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PubMed1990

The nutritional value of dehydrated, blue-green algae (Spirulina platensis) for poultry.

Three experiments were conducted to evaluate the nutritional value of the blue-green algae, Spirulina platensis, grown on a synthetic media. In Experiment 1, day-old, White Leghorn cockerel chicks (120) were fed isonitrogenous diets containing 0, 5, 10, 15, and 20% of dried spirulina. At 3 wk of age, the growth of the chicks fed 10 and 20% of spirulina was depressed (P less than .05), although feed efficiency was not affected. In Experiment 2, 250 1-day-old, Hubbard by Hubbard, male broiler chicks were fed experimental diets containing 0, 1.5, 3.0, 6.0, or 12.0% of spirulina for 41 days. Although the growth of the chicks fed the spirulina diets was not different from that of the chicks receiving the control diet, the birds receiving the 12% spirulina diet grew slower (P less than .05) than the chicks fed all of the other spirulina diets. In Experiment 3, 600 1-wk-old, Japanese qual were used to study the effects of 0, 1.5, 3.0, 6.0, and 12.0% of spirulina on growth, egg production, egg quality, fertility, hatchability, and the growth of the F1 generation of dams fed Spirulina. There were no significant differences due to the spirulina content in any of the parameters studied-except for yolk color, which increased with each succeeding level of spirulina, and for fertility, which was higher for all spirulina treatments versus the control.

Animal Feed↗

PubMed2001

Effect of supplementary choline on the performance of broiler breeders fed on different energy sources.

1. Laying performance, egg quality, fertility and hatchability, and fat deposition in liver and abdomen were recorded in broiler breeders (29 to 48 weeks of age) fed on diets containing perarl millet (Pennisetum typhoides) (PM), broken rice (BR) or yellow maize (YM) (600 g/kg diet). Constant ratios of metabolisable energy (ME) to other nutrients were maintained in all the diets. Food grade choline chloride (50%) was added to the diets at 3 concentrations (0, 760 and 1,520 mg/kg). Each diet was offered to 3 replicate groups of 15 birds (12 hens and 3 cockerels), maintained in deep litter pens, to provide 1.46 MJ ME/bird/d. 2. Neither the source of energy nor dietary choline content had any influence on hen-d egg production, fertility or hatchability. Food efficiency and egg weight were significantly reduced in BR-fed groups compared to those fed on the other energy sources. 3. The efficiency of energy and protein utilisation increased and liver fat content was decreased significantly by dietary choline supplementation. 4. Haugh unit score, egg shell weight, liver weight and intestinal weight were not influenced by either supplementary choline or the source of energy. However, the yolk colour index was significantly reduced in PM- or BR-fed groups compared to those fed on the maize-based diet. 5. Deposition of abdominal fat was significantly greater in BR-fed birds compared to those fed on the YM-based diet, while liver fat content was significantly greater in the birds fed on the PM-or BR-based diets than those based on YM. Although supplementation of the diet with choline had no influence on abdominal fat deposition, liver fat content was significantly reduced in birds given diet containing 760 mg supplemental choline/kg diet. 6. The present study indicates that PM or BR can be used as principal energy sources in place of YM in broiler breeder diets without affecting egg production, fertility or hatchability. Liver fat content can be reduced by adding choline at 760 mg/kg to diets based on different energy sources.

Abdomen↗

PubMed2002

A method using sustainability indicators to compare conventional and animal-friendly egg production systems.

The objective of this paper was to describe a method that enables a comparison of egg production systems for their contribution to sustainable development of egg production, using data from the Netherlands for demonstration purposes. One conventional system, the battery cage system, and two animal-friendly systems, the deep-litter and the aviary systems, illustrate this method. The method is based on a three-phase framework that identifies relevant issues regarding sustainable development (Phase 1), translates issues into sustainability indicators (Phase 2), and assesses the contribution of sustainability indicators to sustainable development (Phase 3). Phases 1 and 2 are based on analysis of literature and consultation with experts. Phase 3 is based on graphical and numerical comparisons. A graphical comparison presents the relative deviation between actual and target values for each sustainability indicator. A numerical comparison combines the relative deviation for each sustainability indicator into an overall contribution of an egg production system to sustainable development. Sustainability indicators selected include economic performance, ammonia emission, energy use, hen welfare, farmer welfare, and egg quality. Based on equal importance of these indicators, the battery cage system shows the least negative contribution to sustainable development. The aviary system is considered a better animal-friendly alternative for a battery cage system when compared with a deep-litter system. The aviary system especially needs to improve economic performance and farmer welfare. The conclusion can only be tentative, however, because methodological aspects such as selection and weighting of sustainability indicators will need careful attention and further research.

