Changes in eggshell mechanical properties, crystallographic texture and in matrix proteins induced by moult in hens

The effect of moult on eggshell mechanical properties, on composition and concentrations of organic matrix components and on eggshell microstructure was investigated. The observed changes were studied to understand the role of organic matrix and eggshell microstructure in eggshell strength. Moult was induced by zinc oxide (20 g zinc/kg diet) in 53 ISA Brown laying hens at 78 weeks of age. No difference was observed for egg or eggshell weights after moult. In contrast, moult improved the shell breaking strength (28.09 vs 33.71 N). After moult, there was a decrease in the average size of calcite crystals composing the eggshell and in their heterogeneity, whereas crystal orientation remained basically the same. After moulting, the total protein concentration in eggshell increased slightly. The comparisons of SDS-PAGE profiles of the organic matrix constituents extracted before and after moulting showed changes in staining intensity of certain bands. After moult, bands associated with main proteins specific to eggshell formation (OC-116 and OC-17) showed higher staining intensity, while the intensity of the egg white proteins (ovotransferrin, ovalbumin and lysozyme) decreased. ELISA confirmed the decrease in ovotransferrin after moult. Its concentration was inversely correlated with breaking strength before moult. These observations suggest that changes in eggshell crystal size could be due to changes in organic matrix composition. These changes may provide a mechanism for the improvement in shell solidity after moulting.     

Lithospheric Contributions to Arc Magmatism: Isotope Variations Along Strike in Volcanoes of Honshu, Japan

Major chemical exchange between the crust and mantle occurs in subduction zone environments, profoundly affecting the chemical evolution of Earth. The relative contributions of the subducting slab, mantle wedge, and arc lithosphere to the generation of island arc magmas, and ultimately new continental crust, are controversial. Isotopic data for lavas from a transect of volcanoes in a single arc segment of northern Honshu, Japan, have distinct variations coincident with changes in crustal lithology. These data imply that the relatively thin crustal lithosphere is an active geochemical filter for all traversing magmas and is responsible for significant modification of primary mantle melts.     

Size Dependence of Structural Metastability in Semiconductor Nanocrystals

The kinetics of a first-order, solid-solid phase transition were investigated in the prototypical nanocrystal system CdSe as a function of crystallite size. In contrast to extended solids, nanocrystals convert from one structure to another by single nucleation events, and the transformations obey simple unimolecular kinetics. Barrier heights were observed to increase with increasing nanocrystal size, although they also depend on the nature of the nanocrystal surface. These results are analogous to magnetic phase transitions in nanocrystals and suggest general rules that may be of use in the discovery of new metastable phases.     

Synergistic Effect of Porcine Follicular Fluid and Dibutyryl Cyclic Adenosine Monophosphate on Development of Parthenogenetically Activated Oocytes from Pre‐Pubertal Gilts

This study investigated the effect of porcine follicular fluid (PFF) and dibutyryl cyclic adenosine monophosphate (dbcAMP) during in vitro maturation (IVM) of porcine oocytes on meiotic maturation, fertilization and embryo development, and compared the effect of supplementing the embryo culture media with PFF or foetal bovine serum (FBS) on embryo development. Oocytes from pre‐pubertal gilts were IVM for 44 h, and parthenogenetically activated or in vitro‐fertilized. Embryos were cultured in porcine zygote medium (PZM3) for 7 days. Cleavage and blastocyst rates were evaluated at 48 h and 7 days of culture. The supplementation of the IVM medium with 25% PFF and 1 mm dbcAMP for the first 22 h resulted in more (p < 0.05) embryos developing to the blastocyst stage as compared with the inclusion of dbcAMP alone. The dbcAMP + PFF combination increased (p < 0.05) the average number of nuclei per blastocyst as compared with either of these components alone or in its absence. A synergistic effect of dbcAMP + PFF during IVM was also reflected in the capacity of oocytes to regulate sperm penetration and prevent polyspermy, as twice as many oocytes from the control group were penetrated by more than one sperm as compared with those matured in the presence of both dbcAMP and PFF. The supplementation of PZM3 with 10% FBS from days 5 to 7 of culture significantly improved the total cell quantity in embryos derived either from control or dbcAMP + PFF matured oocytes. There was no effect on the total cell quantity when FBS was replaced by the same concentration of PFF. These studies showed that dbcAMP, PFF and FBS can improve both the quantity (57.3% vs 41.5%) and quality (74.8 vs 33.3 nuclei) of porcine blastocysts derived from oocytes recovered of pre‐pubertal gilts.     

