In this study, fibroblast cells were stably transfected with mouse POU5F1 promoter-driven enhanced green fluorescent protein (EGFP) to investigate the effect of S-adenosylhomocysteine (SAH), the reversible non-toxic inhibitor of DNA-methyltransferases (DNMTs), at different intervals post-fusion on in vitro development of cloned bovine embryos. Treatment with SAH for 12 hr resulted in 54.6 ± 7.7% blastocyst production, which was significantly greater than in vitro fertilized embryos (IVF: 37.2 ± 2.7%), cloned embryos treated with SAH for 72 hr (31.0 ± 7.6%), and control cloned embryos (34.6 ± 3.6%). The fluorescence intensities of the EGFP-POU5F1 reporter gene at all intervals of SAH treatment, except of 72 hr, were significantly higher than control somatic cell nuclear transfers (SCNT) embryos. The intensity of DNA-methylation in cloned embryos treated with SAH for 48 hr was similar to that of IVF embryos, and was significantly lower than the other SCNT groups. The levels of H3K9 acetylation in all SCNT groups were significantly lower than IVF embryos. Real-time PCR analysis of gene expression revealed significantly higher expression of POU5F1 in cloned versus IVF blastocysts. Neither embryo production method (SCNT vs. IVF) nor the SAH treatment interval affected expression of the BCL2 gene. Cloned embryos at all intervals of SAH treatment, except for 24 hr, had significantly increased VEGF transcript compared to IVF and control SCNT embryos. It was suggested that the time interval of DNMT inhibition may have important consequences on different in vitro features of bovine SCNT, and the improving effects of DNMT inhibition on developmental competency of cloned embryos are restricted to a specific period of time preceding de novo methylation.

Domestic beef production in Malaysia is mainly contributed by the indigenous Kedah-Kelantan (KK) and their crossbred cattle. This study was conducted to compare growth performance and sexual maturity of KK and KK × Brangus bulls. Ten (10) experimental bulls with similar ages were kept under the same paddock and fed with equal quality and quantity Guinea grasses and palm kernel cakes. Body weight was measured at monthly basis by using a digital animal weighing scale. Age at sexual maturity was determined by the time of semen ejaculation and quality. The results revealed significantly (p<0.05) greater body weight in KK × Brangus bulls (230.50±9.3 kg) as compared to the pure-bred KK bulls (204.5 ±13.2 kg) at 24 months of ages. KK bulls attained sexual maturity at an earlier age of 21.5±0.4 months, while KK × Brangus bulls attained at 28.8±0.5 months. The growth performance of KK × Brangus bulls was significantly (p˂0.05) higher than KK bulls. Age showed a significant positive correlation with body weight and average daily weight gains. In conclusion, KK pure-bred bulls were superior in terms of attaining age at puberty and sexual maturity earlier, whereas KK × Brangus bulls were better for growth performance.

Implantation is a crucial step in mammalian reproduction as it is a gateway to further embryonic development and successful pregnancy. Changes in the environmental factors, such as temperature have adverse effects on reproduction. However, the impact of elevated temperature on the implantation process is not well defined. The objective of this study was to investigate the possible effect of elevated ambient temperature on implantation time and rate. The results revealed that exposure to elevated ambient temperature leads to a delayed implantation and reduced number of implantation sites in Sprague Dawley rats. Moreover, the exposure to elevated temperature resulted in change in the progesterone and estradiol patterns during the implantation time. These findings indicate that elevated temperature disturbs the implantation process.