Animal Welfare↗

PubMed2001

Effects of mould and toxin contaminated barley on laying hens performance and health.

Moulded and mycotoxin containing barley was incorporated into the diets for laying hens to study the effects on performance and health. Health indicators were different blood plasma parameters and liver vitamin A and E levels. A total of 30 hens were fed 3 diets, one supplemented with 30% of toxin-free and two with differently moulded barley from 1997 and 1998 for 7 weeks. The moulded diets contained low to moderate concentrations of ochratoxin A, zearalenone, deoxynivalenol and nivalenol. Inclusion of mouldy barley in the diets had an adverse effect on feed intake, feed conversion, digestibility of nutrients, egg production and egg quality. Plasma alkaline phosphatase was increased and certain biochemical blood parameters (bilirubin, uric acid, chlorine, protein, albumin, vitamin A) were also higher or changed compared to control. The ochratoxin A contamination although relatively low could have contributed to some of these effects as well as reduced intake of feed. The higher mould contamination and an unidentified cell-toxic constituent in the diet containing barley from 1998 can probably also explain the more marked effects from this diet.

Animal Feed↗

PubMed1975

Some effects on layers of sodium sulfate and magnesium sulfate in their drinking water.

Potential for increasing contamination of water supplies with such materials as dissolved inorganic solids suggests more precise water quanlity standards for poultry. Commercial strain S.C.W.L. hens were supplied water containing sodium sulfate (Na2SO4) or magnesium sulfate (MgSO4) (250, 1,000, 4,000, or 16,000 p.p.m.) on a total sulfate basis in Exp. 1 and on a total salt basis in Exp. 2. All data are expressed as percentages deviated from pre-treatment performance. Four thousand p.p.m. of total sulfate as Na2SO4 or MgSO4 significantly depressed feed consumption and hen-day production. Magnesium sulfate (4,000 p.p.m.) had a more depressing effect than Na2SO4 (4,000 p.p.m.) on hen-day production (-80.4 vs. -24.4%). At that level, Na2SO4 significantly increased water consumption and fecal moisture content, while MgSO4 significantly decreased water consumption. All hens on 1l,000 p.p.m. of either salt died during the experiment. No effect on egg quality was observed before the hens died. On a total salt basis (Exp. 2) 16,000 p.p.m. of either Na2SO4 or MgSO4 significantly depressed hen-day production, body weight, and feed comsumption, but increased water consumption. Hens receiving 16,000 p.p.m. Na2SO4 increased water consumption more than those receiving 16,000 p.p.m. MgSO4(146.7 and 24.6%). No significant differences between treatments were observed for mortality (Exp. 2). Mortality data suggest that lethal levels of Na2SO4 and MgSO4 are between 16,000 and 20,032 or 23,680 p.p.m. total salt, respectively.

Administration, Oral↗

PubMed2003

Testing hypotheses of aging in long-lived painted turtles (Chrysemys picta).

