Biomedical subjects

I Rozenboim

Publications and source records attributed to I Rozenboim.

At least 19 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↗

PubMed2004

Monochromatic light stimuli during embryogenesis enhance embryo development and posthatch growth.

Photostimulation with green light accelerated BW and muscle development of broilers. In experiment 1, temperature sensors were inserted into 50 broiler eggs. The eggs were placed under 5 green light-emitting diode (LED) lamps at an intensity of 0.1 W/m2 at eggshell level for 5, 10, 15, 20, and 25 min (n = 10). Egg temperatures were recorded continuously. A high correlation was found between lighting period and egg temperature elevation, and an intermittent light regimen of 15 min on and 15 min off was found to eliminate light-induced egg overheating. In experiment 2, the effect of in ovo green light photostimulation on embryonic development was studied. Five hundred fertile eggs were divided into 2 groups: the first was photostimulated with green light from 5 d of incubation until hatch (0.1 W/m2 intensity) and the second was incubated in the dark. In ovo green light photostimulation caused a significant elevation in BW and breast muscle weight during embryo development and posthatch until 6 d of age. In experiment 3, 240 fertile broiler eggs were divided into 2 groups as described in experiment 2. At hatch, chicks from each in ovo light treatment were divided into 2 subgroups: the first was reared under green light and the second under white light. In ovo photostimulation with green light enhanced BW and breast muscle weight. However, rearing under green light did not have any synergistic effect on BW. Collectively, the results suggest that stimulation with green light enhances development and growth in chicks and that the best effect is achieved when this stimulus is provided during incubation.

Animals↗

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↗

PubMed2003

Effect of embryonic photostimulation on the posthatch growth of turkey poults.

Artificial illumination, including light quality, is important in modern meat-type poultry management. In the present study, the effect of in ovo monochromatic green light photostimulation on posthatch growth of turkey poults was investigated. In experiment 1, 182 turkey eggs were divided into two light treatment groups (n = 91). The first group was intermittently photostimulated (3 min on and 3 min off) with green light provided by five light-emitting diodes (LED) per egg at 0.1 W/m2 at the upper eggshell surface. The second group was incubated in the dark and served as the control. Posthatch BW were recorded at 0, 2, 6, 13, 20, 28, 35, and 59 d of age. A heavier BW, occurring at 28 d of age and persisting until the end of the experiment (59 d of age), was observed in the in ovo green light stimulated females as compared to their corresponding controls. In experiment 2, 273 turkey eggs were divided into three light treatment groups (n = 91). The first group was intermittently photostimulated (15 min on and 15 min off) with green light provided by seven LED per egg at 0.14 W/m2. The second group was photostimulated with white light provided by one mini-incandescent lamp per egg at light intensity and schedule similar to the first group. Eggs of the third group were incubated in the dark and served as controls. Posthatch BW were recorded at 0, 7, 14, 28, 42, 56, and 79 d of age. No differences were found among the BW of males incubated under different light conditions. As in experiment 1, female turkeys with stimulated green light in ovo had greater BW compared to their corresponding control and white light groups from 28 d of age until termination of the experiment at 79 d of age. Breast muscle weight was greater in female turkeys incubated under green light when compared to white and dark incubation treatment groups. We suggest that in ovo green light photostimulation enhances the posthatch BW of female turkey poults.

Aging↗

PubMed2002

The effect of melatonin administration on circulating plasma luteinizing hormone concentration in castrated White Leghorn roosters.

