The objective of this study was to examine the effect of administration of FSH in aluminum hydroxide gel (Gel; an adjuvant and adsorbent of large molecules) by a single injection on superovulatory response and embryo recovery in cattle. In this study, cloprostenol-synchronized (PGF; Clopromate C; Sumitomo Pharmaceuticals Co., Tokyo, Japan) nonlactating Holstein cows were divided into 2 groups (Gel-treated and Controls) between Days 8 and 11 after estrus in 2 experiments in a crossover design. In Experiment 1, 40 mg FSH (Antrin-R10; Kawasaki Mitaka Pharmaceutical Co., Tokyo, Japan) was mixed with 10 mL aluminum hydroxide suspended in saline at a concentration of 3 mg Al mL-1 and administered by a single IM injection (n = 12; 10 mL-Gel group). Blood samples were collected at 0, 1, 2, 4, 8, and 12 h, and thereafter every 24 h until embryo recovery for measurement of FSH levels in a time-resolved fluoroimmunoassay. In Experiment 2, 40 mg FSH was mixed with 5 mL Gel and injected into fat in the inguinal region (n = 8, 5 mL-Gel group). The Control group in both experiments (n = 2 and n = 8, respectively) received 40 mg FSH twice daily for 4 days in decreasing doses (8, 8, 6, 6, 4, 4, 2, and 2 mg) by IM injection (Experiment 1), or in the inguinal region (Experiment 2). PGF (0.75 mg) was administered twice on the third day of treatment, and cows were inseminated 48 and 60 h after second PGF dose; embryo recovery was performed 7 days later. Follicular development was monitored ultrasonically every 24 h from the first FSH treatment to ovulation, and the numbers of medium (MF, 5–8 mm) and large (LF, >8 mm) follicles, and corpora lutea (CL) were counted on the day of embryo recovery. Data were analyzed by Student's t-test. In Experiment 1, there were no differences in the mean (� SD) number of CL or transferable embryos between the 10 mL-Gel (10.5 � 9.6 and 6.0 � 8.0, respectively) and Control (14.8 � 9.6 and 9.0 � 6.6, respectively) groups (P > 0.1). The growth of LF and MF in the 10 mL-Gel group occurred 24 h earlier than in the Control group (24 and 48 h after initiation of FSH treatment, respectively; P < 0.05). However, follicle growth stopped at 72 h in the 10 mL-Gel group and at 96 h in the Control group (P < 0.01). FSH concentrations in the 10 mL-Gel group increased markedly to 2.0 � 0.7 ng mL-1 at 12 h, remained there at 24 h, and decreased to 1.0 � 0.3 ng mL-1 at 72 h, whereas FSH concentrations in the Control group increased gradually to 1.1 � 0.3 ng mL-1 at 24 h, remained at 1.2 � 0.3 ng mL-1 from 24 to 96 h, and then decreased to baseline (0.9 � 0.3 ng mL-1) at 120 h (P < 0.05). In Experiment 2, no significant differences in number of CL or transferable embryos were found between the 5 mL-Gel (11.8 � 13.0 and 4.1 � 4.0, respectively) and Control (12.0 � 11.0 and 4.0 � 3.1, respectively) groups, and follicular growth profiles did not differ between groups (P > 0.4). Results suggest that administration of FSH in 5 mL Gel by a single injection in the inguinal region is effective in inducing superstimulation in Holstein cattle.
This work was supported by a grant of the Research Project for Utilizing Advanced Technology (04-1676).
The effect of treatment with a slow-releasing oxytocin preparation at the onset of oestrus on the ovulation rate of Merino ewes : research note