For 38 of the past 50 years, Painted Turtles were studied on the University of Michigan's E.S. George Reserve in southeastern Michigan. We compared age specific body sizes, reproductive traits and survival of Painted Turtles ranging from 9 to 61 years of age to test contrasting predictions of the Relative Reproductive Rate and Senescence Hypotheses of aging. Indeterminate growth (i.e. continued body growth of adults) was important in increasing reproductive output of older turtles; however, growth rate of the oldest age-group was reduced compared to that of younger adults. Although clutch size and among year reproductive frequency did not increase with age, within year reproductive frequency (production of second clutches), egg size, and hatchling size did. Nest predation rates and the proportion of surviving nests that produced hatchlings were similar among age groups, and embryo mortality in nests was not related to age. Survivorship of males was less than that of females, and survivorship of the oldest group of females was not statistically different from that of a younger group of females. No decline in reproductive output or survivorship was detected in the oldest females as predicted by the Senescence Hypothesis. Thus, the majority of data on reproductive traits and survivorship support the Relative Reproductive Rate Hypothesis. We also compared Painted Turtles to Blanding's Turtles, another species studied on the E.S. George Reserve. That Painted Turtles exhibit indeterminate growth whereas Blanding's Turtles do not, appears to be a primary mechanism for some differences between species in the relationships between reproductive traits and age. An important mechanism for increasing reproductive output in both species was increased reproductive frequency in older females. Painted Turtles also increased offspring quality (egg and hatchling size) with age, whereas Blanding's Turtles did not. Compared to younger individuals, there was no reduction in survivorship in the oldest Painted Turtles and survivorship increased in the oldest Blanding's Turtles.

Aging↗

PubMed1998

Neem (Azadirachta indica) kernel meal in the diet of White Leghorn layers.

1. Neem kernel meal (NKM) was incorporated into a standard layer diet at 0, 100, 150 and 200 g/kg, replacing parts of the soyabean meal and deoiled rice bran. Each diet was offered to 18 White Leghorn layers (25 weeks, 50% egg production) in individual cages for a period of 12 weeks. 2. Results indicated significantly lower food intakes (P < 0.01), rates of egg production and egg weights in birds fed on the diets with NKM at 150 and 200 g/kg. Fertility and hatchability were also adversely affected by the higher inclusion rates of NKM. 3. Except for lower egg shell weight and shell thickness (P < 0.05) in hens fed NKM at 150 and 200 g/kg, the internal egg quality characteristics were comparable in all groups. 4. Feeding NKM beyond 100 g/kg to laying hens significantly (P < 0.01) reduced the content of haemoglobin, erythrocyte count, packed cell volume, serum calcium and uric acid concentrations. However, the leucocyte count, plasma glucose concentration and serum glutamate oxaloacetate transaminase activity were unaltered. Serum glutamate pyruvate transaminase activity was significantly (P < 0.05) reduced in birds fed NKM at 200 g/kg. 5. Thus NKM at 100 g/kg in a layer diet would appear to be safe and cost-effective.

Alanine Transaminase↗

PubMed2000

Avian infectious bronchitis virus.

Infectious bronchitis virus (IBV) is prevalent in all countries with an intensive poultry industry, with the incidence of infection approaching 100% in most locations. Vaccination is only partially successful due to the continual emergence of antigenic variants. At many sites, multiple antigenic types are simultaneously present, requiring the application of multiple vaccines. Although many countries share some common antigenic types, IBV strains within a geographic region are unique and distinct, examples are Europe, the United States of America and Australia. Measures to restrict the introduction of exotic IBV strains should therefore be considered. Infectious bronchitis has a significant economic impact; in broilers, production losses are due to poor weight gains, condemnation at processing and mortality, whilst in laying birds, losses are due to suboptimal egg production and downgrading of eggs. Chickens and commercially reared pheasants are the only natural hosts for IBV. Other species are not considered as reservoirs of IBV. The majority of IBV strains cause tracheal lesions and respiratory disease with low mortality due to secondary bacterial infections, primarily in broilers. Nephropathogenic strains, in addition to tracheal lesions, also induce prominent kidney lesions with mortality of up to 25% in broilers. Strains of both pathotypes infect adult birds and affect egg production and egg quality to a variable degree. Infected chicks are the major source of virus in the environment. Contaminated equipment and material are a potential source for indirect transmission over large distances. Virus is present in considerable titres in tracheal mucus and in faeces in the acute and recovery phases of disease, respectively. Virus spreads horizontally by aerosol (inhalation) or ingestion of faeces or contaminated feed or water. The virus is highly infectious. Clinical signs will develop in contact chicks within 36 h and in nearby sheds within one to two days. Infection is resolved within fourteen days with a rise in antibody titres. In a small number of chicks, latent infection is established with subsequent erratic shedding of virus for a prolonged period of time via both faeces and aerosol. Movement of live birds should be considered as a potential source for the introduction of IBV. Isolation and identification of IBV is needed for positive diagnosis. The preferred method of isolation is to passage a sample in embryonating specified-pathogen-free chicken eggs. Identification is either by monoclonal antibody based enzyme-linked immunosorbent assay (ELISA) or polymerase chain reaction. Virus neutralisation test in tracheal organ culture is the best method for antigenic typing. Continual use of live vaccines complicates diagnosis since no simple diagnostic tool can differentiate a field from a vaccine strain. Nucleotide sequencing of the S1 glycoprotein is the only method to discriminate between all IBV strains. Serology is also complicated by continual use of live vaccines. For surveillance purposes, ELISA is the method of choice, regardless of the antigenic type of IBV involved. The assay is used to monitor the response to vaccination, but field challenge can only be detected if flock antibody status is monitored continually. The antigenic type of a challenge strain involved cannot be ascertained by ELISA.

