Native chickens hold a significant share of the market in China. In response to the huge demand from the market, the productivity of Chinese native chickens needs to be improved. Cross breeding is an effective method to increase productivity, although it might affect meat quality. In this study, two pure lines (SD02 and SD03) of Erlang mountainous chickens were hybridized with a yellow feather and faster growing line (SD01). The effect of hybridization on carcass and meat quality (physiochemical and textural traits) was measured in the F1 population at d 91 of age. The hybrids exhibited higher body weight and dressed weight, and amount of semi-eviscerated, eviscerated, breast muscle and abdominal fat (p<0.05). Abdominal fat yield also increased (p<0.05) compared to the offspring of the two pure-lines. Meanwhile, there was no significant difference in meat quality traits except for the myofiber diameter and density and the shear force of the breast muscle. Overall, the offspring of cross-lines were similar to pure lines in meat color, pH value, inosinic acid, crude protein, crude fat, dry matter, moisture content and amino acid composition in the breast muscle. These results suggest that productivity can be improved via cross-breeding while maintaining meat quality of the Erlang mountainous chicken.

Phosphoglycerate mutase (PGAM2) catalyzes the conversion of 3-phosphoglycerate into 2-phosphoglycerate and releases energy during glycolysis in muscle tissues. PGAM2 has been considered as a candidate gene to influence growth, development, and carcass traits in livestock. The aim of this study was to investigate the association between polymorphisms of PGAM2 and growth traits in rabbits. Three single nucleotide polymorphisms (SNPs) were identified by direct sequencing in 20 random individuals from three breeds, including c.-10C>T, c.195C>T, and c.414+17C>T. The c.195C>T was genotyped by PCR-RFLP in a total of 222 rabbits of three breeds (Tianfu black, 53 animals; Ira, 91 animals; Champagne, 78 animals). The average allele frequency among the breeds was 0.52 for allele T and 0.48 for C. The heterozygosity and effective number of alleles were 0.4992 and 1.996, respectively. The association results revealed the CT genotype of c.195C>T was associated significantly (P < 0.05) with greater body weight at 84 days of age (BW84) and with average daily weight gain (ADG). However, association of the genotypes with other production traits was not observed. The results of this study suggested PGAM2 is one of the candidate genes affecting BW84 and ADG in the rabbit.

Dectin-1 plays a critical role in the pathogenesis of intestinal inflammation by recognizing the pathogenic agents and mediating cytokine responses. The objective of this study was to establish the association between dectin-1 polymorphisms and susceptibility to nonspecific digestive disorders (NSDD) and cytokine expression in rabbits. A total of 7 coding SNP were detected in dectin-1 gene. The genetic association between SNP (ss707197675A > G) and susceptibility to NSDD was evaluated using a case-control study (178 cases and 174 controls). The results revealed that the A allele was associated with an increased risk of developing NSDD in rabbits. The AA genotype significantly increased the genetic susceptibility to NSDD with odds ratio of 4.76 (95% confidence interval, 1.92-12.50, P = 0.0002) compared with GG and GA genotypes. We also experimentally induced NSDD in another independent growing rabbit population by feeding a low-fiber diet and subsequently investigated the cytokine mRNA expression. Among the 4 studied cytokines, the expression of interferon-γ, IL-17F, and IL-22 were increased 2.8 to 6.0-fold in AA genotype compared with GG genotype (P < 0.01). The greater IL-17F and IL-22 mRNA expressions indicated a positive correlation with severe intestinal inflammation (P < 0.05). The decreased expression of IL-10 was associated with severe intestinal inflammation (P = 0.006), but IL-10 expression was not influenced by dectin-1 genotype. In conclusion, polymorphism ss707197675 of dectin-1 is related with susceptibility to NSDD and increased expression of proinflammatory cytokines, and dectin-1 could be an important candidate gene associated with NSDD in rabbits.

Cellular retinol-binding protein II (CRBP II) belongs to the family of cellular retinol-binding proteins and plays a major role in absorption, transport, and metabolism of vitamin A. In addition, because vitamin A is correlated with reproductive performance, we measured CRBP II mRNA abundance in erlang mountainous chickens by real-time PCR using the relative quantification method. The expression of CRBP II showed a tissue-specific pattern and egg production rate-dependent changes. The expression was very high (p<0.05) in jejunum and liver, intermediate in kidney, ovary, and oviduct, and lowest (p<0.05) in heart, hypothalamus, and pituitary. In the hypothalamus, oviduct, ovary, and pituitary, CRBP II mRNA abundance were correlated to egg production rate, which increased from 12 wk to 32 wk, peaked at 32 wk relative to the other time points, and then decreased from 32 wk to 45 wk. In contrast, the expression of CRBP II mRNA in heart, jejunum, kidney, and liver was not different at any of the ages evaluated in this study. These data may help to understand the genetic basis of vitamin A metabolism, and suggest that CRBP II may be a candidate gene to affect egg production traits in chickens.