Pulsatile secretion of prolactin in laying and incubating turkey hens.

Incubation behavior in the turkey hen is associated with a large increase in prolactin secretion. Previous research using hourly sampling of incubating hens has shown that prolactin levels fluctuate widely throughout a 24-hr period, suggestive of pulsatile secretion. This study compared the prolactin secretory patterns of laying and incubating turkeys to determine if prolactin is secreted episodically and if the high prolactin levels characteristic of the incubating hen may result, at least in part, from a change in the amplitude or frequency of secretory pulses. Blood samples were collected from cannulated, unrestrained laying and incubating hens at 10-min intervals for up to 24 hr. Data were analyzed with the PULSAR program to determine baseline prolactin levels and to establish the magnitude, frequency, and duration of episodic secretory peaks. The results revealed tha prolactin is secreted in a pulsatile pattern in both laying and incubating turkey hens. Incubating hens had ninefold higher mean and baseline plasma prolactin levels than laying hens. The prolactin pulses were of approximately 12-fold greater amplitude in incubating hens than in laying hens, but the duration and frequency of pulses were the same in both groups. Therefore, the high prolactin levels required for incubation do not appear to result from an increase in the frequency of lactotroph stimulation, but rather from an increase in the prolactin secretion rate.

Physiological and behavioral effects of coniferyl benzoate on avian reproduction.

Various plant secondary metabolites related to cinnamic acid are of interest because of their repellency to birds and their occurrence in ecologically important food items. Coniferyl benzoate (CB), a phenylpropanoid ester that occurs in quaking aspen (Populus tremuloides) is of particular ecological interest because of its effect on ruffed grouse (Bonasa umbellus) feeding behavior and its possible influence on the population dynamics of this bird. During detoxification processes, CB and other analogous compounds are metabolized into by-products, such as ferulic acid (FA), that can cause anti-reproductive effects. We tested whether consumption of CB produces antire-productive effects similar to FA using male and female Japanese quail (Coturnix coturnix) as avian models for ruffed grouse. The parameters we investigated included: the production, morphology, and development of eggs; reproductive characteristics influenced by estrogen; serum prolactin levels; and male reproductive behavior. Dietary CB did not produce antireproductive effects similar to FA at intake levels that Japanese quail and ruffed grouse would freely consume. Consumption of CB by Japanese quail significantly reduced egg production and body mass but did not affect male reproductive performance. Coniferyl benzoate's effect on egg production may be explained by lower energy acquisition and retention rather than endocrine changes per se. Contrary to previous reports, it is unlikely that FA, or similar compounds act directly as estrogen mimics or antagonists. Although, CB did reduce egg production in quail, it is unlikely that it would affect egg production in wild ruffed grouse. Detoxification costs and the effects of CB on nutrient utilization may explain why ruffed grouse avoid high dietary levels of CB.

The effects of busulfan on gonadal differentiation and development in Japanese quail (Coturnix coturnix japonica).

To determine the effects on gonadal differentiation and development, two concentrations of busulfan (1,4-butanediol dimethanesulfonate) were injected into the albumen of unincubated Japanese quail eggs, and the eggs were then incubated. Half of the hatchlings were killed at 3 days of age and the rest at 10 wk of age (4 wk past puberty). Hatchability of fertile eggs was lowest in those eggs injected with 420 micrograms of busulfan (19.6%), intermediate in the 210-micrograms group (54.7%), and highest in the sham-injected control group (73.3%). Gonads were examined histologically for germ cells and normal development. All 23 birds evaluated after injection with 210 micrograms of busulfan had histologically normal gonads. In the 420-micrograms group, six out of eight birds were abnormal. Three females and one male in this group had gonads lacking germ cells, and two males had testicles with a combination of normal seminiferous tubules and tubules lacking spermatogonia.

Manipulation of avian primordial germ cells and gonadal differentiation.

