Search

1. Killing male one-day-old chicks, especially from layer lines, is banned in some European countries. Therefore, dual-purpose chickens, where each sex is used for meat and egg production, respectively, offer an alternative production solution. This study evaluated the British purebred breed Ixworth as a dual-purpose chicken for meat and egg production. 2. Ixworth chicks (n = 167) were hatched and reared mixed-sex in a floor housing system, with two groups receiving a commercial pullet diet (treatment 1) and two groups receiving a diet composed for males of layer lines (treatment 2). Individual chick performance data were recorded. Males were slaughtered at 12 weeks of age, and their growth rate and carcase variables were analysed. All hens were continuously reared on the pullet diet and kept in a free-range system from 20 weeks old for one laying period (52 weeks). In addition, group-based feed consumption and mortality were recorded. 3. Cockerels in treatment 1 and 2 showed significantly different [T(88) = −2.846, P = 0.003] growth rates (25.3 vs. 27.4 g/day) and average final weights (2166 g vs. 2344 g). The hens in treatment 1 (n = 41) laid an average of 193 eggs per hen housed (mean egg weight: 56.9 g), whereas those in treatment 2 (n = 35) laid 195 eggs per hen housed (mean egg weight: 56.5 g). Nest acceptance was >97.5% and feed consumption was up to 140 g/bird/day. 4. The results showed that the Ixworth may be a suitable breed for dual-purpose use and could be improved through selective breeding, offering potential for preservation of this local breed as well as general biodiversity in poultry farming. [ABSTRACT FROM AUTHOR]

1. Korat (KR) chicken is a new meat-type chicken breed established with the purpose of developing Small and Micro Community Enterprise Production. This slow-growing chicken has been recognised for its good texture and flavour, but its low feed efficiency is associated with high cost of production which can hamper the development of local production. This has highlighted the importance of studying the trade-off between feed efficiency and meat quality in KR chicken. 2. This study investigated the phenotypic correlations between feed efficiency, growth performance, and meat quality in KR chicken. Individual body weight and feed intake were recorded weekly for 75 male KR chickens for the calculation of feed conversion ratio (FCR) and residual feed intake (RFI). The growth curve was modelled by Gompertz function and meat quality evaluated at 10 weeks of age, through the measurement of pH (pHu), water-holding capacity (WHC) and drip loss (DL) in breast and thigh muscle. 3. Faster growth rate at young age appeared favourable, regarding feed efficiency, since a moderate negative correlation was found between FCR and initial growth rate. Chickens with a higher initial growth and maturation rates were characterised by lower water-holding capacity in meat. This was not associated with acidic meat, since a higher speed of growth (especially in the first weeks) was positively associated with final pH in breast meat. Relationships between RFI and meat quality traits appeared to be weak. While better FCR could be achieved by increased initial growth rate, this seemed to negatively impact water-holding capacity of the meat. 4. RFI appeared as an interesting alternative as a compromise between FCR and meat quality. [ABSTRACT FROM AUTHOR]

1. The DNA/RNA binding protein YBX3 is associated with gene transcription, DNA repair, and the progression of various diseases and is highly conserved from bacteria to humans. 2. The following experiment found a 27-bp insertion/deletion polymorphism in the intron region of the YBX3 gene through resequencing. In cross-designed, F2 resource groups, the indel was significantly associated with broiler weight and body size at 0, 2, 4, 6, 8, 10 and 12 weeks of age and several other traits (semi evisceration weight (SEW), evisceration weight (EW), semi evisceration rate (SER), evisceration rate (ER), head weight (HW), claw weight (CLW), wing weight (DWW), gizzard weight (GW), pancreas weight (PW), chest muscle weight (CMW), leg weight (LW), leg muscle weight (LMW), shedding weight (SW), carcase weight (CW) and pectoral area (PA)) (P < 0.05). 3. The insertion-insertion (II) genotype was significantly associated with the greatest growth traits and carcase traits, whereas the values associated with the insertion-deletion (ID) genotype were the lowest in the F2 reciprocal cross chickens. 4. The mutation sites were genotyped in 3611 individuals from 13 different chicken breeds and cross-designed F2 resource groups. The II genotype is the most important in commercial broilers, and the I allele frequency observed in these breeds was relatively high. However, there is still considerable potential in breeding dual-purpose chickens and commercial laying hens. 5. The mRNA expression of the YBX3 gene in tissues from different breeds and developmental stages demonstrated that the 27-bp indel may affect the entire development process of poultry by affecting muscle development. These findings are beneficial for elucidating the function of the YBX3 gene and facilitating enhanced production in the chicken industry. [ABSTRACT FROM AUTHOR]

