Biomedical subjects

A Rosenstrauch

Publications and source records attributed to A Rosenstrauch.

12 recordsLinked to original sources

PubMed2004

The role of prolactin in reproductive failure associated with heat stress in the domestic turkey.

Reproductive failure associated with heat stress is a well-known phenomenon in avian species. Increased prolactin (PRL) levels in response to heat stress have been suggested as a mechanism involved in this reproductive malfunction. To test this hypothesis, laying female turkeys were subjected to 40 degrees C for 12 h during the photo-phase daily or maintained at 24-26 degrees C. Birds in each group received oral treatment with parachlorophenyalanine (PCPA; 50 mg/kg BW/day for 3 days), an inhibitor of serotonin (5-HT) biosynthesis, or immunized against vasoactive intestinal peptide (VIP). Both treatments are known to reduce circulating PRL levels. Nontreated birds were included as controls. In the control group, high ambient temperature terminated egg laying, induced ovarian regression, reduced plasma luteinizing hormone (LH) and ovarian steroids (progesterone, testosterone, estradiol) levels, and increased plasma PRL levels and the incidence of incubation behavior. Pretreatment with PCPA reduced (P < 0.05) heat stress-induced decline in egg production, increase in PRL levels, and expression of incubation behavior. Plasma LH and ovarian steroid levels of heat stressed birds were restored to that of controls by PCPA treatment. As in PCPA-treated birds, VIP immunoneutralization of heat-stressed turkeys reduced (P < 0.05) circulating PRL levels and prevented the expression of incubation behavior. But it did not restore the decline in LH, ovarian steroids, and egg production (P > 0.05). The present findings indicate that the detrimental effect of high temperature on reproductive performance may not be related to the elevated PRL levels in heat-stressed birds but to mechanism(s) that involve 5-HT neurotransmission and the induction of hyperthermia.

Animals↗

PubMed2004

The effect of a green and blue monochromatic light combination on broiler growth and development.

Previous reports have suggested that green light enhances broiler growth at an early age, whereas blue light enhances growth at older ages. The aim of this study was to examine the effect of a switch in monochromatic light at 2 ages on growth and development of broilers. Male chicks (Anak, n = 640) were used. After hatch, chicks were weighed, wing-banded, and blocked into treatment groups. Chicks were grown in 1-m2 pens in 8 isolated light-proof rooms (20 birds/pen). The light treatments were (1) Control white (mini-incandescent lamps), 2) blue light-emitting diode (LED) lamps, 3) green LED lamps, 4) blue LED switching to green at 10 d of age, 5) blue LED switching to green at 20 d of age, 6) green LED switching to blue at 10 d of age, and 7) green LED switching to blue at 20 d of age. There were 8 pens for treatment 1, and 4 pens for each of the other treatments. The light schedule was 23L:1D, and intensity was 0.1 watts/m2. BW and feed consumption were recorded. Green light birds were significantly heavier at 4 d of age. Switching light at 10 d of age from green to blue caused a further increase in BW. This improved growth was maintained until the end of the experiment. Light switching from blue to green at 20 d of age also improved growth as compared with white light. Average feed efficiency and mortality rate did not differ between groups. No association was observed among light treatment, performance, and plasma triiodothyronine concentration. We suggest that green light stimulated growth of birds at early age, and shifting birds to a different light environment at 10 or 20 d of age might further stimulate growth.

Aging↗

PubMed2003

Method for collecting semen from the ostrich (Struthio camelus) and some of its quantitative and qualitative characteristics.