Animals↗

PubMed2006

Laying performance of pearl gray guinea fowl hens as affected by caging density.

The caging density required for optimal egg production by various avian species and varieties is highly variable. Even so, little is known of the required cage density for optimum performance of the laying guinea fowl (Numida meleagris). The objective of this study was to assess the effect of varying cage densities on production performance of pearl gray guinea fowl laying hens. In 3 replicates, 270 pearl gray guinea hens [28 wk of age (WOA)] were weighed individually and randomly assigned to laying cages at densities of 1, 2, and 3 birds/cage, equivalent to 1394, 697, and 465 cm2/bird, respectively. During the experiment, all birds received a 16-h lighting regimen and were fed the same diet, comprising 2800 kcal of ME/kg of diet and 16% CP (28 to 59 WOA) and 2800 kcal of ME/kg of diet and 14% CP (60 to 76 WOA). Feed and water were provided for ad libitum consumption. Experimental birds were observed for feed consumption (FC), hen-day egg production (HDEP), egg weight, egg mass (EM), feed conversion ratio, internal egg quality, and shell thickness at the end of each 28-d lay period for 11 consecutive periods. Mean FC and HDEP decreased significantly with increases in cage density, such that 1394 > 697 > 465 cm2/bird. Mean EM was also higher (P < 0.05) for birds reared in cages at 1394 cm2/bird than those reared in cages at 697 and 465 cm2/bird (24.8, 17.4, and 14 g/hen per d, respectively). Feed conversion, HDEP, and EM were negatively correlated with cage density (P < 0.05). Mean feed conversion ratio and percentage of mortality were also lower in birds reared in cages at 1394 cm2/bird than in other treatment groups. Therefore, laying guinea fowl hens exhibited superior performance when raised at a density of 1 bird/cage (1394 cm2/bird) than those reared at densities of 2 and 3 birds/cage (697 and 465 cm2/bird, respectively).

Aging↗

PubMed2005

Response of laying hens and growing broilers to the dietary inclusion of mango (Mangifera indica L.) seed kernel meal.

Studies were carried out to assess the nutritive value and utilization of mango (Mangifera indica L.) seed kernel (MSK) in the diets of layer and broiler chickens. The physical component of mango seeds was found to consist of 678 g/kg kernel, 292 g/kg shell and 30 g/kg testa. Meal from the seed kernel contained 61.6 g crude protein, 136.2 g ether extract, 22.3 g ash, 46.4 g crude fibre, 673.5 g nitrogen-free extract and appreciable mineral content. In the layers trial, MSK replaced maize weight for weight at 0, 50, 100, 150, 200 and 250 g/kg. Results indicated a significant decrease (p < 0.05) in feed intake, rate of lay, egg mass and feed efficiency with increase in MSK. Layers on 150, 200 and 250 g/kg MSK exhibited the highest body weight losses. Except for lower shell thickness (p < 0.05) in hens fed MSK at 200 and 250 g/kg, the internal egg quality characteristics were comparable. In the broiler experiment, MSK was incorporated at levels of 0, 50, 100, 150 and 200 g/kg at the expense of maize but with slight adjustments to the soybean meal so as to achieve isonitrogenous diets. Body weight and body weight gains increased significantly (p <0.05) up to 100 g/kg and then decreased. MSK at 150 or 200 g/kg had no significant effects (p >0.05) on feed intake and feed efficiency when compared with control diet. Organ weights with the exception of liver and lung were unaffected by dietary MSK. Haematological indices were not influenced (p > 0.05) by dietary MSK except haemoglobin and mean cell haemoglobin, which were higher (p<0.05) in broilers fed 100 g/kg MSK. Neutrophils, lymphocytes and albumin/ globulin ratio were similar on all diets. The results indicated that at higher weight for weight levels, MSK cannot readily substitute maize in layer diets, whereas a marginal improvement was recorded in the broiler diet, albeit with nutrient supplementation.

