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PubMed1986

Effect of experimentally induced calcium deficiency on development, metabolism and liver morphogenesis of the chick embryo.

To study the effects of systemic calcium deficiency on embryonic development, chick embryos maintained in long-term shell-less cultures were compared to control embryos incubated in ovo with respect to various parameters of metabolism and growth. After incubation day 14, retarded growth and development were apparent in shell-less embryos which exhibited severe hypocalcaemia and hyperphosphataemia. A development-specific necrosis of the liver tissues was observed in both shell-less and control embryos, but the frequency and extent of tissue abnormality were significantly greater in the former. Serum levels of lactate dehydrogenase and alkaline phosphatase were considerably elevated in shell-less embryos. Electrophoretic analysis revealed that the relative levels of two major serum proteins were also altered in shell-less embryos.

Alkaline Phosphatase↗
PubMed1999

Effect of induced molting in laying hens on production and immune parameters.

A total of 600 commercial strain (DeKalb) Single Comb White Leghorn hens, 80 wk of age, were used in this study to determine the effects of different induced molting programs on production and immune parameters. The hens were randomly divided into four treatment groups (three experimental and one control) of 150 hens each. The hens in the first treatment group were fed a layer ration containing 20,000 ppm of zinc for 5 d, and received a reduced photoperiod of 8 h/d for 5 d (Zn group). In the second group, feed was withdrawn for 10 d, the photoperiod was reduced to 8 h/d and oyster shell and water were provided for ad libitum consumption. At Day 11, hens consumed corn and oyster shell ad libitum until Day 30 and at Day 31, hens were returned to a full feed layer ration and received 16 h of light/d [California treatment (CAL group)]. In the third treatment, light was reduced to 8 h/d, and oyster shell was provided for ad libitum consumption until Day 60. Feed and water were removed for the first 2 d and on Days 4, 6, and 8. On Days 3, 5, 7, and 9, hens were fed 45 g of feed per hen. On Day 10 until Day 60, hens were fed 90 g/hen and at Day 61, hens were returned to the layer ration ad libitum and received 16 h of light/d [on-again, off-again program (ON-OFF group)]. The last group served as controls (CONT). Body weight, egg production, egg size, internal egg quality, shell weight, and mortality were determined. Total circulating leukocytes, differential leukocyte counts, and antibody production were also measured. The results demonstrated that induced molting significantly increased egg production from 64% to 77 to 83%, Haugh units from 80.4 to 85.9 to 87.3, and shell weight from 5.3 g to 6.3 to 6.4 g when compared to CONT. The body weight of the molted hens decreased significantly to 84.8, 74.5, and 88% of the initial body weight for Zn, CAL, and ON-OFF groups, respectively. The total circulating leukocytes was significantly lower in molted hens than in CONT hens. Differential leukocyte counts were affected by all induced molting programs and the heterophil to lymphocyte ratio was significantly increased, reaching 0.61, whereas that of CONT was only 0.20. Antibody production was largely unaffected by any of the induced molting programs.

Animals↗
PubMed2001

Plasma progesterone levels and luteal activity during gestation and prolonged oviductal egg retention in a tropical lizard, Calotes versicolor.

Plasma progesterone (P) levels and luteal and adrenal activities were studied during normal gestation and unusual prolonged period of oviductal egg retention in a polyautochronic, multiclutched lizard, Calotes versicolor. The normal gestation period (approximately 15 days) was categorized into four stages: stage I--a few hours following ovulation, stage II--eggs with shell and embryo at primitive streak, stage III--embryonic stages 16-20, and stage IV--prior to ovipostion (stages 26-27). The gravid lizards maintained in captivity retained eggs in their oviducts for 45 days. Plasma P levels were low in stage I, increased significantly during stage II, declined in stage III, and reached their lowest in stage IV of gestation. 3Beta-hydroxysteroid dehydrogenase (3beta-HSDH) activity was greater in lutein cells at stage II and was present in traces in stage IV gestation. Interestingly, plasma P titers that were high in lizards with eggs retained longer though the corpora lutea (CL) showed a trace 3beta-HSDH activity. However, 3beta-HSDH activity was greater in the adrenocortical cells in these lizards than that in lizards during a normal gestation period. The present study on C. versicolor shows that the CL remains active and secretes P only during the early part of the gestation. The drop in P level during the later part of gestation might facilitate growth of a second set of vitellogenic follicles. During unfavorable conditions when the lizards are forced to retain eggs in the oviduct, the adrenal glands seem to secrete progesterone to help in egg retention and in inhibition of oviposition.

