Genetic Polymorphisms in LTF/EcoRI and TLR4/AluI loci as candidates for milk and reproductive performance assessment in Holstein cattle.

ABSTRACT

The aim of this study was to explore the genetic polymorphisms in LTF/EcoRI and TLR4/AluI loci and their association with milk and reproductive performance in Holstein cattle. A randomly selected 800 Holstein dairy cows from two dairy farms (400 animals each) in Egypt were used. Based on the two farm records, association between LTF/EcoRI genotypes and milk performance traits (order of lactation, daily milk yield, days in milk, corrected milk at 305 day and dry period) was carried out. Meanwhile, exploring of TLR4/AluI genotypes effect was done on data for reproductive performance (age at first freshening, calving interval, number of services per conception, ovarian rebound and days open). DNA was extracted from blood samples collected from Holstein dairy cows of the both farms and restriction analysis of 301-bp PCR products of LTF gene revealed two genotypes AA genotype (301 bp) and AB genotype (301, 201 and 100 bp). Meanwhile, restriction analysis of 382-bp PCR products of TLR4 gene digested with AluI yielded two alleles (A and B) and three genotypes (AA, AB and BB). The A allele was indicated by two bands at 300 and 82 bp, and the B allele resulted in three fragments of 160, 140 and 82 bp. There was a significant association (p ≤ 0.05) between LTF genotypes and milk performance traits except for days in milk. The TLR4 genotypes had significant effects (p ≤ 0.05) on age at first freshening, calving interval, number of services per conception, ovarian rebound and days open. Ordinal logistic regression statistical model also revealed that it is possible to calculate high reproductive performance traits and to predict favourable dairy cows based on LTF and TLR4 genotypes. This research reveals the effectiveness of LTF/EcoRI and TLR4/AluI loci as candidates for reproductive performance assessment in Holstein cattle.