Ovulatory response and embryo yield in superovulated holstein heifers given a priming dose of FSH-P at day 2 of the estrous cycle

Mature Holstein heifers were given either a priming dose of follicle-stimulating hormone-pituitary (FSH-P, 10 mg) or saline on Day 2 of the estrous cycle, or no pretreatment. All animals were subsequently given a decreasing dose superovulatory treatment of FSH-P beginning between Days 8 and 14, coupled with an injection of prostaglandin F2a to induce luteolysis. Pretreatment with FSH-P had no effect on the total superovulatory response or on the number of transferable embryos collected at Day 7 of gestation. Comparison of the results of our study with previous reports in the literature may suggest that FSH-priming early in the cycle may be advantageous in promoting superovulation only when the superovulatory response of the population of animals is otherwise weak.     

Relationships between Brucella ovis semen culture and various semen and serology parameters

Semen and blood samples from 154 rams from two Montana range flocks (Flock A, vaccinated for Brucella ovis ; Flock B, nonvaccinated) were evaluated to determine the relationship between Brucella ovis (B. ovis ) semen culture results and various semen and blood parameters. All rams utilized in this study exhibited no palpable ram epididymitis lesions. Thirteen and 25.6% of the rams tested in Flocks A and B, respectively, had positive B. ovis semen cultures. Only age of ram and ram condition scores differed (P<0.05) between flocks. No flock by semen culture interactions were detected (P>0.05) for any of the parameters evaluated. Age of ram, ram condition score, and spermatozoa rate from forward movement were unrelated (P>0.05) to B. ovis culture results. Rams with positive B. ovis semen cultures had lower sperm motility (P<0.05), higher percentage of abnormal spermatozoa cells (P<0.05), higher percentage of spermatozoa head abnormalities (P<0.01), lower percentage of live-normal cells (P<0.05), higher incidence of white blood cells in semen (P<0.01) and higher complement fixation (CF) titers (P<0.01).     

Effects of photoperiod and intermittent lighting on reproduction in pheasant hens

Forty 28-wk-old ring-necked pheasant hens were equally distributed among 5 treatment groups and exposed to the following light schedules for 36 wk: Treatment 1 - 16L:8D; Treatment 2 - 1L:11D:4L:8D; Treatment 3 - 1L:13D:2L:8D; Treatment 4 - 1L:14D:1L:8D; and Treatment 5 - 1L:14.5D:0.5L:8D. The number of days from stimulatory lighting to the first egg was significantly (P<0.05) greater under the intermittent schedules (20.3, 29.5, 40.3, 44.4, and 57.7 d, respectively) when the subjective daylength was shorter than 13 h. Despite the delay in initiation of laying, average egg production was higher under intermittent lighting (23.0, 36.0, 48.6, 43.8, and 42.3% or 58.0, 93.0, 122.5, 110.4, and 106.6 eggs). Patterns of oviposition indicated a tendency in the birds exposed to intermittent lighting to have synchronized laying, with the period opposite the longest scotoperiod provided by their light schedule; thus subjective daylengths of 13, 11, 10 and 9.5 h, respectively, were created. Fertility was significantly (P<0.05) lower under intermittent lighting and was apparently associated with a high proportion of eggs in the late stages of oviducal development at the time of insemination.     

Fertility of the early postpartum, lactating domestic rabbit

Sixty-four crossbred primiparous lactating does each suckling six pups were allocated at random into four groups and were mated on either Day 1, 2, 3, or 4 post partum (where Day 0 = the day of parturition). They were subsequently killed on Day 10 post coitum (where Day 0 = the day of mating) to assess fertility. There were no significant differences between treatment groups in their mating response (97% overall), ovulation response (77% overall), implantation response (83% overall), implantation rate (8.7 overall), or preimplantation mortality rate (24% overall). Ovulation rate was significantly increased in does mated on Days 3 and 4 (13.3 and 13.1, respectively), compared with those mated on Day 1 (10.2, P<0.05) and Day 2 (9.6, P<0.01) post partum. From these results we conclude that fertility is high throughout the early postpartum period in the lactating rabbit.     

Comparative histology of antelope placentomes

The histological structure of ruminant (family: Bovidae) placentomes in eight antelope species was compared to that of domestic cattle and sheep. The chorioallantoic villi differed in degree of branching, surface corrugation, and complexity of utero-placental junction. All species had the epitheliochorial type of placenta, with the epithelial lining of maternal caruncular crypts varying between cellular and syncytial types.     

