Czech Journal of Animal Science - In Press
The effect of maturation and aging on the quality of mammalian oocytesReview
Andrea Nesvadbova, Jiri Bezdicek, Alexander Makarevich, Ludek Stadnik
The aim of this review was to summarize current knowledge regarding the effects of maturation, activation and aging on oocyte quality. Two main forms of aging were distinguished: (1) postovulatory aging, which occurs after ovulation due to a prolonged period before fertilization and (2) age-related aging, which is associated with a gradual decline in ovarian reserve and oocyte quality. Proper embryo development strongly depends on oocyte quality, which is most often assessed according to morphology. Numerous observations have demonstrated the influence of oocyte maturation, during which controlled cytoplasmic and nuclear modifications occur, and the influence of the timing of oocyte activation by the fertilizing sperm. Post-ovulatory aging of an oocyte, which was not fertilized during the optimal period, manifests as impaired embryo development and results in fragmentation and embryonic mortality. Age-related oocyte aging leads to mitochondrial damage due to the long-term effects of reactive oxygen and nitrogen species (RONS), which play a key role in regulating physiological processes in the ovaries, including ovulation and oocyte maturation. Overall, it can be concluded that oocyte quality is the result of a complex interaction of meiotic, metabolic and redox mechanisms, which are significantly influenced by age, hormonal stimulation and the follicular microenvironment. Oocyte aging is associated with predominantly irreversible structural and functional changes leading to aneuploidy, mitochondrial dysfunction and failure of embryonic development.
Associations of SLC45A2 Variation and MC1R/cAMP-Related Molecular Characteristics with the ‘Cloudy Feather’ Phenotype in Qiangshan Cloud ChickensOriginal Paper
Ronghong Li, Min Xiao, Yuzhen Zhou, Xilamu Yi, Sang Mu
Objective: Qiangshan Cloud chicken is a local chicken breed unique to Aba Prefecture, Sichuan Province, characterized by its distinctive "cloudy feather" phenotype, where black feathers form the base with attached cloud-like white feathers. This study aimed to evaluate genetic associations with this phenotype and to explore whether MC1R expression, cAMP concentration, melanogenesis-related transcript patterns, and qualitative histology were consistent with a multi-gene working model. Methods: The research was conducted in two phases. Phase I involved 220 adult chickens (110 Qiangshan Cloud chickens and 110 Fengwei chickens) for SLC45A2 and TYR genotyping and reciprocal crossing experiments. Phase II comprised the same 220 birds plus 30 recessive white-feathered chickens for MC1R genotyping. For qPCR and cAMP ELISA, 24 biologically independent birds were selected from each breed; qPCR was performed in three technical wells per bird and ELISA in two technical wells per bird, with the technical-well mean used as one biological observation. Histology included three independent birds per breed and three microscopic fields per bird and was evaluated qualitatively. Results: Phase I supported a significant association (P < 0.01) between the SLC45A2 c.1039C>A (Leu347Met) variant and the cloudy feather phenotype; 87 of 110 Qiangshan Cloud chickens (79.1%) carried the variant genotype, and the crossing results were consistent with sex-linked inheritance. The 7.7 kb insertion in TYR intron 4 was present in 20% of Qiangshan Cloud chickens, but no obvious feather-color difference was detected between sampled cc and CC birds. The MC1R E allele frequency was 98.2% in Qiangshan Cloud chickens. MC1R expression and cAMP concentration were higher in Qiangshan Cloud chickens than in the comparison breeds (P < 0.01). MC1R and TYR expression were positively correlated in the Qiangshan Cloud wild-type subgroup (n = 18, r = 0.656, P = 0.0031), whereas the mutant subgroup showed a nonsignificant inverse trend (n = 6, r = -0.710, P = 0.114). Positive correlations were also observed in Fengwei chickens (n = 24, r = 0.813, P = 1.35 × 10^-6) and recessive white-feathered chickens (n = 24, r = 0.616, P = 0.00134). Representative histological sections qualitatively showed more extensive brown-black staining in Qiangshan Cloud chickens; melanin content was not quantified. Conclusion: The data support SLC45A2 c.1039C>A as a sex-linked candidate variant associated with cloud-like white-feather distribution. The high frequency of the MC1R E allele, higher MC1R expression and cAMP concentration, and the observed TYRP1 and DCT expression patterns are consistent with enhanced melanogenic signaling in Qiangshan Cloud chickens. However, direct negative regulation of TYR, functional compensation for the TYR insertion, and causal pathway relationships were not established and require functional validation. Because the comparisons involved genetically distinct breeds and MC1R was nearly fixed within Qiangshan Cloud chickens, the present design does not isolate an MC1R single-locus effect.
