Two sequential experiments examined the effects of abrasive grit on seedlings of grass weeds and young shoots of perennial weeds. First, four types of grit derived from agricultural residues (bone meal, eggshell, hazelnut shell, and sugar beet pulp) were tested under high air pressure in a controlled environment for their abilities to abrade seedlings of an annual grass, Setaria faberi Herrm., and the perennials Festuca arundinacea Schreb., Poa pratensis L., and Elymus repens (L.) Gould. Differing grit particle sizes and amounts, as well as weed seedling stages, were examined for efficacy after abrasion by each type of grit. Second, hazelnut shell grit was used to control P. pratensis and Taraxicum officinale Weber in field trials with aronia (Aronia melanocarpa [Michx.] Elliott), which is a new, shrubby, berry crop in the midwestern USA. Grit weeding was compared to two other treatments: manual weeding (hand-hoeing + hand-pulling) and no weed control (weedy check) over two years. In the grit comparison experiment, control of S. faberi was highest for egg-shell grit (63–100% across grit particle sizes, rates, and seedling stages) and least for sugar beet pulp (17–97%). The former grit had the highest bulk density of all grits, and the latter had the lowest bulk density. For damage to perennial weeds, egg-shell grit performed best (17–80% control) and bone meal least (10–47% control). Elymus repens was controlled better than other perennial grasses, especially by eggshell grit (up to 73% control) and hazelnut shell grit (up to 67% control) with particle sizes of 1–2 mm. In the aronia experiment, both grit abrasion and manual weeding achieved comparable levels of weed suppression (≥87%) and required similar amounts of cumulative seasonal time spent weeding (3–4 min per shrub). Thus, applications of abrasive grit derived from agricultural residues are potential alternatives for non-chemical management of weeds in aronia and, perhaps, in other high-value perennial crops.

The aim of this study was to investigate the effects of different levels of cadmium supplementation (0, 5, 10, 20, 40 and 80 mg/kg) in the diet on performance, egg quality, tibia biomechanical properties and eggshell and bone mineral contents in laying quails. In this 10-week trial, a total of 96 laying quails, aged 21 weeks, were randomly distributed among six experimental groups. Each experimental group contained four replicates of four birds each. The performance parameters were adversely affected quadratically when cadmium was added to the diets in the concentrations of 20 mg/kg and above (P<0.01). The specific gravity and eggshell weight were maximal with the addition of 20 mg/kg cadmium to the diet. The biomechanical properties of the tibia were negatively affected by cadmium supplementation in quails (P<0.05). The eggshell boron content decreased linearly (P<0.001) with cadmium supplementation to the diet. The cadmium content in bone increased when cadmium was added to the diets (P<0.001). The bone boron concentration decreased as dietary cadmium supplementation was increased (P<0.001).

Trematode tyrosinases (TYRs) play a major role in the tanning process during eggshell formation. We investigated the molecular and biochemical features of Paragonimus westermani TYR (PwTYR). The PwTYR cDNA was composed of 1568-bp encompassing a 1422-bp-long open reading frame (474-amino acid polypeptide). A strong phylogenetic relationship with Platyhelminthes and Deuterostomian orthologues was evident. The recombinant PwTYR expressed in prokaryotic cells promptly oxidized diphenol substrates, with a preferential affinity toward ortho-positioned hydroxyl groups. It demonstrated fairly weak activity for monophenol compounds. Diphenol oxidase activity was augmented with an increase of pH from 5·0 to 8·0, while monophenol oxidase activity was highest at an acidic pH and gradually decreased as pH increased. Transcription profile of PwTYR was temporally upregulated along with worm development. PwTYR was specifically localized in vitellocytes and eggs. The results suggested that conversion of tyrosine to L-dihydroxyphenylalanine by PwTYR monophenol oxidase activity might be rate-limiting step during the sclerotization process of P. westermani eggs. The pH-dependent pattern of monophenol and diphenol oxidase activity further proposes that the initial hydroxylation might slowly but steadily progress in acidic secreted vesicles of vitellocytes and the second oxidation process might be rapidly accelerated by neural or weak alkaline pH environments within the ootype.

Calcium is an important nutrient for birds, especially for eggshell production and the mineralization of the skeleton of developing young. In temperate regions insects and seeds that form the bulk of the diet of breeding passerines do not contain sufficient calcium to meet the needs of breeding females and young; these birds obtain their calcium by eating snails, woodlice and millipedes. Little is known about the way tropical frugivorous passerines meet their calcium needs. The calcium contents of fruits of 34 species eaten by birds during the breeding season in mature floodplain forest in south-eastern Peru were determined. The suitability of these fruits as calcium sources for hypothetical 10-g and 25-g birds and for 26 species of frugivore that breed at the study site was evaluated based on bird body weight and on the rictal width of the bill, which influences feeding. Fruits of five species in the study area appear to be suitable sources of calcium for birds ≤25 g, although those of Ficus killipii (Moraceae) are likely optimal. The latter contain a lot of calcium (2.48% dry weight of pulp or c. 4.15 mg per pulp per fruit) and are small enough (mean diam. = 9 mm) for most birds to swallow whole, and trees produce large crops. Snails, woodlice and millipedes are common in the area and also contain sufficient calcium to meet birds’ needs. In addition, birds could likely meet their calcium needs through geophagy at natural mineral licks.

