Candidate genes associated with reproductive traits in rabbits.

In the era of scientific advances and genetic progress, opportunities in the livestock sector are constantly growing. The application of molecular-based methods and approaches in farm animal breeding would accelerate and improve the expected results. The current work aims to comprehensively review the most important causative mutations in candidate genes that affect prolificacy traits in rabbits. Rabbits are a source of excellent-tasting meat that is high in protein and low in fat. Their early maturity and intensive growth are highly valued all over the world. However, improving reproductive traits and prolificacy in rabbits could be very tricky with traditional selection. Therefore, traditional breeding programs need new methods based on contemporary discoveries in molecular biology and genetics because of the complexity of the selection process. The study and implementation of genetic markers related to production in rabbits will help to create populations with specific productive traits that will produce the desired results in an extremely short time. Many studies worldwide showed an association between different genes and productive traits in rabbits. The study of these polymorphisms and their effects could be useful for molecular-oriented breeding, particularly marker-assisted selection programs in rabbit breeding.

Influence of polymorphisms in candidate genes on carcass and meat quality traits in rabbits.

Candidate gene is a powerful approach to study gene-trait association and offers valuable information for genetic improvement using marker-assisted selection. The current work aimed to study the polymorphisms of four single nucleotide polymorphism (SNPs) at located growth hormone (GH), insulin-like growth factor-II (IGF-II), fat mass and obesity-associated (FTO), and insulin receptor substrate-1 (IRS-1) genes, and their association with the carcass, and meat quality traits in rabbits. The SNPs were genotyped using RFLP-PCR in New Zealand White and local Baladi rabbits. The results revealed that the heterozygous genotype was the most frequent in all cases, except for the FTO SNP in LB rabbits. There was a significant effect for GH genotypes on meat lightness after slaughter and hind-part weight. While, IGF-II mutation significantly affected slaughter, hot carcass, commercial carcass, and hind-part weights. The FTO SNP was associated with cooking loss and intramuscular fat weight, and the IRS-1 SNP was significantly associated with drip loss and intramuscular fat. Specific-breed effects were obtained for IGF-II SNP on cooking loss, and for the intramuscular fat. Although the results suggested that these mutations are useful candidate genes for selection, more research for detecting more variants associated with carcass and meat quality traits in rabbits are recommended.

Genome-wide in silico characterization, validation, and cross-species transferability of microsatellite markers in Mallard and Muscovy ducks.

BACKGROUND: Microsatellites are important markers for livestock including ducks. The development of microsatellites is expensive and labor-intensive. Meanwhile, the in silico approach for mining for microsatellites became a practicable alternative. Therefore, the current study aimed at comparing whole-genome and chromosome-wise microsatellite mining approaches in Muscovy and Mallard ducks and testing the transferability of markers between them. The GMATA software was used for the in silico study, and validation was performed using 26 primers. RESULTS: The total number of the detected microsatellites using chromosome-wise was 250,053 and 226,417 loci compared to 260,059 and 238,462 loci using whole genome in Mallards and Muscovies. The frequencies of different motifs had similar patterns using the two approaches. Dinucleotide motifs were predominant (> 50%) in both Mallards and Muscovies. The amplification of the genomes revealed an average number of alleles of 5.08 and 4.96 in Mallards and Muscovies. One locus was monographic in Mallards, and two were monomorphic in Muscovies. The average expected heterozygosity was higher in Muscovy than in Mallards (0.45 vs. 0.43) with no significant difference between the two primer sets, which indicated the usefulness of cross-species amplification of different primers. CONCLUSION: The current study developed a whole-genome SSR panel for ducks for the first time, and the results could prove that using chromosome-wise mining did not generate different results compared to the whole-genome approach.

The comparison of two different plumage-color lines of Japanese quail (Coturnix japonica) disclosed a significant effect in increasing abdominal fat contents with increasing age.