Animal Feed↗

PubMed2006

Inactivation of Salmonella serovars in liquid whole egg by heat following irradiation treatments.

Salmonella is a frequent contaminant on eggs and is responsible for foodborne illnesses in humans. Ionizing radiation and thermal processing can be used to inactivate Salmonella in liquid whole egg, but when restricted to doses that do not affect egg quality, these technologies are only partially effective in reducing Salmonella populations. In this study, the effect of ionizing radiation in combination with thermal treatment on the survival of Salmonella serovars was investigated. Of the six Salmonella serovars tested, Salmonella Senftenberg was the most resistant to radiation (Dgamma = 0.65 kGy) and heat (D(55 degrees C) = 11.31 min, z = 4.9 degrees C). Irradiation followed by thermal treatment at 55 or 57 degrees C improved the pasteurization process. Radiation doses as low as 0.1 kGy prior to thermal treatments synergistically reduced the D(55 degrees C) and D(57 degrees C) of Salmonella Senftenberg 3.6- and 2.5-fold, respectively. The D(55 degrees C) and D(57 degrees C) of Salmonella Typhimurium were reduced 2- and 1.4-fold and those of Salmonella Enteritidis were reduced 2- and 1.6-fold, respectively. Irradiation prior to thermal treatment would enable the reduction of heat treatment times by 86 and 30% at 55 and 57 degrees C, respectively, and would inactivate 9 log units of Salmonella serovars.

Animals↗

PubMed1995

Effect of substituting sesame meal for soybean meal on layer and broiler performance.

Sesame meal (SM, 47.1% CP) has an amino acid composition similar to that of soybean meal (SBM, 47.7% CP) with the exception of lower lysine and higher methionine, but has been relatively underutilized in poultry feeds. Two experiments (1 and 2) were conducted to measure laying performance and hatchability of White Leghorn hens fed practical diets (17% CP), and two additional experiments (3 and 4) examined the performance of broiler chicks fed practical diets (22% CP) with varying substitution levels of screw-pressed SM for solvent-extracted SBM. In Experiment 1, SM contributed 0, 12.6, 25.3, 38, or 50.6% of dietary CP, and each diet was fed to hens for 6 wk. In Experiment 2, SM contributed 0, 4.7, 9.4, 14.1, 18.8, or 23.6% of dietary CP, and each diet was fed for 4 wk. In Experiment 3, SM contributed 0, 15, 30, 45, or 60% of dietary CP, and in Experiment 4, SM contributed 0, 38, or 76% of dietary CP; in these experiments, diets were fed to broiler chicks for 3 wk. There were no differences in egg production, egg weight, egg mass, daily feed intake, or body weight measurements among control hens fed SBM and hens fed SM at 12.6% (Experiment 1) or 4.7 to 18.8% of dietary CP (Experiment 2). Hens consuming these diets were able to satisfy their daily requirements for essential amino acids. Egg quality measurements were similar among hens fed the control SBM diet and those fed SM at 12.6 or 25.3% of dietary CP in Experiment 1, and at 4.7 to 23.6% of dietary CP in Experiment 2. All production variables were significantly depressed in hens that were fed SM at 38 or 50.6% of dietary CP, but Haugh units increased. In Experiment 3, the performance of broiler chicks fed the diet containing SM at 15% of dietary CP was not different from that of the control chicks fed the SBM diet, and both diets contained essential amino acids at required levels. Feed intake, body weight gain, and feed conversion were consistently depressed with increased SM substitution at 30, 45, or 60% of dietary CP. In Experiment 4, feed intake was not different between the control chicks fed the SBM diet and those fed the diet containing SM at 38% of dietary CP. However, body weight gain and feed conversion of chicks fed diets containing SM at 38 or 76% of dietary CP were significantly lower than those of the control chicks fed the SBM diet.

