The present study aimed to investigate the effects of vitamin B(12) supplementation on standard bovine semen quality parameters and anti-oxidative enzyme activities. Vitamin B(12) was supplemented at concentrations of 1.25, 2.5, 3.75 and 5.0 mg/ml to bovine semen cryoprotective medium. The results indicated that the motility and straight line velocity, curvilinear velocity, mean coefficient, velocity of the average path values of sperm supplemented with 2.50 mg/ml vitamin B(12) were significantly higher than that of other groups (p<0.05). No significant difference was observed for linearity index, lateral head displacement values and the percentage of grade A spermatozoa between the extenders containing 2.50 and 3.75 mg/ml vitamin B(12) (p>0.05). The percentages of acrosome-intact and plasma membrane-intact spermatozoa were significantly improved (p<0.05) by supplementing with 2.50 mg/ml vitamin B(12) . The results of biochemical assay revealed that vitamin B(12) supplementation did not cause significant changes in superoxide dismutase levels compared with control (p>0.05). However, the catalase levels were higher in the treatment supplemented with vitamin B(12) at 2.50 mg/ml, when compared with other groups (p<0.05). The extender supplemented with vitamin B(12) significantly decreased glutathione peroxidase activity compared with the control (p<0.05). The supplementation of 3.75 mg/ml vitamin B(12) caused the highest value of glutathione reductase activity, compared with other groups (p<0.05). In conclusion, the extender supplemented with vitamin B(12) could reduce the oxidative stress provoked by freezing-thawing and improve bovine semen quality. Further studies are required to obtain more concrete results on the determination of lipid peroxidation and antioxidant capacities of vitamin B(12) in cryopreserved bovine semen.

ABSTRACT. Myopalladin (MYPN) is a multifunctional protein that maintains sarcomeric integrity and regulates Z-line structure. It is an important candidate gene for meat quality selection through markerassisted selection. Using PCR-RFLP technology, we discovered a singlenucleotide polymorphism (SNP) (A1795G in exon 9) of the MYPN gene. Allele frequencies of this SNP were investigated and evaluated by the χ 2 test in 660 cattle populations in China; only the Nanyang population was not in Hardy-Weinberg equilibrium. Gene heterozygosity, effective allele number and polymorphism information content of the bovine MYPN locus in seven populations varied from 0.3888 to 0.4998, 1.6360 to 1.9992, and 0.3132 to 0.3749, respectively. We also looked for a potential association of this SNP with ultrasound traits in 399 individuals and found a significant effect on the ultrasound loin-muscle area. Meat quality traits were analyzed in another 61 Qinchuan individuals to analyze associations with genotype. Animals with the genotype GG had higher mean values for loin-eye area (P < 0.05) and water-holding capacity (P < 0.01) than those with AA or AG genotypes. We conclude that this SNP of the MYPN gene has potential as a genetic marker for meat quality traits in cattle reproduction and breeding.

ABSTRACT. We examined the cytogenetics of mithun (Bos frontalis), a domesticated version of the Asian gaur, and hybrids (F 1 generation) produced by artificial insemination of Brahman cows (Bos indicus) with mithun semen. Reproductive potential was also examined in the F 1 generation and a backcrossed heifer for utilization of heterosis. Metaphase chromosome spreads were examined by conventional staining and fluorescence in situ hybridization hybridized with the entire chromosome 1 of mithun as a specific probe. Chromosome 1 of mithun was found to be equivalent to Bos taurus chromosomes 2 and 28. The karyotype of the female mithun (N = 4) comprised 58 chromosomes, including 54 acrocentric and four large submetacentric chromosomes, without the four acrocentric chromosomes found in the domesticated species B. indicus. However, one of the four female mithuns with a normal mithun phenotype had an abnormal karyotype (2n = 59), indicating introgression from B. taurus or B. indicus. The F 1 karyotypes (N = 6, 3♂3♀) of the mithun bull × Brahman cow cross had 2n = 59, intermediate between their parents; they were consistent heterozygous carriers with a centric fusion involving rob(2;28), as expected. Two pronounced red signals were seen in the mithun karyotypes, three red signals in the mithun × Brahman hybrids, and four red signals in the Brahman cattle, in good agreement with centric fusion of bovine rob(2;28). The female backcross hybrid (N = 1) with 2n = 59 had a similar chromosome configuration to the F 1 karyotypes and had rob(2;28). Such female backcross hybrids normally reproduce; however, the F 1 bulls (N = 3)had not yet generated normal sperm at 24 months.

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