Chicken prolactin (PRL) is a physiological candidate gene for egg production. The objective of the current research was to investigate the association of polymorphisms in the chicken PRL promoter region with egg production. Genotyping of 177 individuals from White Leghorn, Yangshan, Taihe Silkies, White Rock, and Nongdahe breeds for 6 single nucleotide polymorphisms (C-2402T, C-2161G, T-2101G, C-2062G, T-2054A, and G-2040A) and 1 24-bp indel (insertion-deletion) at the site of -358 of the chicken PRL gene revealed large breed differences in allelic frequencies for all but the T-2101G and T-2054A polymorphisms. An F2 population produced from Nongdahe x Taihe Silkies chickens consisted of 374 hens, which were recorded for egg production traits and genotyped for the above 7 polymorphisms. Marker-trait association analysis indicated that the 24-bp indel was associated with egg production (P < 0.01) and that H3 (C C T C T G) was the most advantageous haplotype for egg production.

Microcin J25 (MccJ25) is an antimicrobial peptide produced by a fecal strain of Escherichia coli containing 21 AA. This study was performed primarily to evaluate the effects of MccJ25 as a potential substitute for antibiotics (AB) on growth performance, nutrient digestibility, fecal microbiota, and intestinal barrier function in weaned pigs. In the present study, 180 weaned pigs (7.98 ± 0.29 kg initial BW) were randomly assigned to 1 of 5 treatments, including a basal diet (CON) and CON supplemented with AB (20 mg/kg colistin sulfate; ABD) or 0.5, 1.0, and 2.0 mg/kg MccJ25. On d 0 to 14, dietary supplementation with MccJ25 and ABD had positive effects on ADG, ADFI, diarrhea incidence, and G:F ( < 0.05). Pigs fed the 2.0 mg/kg MccJ25 diet had greater ADG ( < 0.05) and marginally greater G:F ( < 0.10) compared with pigs fed the ABD diet. Compared with the CON diet, the 2.0 mg/kg MccJ25 diet sharply improved ( < 0.05) ADG and G:F and decreased ( < 0.05) diarrhea incidence (d 15 to 28 and d 0 to 28). Apparent digestibility of nutrients in pigs fed 1.0 and 2.0 mg/kg MccJ25 was improved ( < 0.05) compared with that of pigs fed CON and ABD. The serum cytokines IL-6 and IL-1β and tumor necrosis factor-α levels in pigs fed MccJ25 were greater than in pigs fed CON ( < 0.05). Additionally, the IL-10 concentration in pigs fed MccJ25 was sharply increased ( < 0.05) compared with that of pigs fed CON. Pigs fed 1.0 and 2.0 mg/kg MccJ25 diets had remarkably decreased lactate, diamine oxidase, and endotoxin concentrations and fecal numbers ( < 0.05) and improved fecal and numbers ( < 0.05). Compared with the ABD diet, the diet containing 2.0 mg/kg MccJ25 did not increase lactate, diamine oxidase, and endotoxin (d 14) concentrations ( < 0.05) or decrease the and (d 28) numbers ( < 0.05). The diets containing 1.0 and 2.0 mg/kg MccJ25 and ABD (d 28) improved lactate concentration and short-chain fatty acid concentrations, including acetate, propionate, and butyrate, in feces ( < 0.05). Moreover, the pigs fed 2.0 mg/kg MccJ25 had greater lactate, butyrate (d 14), and propionate concentrations than the pigs fed the ABD diet ( < 0.05). In conclusion, dietary supplemented MccJ25 effectively improved performance, attenuated diarrhea and systematic inflammation, enhanced intestinal barrier function, and improved fecal microbiota composition of weaned pigs. Therefore, MccJ25 could be a potential effective alternative to AB for weaned pigs.

The discovery of copy number variation (CNV) in the genome has provided new insight into genomic polymorphism. Studies with chickens have identified a number of large CNV segments using a 385k comparative genomic hybridization (CGH) chip (mean length >140 kb). We present a detailed CNV map for local Chinese chicken breeds and commercial chicken lines using an Agilent 400k array CGH platform with custom-designed probes. We identified a total of 130 copy number variation regions (CNVRs; mean length = 25.70 kb). Of these, 104 (80.0%) were novel segments reported for the first time in chickens. Among the 104 novel CNVRs, 56 (53.8%) of the segments were non-coding sequences, 65 (62.5%) showed the gain of DNA and 40 (38.5%) showed the loss of DNA (one locus showed both loss and gain). Overlapping with the formal selective sweep data and the quantitative trait loci data, we identified four loci that might be considered to be high-confidence selective segments that arose during the domestication of chickens. Compared with the CNVRs reported previously, genes for the positive regulation of phospholipase A2 activity were discovered to be significantly over-represented in the novel CNVRs reported here by gene ontology analysis. Availability of our results should facilitate further research in the study of the genetic variability in chicken breeds.

Transmissible spongiform encephalopathy (TSE) is a neurodegenerative disorder in humans and animals. Polymorphisms and mutations in the prion protein (PRNP) gene have been associated with the incidence of natural and experimental TSE and the incubation period length. In this study, we determined PRNP polymorphisms in Chinese ovine, caprine and bovine breeds using 400 samples from 13 ovine and caprine breeds and 250 samples from nine bovine breeds. In the ovine and caprine PRNP gene, we found five previously unreported amino acid polymorphisms and two silent nucleotide alterations. In bovine PRNP, we found eight previously unreported amino acid polymorphisms and six silent nucleotide alterations.

A genetic study of 32 local Chinese, three foreign pig breeds [Duroc (DU), Landrace and Yorkshire], and two types of wild boar (Hainan and Dongbei wild boar) based on 34 microsatellite loci was carried out to clarify the phylogeny of Chinese indigenous pig breeds. The allele frequencies, effective numbers of alleles, and the average heterozygosity within populations were calculated. The results showed that the genetic variability of the Lingao pig was the largest, while the Jiaxing pig was the lowest. The greatest distance between domestic pigs was found between Shanggao and DU pig and the shortest was found between Wuzhishan and Lingao pig, respectively. A neighbour-joining tree constructed from Modified Cavalli-Sforza genetic distances divided Chinese pigs into two clusters; four subclusters were also identified. Our results only partly agree with the traditional types of classification and also provide a new relationship among Chinese local pig breeds. Our data also confirmed that Chinese pig breeds have a different origin from European/American breeds and can be utilized in programmes that aim to maintain Chinese indigenous pig breeds.