Hard-shelled Eggs Research Articles

A developmental staging system and musculoskeletal development sequence of the common musk turtle (Sternotherus odoratus)

The extremely derived body plan of turtles has sparked a great interest in studying their developmental biology. Here, we describe the embryonic development of the Stinkpot, or common musk turtle (Sternotherus odoratus), a small aquatic turtle from the family Kinosternidae. We identify 20 distinct developmental stages, some comparable to stages described by previous studies on other turtles and some in between these, improving the resolution of the generalities of turtle development. We provide a detailed account of both the external morphology and skeletal development, as well as a general look at the early stages of muscular development until the attainment of the adult muscular anatomical pattern. Several potential skeletal and muscular apomorphies of turtles are identified or elaborated. The musk turtle, with its small size and hard-shelled egg, could become an important species for the study of turtle evolution and development, suitable for in ovo experimentation and late stage imaging of well-advanced anatomical features.

The first dinosaur egg was soft.

Calcified eggshells protect developing embryos against environmental stress and contribute to reproductive success1. As modern crocodilians and birds lay hard-shelled eggs, this eggshell type has been inferred for non-avian dinosaurs. Known dinosaur eggshells are characterized by an innermost membrane, an overlying protein matrix containing calcite, and an outermost waxy cuticle2-7. The calcitic eggshell consists of one or more ultrastructural layers that differ markedly among the three major dinosaur clades, as do the configurations of respiratory pores. So far, only hadrosaurid, a few sauropodomorph and tetanuran eggshells have been discovered; the paucity of the fossil record and the lack of intermediate eggshell types challenge efforts to homologize eggshell structures across all dinosaurs8-18. Here we present mineralogical, organochemical and ultrastructural evidence for an originally non-biomineralized, soft-shelled nature of exceptionally preserved ornithischian Protoceratops and basal sauropodomorph Mussaurus eggs. Statistical evaluation of in situ Raman spectra obtained for a representative set of hard- and soft-shelled, fossil and extant diapsid eggshells clusters the originally organic but secondarily phosphatized Protoceratops and the organic Mussaurus eggshells with soft, non-biomineralized eggshells. Histology corroborates the organic composition of these soft-shelled dinosaur eggs, revealing a stratified arrangement resembling turtle soft eggshell. Through an ancestral-state reconstruction of composition and ultrastructure, we compare eggshells from Protoceratops and Mussaurus with those from other diapsids, revealing that the first dinosaur egg was soft-shelled. The calcified, hard-shelled dinosaur egg evolved independently at least three times throughout the Mesozoic era, explaining the bias towards eggshells of derived dinosaurs in the fossil record.

Post-photostimulation energy intake accelerated pubertal development in broiler breeder pullets

The effect of ME intake (MEI) on the reproductive system was evaluated. Ross 308 broiler breeder pullets (n = 140) were assigned to 2 treatments from 22 to 26 wk of age: (1) Low-energy diet fed restricted (2,807 kcal/kg, low MEI) and (2) high-energy diet fed unrestricted (3,109 kcal/kg, high MEI). Daylength was increased from 8 to 14 h at 22 wk of age with a light intensity of 30 lux. Daily palpation was used to detect sexual maturity via the presence of a hard-shelled egg in the shell gland. Expression of gonadotropin releasing hormone-I (GnRH) and gonadotropin inhibitory hormone (GnIH) genes in the hypothalamus and GnRH receptor (GnRH-RI) and GnIH receptor (GnIH-R) genes in the anterior pituitary gland of each pullet was evaluated from 22 to 26 wk of age using quantitative real time-PCR. Blood samples were taken weekly and luteinizing hormone (LH), follicle stimulating-hormone (FSH), and 17-beta-estradiol (E2) determined using commercial ELISA kits. Carcass samples were used for determination of CP and fat content. Data were analyzed using the MIXED procedure in SAS, and differences were reported where P ≤ 0.05. High MEI treatment pullets had 2.3-fold higher GnRH and 1.8-fold higher GnRH-RI mRNA levels than low MEI pullets. MEI affected neither expression of GnIH and GnIH-R nor carcass protein content. For high MEI (489 kcal/D) and low MEI treatments (258 kcal/D), respectively, from 22 to 26 wk of age (P ≤ 0.05), LH concentration was 3.05 and 1.60 ng/mL; FSH concentration was 145 and 89.3 pg/mL; E2 concentration was 429 and 266 pg/mL, and carcass lipid was 13.9 and 10.3%. The onset of lay for pullets in the high MEI treatment advanced such that 100% had laid by 26 wk of age compared with 30% in the low MEI treatment. We concluded that higher MEI advanced the activation of the hypothalamic–pituitary–gonadal axis and also increased body lipid deposition, and moreover, stimulated reproductive hormone levels which overall accelerated puberty in broiler breeder pullets.

