The Ac chicken (Gallus gallus domesticus Brisson) is commonly raised alongside other domestic chicken breeds in the Mekong Delta region. This study was conducted to analyze the impact of INHA/PstI and VIPR1/HhaI polymorphisms on the reproductive characteristics of this breed. A total of 380 Ac hens from 16-40 weeks of age were used, each placed in a separate cage for data collection. DNA isolation was performed using feather samples, and genotypes were detected by applying the PCR-RFLP technique. Two polymorphisms were identified, namely C829T (INHA /PstI) in exon 1 of the INHA gene and C42913T (VIPR1/HhaI) in intron 6 of the VIPR1 gene. At both sites, two polymorphisms did not follow the Hardy -Weinberg equilibrium . The INHA /PstI and VIPR 1/Hha I polymorphisms demonstrated a statistically significant association with the total number of eggs produced and the laying rate (pPstI) had the highest egg production (72.4 eggs/hen/24 laying weeks ). In contrast , those with the CC genotype produced approximately 9 fewer eggs (63.2 eggs /hen), resulting in laying rates of 45.2% and 40.3%, respectively .Additionally , the INHA /PstI polymorphisms showed a notable and significant association with the average age of the first egg (pAc chickens through selective breeding, it is recommended to prioritize the use of birds with the TT genotype at the INHA/PstI locus.

Keywords: Egg number, Polymorphisms, Reproductive traits, Ac chicken, SNP.