Animal Feed↗

PubMed2002

Physiological changes in the spawning gilthead seabream, Sparus aurata, succeeding the removal of males.

The physiological effects triggered in females by the removal of males from a group of spawning fish were examined in the multiple batch spawner, the gilthead seabream, Sparus aurata. One week after the removal of males, a large portion of the oocytes underwent atresia, and sporadic release of low quality eggs continued at low frequency over a period of seven weeks. The transcript levels of the three native gonadotropin releasing hormone (GnRH) forms, salmon (s)GnRH, seabream (sb)GnRH, and chicken (c)GnRH-II, and the two beta GtH subunits were measured. Brain mRNA levels for all three GnRHs and pituitary beta LH mRNA levels significantly declined in the females as a result of removing the males compared to females that were maintained with males. Pituitary beta FSH mRNA levels showed the opposite trend and were significantly higher in females that were separated from males. Circulating levels of LH, testosterone, estradiol, 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one, and 17 alpha, 20 beta,21-trihydroxy-4-pregnen-3-one all declined in the group of females without males. These results imply the existence of an endocrine response to socio-sexual stimuli during the reproductive process in the gilthead seabream.

Animals↗

PubMed1991

Genetic analysis of androgenetic rainbow trout.

We analyzed a number of genetic characteristics in androgenetic rainbow trout (Oncorhynchus mykiss) and their progeny. The androgenetic progeny of individual androgenetic males appeared genetically identical to each other based on eight enzyme loci. Their viability was no higher than that of androgenetic progeny of outbred males. Homozygous androgenetic female rainbow trout produced very poor quality eggs. When common eggs and sperm from outbred individuals were used to produce androgenetic and gynogenetic progeny, the yield of gynogenetic progeny was higher but some were heterozygous at protein loci, while no androgenetic progeny were heterozygous. Some androgenetic diploid rainbow trout were successfully produced from cryopreserved sperm. The progeny of some androgenetic males crossed to normal females were virtually all males, while the progeny of other males were virtually all females. This suggests that both XX and YY androgenetic individuals may develop as males. Androgenesis is likely to be useful for generating homozygous clones for research and for recovering strains from cryopreserved sperm.

Animals↗

PubMed2004

Messenger RNA stockpile of cyclin B, insulin-like growth factor I, insulin-like growth factor II, insulin-like growth factor receptor Ib, and p53 in the rainbow trout oocyte in relation with developmental competence.

In the present study, correlations between the oocyte messenger RNA (mRNA) stockpile of Cyclin B, insulin-like growth factor I (IGF-I), insulin-like growth factor (IGF-II), insulin-like growth factor receptor Ib (IGFR Ib), and p53 transcripts and the developmental competence of the oocyte were studied. For this purpose, post-ovulatory ageing was used as a tool to generate oocytes of varying developmental competence. Mature female rainbow trout were held at 12 degrees C and periodically checked for ovulation. Oocytes were collected from each female at ovulation and 5, 14, 21 days later. For each collected egg batch, the abundance of several mRNAs in the oocyte was analyzed by real-time PCR and embryo development was monitored after fertilization. Egg quality was estimated not only through embryonic survival but also by studying the occurrence of specific morphological abnormalities. The present study showed that oocyte post-ovulatory ageing was associated with variations of the relative abundance of several studied transcripts within the oocyte. In addition, the abundance of specific mRNAs could be correlated with either the embryonic survival or the occurrence of malformations. Thus, the abundance of IGFR Ib and Cyclin B transcripts in the oocyte was correlated with the occurrence of morphological abnormalities observed at yolk-sac resorption (negatively for IGFR Ib and positively for Cyclin B), while the maternal stockpile of IGF-I, IGF-II, and IGFR Ib mRNAs was positively correlated with embryonic survival.