Reproductive ecology of the endangered Beal's-eyed turtle, Sacalia bealei.

The Beal’s-eyed turtle (Sacalia bealei) is endemic to southeastern China and endangered due to poaching and habitat loss. Knowledge of S. bealei ecology is lacking and this study provides baseline information of its reproduction in a natural environment. We studied the reproductive ecology of S. bealei using X-ray, spool-and-line tracking, and direct observation. Six nesting females were successfully tracked and their nesting behaviors are documented in detail. Females produced a mean clutch size of 2.2 eggs (range 1–3). The hard-shelled eggs were ellipsoidal with a mean length of 45.50 mm, a mean width of 23.20 mm, and mean weight of 14.8 g. The relative clutch mass was 9.47%, while the relative egg mass was 4.60%. The mean incubation period was 94.7 days with a mean nest temperature of 25.08 °C. Hatchlings had a mean weight of 9.7 g, carapace length of 40.1 mm, carapace width of 33.3 mm, carapace height of 17.4 mm, plastron length of 31.6 mm, and plastron width of 25.4 mm. The results of this study provide important information to inform conservation plans and ex-situ breeding for this endangered species.

Effects of intraguild predators on nest-site selection by prey

Nest-site selection involves tradeoffs between the risk of predation (on females and/or nests) and nest-site quality (microenvironment), and consequently suitable nesting sites are often in limited supply. Interactions with "classical" predators (e.g., those not competing for shared resources) can strongly influence nest-site selection, but whether intraguild predation also influences this behavior is unknown. We tested whether risk of predation from an intraguild predator [the diurnal scincid lizard Eutropis (Mabuya) longicaudata] influences nest-site selection by its prey (the nocturnal gecko Gekko hokouensis) on Orchid Island, Taiwan. These two species putatively compete for shared resources, including invertebrate prey and nesting microhabitat, but the larger E. longicaudata also predates G. hokouensis (but not its hard-shelled eggs). Both species nested within a concrete wall containing a series of drainage holes that have either one ("closed-in") or two openings ("open"). In allopatry, E. longicaudata preferred to nest within holes that were plugged by debris (thereby protecting eggs from water intrusion), whereas G. hokouensis selected holes that were open at both ends (facilitating escape from predators). When we experimentally excluded E. longicaudata from its preferred nesting area, G. hokouensis not only nested in higher abundances, but also modified its nest-site selection, such that communal nesting was more prevalent and both open and closed-in holes were used equally. Egg viability was unaffected by the choice of hole type, but was reduced slightly (by 7%) in the predator exclusion area (presumably due to higher local incubation temperatures). Our field experiment demonstrates that intraguild predators can directly influence the nest density of prey by altering maternal nest-site selection behavior, even when the predator and prey are active at different times of day and the eggs are not at risk of predation.

