Feasibility of artificial light regimes to increase the vitamin D content in indoor-laid eggs.

Vitamin D insufficiency is prevalent worldwide. Recently, we showed that exposure of laying hens to sunlight or artificial ultraviolet B (UVB) light is an efficient strategy to increase the vitamin D content in eggs. In the current study, using 2 different chicken genotypes and stocking densities, we addressed the question of whether different UVB-emitting regimes work under real indoor housing conditions in a floor system or in furnished cages. Here, we found a 3.7-fold increase in the egg vitamin D content in Lohmann Selected Leghorn hens and a 4.2-fold increase in Lohmann Brown hens after UVB exposure for 6 h/d. The data further reveal that UVB exposure under high stocking density is equally effective compared to that at low stocking density. The different light regimes were not associated with changes in the behavior of these animals. To conclude, artificial UVB-emitting light regimes are a practical strategy to increase the vitamin D content in indoor-laid eggs.

Lucerne silage in high yielding dairy cows: effect of parity and analysis of reasons in mixed-parity group housing using random regression test-day models.

A study with high-yielding dairy cows was re-analysed in order to test the suitability of lucerne silage separately for primi- and multiparous cows as an alternative to grass silage in maize-based total mixed rations (TMR). Lactation curves were fitted using random regression test-day models for energy corrected milk (ECM) and dry matter intake (DMI) as well as for number and duration of feeder visits (NFV and DFV, respectively). Existing models for ECM and DMI were extended by animal-specific random effects, which were formulated in their dependency on days in milk. For NFV and DFV random regression models were applied for the very first time. The chosen approach of statistical analysis permitted comparisons of the lactation curves as well as of least square means for sub-periods to answer nutritional questions. Whilst primiparous cows had generally lower DMI and ECM as compared to multiparous cows, only in primiparous cows a negative effect of lucerne TMR on ECM was observed, especially in early lactation. Nutritional factors should be rejected because of very similar ECM between the various TMR in multiparous cows. Traits of feeding behaviour indicated that particle size could contribute to the decreased ECM. Even more impact on the lower ECM should be addressed to domination behaviour of multiparous cows. The resulting restlessness of primiparous cows caused a reduced intake per minute spent at the feeder. Further studies should focus on optimising the proportion and chopping length of lucerne in the diet and to improve flock management to maximise feed intake of primiparous cows. Generally, statistical analysis of lactation data became a very complex issue. It seems inevitable that nutritionists and statisticians team up to address this problem.

Notch signaling during larval and juvenile development in the polychaete annelid Capitella sp. I.

Notch signaling is involved in a large range of developmental processes, and has been functionally implicated in body plan segmentation in two of the three diverse segmented taxa, the vertebrates and arthropods. Here we investigate expression of Notch, Delta, and hes gene homologues during larval and juvenile development in the polychaete annelid Capitella sp. I., a member of the third group of segmented animals. During larval stages, CapI-Notch, CapI-Delta, CapI-hes2, and CapI-hes3 transcripts are initially detected in broad ectodermal domains in future segments as well as in the brain and foregut; later, CapI-Notch, CapI-Delta, and CapI-hes2 transcripts are detected in the presumptive chaetal sacs. In contrast, CapI-hes1 has a segmentally reiterated pattern in a restricted region of the mesoderm in each presumptive segment. CapI-Notch, CapI-Delta, CapI-hes2, and CapI-hes3 and CapI-hes1 are all expressed in the terminal growth zone that generates post-metamorphic segments, however, CapI-hes1 has a non-overlapping complementary expression pattern to that of CapI-Notch and CapI-Delta. CapI-Delta and CapI-Notch transcripts are localized to already formed segments, with posterior boundaries that correlate with the posterior boundary of the nascent segment, while CapI-hes1 lies posterior to CapI-Notch and CapI-Delta. The localization of CapI-Notch, CapI-Delta, and CapI-hes transcripts correlate with areas of rapid cell proliferation in Capitella, which include the brain, foregut, and terminal growth zone.

Characterization of twist and snail gene expression during mesoderm and nervous system development in the polychaete annelid Capitella sp. I.

To investigate the evolutionary history of mesoderm in the bilaterian lineage, we are studying mesoderm development in the polychaete annelid, Capitella sp. I, a representative lophotrochozoan. In this study, we focus on the Twist and Snail families as candidate mesodermal patterning genes and report the isolation and in situ expression patterns of two twist homologs (CapI-twt1 and CapI-twt2) and two snail homologs (CapI-sna1 and CapI-sna2) in Capitella sp. I. CapI-twt1 is expressed in a subset of mesoderm derivatives during larval development, while CapI-twt2 shows more general mesoderm expression at the same stages. Neither twist gene is detected before the completion of gastrulation. The two snail genes have very distinct expression patterns. At cleavage and early gastrula stages, CapI-sna1 is broadly expressed in precursors of all three germ layers and becomes restricted to cells around the closing blastopore during late gastrulation; CapI-sna2 expression is not detected at these stages. After gastrulation, both snail genes are expressed in the developing central nervous system (CNS) at stages when neural precursor cells are internalized, and CapI-sna1 is also expressed laterally within the segmental mesoderm. Based on the expression patterns in this study, we suggest a putative function for Capitella sp. I twist genes in mesoderm differentiation and for snail genes in regulating CNS development and general cell migration during gastrulation.

Growth patterns during segmentation in the two polychaete annelids, Capitella sp. I and Hydroides elegans: comparisons at distinct life history stages.

Many animals generate new body segments sequentially from a posterior growth zone, and this is generally thought to be the case for the annelids. Most annelids, including polychaetes, have an indirect life cycle and generate their earliest segments during larval life. We have characterized the nature of the growth zone in two polychaetes, Hydroides elegans and Capitella sp. I, during both larval and juvenile stages of segment formation by examining cell division patterns with 5-bromo-2'-deoxyuridine incorporation. Cell division patterns show commonalities between the two species, even though they have distinct body plans and life history characteristics. In both polychaetes, larval segments arise from a field of dividing cells located in lateral regions of the body, rather than from a localized posterior growth zone. Circumferential expansion of the forming segmental tissue is particularly pronounced in Capitella sp. I. Post-metamorphic segments, in contrast, originate from a classical posterior growth zone, with the exception of four posterior thoracic segments of H. elegans, which appear to arise from an area in the middle of the body, indicating plasticity of segment-generating mechanisms present in different annelid life histories. The distinct nature of larval versus juvenile growth zones in H. elegans and Capitella sp. I raises the question of the mechanistic relationship between these two growth zones. The results of this study increase our understanding of the cellular origins of segments in annelids, and serve as a basis for interpretation of molecular expression patterns associated with segment formation in polychaetes.