1. Four methods of semen collecting that involved interruption of mating in two breeding ostrich pairs were tested: an artificial vagina was tested without promising results; the funnel method, in which a funnel was placed under the phallus of the tested male immediately after mating allowing semen drips to be collected; the vacuum method, using a turkey semen collector, inserted into the seminal canal; and the tube method, conducted by placing a test tube inside the seminal canal, allowing semen to enter by gravity. 2. For the funnel, vacuum and tube methods, respectively, average semen volume was 0.1 +/- 0.02, 1.12 +/- 0.22, and 0.58 +/- 0.13 ml, sperm concentration was 0.66 +/- 0.14, 2.35 +/- 0.26, and 2.13 +/- 0.27 x 10(9) cells/ml, and percentage of abnormal cells was 5.82 +/- 1.79%, 4.68 +/- 1.19%, and 7.09 +/- 1.72%. 3. Semen characteristics varied throughout the reproductive season reaching peak concentration in June-July. 4. The vacuum method proved to be the most efficient and was a low stress, restraint-free method for collecting ostrich semen.

Analysis of Variance↗

PubMed1999

Fertility decline in aging roosters is related to increased testicular and plasma levels of estradiol.

The relationships between testicular and plasma hormone levels and the decline in fertility in aging roosters were examined. Body mass, testicular mass, and fertility were measured in roosters from 20 to 72 weeks of age. Plasma was assayed for LH and testosterone, and estradiol and testicular extracts were assayed for testosterone and estradiol contents. Fertility increased rapidly in young roosters to a peak of 96.2 +/- 3.9% at 37 weeks of age. Thereafter, fertility declined and by 72 weeks of age was significantly lower than at 37 weeks. Plasma LH reached 16.8 +/- 2.5 ng/ml at 27 weeks and remained high until 60 weeks of age, when it decreased significantly. Plasma and testicular testosterone levels increased from low levels in young birds to a peak that coincided with highest fertility and declined thereafter. Plasma and testicular estradiol showed a striking inverse relationship with testosterone. Plasma estradiol was 29.4 +/- 4.0 pg/ml in 20-week-old birds, decreased rapidly as testosterone increased, and increased again in older birds as testosterone decreased. Thus, the decline in fertility in aging roosters was associated with a decrease in plasma LH and testosterone and an increase in plasma and testicular estradiol. It is suggested that plasma levels of LH and testosterone in roosters are regulated by a negative feedback mechanism involving estradiol that is produced not only by the aromatization of testosterone in the brain but also by peripheral estradiol originating in the testes and that estradiol has a major role in the decline in fertility in aging roosters.

Aging↗

PubMed1999

Low fertility in aging roosters is related to a high plasma concentration of insulin and low testicular contents of ACTH and lactate.

Fertility in roosters peaks between 30 and 40 weeks of age and declines rapidly from about 50 weeks of age. Low-fertility, aging roosters have a higher density of elongated spermatids attached to Sertoli cells than do high-fertility roosters, but display normal spermatogenesis and ejaculated spermatozoa. Plasma levels of insulin and lactate and testicular contents of ACTH and lactate were compared in Cornish roosters aged 27 weeks (early state of sexual maturity), 37 weeks (high fertility), 67 weeks (reduced fertility), and 72 weeks (low fertility). Insulin may act as an endocrine regulator of Sertoli cell function, and ACTH as an autocrine regulator of Leydig cells for androgen production and as a paracrine regulator of Sertoli cells by amplifying FSH response. Lactate is the primary energy substrate of spermatocytes and spermatids in the adluminal compartment. Roosters aged 67 and 72 weeks had higher (P < 0.05) plasma insulin levels but lower (P < 0.05) testicular lactate content than roosters aged 27 and 37 weeks. The lower lactate content in testes of low-fertility roosters may reflect an increased consumption of lactate due to the higher density of elongated spermatids. Furthermore, the content of testicular ACTH was lower in low-fertility roosters than in 27-week-old roosters. These results suggest that ACTH may be involved indirectly in the mechanism responsible for the high density of spermatids in the tubuli and the lower spermatozoa concentration in the ejaculate of low-fertility roosters, as was reported in previous studies, since this hormone may serve as a paracrine regulator of Sertoli cell function.

Adrenocorticotropic Hormone↗

PubMed1999

Effect of light source and regimen on growing broilers.