Effects of Fresh Olive Cake Inclusion in Ensiled Total Mixed Rations on In vitro Rumen Fermentation Kinetics and Methane ProductionOriginal Paper
ER Murat, Kanber KARA, Eren KUTER, Hulusi AKÇAY, Sena YILMAZ ÖZTAŞ
This study evaluated the effects of replacing maize silage with increasing levels of olive cake (OC) in ensiled total mixed rations (ETMR) on microbial quality, in vitro rumen fermentation kinetics, methane production, and estimated energy parameters. Three experimental diets were formulated to contain 0% (Control), 10% (OC10), and 20% (OC20) olive cake on a dry matter basis and were ensiled for 60 days. On day 60, ETMRs were opened, microbial composition was assessed, and in vitro ruminal fermentation was conducted for 24 h using the gas production technique. No significant differences were observed among treatments in bacterial counts (P > 0.05), and coliforms and enterobacteria were below detectable limits in all groups. Increasing OC inclusion significantly reduced butyric and propionic acid concentrations (P < 0.05), whereas acetic acid remained unaffected. Total volatile fatty acid (VFA) concentration tended to decrease with increasing OC inclusion (P = 0.060). Furthermore, OC inclusion significantly reduced total gas production, metabolizable energy (ME), organic matter digestibility (OMD), and net energy for lactation (NEL) (P < 0.001). Methane production (mL/0.2 g DM) decreased numerically by approximately 14%, although this reduction was not statistically significant. Methane as a proportion of total gas was also unaffected. Ammonia-N concentrations did not differ among treatments. The reduction in methane output appeared to be associated with a general suppression of fermentative activity rather than a shift toward propionate-driven hydrogen utilization. The lipid-rich and phenolic composition of OC may have contributed to reduced microbial fermentation intensity and hydrogen availability. Although higher inclusion levels negatively affected digestibility and energy values, moderate inclusion may offer a balance between environmental benefits and nutritional efficiency.
Associations of TERB2 and LRP6 polymorphisms with cashmere, growth, lactation and reproductive traits in Liaoning Cashmere goatsOriginal Paper
Qiying Zhan, Ran Duan, Qingyu Yuan, Yanqin Meng, Shuaitong Li, Hao Lin, Weihang Hong, Hua Ma, Lingchao Kong, Wangshu Li, Haoran Wang, Xiaochen Kou, Dakun LYU, Yunlong Guo, Jiamei Liang, Zeying Wang
This study evaluated associations of TERB2 and LRP6 polymorphisms with economically important traits in 1 181 Liaoning Cashmere goats (Capra hircus). Two exonic single nucleotide polymorphisms (SNPs), G841C in TERB2 and C98161A in LRP6, were identified by polymerase chain reaction (PCR) and bidirectional sequencing. Genotype–trait associations for cashmere production, body size, lactation, reproductive, slaughter, and meat-quality traits were analysed separately by sex where appropriate, with Benjamini–Hochberg false discovery rate correction applied to overall genotype effects. The G841C locus showed low polymorphism, with polymorphism information content values of 0.17 and 0.19 in bucks and does, respectively, whereas C98161A showed moderate polymorphism (0.37 in both sexes). Significant genotype effects on several cashmere traits remained after false discovery rate correction (Q < 0.05). In does, the LRP6 CA genotype had finer cashmere than the CC genotype (16.5 vs 16.8 μm; P < 0.05) and a higher cashmere yield rate (75.8% vs 72.7%; P < 0.01). The AA genotype showed greater cashmere yield (1 879 vs 1 804 g; P < 0.01) and fibre length (110 vs 86.6 mm; P < 0.01) than CC. Combined-genotype analysis also detected significant overall effects on all seven cashmere traits after false discovery rate correction (Q < 0.05). Cashmere yield rate was the principal predictor of fibre fineness; the final regression models explained 83.9% and 87.2% of the variation in bucks and does, respectively (adjusted R2 = 0.832 and 0.871). These polymorphisms may provide preliminary marker information for cashmere-related traits, but independent population validation and functional studies are required before breeding application.
Influence of L-selenomethionine on Pigeon Breeder’s Reproductive Performance and Squab’s Growth and Pectoral Muscle DevelopmentOriginal Paper
Haopeng Lu, Yunyan Huang, Jiashui Liang, Shihong Wu, Guolong Zhang, Anjie Chen, Xiaoyu Zhou, Xinting Lai, Lvying Yang, Yuxi Liang, Xuekang Xia, Shuo Zhou, Yayan Liang
This study evaluated the impact of L-selenomethionine supplementation on breeding pigeons and their squabs. 48 pigeon pairs were divided into 2 groups: a control group receiving a basal diet and an experimental group receiving the same diet supplemented with selenium as L-selenomethionine at a concentration of 0.1 mg/kg. Both groups were fed for 45 days following a '2+4' pattern. During brooding, experimental males exhibited a significant decrease in body weight, whereas females showed a decreasing trend toward weight loss. Squabs from the experimental group had greater nest weights at 14 days and higher weight gains between 8–14 days and 15–21 days. They also had significantly higher individual weights at 14 days. The breast and leg muscle fibre area and diameter in experimental squabs were significantly reduced, indicating potential improvements in meat tenderness. L-selenomethionine increased plasma total superoxide dismutase (T-SOD) activity in breeding pigeons and reduced malondialdehyde (MDA) content in squab leg muscle. It also upregulated glutathione peroxidase-1 (GPX1) expression in breast muscle and glutathione peroxidase-2 (GPX2) expression in leg muscle mRNA. In conclusion, 0.1 mg/kg of L-selenomethionine supplementation enhanced antioxidant capacity, promoted early squab growth and improved meat quality without adverse effects on breeding performance.