3-Hydroxysteroid Dehydrogenases↗
PubMed2004

Immunohistochemical localization of the progesterone and oestrogen receptors in the shell gland of sexually immature ostriches (Struthio camelus) with active or inactive ovaries.

The immunohistochemical localization of progesterone and oestrogen receptors was studied in the shell gland of the immature ostrich (Struthio camelus) during periods of ovarian activity and inactivity. In birds with active ovaries moderate to strong immunostaining for the progesterone receptor was observed in the surface epithelium and tubular glands. In contrast faint progesterone receptor immunostaining was observed in the surface epithelium of the shell gland in ostriches with inactive ovaries. In addition, bud-like invaginations of the surface epithelium, which signaled tubular gland development, were negative for the progesterone receptor. Oestrogen receptor immunostaining, which was seen only in birds with active ovaries, was weak and restricted to nuclei of the surface epithelium. These results suggest that steroid hormones secreted by the active ovary regulate the differentiation of the shell gland. Furthermore, the influence of these hormones on the shell gland appears to be mediated predominantly through the activation of the progesterone receptor.

Animals↗
PubMed1986

Effect of some metal compounds on the Ca2+ binding and Ca2+-Mg2+-ATPase activity of eggshell gland mucosa homogenate from the domestic fowl.

Some metal ions, e.g. Hg2+, Cd2+ and Al3+, can have the effects as ecotoxicological agents, of causing eggshell thinning and breakage in birds. In a homogenate of the Ca2+-secreting part of the eggshell gland mucosa, a study was made of the influence of Hg2+, Cd2+, Cu2+, Pb2+, methyl-Hg+, Zn2+, V3+, Al3+ and Ni2+ in different concentrations on the rate of ATP-dependent 10(-4) M Ca2+ binding. All compounds had an inhibitory action. The most potent metal (Hg2+) produced 50% inhibition (IC50) at 1.1 X 10(-6) M, whereas this value for the least potent compound (Ni2+) was 9 X 10(-4) M. The specific Ca2+-Mg2+-ATPase activity was also inhibited by the tested metal ions. In all cases except methyl-Hg+ the IC50 for this activity was lower than that for Ca2+ binding. The most potent ion in this respect was Cd2+, with an IC50 of 8 X 10(-8) M, and the least potent was methyl-Hg+, with an IC50 of 1.4 X 10(-3) M. Pb2+ and Cd2+ in a concentration range of 10(-5)-10(-4) stimulated the Mg2+-ATPase activity, however, to almost the same extent as 10(-4) M Ca2+. A possible explanation for this effect is that these ions may have an affinity for sites of Ca2+ binding of the polypeptide calmodulin and thereby influence the Ca2+ metabolism of the shell gland mucosa.

Animals↗
PubMed1980

Influence of dietary protein during the pre-breeder period on subsequent reproductive performance of large white turkeys. 1. Growth, feed consumption, and female-sex-limited reproductive traits.

Large White female turkeys of a commercial variety were used to determine the effects of low dietary protein during the pre-breeder period (12 to 32 weeks of age) on subsequent reproductive performance. Diets containing 10, 12, 14, and 17% protein were fed from 12 weeks or 20 weeks to 32 weeks of age. At 32 weeks of age, all females were fed a 17% protein breeder diet. Reproductive performance was measured for a 24-week production period. Pre-breeder feed consumption and body weight gain from 12 to 32 weeks of age increased with increased dietary protein until diets contained 14% protein. Similar results were obtained when females were fed varying protein levels from 20 to 32 weeks of age. Egg production also showed an increase with increased pre-breeder dietary protein level until diets contained 14% protein. Ten fewer eggs per hen were obtained from females previously fed the 10% protein diet than those fed the 14% (20 to 32 weeks) and 17% protein diets. Pre-breeder dietary protein level did not affect age at sexual maturity, egg weight, specific gravity or shell thickness of eggs, mortality or growth, and feed consumption of progeny. Based upon the results of this study, female breeder turkeys require at least 14% protein to 20 weeks of age and 14% from 20 to 32 weeks of age for optimum egg production.

Animals↗
PubMed1990

Production and egg-quality responses of White Leghorn layers to anticoccidial agents.