The aim of this study was to determine the effect of different light sources and light schedules on the growth and quality of commercial broilers. In each experiment 810 broiler chicks were divided into 3 groups, 3 replicates per group. All were reared at 20 lux. Body weight and food consumption were recorded weekly. Experiment 1. Birds were reared under 3 light sources: incandescent light bulb, warm-white fluorescent light tube or warm-white mini-fluorescent light bulb. Experiment 2. Birds were reared on 3 light schedules. 23 h light and 1 h dark (23L: 1D) throughout; an increasing light schedule with initial 23L:1D then 8L: 16D increasing daylight gradually to 16L:8D or an intermittently increasing daylight schedule (16:8P) where light and dark periods were shorter but portioned to achieve the same total hours per day up to 16L:8D. Broilers reared under mini-fluorescent light bulb were heavier than those under fluorescent tubes or incandescent bulbs by 49 d. Until 42 d of age, photoperiod had no effect on growth. However, at 49 d broilers reared under 16:8P and 16L:8D regimens were heavier than those or 23L:1D. At 42 d, female broilers on 23L:1D, were heavier than those on 16L:8D and 16:8P. Mortality was higher in groups on 23L:1D than on 16L:8D on 16:8P. At 49 d incidence of leg condemnation was higher in the 16:8P group. However, skin damage was lower in this group than in those on 23L: 1D and 16L:8D.

Animals↗

PubMed1998

Leydig cell functional structure and plasma androgen level during the decline in fertility in aging roosters.

In roosters, fertility peaks to 96% at 32 weeks, shortly after sexual maturation, and then declines rapidly to 68% at 70 weeks and to less than 10% at 110 weeks, as a result of intratesticular retention of spermatozoa. The reduction in fertility is associated with functional structural changes of the interstitial tissue, reflected in decreased plasma androgen levels from 2.7 ng/ml at 32 weeks to less than 0.5 ng/ml at 110 weeks. In high fertility roosters, the interstitial tissue is tightly packed with Leydig cells, which contain relatively large amounts of rough endoplasmic reticulum and lipid droplets, both related to androgen synthesis. In the old rooster, which has a low fertility, the interstitial tissue contains only occasional Leydig cells within an enlarged intercellular space. These Leydig cells contain small amounts of endoplasmic reticulum, mainly rough, and there are low plasma androgen levels. It is concluded that differentiation of roosters' interstitial tissue is reflected by plasma levels of androgen. This, in turn, is related to the mechanism of spermatozoa release from Sertoli cells and, consequently, with the level of fertility.

Aging↗

PubMed1994

Seasonal plasma levels of luteinizing and steroid hormones in male and female domestic ostriches (Struthio camelus).

Ostriches are low-latitude birds and can be considered to be seasonal breeders. However, they are also opportunistic in that they can breed all year round. Monthly hormonal plasma concentrations were measured in six female and six male domestic ostriches kept at a latitude of 31 degrees 20'N. Measurements were made over a year, during which time each female laid an average of 28.7 eggs. Egg laying occurred between March and September, with peak numbers in May-June. Concentrations of plasma luteinizing hormone (LH) increased in February in both sexes and started declining before termination of egg laying. Plasma testosterone concentrations in males increased in April, about 2 months after the increase in LH. In females, plasma estradiol concentrations peaked in May but were elevated from March to August, basically all of the egg-laying period. Plasma hormonal changes in the ostriches were gradual and not abrupt, as seen in many wild seasonal breeders of higher latitude.

Animals↗

PubMed1994

Spermatozoa retention by Sertoli cells during the decline in fertility in aging roosters.

Fertility of domestic roosters peaked and then began a steep decline within the first year of life. The decline was concomitant with a steady reduction in total number of spermatozoa per ejaculate. We found that 1) the decline was neither related to germinal epithelium regression nor to spermatozoa abnormalities, as reported for aging males of nonseasonal breeders and for fertile seasonal breeders during the nonmating period and 2) seminiferous tubules of extremely low-fertility aging roosters contained more Sertoli cell-spermatozoa complexes than did more fertile roosters, which is in sharp contrast to what occurs in other domestic males. We further observed that Sertoli cells of low-fertility roosters had smaller diameters, cytoplasm that stained deeper, and more crowded cytoplasmic inclusions than did Sertoli cells of high-fertility roosters. We conclude that the decline of fertility in aging roosters is related to changes in Sertoli cells that impair the regular release of spermatozoa. Spermatozoa remain within the testicular tubules and thus fewer spermatozoa are available for insemination.