The authors hypothesized that donor primordial germ cells (PGC) are useful as vehicles of gene transfer in birds. The PGC have been identified in the blastula prior to incubation. They have been isolated from the Stage 7 germinal crescents, Stage 17 blood, and Stage 30 gonads. The percentages of PGC in these three embryonic sources were 2, .003 and 1.5%, respectively. The isolated PGC have been used as antigens to produce specific antibodies that have served as major tools in identification, isolation, and forming enriched in vitro cultures of PGC. Sterile hosts for normal donor PGC have been induced by use of ultraviolet irradiation, treatment with the chemical busulfan, and crossing rooster with female quail to form a sterile host termed "quickens." Micromanipulator technology, along with refinement of techniques to avoid trauma, will allow 80% hatchability. Integration of all the above biotechnology has led to successful use of PGC as vehicles of gene transfer and production of autogenic quail.

Function of bilateral oviducts in double oviduct hens following surgery.

A double oviduct line of Rhode Island Red chickens has been maintained as a closed flock at the Wisconsin Experiment Station since 1970. Sixty-four percent of the stock reared during the 3-yr study period had complete left and right oviducts. Experiments were designed to determine whether the right oviduct of double oviduct hens was functional. Two surgical procedures were chosen in which either a piece of the left ovary was transplanted to the right side, or the abdominal-midline tunica serosa was opened and the left ovary was pulled to the right side. In one experiment the left oviduct was also made nonfunctional. Laparotomized hens served as controls. Insemination with semen from dominant barred males as a genetic marker, followed by physical examination, confirmed right oviduct function. Hens that formed the egg in the normal left oviduct laid significantly more eggs of much greater weight and had higher percentage fertility than hens with functional right oviducts.

Comparisons of the ability of follicular fluid glycosaminoglycans and chemically desulfated heparin to compete for heparin-binding sites on granulosa cells.

Glycosaminoglycans (GAGs) were purified from bovine follicular fluid, and their effectiveness to compete for heparin-binding sites in granulosa cells was evaluated. The GAGs dermatan sulfate (DS) and heparan sulfate (HS) were purified by anion-exchange high-performance liquid chromatography. Approximately 5 micrograms of protein from suspensions of bovine granulosa cells were incubated with 101 pmoles of [3H]heparin and 0.01-5.0 mg/ml of HS or DS for 2 h at 37 degrees C in 40 mM tris(hydroxymethyl)aminomethane (Tris), pH 7.35. Heparan sulfate obtained from small and medium follicles displaced [3H]heparin in a dose-dependent manner from 0.1 to 5 mg/ml, but HS from large follicles did not displace [3H]heparin. The DS obtained from small, medium, and large follicles displaced [3H]heparin in a dose-dependent manner, and the potency of the DS to displace [3H]heparin increased as the size of the follicles from which the DS was purified increased. Those results were independent of the maturational state of the granulosa cells. In a separate experiment, heparin (17.1% sulfate) was N-desulfated (11.8%), and the desulfated heparin did not displace [3H]heparin. It was concluded that the effectiveness of follicular HS and DS to compete for heparin-binding sites on granulosa cells was dependent on the maturation of the follicle from which the fluid was obtained rather than on the source of granulosa cells. The binding interaction of the GAGs relies, to some extent, on the presence and positions of sulfate moieties.

Lighting and sex ratio for breeding ringnecked pheasants in confined housing.

In two trials with breeding pheasants, pheasants were assigned to two male:female sex ratios (1:12 and 1:18) arranged factorially with two lighting regimens (14 or 16 hr of light) in a 24-hr period. In each trial, 1644 or 1680 pheasant hens divided in two replicates were assigned to each experimental treatment and placed in controlled environment housing. Hen mortality, percent culled eggs, total eggs per hen-housed, fertility, hatchability, and usable chicks per hen-housed were determined over a 9-week production period. Although mortality and percent hatch were not affected by either sex ratio or lighting, percent culled eggs increased with increased light (16 hr light) and usable chicks per hen-housed decreased with increased light. Increasing the sex ratio from 1:12 to 1:18 increased egg production but decreased fertility. These data demonstrate that pheasants reared in a controlled environment require less than 16 hr light for maximizing usable chick production per hen-housed and there is a trade-off between fertility and egg production.

Serum corticosterone levels in embryos, newly hatched, and young turkey poults.

