characterize the bovine fatty acid binding protein (FABP4) gene 3691g>A and 2834c>g polymorphisms and to evaluate interaction effects on the live weight, carcass characteristics and meat quality of holstein bulls in the south marmara region of turkey. A total of 400 holstein bulls grown on a private farm and slaughtered at 14-21 months of age, were randomly selected for use in this study. initially, genotyping was performed by pcr-rflp method and statistical analysis was carried out using least square methods of the glm procedure. A snp located in intron 1 (2834c>g) was associated with desirable increases in live weight, hot carcass weight and chilled carcass weight, and a snp located in exon 3 (3691g>A) was associated with significant increases in marbling scores and first compressive stress point of the longissimus dorsi muscle (p<0.05). the interaction analysis of the 3691g>A and the 2834c>g polymorphisms revealed significant effects for hot carcass weight, chilled carcass weight and backfat thickness (P<0.05). There were no significant associations between the SNPs and carcass measurements. results indicated that the FABP4 3691g>A and 2834c>g polymorphisms and the 3691g>A and 2834c>g interactions can be used as selection parameters in breeding programmes to improve meat yield and carcass characteristics.

A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) test was performed on DNA samples extracted from blood samples of 189 Holstein Friesian cows to detect genotypic distribution of polymorphic markers in the bovine beta-casein (CSN2), kappa-casein (CSN3), beta-lactoglobulin (LGB) and alfa-lactalbumin (LALBA) genes responsible for milk production traits. Statistical analysis was carried out using least square methods of the general linear model (GLM) procedure. CSN2 locus was significantly associated with the following traits: 305-day milk yield, days before peak milk production, fat percentage and protein yield. There was no significant effect of CSN3, LGB and LALBA markers on the traits analysed. These results suggested that CSN2 marker may be evaluated in selection programmes regarding not only milk content but also milk production.

The objectives of the study were to evaluate allelic frequencies and test the association between STAT1, OLR1, CSN1S1, CSN1S2, and DGAT1 gene polymorphisms and milk production traits including lactation milk yield, 305 days milk yield, days before peak milk production, and peak milk yield. In addition, samples of milk were analysed for fat, protein, lactose, and total solid contents. A total of 168 purebred Holstein-Fresian cows were genotyped using polymerase chain reaction and restriction fragment length polymorphism methods. Statistical analysis was carried out using least square methods of the general linear model procedure. Significant differences were found between genotypes of the CSN1S2 locus in relation to milk protein content. In addition, DGAT1 was significantly associated with peak milk production. These results suggested that CSN1S2 and DGAT1 markers may be evaluated to achieve various commercial goals in dairy cattle production.

This study investigated the impact of nine polymorphisms located in the CSN2, CSN3, CSN1S1, CSN1S2, OLR1, LALBA, STAT1, DGAT1 and LGB genes, and environmental factors including calving year, season and parity on reproductive traits. The analysis was conducted on 165 Holstein-Friesian cows. Genotypes were identified using PCR-RFLP. The data of reproductive traits for four lactations were evaluated. Statistical analysis was carried out using least squares of the GLM procedures. Results indicated that CSN2 had significant effects on days before first insemination and first insemination to pregnancy interval. The SNP at the CSN3 was significantly associated with gestation length. A novel effect of OLR1-C223A on age at first calving was observed in the present study. Moreover, DGAT1 and LGB markers were significantly associated with calving interval and days before first insemination, respectively. In addition, significant environmental effects were as follows: calving year with days before first oestrus, days open, and first insemination to pregnancy interval; season with days open, first insemination to pregnancy interval, and calving interval; parity with days before first oestrus and days open. The present results and novel associations may therefore be useful and indicative for future studies on a genetic basis of cattle reproduction traits.