1. To evaluate the inbreeding of yellow-feathered chickens (YFCs) and identify genes related to their unique characteristics, whole-genome re-sequencing data were applied to detect runs of homozygosity (ROH) in the genomes of 10 YFC chickens from each of 10 different YFC breeds. The number, length, distribution of ROH, and inbreeding coefficient in different YFC populations were calculated. Genomic regions with high frequency in ROH were annotated. 2. In total, 25,547 ROH with an average length of 335 kb were detected, with most being <1 Mb. The domination of short ROH reflected the long breeding history of this chicken. The number, length, frequency, and distribution of ROH varied among chicken populations, and high genetic diversity was maintained. 3. Numerous genes related to YFC characteristics were identified in the high-frequency ROH regions. Among these, IFNA, IFNB, IL11 RA, IL22 RA1, IFNLR1, and TRIF genes were involved in disease resistance. The AMY, G6PC, SDHB, GCNT4, and ACO genes were associated with energy material metabolism; and FABPL, AQP7, ACAA2, and RYR2 were related to meat quality and flavour. The KITLG, CREB3, RYR2, and LGR4 genes, related to pigmentation, were detected. 4. This ROH-based inbreeding evaluation lays the foundation for breeding and conservation of YFC populations, and the candidate genes identified can be used for marker-assisted selection. [ABSTRACT FROM AUTHOR]

1. Individually-caged Ross 308 broiler breeders were transferred temporarily at 147 d from 8 to 14-h photoperiods and back to 8 h at 5-d intervals from 5 to 25 d and at 32 d. Control birds were maintained on 8 h or transferred permanently to 14 h. 2. Five long days had minimal effect on age at first egg, between 10 and 25 long days progressively accelerated sexual development, and maximum advance was achieved by 32 long days. However, a model involving the ogive of a normal distribution with a mean of 14 long days and an SD of 5.3 indicated that 28 long days would be sufficient to maximise sexual development. 3. The similarity of this model for broiler breeders with one previously produced for egg-type pullets suggested a common physiological mechanism for photosexual responses to two opposing changes in photoperiod. [ABSTRACT FROM AUTHOR]

1. A stock of cross-bred CD hens was divided into ‘resistant’ (R) and ‘sensitive’ (S) to stress on the basis of the heterophil/lymphocyte (H/L) ratio using the lower 99% confidence limit method for selection. A first generation was produced from these R and S females mated with similarly selected R and S local Barred males. The association between ‘resistance’ and some production traits was investigated. 2. The proportions of R:S among CD females and Barred males was 51·2:48·8 and 52:48, respectively. Mean H/L ratios for Barred males and females, respectively, were 0·87&ThickSpace;±&ThickSpace;0·03 and 0·83&ThickSpace;±&ThickSpace;0·03 ( P &ThickSpace;>&ThickSpace;0·05). 3. Compared with the S group in CD females, the R group had greater egg production (59% vs 51%), egg weight (65·5&ThickSpace;g vs 62·6&ThickSpace;g) and body weight at 39 weeks (115&ThickSpace;g heavier). 4. The superiority of R in terms of proportion of fertile eggs, hatchability and the proportion hatched from those set amounted to 4·8, 6·1 and 5·4%, respectively. 5. The proportion of dead embryos in the R group (5·4%) was lower than in the S group (9·3%). 6. With the F1 generation the R chicks were heavier at hatching. 7. Percentage mortality of male F1 chicks, from hatching to 4 weeks and from 4 to 8 weeks, was lower in the R group. A similar, but non-significant, trend was noted for R females. 8. The progeny of the R group was heavier than the S progeny at 4 and 8 weeks and also the percentage dressed weight of males was greater at 8 weeks. The R group was heavier than the S group at 4, 8 and 12 weeks. 9. These results suggest that selection for general ‘resistance’, on the basis of the H/L ratio using the 99% lower confidence limit method of selection, is positively correlated with several important production and reproduction traits. Establishing resistant lines with high production rates seems feasible. [ABSTRACT FROM AUTHOR]