298 EFFECT OF TWO DIFFERENT DOSES OF FOLLICLE-STIMULATING HORMONE IN ALUMINUM HYDROXIDE GEL BY A SINGLE INJECTION ON ESTRUS AND SUPEROVULATORY RESPONSE IN HOLSTEIN CATTLE

Abstract

We investigated the effect of administration of different dosage of FSH in aluminum hydroxide gel (Gel; an adjuvant and absorbent of large molecules) by a single injection on induction of estrus, superovulatory response, and embryo recovery in Holstein cattle. In this study, six cloprostenol-synchronized [PGF (0.75 mg, IM); Clopromate C; Sumitomo Pharmaceuticals Co., Tokyo, Japan], nonlactating Holstein cows were divided into three groups (Gel-40, Gel-30, Controls) between days 8 and 11 (day 0 = the day of estrus) in a Latin square design. Forty mg (Gel-40 group) FSH (Antrin-R10; Kawasaki Mitaka Pharmaceutical Co., Tokyo, Japan) or 30 mg (Gel-30 group) FSH were mixed with 5 mL Gel and administered by a single injection into fat in the ischiorectal fossa. The control group received 40 mg pFSH twice daily for 4 d in decreasing doses (8, 8, 6, 6, 4, 4, 2, and 2 mg) into the ischiorectal fossa. Then, all cows received PGF (0.75 mg, IM) twice on the third day of the treatment, and cows were inseminated at 48 and 60 h after second PGF treatment; embryo recovery was performed 7 d 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) sized follicles, and corpora lutea (CL) were counted on the day of embryo recovery. Estrous status was determined by walking activity of cows as an estrous index. Each cow was fitted with a pedometer (Gyuho; Comtec, Miyazaki, Japan) that measures total amount of walking activity per hour, and data of individual cows were sent to a personal computer in real time. Estrus was defined as an increase in number of steps to more than the value of mean steps plus standard deviation recorded for the preceding 240 h. Data were analyzed by one-way ANOVA. There was no significant difference among the Gel-40, Gel-30, and control groups for the mean ( � SD) duration of estrus (22.3 � 5.2 h, 18.0 � 2.8 h and 18.5 � 5.3 h, respectively), increments of estrous activity (398.3 � 135.3%, 388.9 � 44.4% and 393.9 � 82.1%, respectively), and the mean interval from the first PGF to onset of estrus (35.5 � 2.2 h, 37.8 � 5.7 h and 39.3 � 5.6 h, respectively). There was no significant difference among the Gel-40, Gel-30, and control groups for the mean number of large follicles at the time of estrus (21.3 � 10.2, 21.5 � 7.6 and 21.0 � 9.4, respectively), number of CL at the time of ova/embryo collection (21.5 � 10.2, 19.2 � 4.9, and 20.5 � 9.5, respectively), the total number of ova/embyos recovered (12.3 � 8.3, 12.5 � 7.8, and 13.8 � 9.2, respectively), or transferable embyos (3.3 � 4.8, 4.5 � 3.5, and 5.5 � 4.5, respectively). Results suggested that administration of 30 mg of FSH in 5 mL Gel by a single injection in the ischiorectal fossa was effective in inducing superstimulation in Holstein cattle. This work was supported by a grant of the Research Project for Utilizing Advanced Technology (04–1676).