English

An experiment was conducted to evaluate responses of feed-satiated and feed- restricted breeder hens to daily injection of progesterone (P4). A total of 64 Cobb 500 hens were fed either restricted or ad libitum from 27 to 38 wk of age. Fourteen laying hens from each group were selected to conduct P4 injection assay. Half of birds in each group (n = 7) were injected daily by 2.5 mg P4/kg BW and remaining birds were used as control. The P4 was injected subcutaneously, at the base of the neck daily (at 0900 h) for 21 d. Settable and abnormal eggs were recorded daily. Blood samples were taken just before initiation of injections, 10-d and 20-d after initiation of injection. Plasma samples were analyzed for glucose, cholesterol, triacylglycerol (TAG), P4, estradiol (E2), testosterone, T3 and T4 concentration. Settable egg production declined following P4 injection, whereas total egg production (including soft shell egg) remain at high levels in injected birds during the first week after initiation of P4 injection. Progesterone injection in feed-satiated and feed-restricted birds resulted in ovary regression; the ovary of these birds had no hierarchical follicle. Progesterone injection increased incidence of holding hardshelled eggs in the uterus. Plasma E2 concentrations were affected both by feeding pattern and P4 injection. Progesterone injection depressed plasma E2 concentration in both ad libitum and restricted fed hens. Hens with free access to feed had significantly lower plasma E2 levels compared to restricted fed hens. Our results revealed that whereas injection of P4 induced frequent ovulation early in the injection period in both feed- satiated and feed-restricted breeder hens; however this higher ovulation rate did not result in more settable egg production.

Mesotocin Receptor Binding in Oviduct Uterus of the Hen Before and After Oviposition

[125 I]mesotocin (MT) binding of membrane fractions of the oviduct uterus in laying hens and nonlaying hens was measured by the use of radioligand binding assay to elucidate the presence of MT receptor in the uterine tissue, and whether the binding to the receptor changes before and after oviposition. The uterine tissue of the hen was found to contain a specific [125 I]MT binding component having properties of MT receptor (i.e., binding specificity, saturable binding, high affinity, and limited capacity). The equilibrium dissociation constant (Kd) was 0.46 ± 0.05 nM (x ± SEM; n = 4) in laying hens holding a hard-shelled egg in the uterus (shell gland) and 0.78 ± 0.02 nM (n = 4) in nonlaying hens. The maximum binding capacity (Bmax) was 0.28 ± 0.03 pmol/mg of protein (n = 4) in laying hens and 0.19 ± 0.01 pmol/mg of protein (n = 4) in nonlaying hens. The Kd value of the laying hens varied from 0.37 to 0.91 nM during an oviposition cycle showing a decrease 30 min before oviposition and an increase 4 h after oviposition. The Bmax value also varied from 0.15 to 0.38 pmol/mg of protein showing an increase 3 h before oviposition, a decrease 30 min before oviposition, and an increase 4 h after oviposition. In the nonlaying hen, both values were almost constant during a 24-h day. The changes in the binding affinity and capacity of MT receptor of the uterus may be related to oviposition in the hen.

Observations on the breeding habits, shell development, decollation, and reproductive anatomy of Pontophaedusa funiculum (Mousson 1856) (Gastropoda, Pulmonata, Clausiliidae, Phaedusinae)

The internal and external egg morphology, shell development, decollation process, mating behaviour and reproductive anatomy (genital structure, inner structure of the penis, fine structure of the retractor muscle and the spermatophore) of the clausiliid Pontophaedusa funiculum (Mousson 1856) are described, and illustrated by photographs of the laid eggs, their inner structure, juvenile, young adult and old individuals, as well as a schematic drawing of the mating. P. funiculum is the only known clausiliid species with hard shelled eggs and the only known example of the family Clausiliidae which mates face to face. The taxonomic position within the Phaedusinae subfamily is mentioned.

Bemerkungen zur Biologie sowie Haltung und Vermehrung des Sokotra-Riesengeckos, Haemodracon riebeckii (Peters, 1882)