Two studies were conducted to determine the effects of anticoccidial agents on the production and reproduction of White Leghorns. In Experiment 1, nicarbazin (NCZ) was fed at 0, 20, 50, and 100 ppm. Hen-day egg production, egg weight, the egg-yolk DNC (4-4'-dinitrocarbanilide) level, and egg-yolk mottling were affected by the treatments. When response was evidenced, the relationship between those variables and the level of NCZ was basically linear. Decreased egg production occurred from Days 5 and 6 of the treatment through Days 1 and 2 of withdrawal. On Days 9 and 10 of treatment, the control hens peaked at 92% hen-day production, while hens fed 20, 50, and 100 ppm of NCZ peaked late--at 90, 82, and 80%, respectively. Compared to the controls, egg weight was reduced linearly as the level of dietary NCZ increased. The egg-yolk DNC level increased from Days 3 and 4 of treatment through Days 9 and 10 of withdrawal. Egg yolk mottling generally increased along with the level and duration of feeding NCZ. If the NCZ was mistakenly fed to White Leghorn layers, ill effects would be alleviated within 10 days after drug withdrawal. In Experiment 2, halofuginone (3 ppm), maduramicin (5 ppm), monensin (100 ppm), narasin (70 ppm), nicarbazin (125 ppm), robenidine (33 ppm), and salinomycin (60 ppm) were fed to White Leghorn hens at the levels specified in parentheses. Nicarbazin reduced egg production, depressed egg weight, reduced shell thickness, and caused egg-yolk mottling; but internal egg quality, as measured by Haugh Units, was unaffected. Halofuginone, maduramicin, monensin, narasin, robenidine, and salinomycin did not have a meaningful effect on the variables measured when fed to White Leghorn layers.

Animal Feed↗
PubMed1990

Evaluation of the dietary interaction of calcium and phosphorus in the high producing laying hen.

1. In a 6 x 7 factorial experiment using 2688 22-week-old laying hens of the Lohmann-SL strain kept in cages (4 birds/cage), diets containing six calcium (20, 25, 30, 35, 40, 45 g calcium/kg) and seven phosphorus concentrations (3.2, 4.2, 5.2, 6.2, 7.2, 8.2, 16.2 g total phosphorus/kg (Pt)) were combined orthogonally. The resulting 42 treatments were replicated 8 times so that a replicate consisted of a double cage of 2 x 4 hens. The experiment lasted 40 weeks (10 x 28 days). 2. The experimental diets, based on maize and soyabean meals contained 11.5 MJ metabolisable energy/kg and 175 g/kg protein. Different dietary calcium and phosphorus contents were obtained by substituting oat hulls with limestone and dicalcium phosphate. 3. Mortality, egg production, egg weight, egg mass, food intake and food conversion efficiency were determined as well as the breaking strength, thickness of shells and the percentage of eggs with defective shells. 4. All responses measured were significantly influenced by the variance sources (calcium, phosphorus, interaction). Most of the production traits responded asymptotically to increasing dietary phosphorus concentration, the greatest increases or decreases generally being seen between 3.2 and 5.2 g Pt/kg. Further but weaker increases were seen between 5.2 and 8.2 or 16.2 g Pt/kg. 5. Increases in dietary calcium content always resulted in curvilinear responses. In all cases optimal effects were obtained with diets containing 25 g calcium/kg and the worst values at 45 g calcium/kg. The interaction between calcium and phosphorus was recognised by strong performance depressions and a high mortality at combinations of the lowest phosphorus concentration (3.2 g/kg) with high calcium contents (35 to 45 g/kg). These were largely offset by increasing dietary phosphorus. Thus, between 7.2 and 16.2 g Pt/kg and 25 and 45 g Ca/kg a plateau was formed where only small differences in egg production were observed. 6. From the three egg shell characteristics measured, breaking strength and shell thickness responded differently to the percentage of eggs with defective shells. While breaking strength and shell thickness were respectively negatively and positively influenced by increasing dietary phosphorus and calcium contents, both elements affected the proportion of eggs with defective shells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2002

Reproductive impairment in Japanese quail (Coturnix japonica) after in ovo exposure to o,p'-DDT.