Melatonin (MLT) has a significant role in mammalian reproduction, with little or no effect in birds. In the present study we studied the role of MLT in regulation of luteinizing hormone (LH) secretion in castrated White Leghorn (WL) roosters. In Experiment 1, castrated WL roosters (n = 30) were divided into three groups, and each group (n = 10) was subdivided into two subgroups (n = 5). Birds in one subgroup received an injection of MLT at 5 mg (MLT-5), 20 mg (MLT-20), or 80 mg (MLT-80)/kg BW. Birds in the second subgroup were vehicle-injected and served as controls. Each dose of MLT was administered on a separate day at 1100 h. Blood was sampled 30 min before and 10, 30, 60, and 120 min after MLT or vehicle administration. Ten minutes after MLT administration, a significant reduction in plasma LH was observed in the MLT-20 and -80 groups, i.e., 70.3 +/- 8.3% and 62.2 +/- 4.1% of control values, respectively. In the MLT-80 group, plasma LH further declined to 42.1 +/- 9.7% of control values 60 min after injection. In Experiment 2, 18 castrated WL roosters were divided into three groups of six birds each. Two groups were injected with 80 mg MLT/kg BW at the beginning of the experiment; the second group received an additional dose of 80 mg MLT/ kg BW 140 min after the first injection. The third group was injected twice (as in second group) with vehicle and served as control. Blood was sampled 30 min before and 30, 60, 120, 170, 200, and 240 min after injection. Repeated MLT injection maintained low levels of plasma LH level until the end of the experiment. In Experiment 3, 10 castrated WL roosters were divided into two groups (n = 5). The first group was injected daily, for 10 d, with 80 mg MLT/kg BW, the second group was vehicle-treated and served as a control. At Day 3, there was a significant reduction in plasma LH level in the MLT-treated group, which continued for 7 d. This study demonstrates that, in birds, MLT suppresses LH secretion in a dose- and a time-related manner.

Animals↗

PubMed2001

Photostimulated prolactin release in the Turkey hen: effect of ovariectomy and environmental temperature.

Ambient temperature modulates prolactin (PRL) secretion in birds. It is not known whether this modulation directly affects the PRL controlling mechanism(s) or whether it indirectly influences them through the onset of sexual maturity and/or the onset of incubation behavior. These experiments were designed to investigate the effect of elevated (32 degrees ) and reduced (10 degrees ) ambient temperatures on PRL secretion. Somatically mature, ovariectomized female turkeys were used to avoid the confounding effects of reproductive stage, nesting, and egg stimuli on PRL secretion. Hens were ovariectomized 5 weeks before, on the day of, or 10 days after the inception of photostimulation. Temperature treatments included chronic exposure (5 weeks) to 32 or 10 degrees and acute exposure (i.e., temperature was reversed from 32 to 10 degrees or from 10 to 32 degrees on or after the day of photostimulation). Chronic exposure to either 32 or 10 degrees had no effect on the rise in serum PRL that followed photostimulation in both sham-operated controls and ovariectomized hens. Acute exposure to 10 or 32 degrees altered the photoperiodically stimulated rise in plasma PRL. Birds switched from 10 to 32 degrees showed a significantly greater PRL increase than birds shifted from 32 to 10 degrees. Ovariectomy enhanced the PRL response to the gonadal stimulating photoperiod. The effect was most pronounced in hens photostimulated prior to ovariectomy. These findings suggest that ambient temperature and/or ovariectomy have a modulating effect on the PRL response to long days.

Animals↗

PubMed2001

Evaporative cooling of ventral regions of the skin in heat-stressed laying hens.

Laying hens held in battery cages in naturally ventilated poultry houses in hot countries usually develop hyperthermia, which adversely affects their performance. The present means of cooling alleviate to some degree, but cannot eliminate, the stress imposed by heat. A new approach to cooling of laying hens was developed, based on wetting the skin and promoting evaporation of water from the ventral regions of the bird. The type of plumage in the ventral regions and the exposed skin of the apteria enable more efficient wetting than is possible with dorsal cooling. A ventral cooling regime, comprising an initial period of frequent wettings followed by intermittent wetting for 10 s every 30 min was able to maintain normothermia of laying hens subjected to a 10-h period of heat exposure. Dorsal cooling was less efficient; body temperature and respiration rate were higher and skin temperatures were lower than in ventrally cooled hens. During 10 d of heat exposure, ventrally cooled hens maintained egg weight and shell index (mg/cm2), whereas their food intake decreased moderately. In contrast, egg weight, shell index, and food intake all decreased markedly in uncooled or dorsally cooled hens. Transient alterations in plasma concentrations of corticosterone, progesterone, and estradiol were noted in uncooled and dorsally cooled hens but not in ventrally cooled hens. Results indicate that ventral cooling is an efficient method to alleviate heat stress in laying hens during summer. Successful implementation of ventral cooling in poultry houses will depend on optimal installation of sprinklers and on minimal wetting of manure.

