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The aim of the present study was to compare the efficiency of the solid surface (SSV), cryotop (CT) vitrification methods and cytochalasin B (CB) pretreatment for cryopreservation of immature buffalo oocytes. Cumulus-oocyte complexes (COCs) were placed for 1 min in TCM199 containing 10% dimethylsulfoxide (DMSO), 10% ethylene glycol (EG), and 20% fetal bovine serum, and then transferred for 30 s to base medium containing 20% DMSO, 20% EG and 0.5 mol/L sucrose. CB pretreated ((+)CB) or non-pretreated ((-)CB) COCs were vitrified either by SSV or CT. Surviving vitrified COCs were selected for in vitro maturation (IVM) and in vitro fertilization (IVF). The rate of viable oocytes after vitrification in CT groups (82%) was significantly lower (P < 0.05) than that in a fresh control group (100%), but significantly higher (P < 0.05) than those in SSV groups (71-72%). Among vitrified groups, the highest maturation rate was obtained in the CT (-)CB group (32%). After IVF, the cleavage and blastocyst formation rates were similar among vitrified groups but significantly lower than those of the control group. In conclusion, a higher survival rate of oocytes after vitrification and IVM was obtained in the CT group compared with that in the SSV group, indicating the superiority of the CT method. Pretreatment with CB did not increase the viability, maturation or embryo development of vitrified oocytes.

Four Thai male native beef cattle, initial body weight (BW) of 100 ± 3.0 kg were randomly assigned in a 4 × 4 Latin square design to receive four dietary treatments with inclusion of urea calcium sulphate mixture (U-cas) in feed block (FB) at 0, 120, 150, and 180 g/kg dry matter (DM). Total intakes were increased with the increasing level of U-cas supplementation in FB and the result obtained the highest when supplementation of U-cas in FB at 180, followed by 150, 120, and 0 g/kg DM, respectively. Moreover, supplementation of U-cas in FB at 180 g/kg DM could reduce total N excretion (4.1 g/day), as compared to others treatments, while N retention and proportion of N retention to N intake were increased up to 6.9 g/day and 14.9 %, respectively. On the other hand, the blood biochemistry and hematological parameters were not different among treatments except concentration of plasma urea N, plasma glucose, and total blood protein were improved especially with U-cas supplementation at 180 g/kg DM in FB. In conclusion, supplementation of U-cas at 180 g/kg in FB improved feed intake, N utilization, and blood biochemistry in Thai native beef cattle fed on rice straw.