This study aimed to investigate the characteristic differences between the white and brown-feathered Japanese quails, by evaluating the carcass traits and egg fat content, blood parameters, and intestinal histopathological features. A total of 1200 1-day-old Japanese quail chicks of two varieties (brown and white-feathered) were used in this study. Live body weight and feed intake were reordered every week. At the 4th week of age, 80 birds from each variety were slaughtered and carcass quality measurements and histopathological changes were recorded. After 6 weeks of age, eggs were collected, and egg quality was assessed. The results revealed that white-feathered quails had significantly heavier body weights and higher growth rates. At 4 weeks of age, females of the white-feather quail had significantly heavier slaughter, after de-feathering, and carcass weights. Remarkable variations between the studied quail varieties, with significant dominance of females in both varieties, at the level of water holding capacity, pH, and meat tenderness ascertained an obvious superiority of white-feathered quails compared to brown ones and indicated the higher tendency of the white quails for meat production. These results were linked with significant changes in biochemical profiles including lipids biomarkers, total protein, and Ca and phosphorus levels along with variations in the intestinal morphometry. It can be concluded that white-feathered quails had, in general, higher values of productivity compared with the brown-feathered ones during growing and laying periods.

Association between IRS-1, PPAR-γ and LEP genes polymorphisms and growth traits in rabbits.

Single nucleotide polymorphisms are commonly associated with changes in quantitative traits, and have been considered useful markers for improving different traits in livestock. The current study aimed to explore the effect of three SNPs located in Insulin receptor substrate (IRS-1), Peroxisome proliferator-activated receptor γ (PPAR-γ), and Leptin (LEP) genes on the growth traits of rabbits. Individuals from three rabbit breeds were genotyped using RFLP-PCR. The IRS-1 variant (c.189T > G) was associated with post-weaning body weight, and body weight gains, However, the effect on growth rates was insignificant in Baladi Red and V-line rabbits. The PPAR-γ variant (c.207A > C) was significantly associated with 8-wk body weights in V-line rabbits, 10-wk body weights, and growth rates from 8 to 10 weeks of age in New Zealand rabbits. However, the differences between genotypes were insignificant for body weight gains and average daily gain. The LEP gene mutation (g.16079636C > G) had significant effects on body weights at 6 and 8 weeks of age in New Zealand White rabbits and 8 weeks of age in Baladi Red rabbits were associated with the presence of the C allele. Concludingly, the results stressed the importance of the IRS-1 gene in post-weaning growth and suggested the existence of breed-specific effects for PPAR-γ and LEP.

Genotype by heat conditions interaction effects on growth and litter traits in rabbits.

Heat stress has severe impacts on rabbit performance because they have difficulty getting rid of excess heat. The interaction between genetic and environmental factors plays a vital role in the adaptation process. The current study aimed to evaluate the effects of interaction between the genotype and heat conditions (G×H) on litter size and growth traits. Two rabbit lines were used in the current study, Egyptian maternal line (APRI) and New Zealand White (NZW). The rabbits were raised under normal (22°C) or heat stress (35°C) conditions. The does were raised in individual cages, and their kits were reared under the same conditions. Negative effects of heat conditions were noted for litter traits, as heat stress had significantly reduced the number of born alive, total born, and marketed number rabbits by about 16, 11, and 25%, respectively. Moreover, growth traits were reduced under heat stress conditions compared to normal temperature conditions. Significant differences between genotypes were observed, APRI rabbits were higher than NWZ rabbits in the total born, number of born alive, number weaned, and the number of marketed rabbits by 10, 8, 11, and 10%, respectively. Genotype by heat conditions interaction effects were observed, APRI litters under normal conditions showed significantly higher litter traits than NWZ litters, whereas relevant reductions in litter traits of APRI line than NZW litters when reared in heat conditions. For growth traits, the differences between the two lines under normal conditions were reduced when animals of the two lines were raised under heat stress, for BW28, BW42, BW63, ADG28-42, and DF28-42 while these differences were increased for ADG42-63, DF28-42 and feed conversion during the whole fattening period. Based on the observed G × H interactions, it is important to select the animals under the same production conditions to raise rabbits that can cope with the expected global warming conditions.

Performance and nutrigenomics modulations in response to the inclusion of biologically treated date-palm mulch and enzyme mixture in the diets of growing rabbits.