Animals↗

PubMed2000

Sex-related differences in the effects of late winter pairing activity and seasonal influences on neuroendocrinology and gonadal development of mallards.

The importance of late winter pairing activity on the neuroendocrinology of wild waterfowl is unknown. In this study, we examined the sex-related differences in the roles of late winter pairing activity and seasonal influences on neuroendocrine and reproductive physiology in both male and female mallards. Our main goals were to determine (1) which physiological responses were influenced by pairing status or by seasonal changes and (2) whether responses differed between the sexes. Thus, physiological responses of mallards in different pairing status categories were assessed at two times: January 28 to February 5 and February 24 to March 3. Ducks were assigned to one of the following pairing status categories: strong pairs, temporary pairs, unpaired or lone birds within the flock, or birds isolated in same-sex groups. Seasonal changes correlated with increases in both gonadal mass and hypothalamic content of vasoactive intestinal peptide in both sexes, whereas only pairing status correlated with changes in body mass in both sexes. The main sex-related differences were the following: (1) Seasonal decreases in hypothalamic gonadotrophin releasing hormone II content occurred only in females. (2) Seasonal increases in serum prolactin occurred only in males, whereas levels in females were low throughout the study. (3) Both male and female gonadal masses increased seasonally, but male gonadal mass was initially twice that of females. (4) Body mass of both sexes was influenced by pairing status correlations (i.e., all paired or lone birds were heavier than isolated birds), but body mass in males decreased seasonally. No sex-related differences occurred in hypothalamic gonadotrophin releasing hormone I content or circulating serum luteinizing hormone. Taken together, these results indicate that seasonal reproduction in mallards is regulated not only by seasonal but also by social cues, and differences occur between the sexes, months in advance of actual breeding.

Animals↗

PubMed2000

The effect of light intensity on growth and development of turkey toms.

1. The effect of light intensities from 10 to 700 lux on the performance of 5 to 18 week-old turkey males was studied in 2 trials. 2. Body weight of 18 week-old turkeys, in both experiments, was highest under the lowest light intensity This coincided with higher weight gain and lower food intake, which resulted in significantly better food conversion efficiency 3. Light intensity affected heart muscle weight but not weight of breast muscle, abdominal fat or testis as proportions of body weight. 4. The decline in plasma T3 concentration with age differed from other treatments at the low light intensity, which resulted in a significantly higher T3 concentration in turkeys exposed to 10 lux at the age of 10 to 15 weeks. 5. It is concluded that light intensity significantly affects food conversion efficiency in turkey males. This is likely to be related to differential investment of energy expenditure for maintenance.

Animals↗

PubMed2000

Vitamin A deficiency interferes with proliferation and maturation of cells in the chicken small intestine.

1. The effect of vitamin A on the small intestine was examined in vitamin-A-deficient meat-type chickens. 2. Maturation and activity of the small intestinal cells were assayed by detection of proliferating cells with proliferating cells nuclear antigen, goblet cells with Alcian blue, mature cells with alkaline phosphatase and extent of RNA expression with dot blot analysis. 3. Vitamin A deficiency caused hyperproliferation of enterocytes, a decrease in the number of goblet cells, decreased alkaline phosphatase activity and decreased expression of 2 brush-border enzymes. 4. Our findings suggest that the absence of vitamin A interferes with the normal growth rate in chickens because it influences functionality of the small intestine by altering proliferation and maturation of cells in the small intestinal mucosa.