To date, there are limited studies on loggerhead turtle (Caretta caretta) eggshell ultrastructure and its elemental composition. Eggs were collected from turtle nests immediately after oviposition and post hatching. Three eggshell layers were recognized. The outer calcareous layer consists of loose nodular units of different shapes and sizes with loose attachment between the units, resulting in numerous spaces and openings. Each unit consists of CaCO3 crystals in aragonite (99%) and calcite (1%). The middle layer has several strata with numerous openings connecting the calcareous and the inner shell membrane. Crystallites of the middle layer are a mix of amorphous material with aragonite (62%) and calcite (38%). The inner shell membrane has numerous reticular fibers mixed predominantly with halite (NaCl) and small amounts of sylvite. Thermogravimetry analysis of the calcareous showed a low exothermic peak at 425°C, which corresponds to a transitional phase from aragonite to calcite. A high endothermic peak at 814°C corresponds to decomposition of calcite CaCO3 to CaO and CO2. Electron diffraction confirmed the presence of NaCl halite crystal. A significant difference was found in the percentage of elements and crystal configurations in the three layers. This study has value in assessing the emergence success in this endangered species.

The Chemical nature and mode of stabilization of the eggshell/capsule of Moniezia expansa, Avitellinalahorea and Stilesia globipunctata have been investigated using histochemical techniques. In M. expansa Where vitelline glands are present, the eggshell is stabilized by -S-S and -S-H linkages Whereas in A. lahorea and S. globipunctata, the viteline glands are absent and the double membranes, fibrous capsule and paruterine organ contain mainly elastokeratin-type structural protein. The possible role of the vitellaria in the presence or absence of eggshell and its thickness is discussed.

The chicken egg and foods containing egg components are an important part of human nutrition. Furthermore, eggs are a potential source of bioactive molecules and a potential delivery system for therapeutic proteins, explaining the continuing scientific interest in eggs and their components. Using mass spectrometry-based high-throughput proteomic techniques, 119 proteins in egg yolk, 78 proteins in egg white, and 528 proteins in the decalcified eggshell organic matrix have recently been identified. Most of these proteins were identified in their respective egg compartment for the first time. Some of these proteins were already known from chicken tissues or other egg compartments, but many were novel. In the eggshell soluble matrix 39 phosphoproteins containing more than 150 different phosphorylation sites were identified. Twenty-two of the identified phosphoproteins had not been recognized as phosphoproteins previously.

Some studies of birds suggest that the development of the skeleton may invoke a constraint on the rate of postnatal growth. Other studies have shown that the eggshell is the major source of calcium for skeletal development of the embryo. To test whether avian growth rate is indeed associated with different patterns of skeletal development, we compared the degree of skeletal ossification of the long bones of the wing and the leg of one slowly growing precocial species (quail Coturnix japonica) with that of two rapidly growing altricial species (starling Sturnus vulgaris and fieldfare Turdus pilaris). The degree of skeletal ossification of the long bones of the wings and legs of lines of quails that had undergone long-term selection for high- and low-growth rate, respectively, also was compared with a non-selected control line. Next, the fine structure of the inner eggshell surface (mammillary layer) of both pre- and post-incubated eggs, i.e. before and after embryonic development/calcium removal was compared. The data show that the skeleton of the more rapidly growing species and lines was less ossified than that of the more slowly growing ones. This difference appeared to be associated with different rates of calcium removal from the eggshell. Removal was more extensive in eggs of quail than in eggs of starling and fieldfare, i.e. more extensive in shells with a high number of mammillary tips per unit of surface area than in shells with a lower number. It is therefore concluded that growth rate is of fundamental importance for the pattern of skeletal development. Moreover, the mammillary density varies between different bird species, it is suggested, in order to support the different rates of calcium removal by developing embryos.

The eggshell fine structure of a lepidopteran pest of mulberry, Amata passalis F. (Lepidoptera: Amatidae), was investigated using scanning electron microscopy. The micropylar rosette around the micropyle, shell imprints, aeropyles and regional differentiation were studied. The surface of the amatid eggshell had a highly decorated chorion with structural difference at the anterior and posterior poles. The micropylar structure was at the anterior pole of the spherical eggs (488 ± 0.595 mm in diameter), opposite to its side of attachment to the substratum. The micropylar rosette measured 51.20 ± 0.52 mm in diameter and was formed of 15–19 petal-shaped primary cells. The micropylar opening into the micropylar canal was 3.76 ± 0.52 mm in diameter. The entire surface of the chorion had a reticulate pattern of pentagonal and hexagonal cells, each of which was boarded by 3 to 6 aeropyles of similar size (0.36 ± 0.008 mm in diameter).