The Socotra Giant Gecko, Haemodracon riebeckii, is the largest species of lizard on Socotra Island. The nocturnal, arboreal and rupiculous living geckos are omnivorous. Two pairs were kept in terrariums and were fed with various insects (crickets, locusts, cockroaches), sweet fruits and other feeding stuff (such as meat, fish). Temporarily H. riebeckii was kept together with other lizards ( Eublepharis macularius, Trachylepis socotrana), without any signs of aggressive behaviour. Juveniles and adults of both sexes are able to produce a sound. These acoustic signals seem to be related to predators, because never any intraspecific function could be observed. Within seven years of captive breeding two females produced 253 eggs. Usually two white and sticky soft-shelled eggs were laid within one clutch, more rarely a single egg was laid. The two eggs of a clutch were always laid on the same day. H. riebeckii belongs to the geckos that bury their eggs and practice some brood care, but no special parental care. The female is able to proof with her hind legs the deep and shape of a hollow in the substrate to bury the eggs, which were buried in a sticky and soft-shelled condition. They are oval in shape (egg length 16.4–19.8 mm, egg width 12.4–17.8 mm, quotient EL:EW 1.22±0.05) and have in the beginning a weight ranging from 1.7100 to 2.5201 g. As typical for geckos with hard-shelled eggs the egg weight decreases during the incubation period. The loss can be between 5.59 to 30.29%. The development of eggs up to hatching of young depends upon temperature and the germinal stage in the laid egg. The time difference between the hatching of the young within one clutch of two eggs was usually 1 to 5 days. In some cases there were, however, longer differences (up to 61 days), which are probably caused by different developmental stages of the embryos during the time of egg laying. The shortest incubation period recorded during our investigations was 83 days for eggs incubated at constant temperature of 28 to 29.5 °C and the longest 359 days at 26 to 26.5 °C. Constant high incubation temperatures caused a premature hatching of young. In normal hatched young were the yolk sac retracted and the navel closed. In premature hatched young were the yolk not resorbed and the mortality within the first three month comparatively high. The snout-vent length (SVL) of newly hatched young is from 27 to 39 mm and the tail length (TL) from 25 to 38 mm (SVL:TL index 0.90–1.27), the weight is from 0.7688 to 1.5366 g. Young specimens are distinguished from adults by the brown/white striped lower jaw and the white-banded tail. Young which hatched in the terrarium were eaten by the adults. A loss of young can be avoided if they are raised individually.

Alkaline phosphatase reactivity in the vagina and uterovaginal junction sperm-storage tubules of turkeys in egg production: implications for sperm storage

1. Currently there remains contradictory information on the localisation and possible role of alkaline phosphatase (AP) in the chicken and Japanese quail oviducts. 2. Using turkeys with a hard-shelled egg in their uteri, vaginal and uterovaginal junction mucosae were stretched and fixed as whole mounts prior to the histochemical localisation of AP activity. 3. Scattered AP reactive cells were observed in the vaginal and uterovaginal junction surface epithelia and intense AP reactivity of the sperm-storage tubule (SST) epithelium, localised to its apical border. 4. We suggest that such AP reactivity in hens in egg production may reflect cell differentiation and proliferation in the vagina and SST and possibly a mechanism for the transfer of lipid from the SST epithelia to resident sperm.

Effect of chronic progesterone injection on egg production in Japanese quail

Young laying turkey hens ceased laying and developed a polycystic ovarian follicle (PCOF) syndrome 3 wk after injections of progesterone (P4) ceased. It was hypothesized that laying Japanese quail chronically injected with progesterone (P4) would respond with reduced or arrested egg production and altered ovarian morphology similar to that seen in turkeys expressing the PCOF syndrome, and could thus serve as a model to study the PCOF syndrome. To test these hypotheses, 6 trials were conducted with young photosensitive Japanese quail photostimulated to induce sexual maturity with either 24L:0D or 14L:10D at 6 or 8 wk of age, and used after 3 to 5 wk of egg production. The quail were injected once daily at dosages of 0, 0.17, 0.33, 0.5, 1.5, 3.0, or 4.5 mg of P4/kg per d, or twice daily at dosages of 0 and 1.5 mg of P4/kg for 8 to 14 d and were then necropsied 1 d after the last injection or after waiting an additional 8 to 14 d. During the injection period, egg production was not different among P4 dosages <1.5 mg of P4/kg per d, but decreased at dosages of 1.5 mg of P4/kg per d or greater. A decrease in egg production was found with twice daily injections of 1.5 mg of P4/kg. The decrease in egg production rate ceased and egg production resumed 5 to 7 d after the last injections of 3.0 and 4.5 mg of P4/kg per d or twice-daily injections of 1.5 mg of P4/kg. Compared with control hens, a high percentage of hens (from 12 to 75%) held a hard-shelled egg in the uterus during single daily injections at dosages of 3.0 and 4.5 mg of P4/kg per d and twice daily injections of 1.5 mg of P4/kg. Ovary and oviductal weights, and number of hierarchical follicles were not changed after chronic P4 injection, but more atretic follicles were found in hens at the end of 8 to 12 d of P4 injection. In conclusion, a decreasing egg production rate was induced by chronic P4 injection, but the decrease ceased and egg production resumed 5 to 7 d after the last injections in laying Japanese quail. Young quail hens, unlike young turkey hens, did not develop a PCOF-like syndrome after P4 injection.