Influence of the microstructure on the shell strength of eggs laid by hens of different ages

1. The eggshell is a bioceramic material constructed of columnar calcite crystals preferentially oriented with their c-axis perpendicular to the shell surface. 2. The influence of microstructure (crystal size, shape and crystallographic orientation of crystal grains) on the mechanical properties of eggshells (shell strength) was investigated using eggs from hens of different ages. 3. There was a strong correlation between crystallographic texture and the strength of the eggshell in the case of eggs laid by young hens. The strength of eggshells increased as the preferential orientation of the crystals constituting the eggshell decreased. 4. By comparing two age populations, the effect of hen age on eggshell properties was evaluated. In general, eggshells from aged hens had a lower breaking strength (less than half that of those laid by young hens) and showed a greater variability in their structural properties such as thickness, grain morphology and crystallographic texture. 5. Texture analysis revealed that shells from eggs laid by aged hens have two preferred crystal orientations, after (001) and (104), compared with mainly one, after (001), in eggs laid by young hens. 6. These observed changes in eggshell properties could be due to changes in the organic matrix of the eggshell associated with ageing of the hens.     

Fertility Results after Vaginal Deposition of Frozen‐Thawed Buck Semen Diluted with Two Different Extenders Using One‐ or Two‐Step Procedures

In two field trials (T1 and T2), the effect of two different extenders for buck semen was tested. Semen from six (T1) and seven (T2) bucks of the Norwegian Dairy Goat breed was diluted either in a milk‐based extender containing egg yolk (M) or in a commercially available extender without egg yolk [Andromed^® (A)]. Dilution in M was performed in a two‐step procedure including centrifugation of the ejaculates and removal of the supernatant, while dilution in A was performed in one step. During the two trials (T1 and T2) 514 and 714, does, respectively, were artificially inseminated during natural oestrus, and the farmers performed the inseminations themselves after attending an artificial insemination (AI) training course. Vaginal insemination with 200 × 10⁶ spermatozoa diluted in M resulted in a 25‐day non‐return rate (NRR) and kidding rate of 37.3% and 24.5%, respectively, while semen diluted in A resulted in 31.7% NRR and a kidding rate of 19.8% (T1). In T2, NRR and kidding rate for AI performed with semen diluted with M were 42.7% and 28.5%, respectively, while dilution in A gave 37.2% NRR and a kidding rate of 26.8%. There was no significant effect of extender in the two trials [T1:p = 0.068 (NRR), p = 0.148 (kidding rate), T2:p = 0.096 (NRR), p = 0.38 (kidding rate)], but farmer had a significant effect on the fertility parameters in both trials. In conclusion, the present studies may indicate that Andromed^® is suitable for buck semen. However, more research is necessary to confirm the results and to improve the fertility of does after vaginal AI with frozen‐thawed semen.     

Transient phase-induced nucleation

A transient metastable rotator phase occurring on crystallization of hexadecane into its triclinic phase from the supercooled melt was directly observed with time-resolved synchrotron x-ray scattering. In this system, the limit of supercooling (the crystallization temperature) is determined by the thermodynamic stability of the transient phase with respect to the liquid. The crystallization kinetics of the homologous series of n-alkanes was measured and explained in terms of a crossover from stability to "long-lived" metastability to transient metastability. This crossover allowed further confirmation of the nature of the transient phase.     

ACQUIRED MEGAESOPHAGUS IN A HEIFER

An 18-month-old pregnant heifer, hitherto normal, was noticed to regurgitate wet, partially digested roughage several times a day. On clinical examination, the heifer was losing body weight. There was no obstacle to passing a stomach tube to the rumen. A barium study of the esophagus was performed. Megaesophagus involving the cervical and cranial thoracic esophagus was diagnosed. Postmortem findings were a dilated esophagus, with no gross pathology seen. Histopathology showed extensive submucosal cellular infiltration of eosinophils. The classification and possible etilogy of the case is discussed.     

C, N, and noble gas isotopes in grain size separates of presolar diamonds from efremovka

Nanometer-size presolar diamonds from the Efremovka CV3 chondrite were physically separated into several grain size fractions by ultracentrifugation. The coarsest size fraction is the most enriched in carbon-12; the others have broadly similar carbon isotopic compositions. Measurement of noble gases shows that their concentration decreases with decreasing grain size. This effect is attributed to ion implantation. Such an episode could occur in the envelope of a supernova that produced the diamonds, or in interstellar space; in either case, ions with energies above a certain threshold pass completely through the smaller diamond grains without being captured. Concentrations of nitrogen show only minor variations with grain size, indicating a different mechanism of incorporation into the diamonds.