Effect of incubation conditions, inhibitors, 2-mercaptoethanol and testosterone on RNA synthesis in ram spermatozoa

In vitro studies on RNA synthesis using washed ram spermatozoa were carried out by measuring the incorporation of (3)H-uridine into RNA. Penicillin-G (100 mug/ml medium) was added to prevent contamination by microorganisms. Spermatozoa were quickly separated from seminal plasma by washing twice in Tris-HCl buffer (at pH 7.2) and centrifuged at 1,000 g for 5 min. Washed spermatozoa were then diluted to 1 10 , 1 20 or 1 40 (v/v) by the same buffer system (containing 400 mg% glucose) and were incubated in air at 37 degrees C for 1, 2 and 4 h. Results indicated that the rate of RNA synthesis was maximal at 1 40 semenbuffer dilution (5-8 x 10(7) spermatozoa/ml) and increased linearly up to 4 h of incubation. The rate of RNA synthesis at 1 40 dilution also increased linearly as the dose of exogenous glucose substrate was increased up to 400 mg%. Denaturation of the ram spermatozoa by 1% HgCl(2) caused almost complete inhibition of RNA synthesis that amounted to 97% of the control samples. Incubation of spermatozoa with 50, 100 or 200 mug/ml chloramphenicol also inhibited uridine incorporation by 86 to 94%, while equivalent doses of cycloheximide did not. On the other hand, the incorporation of (3)H-uridine into the RNA of ram spermatozoa was significantly enhanced by graded doses of 2-mercaptoethanol (0.2, 0.4 and 0.8 muM) and of testosterone (15 and 30 mug/ml). The results of this study indicate RNA synthesis, mainly of mitochondrial origin, by mature ram sperm. The data also suggest a role for intracellular cyclic adenosine monophosphate in the regulation of sperm RNA synthesis.     

Comparison of early conceptus mobility between mares and jennies

The caracteristics of early intrauterine mobility of the conceptus were compared between ponies (n = 9) and donkeys (n = 9). The extensive mobility of the early conceptus, previously reported for ponies and horses, was found in donkeys as well. There were no significant differences between donkeys and ponies in the characteristics or patterns of mobility. However, the mean day of fixation was approximately one day later (P<0.05) in donkeys (Day 15.6 +/- 0.3) than in ponies (Day 14.7 +/- 0.2).     

Embryonic development in superovulated dairy cattle exposed to elevated ambient temperatures between Days 1 to 7 post insemination

Holstein heifers (n = 29) were used to determine whether thermal stress during the first 7 d of embryonic development may increase the incidence of embryonic abnormalities in dairy cattle. Heifers were acclimated to environmental chambers at 20 degrees C for 9 d and superovulated with follicle stimulating hormone-pituitary (FSH-P; 40 mg total), beginning on Days 9 to 11 of the estrous cycle. Prostaglandin F(2)alpha (Lutalyse; 50 mg total) was administered on Day 3 of FSH-P. Heifers were inseminated artificially at estrus and then maintained at either thermal neutrality (20 degrees C) or under hyperthermic conditions (daily exposure up to 16 h at 30 degrees C and 8 h at 42 degrees C) for 7 d beginning at 30 h after the onset of estrus. On Day 7 post estrus, embryos were recovered nonsurgically and evaluated morphologically for stage of development and quality. The distribution of embryos classified as normal, abnormal, retarded or as unfertilized ova, differed (P<0.001) between heat stress and thermoneutral treatments. Only 20.7% of 82 embryos recovered from stressed heifers were normal compared with 51.5% of 68 embryos from thermoneutral animals. Stressed heifers had a higher incidence of abnormal and retarded embryos with degenerate nonviable blastomeres. Responses indicated that thermal stress from 30 h after the onset of estrus to Day 7 post estrus increases the incidence of abnormal and retarded embryos in superovulated heifers.     

Sexual maturation of ewes raised without ram exposure in a controlled lighting environment

Finn x Dorset ewe lambs (n = 70) born in the spring (March 28 to April 6) from two successive lambing seasons were evaluated for age at first ovulation in the absence of mature rams. Ewe lambs were born in a controlled, short light (8L:16D) photoperiod or in ambient light (13L:11D). At about 10 to 11 wk of age, ewe lambs were allocated to a short (8L:16D) or long (16L:8D) light environment. Plasma progesterone (P(4)) concentrations were measured as an index of first ovulation. First exposure of ewes to sexually mature rams was in November. Most ewe lambs (77%) ovulated before ram exposure. More lambs (P < 0.025) born in ambient light and raised in short light reached puberty with typical cycles of plasma progesterone compared to other treatments. Long days tended to retard the onset of puberty. Although pregnancy rate did not differ across light treatments, more ewes became pregnant from the ambient-light born and short-light raised treatment. Photoperiod is an important factor affecting the onset of sexual maturation and genesis of normal luteal progesterone secretion in the ewe lamb.     

Characterization of the caprine estrous cycle using enzyme immunoassay for the determination of whole blood progesterone concentration

Eighteen mature female dairy goats were used to determine the feasibility of enzyme immunoassay for the measurement of progesterone in this species. Both quantitative and qualitative enzyme immunoassay kits were used to measure progesterone concentration in unextracted whole blood. Progesterone profiles were similar to those previously reported using either protein-binding or radioimmunoassay as the test. A Pearson's correlation coefficient comparison of our enzyme immunoassay values with radioimmunoassay values gave a correlation coefficient of 0.95. Using the qualitative test, 100% of the samples with high progesterone concentrations had quantitative values greater than 4.00 ng/ml progesterone with a mean of 12.13 ng/ml. Estrus samples had a mean progesterone concentration of 0.70 ng/ml.