The physical characteristics of the egg play an important role in the processes of embryo development and successful hatching. The most influential egg parameters are: weight, shell thickness and porosity, shape index, described as maximum breadth to length ratio, and the consistency of the contents. The average values of the physical characteristics mostly meet the requirements for the embryo's development. For those eggs, whose parameters do not fall in to the average range, the incubation process is more successful if the shell is thicker than average, the eggs are more pointed rather than round, and the contents firm. The results reported for investigations into incubating eggs, whose weights are not within the average values, are contradictory. Both thick shells and firm interiors, which are accepted as being higher than average, lead to an increase in egg weight, which probably results in the more successful hatching of embryos from heavier eggs.

Avian eggshells are natural composite bioceramics containing organic and inorganic phases. The occurrence and role of particular collagens and proteoglycans in the eggshell and their pattern of secretion by the oviduct is discussed. While type X collagen, the main constituent of the shell membranes, functions to inhibit their mineralisation, mammillan, a mammillary keratan sulphate proteoglycan, is involved in nucleation of the first calcite crystals of the shell and ovoglycan, a unique dermatan sulphate proteoglycan, is involved in the growth of the crystalline palisade. Eggshell biomineralisation is effected by specialised oviduct cell populations in a defined topographically and temporally regulated process.

The eggshell of the hen is a highly ordered, mineralised structure deposited within an acellular milieu – the uterine fluid secreted by the distal oviduct. Spherulitic crystal growth is initiated by deposition of calcium carbonate on aggregates of organic material present on the outer surface of the eggshell membranes. Gel electrophoresis reveals a complex array of proteins in uterine fluid and eggshell extracts. The eggshell matrix proteins can be classified as egg white proteins (lysozyme, ovalbumin, ovotransferrin, clusterin), bone protein (osteopontin), or proteins specific to the uterus and eggshell (ovocleidins-17 and –116; ovocalyxins-32 and –36). Eggshell extracts, uterine fluid and purified fractions are able to modify the morphology of calcite crystals in vitro. In young hens the breaking strength of the eggshell is inversely related to the degree of calcite orientation. Conversely, reduced strength in eggshell from aged hens coincides with a high variability in crystallographic texture. In guinea fowl the exceptional mechanical properties of the eggshell are explained by an increase in the amount of eggshell produced and particular features of the crystallographic texture. These observations suggest that the eggshell matrix influences the process of crystal growth by controlling size, shape and orientation of calcite crystals. This structural control probably contributes in a substantial manner to the mechanical properties of eggshell.

A chronological account of observations on the nature of the shell membrane protein system is presented. The review indicates that although the major protein in the shell membrane is not elastin, it does contain desmosine and isodesmosine – the cross-linking amino acids. The membranes also contain small amounts of collagen. The formation of these proteins can be impaired by the inclusion of lathyrogens in the diet of laying hens. This impairment is caused by a failure to synthesize cross-links of membrane protein and this is very similar to the effect obtained when hens are fed copper-deficient diets. The disruption of the protein system has a considerable effect on the development of eggs, which are abnormal in size, shape and shell texture. The lathyrogens also have a depressing effect on egg production. The problems and prospects of utilizing seeds of certain Lathyrus plants containing lathyrogens are indicated.

The structure and size of the eggs and layers of eggshells of some ticks of veterinary importance in Nigeria were studied. The ticks included Amblyomma variegatum, Boophilus decoloratus, B. geigyii, Hyalomma impressum, H. impeltatum, H. truncatum and H. rufipes. The embryonic development of the eggs from the day of oviposition to hatching was also studied.

The freshly laid egg was found to possess 10 protuberances, and the biggest of them are the anterior and posterior ones. The eggs of A. variegatum were found to be the longest, and those of H. truncatum the shortest. The eggshell of all the species is two-layered on one lateral side and three-layered on the other; the middle layer originating from the anterior and posterior protuberances. Several phases of embryonic development are described. The major difference between the embryonic development of the eggs of A. variegatum and that of the others is that there are always phases during which the egg becomes canoe-shaped and later folds back to the normal egg shape. Eggs of B. decoloratus occasionally developed this way as well as those of some Hyalomma species when incubated at 37°C. The period of accomplishment of each phase of development was shortened by high temperatures. Observations on the occlusion periods of various types of eggs showed that the very small eggs would not hatch into larvae. The relevance of these observations to field tick control is highlighted, while the necessity of following up these studies with electron microscopic views of some aspects of the results is stressed.