Effect of time of eCG administration on the fate of ovarian follicle in Holstein heifers

The objective of this study was to investigate the effect of equine chorionic gonadotropin (eCG) on ovarian follicles at three stages of development (emergence, dominance and early static phases) during the first follicular wave (FFW) in Holstein heifers. Heifers (n=20) were randomly assigned into four experimental groups (n=5 in each group). Heifers received eCG (500 IU; Folligon^®; Intervet, Holland; i.m) a) on the day of follicle emergence (day of ovulation; group 1), b) on the dominant phase (dominant follicle (DF): the first day in which follicle was observed at ≥10 mm; group 2, and c) on the early static phase (group 3) of the FFW. Control group heifers did not receive any treatment. Daily ultrasonography was conducted to monitor ovarian structure throughout estrous cycle. All treatment group heifers, regardless of the stage of follicle development, displayed follicle growth after eCG injection. Administration of eCG, in group 1, hastened DF detection and induced co-dominant follicles; whereas, in groups 2 and 3, it delayed DF regression, and increased cycle length compared to control. In all treatment group heifers, DF was present 84 h after eCG injection. Maximum diameter of corpus luteum was larger in eCG treated groups compared to control (P<0.05). In conclusion, depending on the time of eCG administration throughout the FFW (emergence, dominant and early static phases), co-dominancy, maintenance of DF, enhancement of follicle and corpus luteum growth and increase in estrous cycle length could be observed in Holstein heifers.

Enhanced biological nutrient removal in sequencing batch reactors operated as static/oxic/anoxic (SOA) process

An innovative static/oxic/anoxic (SOA) activated sludge process characterized by static phase as a substitute for conventional anaerobic stage was developed to enhance biological nutrient removal (BNR) with influent ammonia of 20 and 40 mg/L in R1 and R2 reactors, respectively. The results demonstrated that static phase could function as conventional anaerobic stage. In R1 lower influent ammonia concentration facilitated more polyphosphate accumulating organisms (PAOs) growth, but secondary phosphorus release occurred due to NOx(-) depletion during post-anoxic period. In R2, however, denitrifying phosphorus removal proceeded with sufficient NOx(-). Both R1 and R2 saw simultaneous nitrification-denitrification. Glycogen was utilized to drive post-denitrification with denitrification rates in excess of typical endogenous decay rates. The anoxic stirring duration could be shortened from 3 to 1.5h to avoid secondary phosphorus release in R1 and little adverse impact was found on nutrients removal in R2.