This study was conducted to evaluate the effects of Allzyme addition on biologically-treated date-palm mulch (DPM) based diets for growing rabbits. DPM was treated by Trichoderma viride, Trichoderma reesi 230, Plorotus oysterous, and Phanaerochyte chrysosporium. Eighty rabbits were assigned to four groups: a control group, tDPM (10% tDPM inclusion of total diet), Allzyme (Allzyme supplementation), and tDPM + Allzyme (tDPM and Allzyme supplementation). The biological treatment resulted in a significant increase in crude protein and reductions in crude fiber. There was an interaction between tDPM and Allzyme at 9- and 10-week BW. The negative effects of tDPM on BW started at 8-week of age. The tDPM had unfavorable effects on slaughter and meat quality traits. The tDPM-by-Allzyme interaction affected total protein and globulin concentrations. However, blood glucose concentration was influenced by both tDPM and Allzyme. A significant tDPM effect was detected on the expression of INSR, GHSR, and IGF1 genes. However, the Allzyme effect was significant for PPARg and FASN genes. In conclusion, feeding tDPM negatively impacted rabbit's performance, however, Allzyme supplementation alleviated some of those effects. Accordingly, tDPM is recommended to be included in the diets of growing rabbits along with Allzyme supplementation.

Candidate genes for marker-assisted selection for growth, carcass and meat quality traits in rabbits.

Growth and meat production are the most relevant targets for animal breeders, there are strong relationships between animal growth regulation, body composition and meat quality. Therefore, it is essential to identify the genetic factors that are controlling growth, carcass, and meat quality traits and to explore the correlations between identified genes of those traits. Identification of candidate genes may shift rabbit breeding from classical to modern approaches, which offer great potential to accelerate genetic improvement plans, especially in developing countries. The current work reviews several genes and mutations affecting growth, carcass and meat quality traits. These candidate genes and mutations can be incorporated into MAS programs to improve rabbit breeds especially local breeds, provided that a reasonable proportion of trait additive genetic variance is explained by the significant marker. Furthermore, we highlighted the indispensable need for more researches investigating candidate genes for different traits.

Tracing Worldwide Turkey Genetic Diversity Using D-loop Sequence Mitochondrial DNA Analysis.

According to recent archeological evidence, turkey (Meleagris gallopavo gallopavo) domestication may have occurred in Mexico around 2000 years ago. However, little is known about the phylogenetic and genealogical background underlying domestic turkey populations. This study aimed to further understand the domestication process and identify inter- or intraspecific connections between turkey populations to determine their origins, trace their global expansion, and define the species' genetic value. Ninety-three domestic turkeys (local breeds) were sampled from populations in Brazil, Mexico, USA, Spain, Italy, Iran, and Egypt. Publicly available sequences from previous studies were also included. Standard mitochondrial DNA, genetic diversity, and haplotype network analyses were performed. Seventy-six polymorphic sites were identified. Turkeys from Mexico showed the greatest number of polymorphic sites (40), while turkeys from Italy and Brazil reported only one site each. Nucleotide diversity was also highest in Mexico and the USA (π = 0.0175 and 0.0102, respectively) and lowest in Brazil and Italy. Of the six major haplogroups defined, the Mexican and USA populations appeared to have remained more stable and diverse than the other populations. This may be due to conservative husbandry policies in the rural areas of other populations, which have prevented the introduction of commercial turkey lines.

Hypobaric bupivacaine spinal anesthesia for cystoscopic intervention: the impact of adding fentanyl.

BACKGROUND AND OBJECTIVE: Addition of fentanyl to hyperbaric bupivacaine spinal anesthesia prolonged the duration of sensory block. This study seeks to test the hypothesis that adding fentanyl to small dose hypobaric spinal anesthesia will improve intraoperative patients and surgeon satisfaction without delay in recovery. METHODS: Patients (n = 80) subjected to minor cystoscopic surgery were randomly assigned to have spinal anesthesia with either 5 mg bupivacaine 0.1% or 5 mg bupivacaine 0.1% mixed with 20 micrograms fentanyl. The main outcome measures included intraoperative patient and endoscopist satisfaction, sedative/analgesic supplementation, postoperative side effects and time to ambulation. RESULTS: Patients in the bupivacaine group needed more analgesic supplementation. Analgesia was more adequate in the bupivacaine-fentanyl group. Pruritus was the main side effect in the bupivacaine fentanyl group. Ambulation and discharge of patients were nearly the same in both groups. CONCLUSIONS: Spinal anesthesia with small dose (5 mg) hypobaric (0.1%) bupivacaine mixed with fentanyl (20 micrograms) produced adequate anesthesia for short cystoscopic procedures with minimal side effects and without delay in ambulation.