Aging↗

PubMed1993

Effect of warm drinking water on the performance and immunological responses of broiler breeder hens raised at low air temperatures.

1. The effect of warmed drinking water on the performance and immunological responses of broiler breeder hens maintained at low air temperatures (5.0 degrees to 12.9 degrees C) was tested. From 22 weeks of age hens (mean body mass = 2.4 kg) were offered either warm water (27.7 degrees C; WARM; n = 24) or tap water (12.7 degrees C; CONR; n = 24) twice daily for a total time of 2.5 h or tap water ad libitum (CONA; n = 16). Food was restricted for all hens. 2. Daily water intake in the WARM hens (103 ml/kg) was similar to that of the CONR (93 ml/kg) and CONA hens (106 ml/kg). 3. There were no significant differences in either body mass change or egg production among treatment groups. 4. There was no difference among groups in heterophil/lymphocyte ratios. Similarly, there was no difference among groups in either phagocytic activity or wattle index after phytohaemagglutinin (PHA) injection. Total and IgG antibody titres to SRBC tended to be highest in the WARM hens and these titres were significantly higher than in CONR hens 14 d after challenge.

Animals↗

PubMed1984

Leydig cell differentiation during the reproductive cycle of the seasonal breeder Camelus dromedarius: an ultrastructural analysis.

Spermatogenesis and Leydig cell development in the dromedary were analyzed at the ultrastructural level and correlated with fluctuations of testosterone synthesis during the mating and nonmating seasons. It was found that (1) spermatogenesis and diameter of the seminiferous tubules are dissociated from seasonal fluctuations of testosterone synthesis as they remain similar throughout the year; (2) the volume of the interstitial tissue and the rate of testosterone synthesis are correlated since both increase during the mating season and both diminish during the nonmating season; (3) during the mating season, reduction of the tubular smooth endoplasmic reticulum (SER) and proliferation of condensed SER correspond to the relatively high rate of testosterone synthesis by the 4-ene pathway; (4) during the mating season there is a drastic reduction of the SER and proliferation of myelin figures within the Leydig cells which disrupt at the end of their differentiation. During the nonmating season, testosterone synthesis is probably impaired only at the final stage of differentiation of the Leydig cell.

Animals↗

PubMed1983

Testicular steroidogenesis in the camel (Camelus dromedarius) during the mating and the nonmating seasons.

Enzyme reactions in the camel testis involved in androgen synthesis were studied to determine the factors which account for the low testosterone production during the non-mating season (NMS). Testes excised during the NMS were found to have a relatively high activity of the 3 beta-hydroxysteroid dehydrogenase systems of pregnenolone, 17 alpha-hydroxypregnenolone, and dehydroepiandrosterone, but the 4-ene-17 alpha-hydroxylase and 4-ene-17,20-lyase systems were apparently less active than the 5-ene-17 alpha-hydroxylase and 5-ene-17,20-lyase. On the other hand, testes excised during the mating season (MS) were found to have a relatively high activity of 4-ene-17 alpha-hydroxylase, 4-ene-lyase, and 17 beta-hydroxysteroid oxidoreductase. The 19-hydroxylation and aromatizing activities for testosterone and androstenedione were not detected in testes excised in either season. It is proposed that during the NMS the predominant route of testosterone biosynthesis is pregnenolone leads to 17 alpha-hydroxypregnenolone leads to dehydroepiandrosterone leads to androst-5-en-3 beta, 17 beta-diol leads to testosterone.

17-alpha-Hydroxypregnenolone↗