Aging↗

PubMed1992

Sperm electron microscopy for the evaluation of in vitro fertilization failures.

When performing IVF, the clinician is frequently confronted with the failure of fertilization. When the standard parameters to evaluate the male factor are "within normal limits," the conclusion is often made that the lack of fertilization is most likely due to "poor egg quality." These two cases demonstrate the fallacy of this approach and support a more rigorous evaluation of the male factor. Ultrastructural analysis of sperm is underutilized and, as demonstrated by these two cases, can play an essential role in this evaluation process.

Adult↗

PubMed1994

Weight, carcase composition and reproductive performance of pheasants (Phasianus colchicus) fed restricted or unrestricted diets.

Artificially reared hen pheasants, released in summer, are reported to have little reproductive success in the wild the following spring. One possible explanation is that such birds are unable to obtain an adequate diet after supplementary feeding ceases in February. When captive hen pheasants were fed an unrestricted diet they maintained constant muscle mass and fat reserves throughout the laying period. Hens restricted to pre-lay maintenance levels of nutrition after photostimulation initially laid good quality eggs at the same rate as the fully fed hens. However, by the time that they had laid the equivalent of one clutch of eggs, their energy reserves were approaching exhaustion, suggesting that they would have been incapable of incubating the eggs successfully. When fully fed hens were given wheat in place of a breeder diet, they quickly stopped laying but recovered equally quickly when fed a balanced ration again.

Animals↗

PubMed2006

Effects of binary mixtures of xenoestrogens on gonadal development and reproduction in zebrafish.

Previous studies exposing fish to xenoestrogens have demonstrated vitellogenin (VTG) induction, delayed gametogenesis, altered sex ratio, and decreased reproductive performance, with a majority of those studies focusing on exposure to single chemicals. The objective of this study was to determine the effects of binary mixtures of a weak estrogen receptor agonist, nonylphenol (NP) and a potent estrogen receptor agonist, 17alpha-ethinylestradiol (EE) on sex ratios, gametogenesis, VTG induction, heat shock protein 70 (HSP70) expression and reproductive capacity in zebrafish (Danio rerio). Fish were exposed from 2 to 60 days post-hatch (dph) to nominal concentrations of 10 or 100 microg/l NP (NP10 or NP100, respectively), 1 or 10 ng/l EE (EE1 or EE10, respectively), 1 ng/l EE+10 or 100 microg/l NP (EE1+NP10 or EE1+NP100, respectively), 10 ng/l EE+10 or 100 microg/l NP (EE10+NP10 or EE10+NP100, respectively) or solvent control (0.01% acetone, v/v) in a static-renewal system with replacement every 48 h. At 60 dph, fish from each treatment were euthanized for histological examination of gonads, and whole body VTG and HSP70 levels. Remaining fish were reared in clean water until adulthood (240 dph) for breeding studies. In all EE10 exposure groups (EE10, EE10+NP10 and EE10+NP100), increasing NP concentration acted antagonistically to the action of EE in terms of VTG induction at 60 dph. Similarly, non-additivity was observed with egg production, where EE1+NP100 exposure resulted in significantly more eggs produced per breeding trial than EE1 alone. Histological staging of oogenesis revealed suppressed gametogenesis in an additive fashion in females at 60 dph. There were no differences among treatment groups in whole body HSP70 expression in 60 dph fish or in gonadal HSP70 expression in adult fish. Although there was no statistical evidence of non-additivity, breeding trials in adults revealed significant reductions in egg viability, egg hatchability and/or F1 swim-up success, suggesting that developmental exposures to xenoestrogens may cause irreversible effects on egg quality and progeny even after periods of depuration. In conclusion, these results suggest that environmentally relevant mixtures of NP and EE can produce additive or non-additive effects that depend on the particular response being determined and the respective exposure concentrations of each chemical.

Animals↗