Ri chicken is the most popular backyard chicken breed in Vietnam, but little is known about the growth curve of this breed. This study compared the performances of models with three parameters (Gompertz, Brody, and Logistic) and models containing four parameters (Richards, Bridges, and Janoschek) for describing the growth of Ri chicken. The bodyweight of Ri chicken was recorded weekly from week 1 to week 19. Growth models were fitted using minpack.lm package in R software and Akaike’s information criterion (AIC), Bayesian information criterion (BIC), and root mean square error (RMSE) were used for model comparison. Based on these criteria, the models having four parameters showed better performance than the ones with three parameters, and the Richards model was the best one for males and females. The lowest and highest value of asymmetric weights (α) were obtained by Bridges and Brody models for each of sexes, respectively. Age and weight estimated by the Richard model were 8.46 and 7.51 weeks and 696.88 and 487.58 g for males and for females, respectively. Differences in the growth curves were observed between males and female chicken. Overall, the results suggested using the Richards model for describing the growth curve of Ri chickens. Further studies on the genetics and genomics of the obtained growth parameters are required before using them for the genetic improvement of Ri chickens.

In this study, partial mitochondrial DNA (mtDNA) D-loop sequences of three Vietnamese indigenous chicken varieties, including Mong Tien Phong, To, and Sau Ngon, were analyzed to access genetic diversity and the maternal lineages of origin. A 525 bp fragment of the mtDNA D-loop region was sequenced from a total of 61 chickens of the three varieties. A neighbor-joining phylogenetic tree was assembled from the haplotypes obtained and reference sequences of mtDNA D-loop sequences of Red Junglefowl and domestic chickens from National Center for Biotechnology Information database. Genetic diversity indices and analysis of molecular variance were performed. Evaluation of genetic relationships between the three varieties was carried out with pairwise fixation index (F_ST). In total, 16 haplotypes were identified in the chickens studied. These haplotypes were classified in three haplogroups (A, B, and E) with the majority grouped in haplogroup B and haplogroup E. All three chicken varieties studied were distributed into 2–3 haplogroups and all three haplogroups found in this study are also represented by Red Junglefowl. In conclusion, all three Vietnamese indigenous chicken varieties have likely originated from multiple maternal lineages and potentially descended from the Red Junglefowl.

The alpha (1) fucosyltransferase gene (FUT1) is a candidate gene for controlling the adhesion of Escherichia coli F18 receptor. Indeed, a single-nucleotide polymorphism, c.307G>A, located in the gene is such that pigs with AA genotype are resistant to entero-toxigenic E. coli F18, whereas those with AG and GG genotypes are sensitive. An experiment was carried out in northern Vietnam from March 2016 to May 2017 to determine FUT1 genotype frequencies and the effect of these genotypes on production performance of Yorkshire pigs. A total of 613 animals were genotyped using polymerase chain reaction – restriction fragment length polymorphism method. The body weights at birth, weaning, initial fattening period, and final fattening period were collected from 611, 516, 479, and 418 animals, respectively, whereas backfat thickness, depth of longissimus dorsi, and lean meat percentage were recorded from 328 animals. The frequencies of FUT1 genotypes were found to be in Hardy–Weinberg equilibrium (P = 0.51). Effect of FUT1 genotype was not observed for all production traits (P > 0.05), whereas final body weight and depth of longissimus dorsi were significantly different between females and males (P < 0.05). These results suggest that selection of Yorkshire pigs resistant to entero-toxigenic E. coli F18 could be effective without adversely affecting average daily gain and lean meat.

| Prolactin receptor (PRLR) and vertnin (VRTN) gene is considered as genetic marker for teat, vertebrae and ribs number in pigs. In this study, the polymorphisms of these genes was investigated in Landrace, Yorkshire and Meishan purebred pigs. A total of 102 animals including 37 Landrace, 35 Yorkshire and 30 Meishan were collected from Thuy Phuong Pig Research and Development Center, Vietnam National Institute of Animal Science, Vietnam. Pig individuals were genotyped with PCR and PCR-RFLP methods. Allelic and genotypic frequencies were calculated. Hardy-Weinberg equilibrium (HWE) was performed using χ 2-test. For PRLR, 3 genotypes (AA, AB and BB) were detected and the most abundant genotype was the heterozygous one. The frequencies of expected genotype AA were 0.35, 0.40, and 0.17 for Landrace, Yorkshire, and Meishan, respectively. Frequencies of allele A were 0.61 (Landrace), 0.69 (Yorkshire), and 0.59 (Meishan). The loci were in HWE for all group of pigs except Meishan. For VRTN, those values for QQ genotype were 0.30 (Landrace), 0.37 (Yorkshire), and 0.10 (Meishan), while Q allele frequencies were 0.43 (Landrace), 0.57 (Yorkshire), and 0.22 (Meishan). HWE was detected for Meishan Pig.