Effects of rearing systems on laying performance, egg quality, and serum biochemistry of Xianju chickens in summer.

The objective of this study was to compare the laying performance, egg quality, and serum biochemistry of hens maintained in conventional cage rearing system (CRS), flat net-rearing system (NRS), and free range system (FRS) under summer conditions. Indigenous Xianju chickens (n = 540) were randomly allocated into cages or pens of rearing system groups, within each system there were 5 replicates with 36 hens in each replicate. The experiment lasted between 21 and 29 wk of age. Hen-day egg production (P = 0.00) and egg mass (P = 0.00) were higher in the CRS but were similar in the NRS and FRS. Lowest egg weight (P = 0.02), yolk weight (P = 0.00) and yolk ratio (P = 0.01), and feed intake (P = 0.01) were observed from the FRS, whereas lowest feed conversion ratio (FCR) was recorded from the CRS (P = 0.01). Rearing systems had negligible effect on egg quality. Serum Ca (P = 0.04) and total protein (P = 0.03) levels were found to be higher in the CRS but were lower in the FRS. Serum levels of glucose (P = 0.01), cholesterol (P = 0.00), and triglyceride (P = 0.00) in the CRS increased compared with the NRS and FRS groups, whereas serum levels of high density lipoprotein cholesterol (HDL-C; P = 0.01) in the CRS decreased. It can be concluded that under summer conditions, Xianju chickens from CRS had an advantage in terms of productivity parameters, but exhibited higher levels of serum lipids and glucose.

Association of MYF5 and KLF15 gene polymorphisms with carcass traits in domestic pigeons (Columba livia).

Single nucleotide polymorphisms (SNPs) in the exons of the myogenic factor 5 (MYF5) and Kruppel-like factor 15 (KLF15) genes were identified and analysed by using DNA sequencing methods in 60 female domestic pigeons (Columba livia). Five SNPs (T5067A, C5084T, C5101T, T5127A and C5154G) were detected in exon 3 of MYF5 and 6 SNPs (C1398T, C1464T, G1542A, C1929T, G1965A and A2355G) were found in exon 2 of KLF15, respectively. The analysis revealed three genotypes, in which the AA genotype was dominant and the A allele showed a dominant advantage. For the MYF5 gene, the C5084T and T5127A SNP genotypes were significantly associated with carcass traits of pigeons. Within those two SNPs, the BB genotype showed relatively higher trait association values than those of AA or AB genotypes. No significant association was observed between the KLF15 SNP genotypes and carcass traits. These results indicated that the MYF5 gene is a potential major gene affecting carcass traits in domestic pigeons. The BB genotype of the C5084T and T5127A SNPs could be a potential candidate genetic marker for marker-assisted selection in pigeon.