Targeting epigenetic nuclear reprogramming in aggregated cloned equine embryos.

Epigenetic perturbations during the reprogramming process have been described as the primary cause of the low efficiency of somatic cell nuclear transfer (SCNT). In this study, we tested three strategies targeting nuclear reprogramming to investigate effects on equine SCNT. First, we evaluated the effect of treating somatic cells with chetomin, a fungal secondary metabolite reported to inhibit the trimethylation on histone 3 lysine 9 (H3K9 me3). Second, caffeine was added to the culture medium during the enucleation of oocytes and before activation of reconstructed embryos as a protein phosphatase inhibitor to improve nuclear reprogramming. Third, we tested the effects of the histone deacetylase inhibitor trichostatin A (TSA) added during both activation and early embryo culture. Although none of these treatments significantly improved the developmental rates of the invitro aggregated cloned equine embryos, the first equine cloned foal born in Australia was produced with somatic cells treated with chetomin. The present study describes the use of chetomin, caffeine and TSA for the first time in horses, serving as a starting point for the establishment of future protocols to target epigenetic reprogramming for improving the efficiency of equine cloning. Cloning is an expensive and inefficient process, but has gained particular interest in the equine industry. In this study we explored different strategies to improve cloning efficiency and produced the first cloned foal born in Australia. Our data serve as a starting point for the establishment of future protocols for improving equine cloning efficiency.

Use of stored equine colostrum for the treatment of foals perceived to be at risk for failure of transfer of passive immunity.

OBJECTIVE-To assess the use of stored equine colostrum for the treatment of foals perceived to be at risk for failure of transfer of passive immunity (FTPI). DESIGN-Cohort study. ANIMALS-232 Thoroughbred foals and 191 Thoroughbred mares (41 mares gave birth to 1 foal on 2 occasions). PROCEDURES-Postpartum, presuckle colostrum samples were collected from mares; samples with a colostral refractive index (cRI) > or = 23% were frozen (-20 degrees C [-4 degrees F]) and stored for > or = 7 days but < 2 years. Foals of dams that produced colostrum with a cRI value < 20% were treated with > or = 300 mL of stored colostrum that was thawed and administered via nasogastric tube on 1 to 4 occasions within 6 hours after parturition. Serum samples were obtained from colostrum-treated and nontreated foals 24 hours after treatment or suckling, respectively, for determination of serum IgG (sIgG) concentration. RESULTS-8 foals and their respective dams were excluded from the analyses. For the remaining 30 treated and 194 nontreated foals, mean +/- SD sIgG concentration was 1,597 +/- 574 mg/dL. Thirteen (5.8%) foals had sIgG concentrations < 800 mg/dL, of which 1 (0.4%) had an sIgG concentration < 400 mg/dL. Nine of these foals had suckled mares producing colostrum with a cRI value > or = 20%, and 2 foals had been treated with stored colostrum. CONCLUSIONS AND CLINICAL RELEVANCE-Treatment with stored colostrum appeared to be effective for prevention of FTPI in at-risk foals. However, foals were still at risk for FTPI despite suckling of or treatment with colostrum with adequate cRI values.