Aminopeptidases↗

PubMed2000

The relationship between neural alterations and behavioral deficits after prenatal exposure to heroin.

The present studies employ multitudinous approaches in order to overcome the methodological obstacles in the understanding of the relationship between neurochemical alterations and behavioral deficits induced by heroin during prenatal development. Mice were exposed prenatally to heroin via daily subcutaneous injections of 10 mg/kg, on gestation days 9-18. At age 50 days, the heroin-exposed offspring displayed behavioral deficits as assessed in the eight-arm and Morris mazes, pointing to possible alteration in the septohippocampal cholinergic innervations. Biochemically there was increased presynaptic activity of these innervations as attested to by the increased [3H]hemicholinium-3 (HC-3) binding sites and by K+-stimulated inositol phosphate (IP) formation. Postsynaptically, there was global hyperactivation along the different components of the nerve conduction cascade, including an increase in M1 muscarinic receptor Bmax, a general increase in G-proteins (GP) including the most relevant, G subtype, and an increase in IP formation and in basal protein kinase C (PKC) activity. However, there was desensitization of PKC activity in response to cholinergic agonist in the heroin-exposed offspring. Transplantation of normal embryonic cholinergic cells to the impaired hippocampus reversed the behavioral deficits and both the pre- and postsynaptic hyperactivity and resensitized PKC activity. To support and further strengthen the findings of the neural grafting study, correlation of the heroin-induced behavioral deficits with the biochemical alterations, done within individuals, was applied. The results showed high r values for IP formation, basal PKC, and PKC desensitization. The r values for HC-3 binding were statistically significant but relatively low. Taken together, the findings of the neural grafting and correlation studies bring us closer to understanding the relationship between the prenatal heroin-induced biochemical and behavioral changes. However, mammalian models possess the inherent methodological hindrances, stemming from possible maternal effects. To provide a control for these confounding variables, a chick embryo model was applied in which filial imprinting, a behavior related to a specific hyperstriatal nucleus, served as an endpoint. Heroin was administered to developing chick embryos by injecting the eggs (20 mg/kg) on incubation days (ID) 0 or 5. Prehatch exposure to heroin markedly diminished the ability for filial imprinting in the hatched chicks.

Acetylcholine↗

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

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↗

PubMed1999

The effect of monochromatic light on broiler growth and development.

Artificial illumination, including light quality, is crucial in modem broiler management. In the present study, a new, highly efficient, monochromatic light system has been developed for broilers. One hundred and eighty male broiler chicks (Anak) were divided into four light treatment groups (n = 45) in three replicates each. All birds were housed in a single room previously divided by wooden bars into 12 sealed cells of 1 m2. Feed and water were provided for ad libitum consumption. Light intensity was 0.1 W/m2 at the height of birds' heads and was scheduled for 23 h of light and 1 h of dark during the entire experimental period. Light treatments were: control white (mini-incandescent light bulbs), blue (480 nm), green (560 nm), and red (660 nm). Body weight was recorded periodically, feed consumption was measured daily, and feed efficiency was calculated. Blood samples were taken at 1, 9, and 32 d of age and plasma testosterone was determined. Two necropsies were conducted, at 23 and 35 d of age, and selected glands and organs were weighed. In the group reared under green light, a significant enhancement in weight gain was observed as early as 3 d of age; this gain was maintained during the entire experimental period. Broilers reared under blue light had a later onset of growth enhancement and were significantly heavier than those reared under white and red light at 20 d of age. Plasma testosterone levels were significantly higher in birds reared under blue light. Breast muscle weights were significantly higher in the birds reared under green light at 23 and 35 d of age. These results suggest that green and blue light stimulate growth.

Aging↗

PubMed1999

Effects of fenfluramine on body weight, feed intake, and reproductive activities of broiler breeder hens.