We have previously described various effects in adult Japanese quail consequent on treatment with oestrogenic compounds in ovo. In the present study, the environmental contaminant o,p'-DDT [1-(2-chlorophenyl)-1-(4-chlorophenyl)-2,2,2-trichloroethane] was administered to quail eggs to further evaluate test endpoints for oestrogenic effects related to reproduction in the Japanese quail. Exposure to 2 mg o,p'-DDT/egg (150 micro g/g egg) resulted in impaired sexual behaviour, reduced cloacal gland area and lowered plasma testosterone concentration in males. Females displayed oviductal abnormalities, including retained right oviduct, decreased length of left oviduct, alterations in shell gland morphology and disrupted distribution of carbonic anhydrase in the shell gland. Egg laying was severely impaired. Consequently, a number of endpoints in adult quail may be useful for demonstrating an oestrogen-like mode of action by environmental contaminants during embryonic development.

Animals↗
PubMed1998

Studies on the effect of feeding cupric sulfate pentahydrate to laying hens on egg cholesterol content.

Two experiments were conducted to test the hypothesis that pharmacological levels of dietary Cu could reduce egg cholesterol content. White Leghorn hens 30 to 39 wk of age were fed corn and soybean meal diets with 0, 125, or 250 mg supplemental Cu/kg diet from cupric sulfate pentahydrate (basal diet = 6.74 mg Cu/kg). Body weight, feed consumption, egg weights, egg specific gravity, and Haugh Units were not consistently affected during the 8-wk feeding trials. Egg production was significantly increased (P < 0.05) in the second 4-wk period by supplemental Cu in both experiments. Egg yolk cholesterol concentrations were decreased by feeding 125 mg Cu/kg diet (11.7 vs 8.6 mg/g, average of two experiments); feeding 250 mg Cu/kg resulted in further declines in egg cholesterol but the differences were not significant (7.9 mg/g). Changes in plasma cholesterol concentrations were similar to those of yolk cholesterol. Small but significant amounts of Cu accumulated in the yolks and shells of eggs from Cu-supplemented hens; however, most of the Cu fed was found in the excreta.

Animal Feed↗
PubMed2001

Maternal plasma and egg yolk testosterone concentrations during embryonic development in green anoles (Anolis carolinensis).

Sex steroids of presumably maternal origin have been found in avian, crocodilian, and chelonian egg yolks, and they can affect offspring morphology and behavior. The present study reports testosterone (T) levels to which embryos are potentially exposed in the green anole (Anolis carolinensis), a lizard with genotypic sex determination. We documented plasma and yolk T concentrations in adult females, in their developing follicles and eggs, and in freshly oviposited and incubating eggs. Plasma T was higher in reproductively active than in reproductively inactive females. Within reproductively active females, those with a single, large yolking follicle had higher plasma T than those that had one or more shelling, oviductal eggs. Individual females contributed different amounts of T to their yolks, but within females, more mature follicles or eggs consistently had higher yolk T concentrations than did less mature follicles or eggs. Similar to previous research, yolk T concentrations at oviposition were higher in male eggs than in female eggs. However, T levels during incubation did not differ by embryo sex, but rather increased in both male and female eggs. These results suggest that T plays a role in the reproductive physiology of females and potentially in the phenotypic development of their offspring. Furthermore, whereas the yolk T increase observed during follicular maturation is clearly a maternal influence, it remains unclear whether that observed during egg development (i.e., postfertilization) results from a lack of T uptake by the embryo as yolk is absorbed, from embryonic production of T that diffuses into the yolk, or from some combination of these processes. Because lizard embryos are comparatively well developed at oviposition, the assumption that yolk steroids are strictly of maternal origin may require modification, and the possibility that embryos are modulating their own steroid environment needs to be explored.

Animals↗
PubMed1987

Survival of shelled acanthors of Moniliformis moniliformis (Acanthocephala) under laboratory conditions.

Shelled acanthors (= eggs) of two isolates of Moniliformis moniliformis (Acanthocephala) were tested for their capacity to respond to a hatching stimulus in vitro and for their retention of infectivity to a natural intermediate host (Periplaneta americana). The shelled acanthors were stored for more than 120 weeks (Australian isolate) and for 104 weeks (Texan isolate) together with rat faeces in an incubator maintained at 22.2 +/- 0.1 degrees C. In both cases, infectivity to P. americana was shown to have been retained. In vitro tests of the hatching response were carried out on many occasions during this period of faecal storage. Shelled acanthors continued to respond and no differences were detected either between isolates or within an isolate through time.

