Abstract
BACKGROUND & OBJECTIVES: Genetic polymorphisms in key candidate genes such as PRL, DGAT1, FSHR, and GH play a pivotal role in regulating lactation and reproductive traits, making them critical markers for breeding programs in buffalo. Molecular characterization and associations of PRL, DGAT1, FSHR and GH candidate genes with test day milk yield (TDMY), fat yield (TDFY), protein yield (TDPY), somatic cell score (TDSCS), age at first calving (AFC), days open (DO) and calving interval (CI) in Egyptian buffalo. METHODS: Lactation and reproduction records were obtained from Egyptian buffaloes reared in three experimental herds affiliated with the Animal Production Research Institute (APRI), Agricultural Research Center (ARC), Ministry of Agriculture, Egypt. For molecular characterization and association analysis of candidate genes with the studied traits, blood samples were collected from a total of 286 animals (both males and females). Specifically, 101 animals were successfully genotyped for PRL and DGAT1 genes, 98 females and 71 males for FSHR gene, and 103 females and 71 males for GH gene. PCR-RFLP technique using XbaI restriction enzyme for PRL gene and using AluI restriction enzyme for DGAT1, FSHR and GH genes was used for animal's genotyping. RESULTS: The generalised least square means (GLSMs) for AA genotype of PRL gene were superior relative to GG genotype, being 6.0 vs. 5.3 kg for TDMY, 390 vs. 340 g for TDFY, 290 vs. 220 g for TDPY and 2.47 vs. 2.50 for TDSCS, while the GLSM for GG genotype was favourable than AA genotype for all the studied reproductive traits. The CC genotype of FSHR gene was superior relative to GG and GC genotypes for all lactation traits, being 6.8 vs. 5.6 and 5.7 kg for TDMY, 380 vs. 360 and 350 g for TDFY, 290 vs. 220 and 230 g for TDPY and 2.41 vs. 2.48 and 2.45 for TDSCS, while the CC genotype was favourable than GG and GC genotypes for AFC, DO and CI. For GH gene, TC genotype was superior compared to CC genotype, being 6.1 vs. 5.6 kg for TDMY, 390 vs. 350 g for TDFY, 290 vs. 220 g for TDPY, 2.41 vs. 2.45 for TDSCS, 34.4 vs. 37.6 mo for AFC, 95 vs. 107 d for DO and 377 vs. 399 d for CI. CONCLUSION: The significant molecular associations detected between AA genotype of PRL gene, CC genotype of FSHR gene and TC genotype of GH gene and lactation and reproduction traits may be helpful for marker-assisted selection programs aiming to improve lactation traits and reproduction performance in Egyptian buffalo.