Inherited overfeeding and fattiness reduce laying performance in broiler breeder pullets. Although feed restriction is used to compensate for overeating and weight gain, this management practice leads to increases in BW variation, labor cost, and bird stress. Dietary supplementation of anorectic agents, such as fenfluramine, may be an alternative. Anak female prebreeder hens (19 wk of age; n = 10 per group) were treated as follows: daily oral administration of 5, 10, 20, or 40 mg DL-fenfluramine/kg BW or saline with food provided for ad libitum intake or administration of saline and feed restriction. Daily feed intake (FI), laying rate, egg composition, and BW were measured. At 40 wk of age, adipose tissue and ovary weights were measured. Fenfluramine depressed (P < 0.05) BW and FI in a dose-dependent manner, but was less effective in reducing BW than feed restriction. Suppression of FI occurred in two phases: a dynamic phase, coinciding with the rapid growth phase, during which FI declined progressively and a static phase during which FI reached a plateau at a significantly low level until the end of the experimental period. Egg production peaked first in saline-treated hens fed for ad libitum intake, but soon after started to decline. In all fenfluramine-treated and feed-restricted hens, egg production peaked 3 to 4 wk later and remained high until the end of the experiment. There were no differences in egg and egg component weights among the experimental groups. Abdominal adipose tissue weight was reduced by fenfluramine in a dose-related manner, and its weight in the group treated with the highest dose was similar to that of feed-restricted hens. In these two groups, ovarian weight was significantly higher than in the saline-treated hens fed for ad libitum intake, and a small, nonsignificant increase in ovary size was observed in groups treated with the two median doses of fenfluramine. The effect of fenfluramine on egg production was similar to that of feed restriction, but it was not dose-dependent and, thus, not directly related to its leaning effect. In broiler breeder hens, oral fenfluramine may be used for chemical feed restriction and diminution of fattiness without reducing egg production relative to manually feed-restricted hens.

Adipose Tissue↗

PubMed1998

Various light source treatments affect body and skeletal muscle growth by affecting skeletal muscle satellite cell proliferation in broilers.

In this study we addressed the effect of various monochromatic light treatments on muscle growth and satellite cell proliferation in broilers (Gallus domesticus). Broilers were reared under green (560 nm), blue (480 nm) and red (660 nm) monochromatic lights and white light as a control from day one until 35 days of age. At five days of age, satellite cells were prepared from the experimental chicks. The number of satellite cells per gram of breast muscle and total number of satellite cells derived from the experimental broilers was substantially higher in the groups reared under green and blue light, compared to the red and white light groups. Growth hormone receptor gene expression was also higher in the former groups. High correlation was found between the breast muscle weight observed on day 35 and the number of satellite cells per gram of breast muscle (r = 0.915) and total number of satellite cells (r = 0.833), derived from the experimental chicks as early as five days of age. In addition, the protein/DNA ratio found in breast muscle at 35 days of age was significantly lower in chicks that were reared under green and blue lights. The lowest ratio which was found in the green group and was twice as low as in the control group, indicates the highest number of nuclei in the former group. As satellite cells are the only source of additional nuclei in skeletal muscles of postnatal animals, our results suggest that the higher muscle weight found in the green and blue light groups was due to increased satellite cell proliferation during the first days of age.

Animals↗

PubMed1998

Testosterone concentrations, testes weight and morphology of mule drakes (Muscovy drake x Khaki Campbell).

1. Mule ducks were produced by naturally mating Muscovy drakes and Khaki Campbell ducks. 2. Semen was collected from 6-month-old mule drakes via an artificial vagina. The fluid was clear without any spermatozoa or spermatids. 3. Testes from 27-week-old mule drakes were smaller in size than those of Khaki Campbell drakes but heavier than Muscovy males of the same age. Histological sections of these testes revealed that spermatogenesis was not complete. 4. Testosterone concentration in the mule drakes was higher than in Muscovy males but similar to Khaki Campbell drakes. 5. Mule drakes have strong sexual drives as a result of high concentrations of testosterone, but, because spermatogenesis is incomplete, their semen had no sperm.

Aging↗