Foam Produced by Male Coturnix Quail: What Is Its Function?

Males of the Old World quail genus Coturnix are unique among birds in possessing a well-developed proctodeal gland. The gland and associated cloacal musculature are sexually dimorphic, androgen dependent, and produce a foamy substance that is introduced into the female along with semen during copulation, suggesting that the foam plays some role in increasing male reproductive success. I experimentally tested three hypotheses about the function of this foam in Japanese Quail (Coturnix japonica): (1) foam functions in sperm competition, (2) foam reduces the female's receptivity to a second male, and (3) foam increases the probability of fertilization when a hard-shelled egg is present in the uterus (hypothesis 3 was originally proposed by Cheng et al. 1989a). Insemination shortly before oviposition fertilized fewer eggs than inseminations earlier in the day, but only if males had a reduced foam complement, supporting the third hypothesis. The other two hypotheses were not supported. Copulation reduced female receptivity, but this effect was not due to the male's foam.

Arginine vasotocin receptor in the vagina of the oviduct of the hen

The presence of receptor for arginine vasotocin (AVT) in the vagina of the oviduct of the hen was demonstrated by the use of radioligand binding assays on membrane fractions of the tissue. The binding to [125I]AVT was highly competitive with unlabeled AVT. Scatchard analysis revealed that the binding sites are of a single class. The equilibrium dissociation constant (Kd) was 0.48+/-0.05 nM (x+/-SEM; n = 6) in laying hens holding a hard-shelled egg in the uterus (shell gland) and 1.01+/-0.02 nM (n = 6) in nonlaying hens. The maximum binding capacity (Bmax) was 0.41+/-0.04 pmol/mg protein (n = 6) in laying hens and 0.81+/-0.01 pmol/mg protein (n = 6) in nonlaying hens. The Kd value of the laying hens varied from 0.39 to 1.20 nM during an oviposition cycle, showing an increase just prior to oviposition, and the Bmax value also varied from 0.30 to 0.66 pmol/mg protein, showing a gradual increase after 6 h prior to oviposition. In the nonlaying hen, both values were almost constant during a 24-h day. The changes in the binding affinity and capacity of AVT receptor of the vagina may be related to oviposition in the hen.

Osmotic balance in the eggs of the turtle Chelodina rugosa during developmental arrest under water.

The tropical Australian turtle Chelodina rugosa normally lays its hard-shelled eggs in mud, under shallow freshwater, during the monsoon season. The eggs undergo developmental arrest until the water recedes and oxygen is able to diffuse into the embryo. This period of arrest can exceed 12 wk without embryonic mortality. To understand how the eggs avoid osmotic absorption of water leading to shell rupture and embryonic death, this study investigates the solute concentrations and volumes of the albumen and yolk compartments during submergence in distilled water. The albumen loses considerable sodium through the shell, particularly during the first week, and its osmotic concentration drops from 234 mmol/kg at laying to about 23 mmol/kg. Meanwhile, water from the albumen slowly moves through the vitelline membrane into the yolk compartment, which enlarges at a constant rate until it approaches the inside of the shell at about 22 wk. Osmotic uptake dilutes yolk solutes, decreasing the osmotic concentration from 281 mmol/kg at laying to 132 mmol/kg at 157 d. Loss of embryonic viability is associated with contact of the vitelline membrane with the inside of the shell. The principal adaptation of this species for protracted developmental arrest under water is a vitelline membrane of such low permeability to water that the expansion of the yolk compartment occurs about 10 times more slowly than in other chelonians.

