The candidate gene approach is a successful approach in identifying genes and could be useful for quickly detection of the associations between genes and lactation traits in dairy cattle. Although lactoferrin gene is highly polymorphic and it has shown some variants related to lactation traits in dairy cattle, the studies concerning their variabilities and associations with economic traits are scarce, particularly those studies performed in developing countries. A total of 494 lactation records from 180 milking cows raised in three experimental herds in Egypt (142 Friesian in Elkarda and Sakha herds and 38 local Baladi in Elserw herd) were used to characterize lactoferrin gene polymorphism in these populations using PCR-RFLP technique and to investigate the association of genotypes of lactoferrin gene with lactation traits. Yields of milk, fat and protein in Friesian breed was recorded for 10 months, while lactation data in local Baladi herd was available only for six months. A mixed model was used in analyzing data of each herd separately. An amplified PCR product of lactoferrin gene was performed at 800 bp and digested using HinfI restriction enzyme. Three genotypes were obtained, involving AA with one band (800 bp), AB with three bands (800, 650 and 150 bp) and BB with two bands (650 and 150 bps). Sakha Friesian herd was in Hardy Weinberg equilibrium for lactoferrin gene, but Elkarada Friesian and Elserw Baladi herds were both in disequilibrium. The gene frequency of B allele was higher than A allele in Elkarada Friesian and Elserw local herds (0.61 and 0.79 vs 0.39 and 0.21), while the reverse was observed in Sakha Friesian herd. The expected heterozygosity (HE) was moderate in Elkarada Friesian herd (0.47) and Sakha Friesian herd (0.26) and low in Elserw local herd (0.18). The polymorphic information content (PIC) and fixation index (FIS) were moderate in Elkarada Friesian herd (0.36 and 0.29) and Elserw local herd (0.27 and 0.37). In Elkarada Friesian herd, the AA genotype was significantly higher in milk yield (2980 kg) and fat yield (59.0 kg) than the BB genotype, while there were insignificant differences among the genotypes for protein yield. In Sakha Friesian herd, cows of AB genotype were significantly higher in milk yield (2996 kg) and protein yield (46.0 kg) than cows of genotype BB. The BB genotype in Elserw local herd had higher significant 180-day milk yield (681kg) and fat yield (17.2 kg), while AA genotype was significantly higher in protein yield (20.0 kg). Analysis across herds and breeds revealed significant molecular associations of lactoferrin gene SNP genotypes (p |
