The effects of perphenazine and bromocriptine on follicular dynamics and endocrine profiles in anestrous pony mares.

Nineteen anestrous pony mares were used in a project designed to determine the effects of altered prolactin concentrations on follicular dynamics and endocrine profiles during spring transition. The dopamine antagonist, perphenazine, was administered daily to mares (0.375 mg/kg body weight) in Group A (n = 6), while Group B mares (n = 7) received 0.08 mg/kg metabolic weight (kg75) dopamine agonist, 2-bromo-ergocriptine, intramuscularly twice daily. Mares in Group C (n = 6) received 0.08 mg/kg75, i.m., saline twice daily. Treatment began January 20, 1994, and continued until ovulation occurred. Mares were teased 3 times weakly with an intact stallion. The ovaries of the ponies were palpated and imaged weekly using an ultrasonic B-mode unit with a 5 Mhz intrarectal transducer until they either exhibited estrual behavior and had at least a 20-mm follicle, or had at least a 25-mm follicle with no signs of estrus. At this time, ovaries were palpated and imaged 4 times weekly. Blood samples were obtained immediately prior to ultrasonic imaging for measurement of prolactin, FSH and estradiol-17 beta. Perphenazine treatment advanced the spring transitional period and subsequent ovulation by approximately 30 d. Group A exhibited the onset of estrual behavior earlier (P < 0.01) than control mares. In addition, Group A mares developed large follicles (> 30 mm) earlier (P < 0.01) than Group B mares, with least square means for Groups A and B of 47.0 +/- 8.8 vs 88.1 +/- 8.2 d, respectively. Control mares developed 30-mm follicles intermediate to Groups A and B at 67.3 +/- 8.8 d. Bromocriptine decreased (P < 0.05) plasma prolactin levels throughout the study, while perphenazine had no significant overall effect. However, perphenazine treatment did increase (P < 0.05) mean plasma prolactin concentrations from Day 31 to 60 of treatment. There were no differences in mean plasma FSH or estradiol-17 beta between treatment groups. We concluded that daily perphenazine treatment hastened the growth of follicles and subsequent ovulation while bromocriptine treatment appeared to delay the growth of preovulatory size follicles without affecting the time of ovulation.

Control of FSH, follicular development and estrus synchronization in the mare with steroid-free follicular fluid.

Twenty-two pony mares were used in a project designed to determine the effectiveness of different treatments in controlling FSH, follicular development and synchronization of estrus and ovulation. Mares in Group 1 (n=8) received daily oral altrenogest (0.044 mg/kg); those in Group 2 (n=7) received daily altrenogest (0.044 g/kg) and, during the last 4 days of treatment they received steroid-free follicular fluid, (15 cc) intravenously (I.V.) two times a day; Mares in Group 3 (n=7) received daily intramuscular (I.M.) injections of progesterone (80 mg) and estradiol valerate (7 mg). All treatments lasted for 10 days, at the end of which prostaglandin (PgF(2)alpha, 10 mg) was administered. Sexual behavior, follicular development and FSH concentrations were monitor daily. Concentrations of FSH in Group 2 mares, were not significantly different (P>0.05) from those of Group 1 until the mares in Group 2 were treated with follicular fluid (P<0.05). Concentrations of FSH in Group 3 mares, were significantly lower than those of Groups 1 and 2 (P<0.05) until the mares in Group 2 were treated with steroid-free follicular fluid. At this point there was no significant difference between groups 2 and 3 (P>0.05). Steroid-free follicular fluid appears to induce atresia in larger follicles (>11 mm), and the initiation of new follicular wave. The combination of progesterone and estradiol valerate appears to delay follicular growth and not to induce atresia, since larger follicles (>11 mm) continued to grow after treatment. Both treatments (groups 2 and 3) resulted in ovulations within 5 days period. The treatment in Group 1 did not have any effect on FSH or follicular development and ovulations were dispersed through a 9-day period. We concluded that steroid-free follicular fluid offers a new possibility to synchronize ovulation in the mare by controlling FSH and follicular development.

Absorption of an alternate source of immunoglobulin in pups.

Newborn pups from 4 large litters were alloted to 6 groups to determine effect of time and route of administration on absorption of an alternate source of immunoglobulin. Selective absorption of specific classes of immunoglobulins was also investigated. The alternate source of immunoglobulin consisted of pooled serum that was administered either PO or SC. Control groups were either left with the dam (group C1) or fed milk replacer (group C2). Blood samples were collected from pups at birth and 24 hours. Immunoglobulin (IgA, IgG, IgM) concentrations were determined by use of radial immunodiffusion on samples of pooled serum, colostrum, and pups' serum (birth and 24 hours). Serum IgA concentration was less than the sensitivity of the procedure and was not included in the statistical analysis. Pups fed 8 ml of pooled serum at birth and 12 hours later (group T1) absorbed more (P less than 0.05) IgG and IgM than did group-C2 pups, but less (P less than 0.05) than did group-C1 pups. Pups fed 8 ml of pooled serum at 12 hours only had significant (P less than 0.05) increase of IgG concentration, but no absorption of IgM (P greater than 0.05) at 24 hours, compared with control pups (group C2). Pups administered 8 ml of pooled serum SC at birth (group SC1) had similar (P greater than 0.05) absorption of IgG and higher (P less than 0.05) absorption of IgM than did pups of group T1.(ABSTRACT TRUNCATED AT 250 WORDS)