Acanthocephala↗
PubMed2004

Changes in light intensity during the rearing period can influence egg production in domestic fowl.

1. A total of 240 Shaver White and 240 ISA Brown pullets that had been reared in multi-bird cages on a 10-h photoperiod, and maintained at a light intensity of 3 or 25 lux, or changed from 3 to 25 lux or from 25 to 3 lux at 9 or 16 weeks of age, were moved into individual-bird cages at 20 weeks and transferred to 15-h photoperiods at 25 lux. 2. In both breeds, birds transferred from 3 to 25 lux at 16 or 20 weeks laid significantly more eggs than birds maintained on the brighter intensity from one day or increased to it at 9 weeks. 3. Mean egg weight, shell deformation, albumen height, feed intake and body weight gain in lay were not significantly affected by the light intensity treatments during the rearing period. There was, however, a small, but significant, negative correlation of egg numbers with mean egg weight, although this only partially explained the difference in egg numbers. The differences in egg production were unrelated to rate of sexual maturation.

Animals↗
PubMed1986

Influence of probucol ((4,4'-isopropylidine dithio)-bis(2,6-di-t-butyl-phenol)) on egg yolk cholesterol content and performance of laying hens.

Addition of the hypocholesteremic agent Probucol ((4,4'-isopropylidine dithio)-bis(2,6-di-t-butyl-phenol)) to the diet of laying hens at up to 1% significantly reduced egg yolk cholesterol content (mg/g yolk) without impairment of rate of egg production, egg weight, shell strength, albumen quality, or other production related parameters. Dietary concentration of .1% Probucol significantly reduced yolk cholesterol within 2 weeks after feeding. Higher concentrations did not further reduce yolk cholesterol. Probucol at .025% reduced egg yolk cholesterol within 4 weeks after feeding, but after 8 weeks of feeding, eggs from hens fed .025% Probucol did not differ significantly in yolk cholesterol from those fed the basal unsupplemented diet. This suggests possible adaptation in cholesterol synthesis by the laying hen.

Animals↗
PubMed1987

Air space: the embryonic medium.

Normalization of gas exchange and growth of chicken embryos incubated under abnormal conditions with regard to eggshell conductance and barometric pressure is directed to restoring the normal water loss from the eggs and the normal pattern of air space gas tensions during development. The latter is achieved by maintaining an O2 tension of 149 torr in the gas mixture supplied to the incubator and by reducing the incubator ventilation rate to compensate for increased, standard or effective, eggshell conductances. Thus, for maintenance of normal air space gas tensions, a decrease of the diffusive resistance of an egg requires a similar increase of the convective resistance so that the total resistance against gas transport remains normal. The latter must be set at a value given by (149-PA)/M, where PA is the normal air space O2 tension, torr, and M is the normal O2 uptake, ml(STPD)/day. This value is independent of embryonic age, because PA is directly proportional to M during development. Thus the convective resistance required for maintenance of normal PA and M values is given by the difference between (149-PA)/M and the diffusive resistance. Such PA and M values can be maintained in eggs with the minimum diffusive conductance, M/(149-PA), thus requiring an infinite convective conductance, to infinite diffusive conductance, which requires a minimum convective conductance, M/(149-PA). This minimum is predicted for all shell-less eggs, viz., for the continuous replacement of diffusive by convective gas transport.

Altitude↗
PubMed1991

Serum corticosterone concentrations in developing shell-less and shelled turkey embryos.

1. Turkey embryos grown in shell-less culture (EO) display normal development to day 14 of incubation, after which growth rate is reduced and mortality increases, compared to age-matched in ovo (IO) embryos (Richards 1982. Long term shell-less culture of turkey embryos. Poultry Sci. 61, 2089-2096). 2. In this study serum corticosterone concentrations were monitored in normally incubated embryos and embryos maintained in shell-less culture. 3. On days 14 and 16 of incubation, corticosterone levels were greater (P less than 0.05) in EO than IO embryos, whereas during the later stages corticosterone increased dramatically in the shelled embryos, and remained relatively constant in the EO embryos. 4. EO embryos do not exhibit a pattern of adrenal hormonal secretion that would indicated a stressful condition. 5. The absence of a normal increase in corticosterone in shell-less embryos may contribute to the abnormal embryological development in the later stages of incubation.

Animals↗