Measured and Predicted Egg Volume of Pseudemys texana with Comments on Turtle Egg Shape

The relationship between egg size (length, width, mass), female body size, and clutch size has been investigated in a variety of reptiles (Ferguson et al., 1982; Congdon and Gibbons, 1985; Bjorndal and Carr, 1989; Ford and Seigel, 1989; Deeming and Ferguson, 1990; Iverson and Ewert, 1991). In spite of this attention, little has been written regarding egg shape and volume and those factors that egg shape and volume might reflect. Turtle eggs are described as being spheres, ellipsoids, or bicones. As a general rule, chelonids, chelydrids, trionychids, and larger tortoises produce round, hard-shelled eggs. Most members of other groups produce some form of an elongated, symmetrical egg. (For reviews of turtle egg biology see Ewert, 1979 and Moll, 1979.) Phylogenetic considerations were given to egg shape and hardness by Iverson and Ewert (1991). Elongated eggs provide greater volume without increasing the short-side diameter beyond presumed morphological constraints; e.g., diameter of pelvic canal (Congdon and Gibbons, 1987) or carapace-plastron exit port (Rose and Judd, 1991). Increased egg volume could add significantly to energy and nutrient storage capacity, resulting in a hatchling with greater fitness (Sinervo, 1990). Large egg or hatchling size would be balanced against negative pressures of reduced reproductive output (Smith and Fretwell, 1974) or restrictions imposed on reproductive product exiting the female (Congdon and Gibbons, 1985). It is surprising, then, that so few workers have addressed the issue of egg volume in turtles (Iverson and Ewert, 1991), especially as it might relate to egg shape. Pseudemys texana, a recently elevated taxon (Ward, 1984), is an emydine turtle that inhabits Texas streams, rivers, and ponds. Information regarding its general biology and reproductive characteristics are scarce despite the fact that this turtle might be the most conspicuous vertebrate in many aquatic systems in Texas. Several fish hatchery ponds and the adjacent San Marcos River on the Southwest Texas State University campus, Hays County, are excellent habitats for this species and females frequently are observed constructing nests during spring and early summer months. Eggs available to us provided an opportunity to evaluate egg shape-volume relationships of a common, relatively unknown, aquatic turtle. We used 14 eggs, selected from two clutches that were laid on 21 May 1994. Each egg was washed, dried and frozen. Upon thawing, we measured length (long axis) and width (short axis) to the nearest mm using Mitutoyo digimatic calipers. Mass was determined to the nearest 0.01 gram with an electronic Mettler BasBal scale. All linear measurements were recorded in mil-

Predietors of fertilization in the Japanese quail, Coturnix japonica

To better understand the relationship between mating behaviour, insemination and fertilization in birds, 233 mating trials were conducted with Japanese quail to determine the percentage of eggs laid that were fertile following a single confirmed or putative insemination. Fertilization success of single inseminations was highly variable. Insemination did not guarantee fertilization of any eggs; following one-third of the trials, no fertile eggs were laid. Only 3% of inseminations fertilized as many as eight eggs, making it unlikely that a single insemination could fertilize an entire clutch in this species. Forced copulations had the same fertilization success as other copulations, and thus could be a successful male reproductive strategy in this species. Voiding of foamy material containing sperm by the female shortly after copulation did not reduce fertilization success in any consistently significant manner. Fertilization success was unaffected by the presence of a hard-shelled egg in the uterus at the time of insemination. Trials in which the female ran from the male's initial approach resulted in fewer fertile eggs following insemination; that is, this behaviour predicted low fertilization success. Fertilization success was highly correlated and thus predictable if the same female was mated again with the same male, but was uncorrelated if she was mated with a different male or if the same male was mated with different females. These two predictors of fertilization success (female behaviour and male-female combination) are interpreted as evidence for female control of paternity via sperm selection (post-copulatory female choice).

Isolation of Salmonella from Ovaries and Oviducts from Whole Carcasses of Spent Hens

Spent hens containing hard-shelled eggs were obtained to study the influence of sample collection and sample preparation methodology on the detection of Salmonella in ovaries. Four hundred eighteen birds from 19 flocks were collected, and the carcasses were opened aseptically within 8-12 hours of collection. A sample set containing hard-shelled egg, ovary, and oviduct section were collected from each carcass, and surface contaminants were removed from ovaries with polyoxyethylene ether. Three of 19 flocks (15.8%) and six of 407 ovary samples were positive for Salmonella; two oviduct samples were positive (0.5%). No eggs were Salmonella-positive. Single and multiple serotypes were detected in ovaries. Results indicated that Salmonella recovery rates can be significantly affected by speed in processing samples after collection, by cleanliness of the tissue-collection environment (laboratory vs. slaughter plant), and by removal of surface contaminants.