The objectives of these experiments were to determine the concentration of corticosterone, the principal adrenocortical steroid in avian species, in serum of turkey embryos (12 to 28 days of development), newly hatched turkey poults (pipped and up to 6 hr posthatch), and poults between 1 and 15 days of age. The effect of giving exogenous doses of corticosterone at a physiological concentration on hatching was also determined. A significant (P less than .01) increase in serum corticosterone from .69 to 1.26 ng/ml occurred in the embryos between 17 and 18 days of development; a second significant increase to 4 ng/ml was just prior to hatching. A decrease in serum corticosterone concentration was noted during hatching and for the first 6 hr after hatching. Concentrations of corticosterone in serum fluctuated as posthatch corticosterone secretion became established between 1 and 15 days posthatch. Treatment of embryos 2 days prior to hatching with exogenous doses of corticosterone (540 ng/embryo) suggested a trend toward shorter mean incubation time and significantly increased hatchability.

Endocrine changes in the incubating and brooding turkey hen.

Turkey hens were allowed to incubate eggs and to hatch and rear young. Plasma prolactin (Prl) levels increased prior to the start of continuous incubation and rose sharply as incubation progressed to reach a peak of 1178.2 +/- 221.8 ng/ml (mean +/- SEM) just before hatching. Prl levels then fell precipitously before the hens left the nest, and returned to preincubation levels (36.8 +/- 3.4 ng/ml) by the time the poults were 2 weeks old. These results show that the high plasma concentrations of Prl found during incubation are not initiated or maintained only by the stimulus of nesting. We suggest that the decline in Prl levels at the end of incubation could be related to the pipping and hatching of eggs, and the consequent shift to maternal behavior. Plasma growth hormone (GH) levels were significantly increased in hens which were brooding poults, but not in hens incubating eggs. An elevenfold, 1-day increase in plasma GH was observed immediately after the hens left the nests. Mean plasma GH levels rose from 12.0 +/- 4.7 ng/ml on the day that the hens left the nests to 133.0 +/- 32.0 ng/ml on the following day, and then declined to 23.1 +/- 9.6 ng/ml after an additional day. There were no significant changes in plasma thyroxine levels during laying, incubation and brooding. Plasma glucose concentration was significantly depressed during incubation.

Effect of laminar air flow and clean-room dress on contamination rates of intravenous admixtures.

The effect of laminar air flow conditions and clean-room dress on the microbial contamination rates of intravenous admixtures was investigated. Intravenous admixtures were prepared by one investigator using aseptic technique under four environmental conditions: laminar air flow conditions with clean-room dress; laminar air flow without clean-room dress; clean table top with clean-room dress; and clean table top without clean-room dress. In each environmental condition, 350 admixtures were compounded. Negative-control samples (n = 150) were also tested, as were 10 positive-control samples. Samples were tested in each of two growth media and incubated at 35 degrees C for 14 days or until growth occurred. The incidence of contamination of admixtures compounded in laminar air flow conditions was significantly less than the contamination of those compounded on a clean table top (p less than 0.05) regardless of the operator's dress. The incidence of contamination of admixtures compounded while wearing clean-room dress was not significantly different from those prepared while not wearing clean-room dress regardless of the environment in which the admixture was prepared. The overall low level of contamination [0.79% (11/1400)] was inconclusive regarding the effect of dress on the incidence of contamination when admixtures were prepared under LAF conditions. It is concluded that, when one adheres to aseptic technique, the environment in which admixtures are compounded is the most important variable affecting the microbial contamination rate.

Ontogenesis of plasma growth hormone in large and midget white strains of turkeys.

The ontogeny of growth hormone (GH) secretion was determined in large and midget white strains of turkeys from day 14 of embryonic development through 32 weeks of age. The strains of turkeys used differed markedly in early growth rate, and exhibited a twofold difference in body size. Growth hormone was not detected in the plasma of either strain prior to day 25 of incubation, and was not found in most birds until the day before hatching. A highly significant (fivefold) increase in plasma GH concentration occurred between hatching and 2 weeks of age in both strains followed by a decline to 1.4% of peak values by 16 and 24 weeks in the large and midget white strains, respectively. Peak levels of circulating GH did not differ between strains, but the rate of decline to adult levels was significantly faster in the large white birds. Sex differences in plasma GH levels were observed only in the large white strain and only between the ages of 9 and 18 weeks. A highly significant positive correlation was observed between weekly percentage rate of growth and plasma GH concentration in both strains, while age and GH concentration were negatively correlated. These results suggest that growth hormone may nor be important in the developing embryo, but may be associated with growth during the rapid phase of postembryonic growth. The slow growth strain was characterized by elevated GH levels, indicating that physiological changes related to depressed growth may occur at some point subsequent to pituitary GH secretion.

