Polymorphisms of the prolactin gene and their association with egg production traits in two Chinese domestic ducks.

1. Prolactin (PRL) as a polypeptide hormone which plays a crucial role in egg production traits. 2. Polymorphisms of the PRL gene were analysed with DNA sequencing and polymerase chain reaction-single-strand conformation polymorphism methods in two Chinese domestic laying duck breeds (Jinding, n = 400, Youxian, n = 400, respectively). 3. The results showed that one polymorphism was detected (A-412G) in intron 1 of the PRL gene, with three genotypes: AA, AG and GG. Association analysis showed that the ducks with the GG genotype had significantly greater egg production and egg weight than those with AG and AA genotype (p < 0.05). Hence, the 412A > G polymorphism of the PRL gene in intron 1 is a potentially valuable genetic marker for laying duck breeding programmes.

Intestinal lactic acid bacteria from Muscovy duck as potential probiotics that alter adhesion factor gene expression.

The purpose of this study was to assess the suitability of lactic acid bacteria (LABs) isolated from Muscovy duck as a potential probiotic. Isolates were identified by targeted polymerase chain reaction and assessed in vitro for probiotic characteristics such as autoaggregation; surface-charge; hydrophobicity; tolerance to acidic pH, bile salts and protease; and expression of genes involved in Caco-2 cell adhesion. The LAB isolates exhibited strong resistance to high bile concentration and acidic pH, produced lactic acid, and bacteriostatic (P < 0.05) were identified as bacilli compared with LAB isolates of cocci. Additionally, the LAB isolates showed high sensitivity to penicillin and tetracycline antibiotics, while they were resistant to ofloxacin, Macrodantin, and cotrimoxazole. The level of F-actin mRNA increased in the groups treated with CM3, Salmonella enterica, and CM3 + S. enterica (P < 0.0001, P < 0.05 and P < 0.05 ). The level of cell adhesion molecule (CAM) and E-cadherin (E-cad) mRNA expression was significantly lower in the treatment group (P < 0.05 for both) than in the control. The F-actin, CAM, and E-cad mRNA levels were significantly lower in the S. enterica and CM3 + S. enterica groups (P < 0.01) than in the CM3 group. Among these, RNA levels were higher in the CM3 + S. enterica than S. enterica group. These results indicate that the natural duck gut microflora is an excellent source for probiotic bacteria and can facilitate the establishment of criteria to select probiotic strains for the prevention of diarrhea.

Analysis of Fcgrt gene polymorphism in indigenous Chinese sheep and its association with colostrum IgG concentration.

The neonatal Fc receptor (FcRn) plays an important role in regulating IgG homeostasis in the body and passive protection to the offspring. Changes in FcRn expression levels caused by genetic polymorphisms of Fcgrt, which encodes FcRn, may lead to inter-individual differences in colostrum IgG levels in sheep. In this study, we sequenced the FcRn partial heavy chain from 179 sheep from Xinjiang Province, China, and detected the differences in colostrum IgG levels and Fcgrt genotypes to identify the correlation between the Fcgrt genotype and colostrum IgG levels in 4 sheep breeds. The DNA sequencing of a 680-bp fragment of the Fcgrt gene revealed various patterns depending on the single-strand conformation in the Suffolk breed. Sequencing analysis revealed a total of 3 patterns, AA, BB, AB, in this fragment, among which the absence of AB and BB genotype acted as a marker for breed identification and characterization, while the AA genotype was shared by Suffolk and 3 other breeds. The only allele found in all 4 breeds was allele A, indicating that natural selection may be favoring the AB and BB genotypes in general and B allele in particular, as the colostrum IgG concentration was relatively higher in the Suffolk breed compared to the other 3 breeds.