CONTRIBUTIONS TO THE KNOWLEDGE OF AFRICAN GECKOS (REPTILIA: SAURIA: GEKKONIDAE) 1. RECORDS OF A FIVE YEAR PERIOD OF MAINTENANCE AND REPRODUCTION OFPACHYDACTYLUS VANSONIFITZSIMONS 1933

ABSTRACT The reproductive potential in captivity of the African gecko Pachydactylus vansoni was investigated. Thes species is semi-terrestrial with a few rows of slightly widened lamellae under the toe tips. In captivity it is predominantly crepuscular. While walking on a horizontal surface the toe tips are curled up with only the palms touching. Males display aggressive behaviour towards one another. Three types of disease are described and vitamin and calcium deficiency symptoms during the reproductive phase received special attention. This medium-sized, robust gecko may live for over eight years. Food intake is described in relation to food composition. Mating behaviour, in comparison to that of diurnal species, appears relatively poorly developed. Progressive mass loss occurs during the incubation period, and this may be related to the type of egg shell (soft-shelled eublepharine and diplodactyline and hard-shelled gekkonine and spaerodactyline eggs) and may have phylogenetic significance. The juvenil...

Response of Layer Breeders to Dietary Acetylsalicylic Acid. 2. Effects on Circulating Concentrations of Prostaglandin F2α

White Leghorn breeder hens were fed 0, .05, or .40% acetylsalicylic acid (ASA) for either 1 wk or 1 mo. Blood samples were collected 4 h postentrance of an egg into the uterus (baseline) and at oviposition of a hard-shelled (HS) egg. Plasma samples were analyzed for prostaglandin (PG) F2α by radioimmunoassay. Peripheral PGF2α concentrations peaked upon oviposition of a HS egg in both ASA-fed hens as well as the controls (0% ASA). The levels of dietary ASA and the duration of time the ASA was administered did not affect baseline or peak PGF2α concentrations. It was concluded that either the timing or route of administration of ASA resulted in the failure of ASA to effectively reduce peak peripheral PGF2α concentrations.

Response of Layer Breeders to Dietary Acetylsalicylic Acid.: 1. Effects on Hen Performance and Eggshell Quality

Acetylsalicylic acid (ASA, aspirin) is an inhibitor of prostaglandin (PG) synthesis and an antipyretic drug. Because PG may be involved in the premature oviposition of some soft-shelled (SS) and shell-less (SL) eggs, the objective of the present study was to determine whether dietary ASA, as an inhibitor of PG synthesis, would convert SS and SL eggs to hard-shelled (HS) eggs, thus increasing total salable egg output and improving feed efficiency.White Leghorn layer breeders were fed 0, .025, .05, .10, .20, and .40% ASA for the first 13 mo of egg production. When averaged over 13 mo, hens fed .40% dietary ASA laid fewer HS eggs (P < .002), had poorer feed efficiency (P < .03), had increased mortality (P < .0001), and laid smaller eggs (P < .01). All levels of dietary ASA resulted in significant decreases in specific gravity (P < .0001), shell thickness (P < .0001), shell weight (P < .0001), and percentage shell (P < .0001).During Month 1 of production, mortality was greatly increased for hens fed .20 and .40% ASA as compared with hens receiving 0, .025, .05, or .10% ASA (diet by month interaction, P < .0001). However, during the other 12 mo of production, only hens receiving .40% dietary ASA experienced a slight increase in mortality. Also during Month 1 of production, hens fed .20% ASA laid fewer SL eggs, whereas hens fed .05 and .40% ASA laid more SL eggs than birds receiving the control diet (diet by month interaction, P < .0007).In conclusion, chronic feeding of ASA did not improve egg production or feed efficiency. In addition, long-term feeding of ASA to layer breeders proved to be detrimental with respect to early hen livability and eggshell quality.