Reproductive performance of turkey hens as influenced by hormone implants.

Large White turkey hens were implanted with silicone capsules containing either cholesterol (control), progesterone, 17-beta oestradiol (E2), oestrone (E1) or a combination of progesterone and E2. Egg production and fertility were measured. Blood samples were collected weekly for measurement of progesterone by radioimmunoassay. 2. Progesterone alone caused a several-fold increase in serum progesterone concentrations initially and significantly depressed egg production. Simultaneous administration of E2 significantly decreased progesterone concentration, but did not ameliorate the decrease in egg production. 3. There were significant positive correlations between serum progesterone concentration and egg production in control birds and those receiving E2 and E1. There was no significant correlation between progesterone concentration and fertility. 4. The results indicated that, within the physiological range, higher progesterone concentrations are associated with higher egg production. However, maintenance of constant progesterone concentrations throughout the reproductive season by means of implants was not achieved. Implants of E1 and E2 did not affect fecundity.

Ovarian responses and serum LH levels after retraction or removal of the oviduct in Japanese quail.

The effects of oviduct removal, oviduct displacement or sham-operation were studied in Japanese quail (Coturnix coturnix japonica). No significant differences were observed between the treatments for body weight, number of follicles larger than or equal to 6 mm diam., or number of ruptured follicles. Retraction or removal of the oviduct resulted in similar significant increases (P less than 0.05) in ovarian weight, diameter of the largest follicle, and serum LH levels when compared with the controls. Injection of yolk into normal hens did not cause any change. It is suggested that the oviduct normally exerts an inhibitory control on ovary growth without appreciable effect on ovulation rate.

A new technique in avian semen evaluation.

Modification of a technique used in human fertility is presented and shown to be a simple, inexpensive and quantitative method for estimating the subsequent fertility of a semen sample.

Plasma LH progesterone concentrations in the turkey hen during the ovulatory cycle.

Progesterone and luteinizing hormone (LH) were measuured in the plasma of Large White turkey hens at frequent intervals during the ovulatory cycle and during the periods when ovulations did not occur. The hormones were quantitated at the beginning and the end of the reproductive season to follow the change in patterns and concentrations of these hormones. Radioimmunoassay procedures were used to assay both hormones. Both progesterone and LH reached a peak amount at about 8 to 2 hours before ovulation. At no time did the progesterone peak precede that of LH. On the other hand, the peak of progesterone was observed to last somewhat longer than the LH peak. Progesterone and LH concentrations demonstrated no peak during the non-ovulatory periods. The patterns of both hormones at the end of the reproductive season was about the same as at the beginning of the season, but with lower concentrations.

Fertility of turkey hens correlated with depth of insemination.

In a two year comparison of shallow insemination (two cm.) and deep insemination (seven cm.) involving both Large White and Bronze hens shallow insemination was superior to deep insemination for Large White hens. Shallow insemination of Large White hens resulted in a longer duration-of-fertility and a higher total fertility (P less than 0.01) than deep insemination. The mean fertiltity in a 51 day duration-of-fertility trial during early production was 56.1% following shallow insemination and 43.1% following deep insemination. Late in the breeding season the mean fertility was 39.7% and 27.4% for shallow and deep insemination, respectively. The mean duration-of-fetility was 40.4 days after shallow insemination and 31.2 days after deep insemination. Shallow insemination was superior to deep insemination whether hens were inseminated at 14 days or 28 day intervals. Fertility following shallow insemination of Bronze hens was not different from fertility following deep insemination. In a duration-of-fertility trial of Bronze hens, the mean fertility was 37.3% for shallow insemination and 39.8% for deep insemination. The mean duration-of-fertility were 51.2 days after shallow insemination and 47.0 days after deep insemination.