Effect of genotype and hens' starting body fat content on the changes in the body fat content of the hens and on the weight and composition of the eggs produced in the first egg laying period

The aim of this study was to examine the effect of genotype and hens’ starting body fat content on the changes in the body fat content of the hens and on the weight and composition of the eggs produced in the first egg laying period. The experiment was carried out with altogether 30 hens (15 TETRA SL brown egg layers and 15 TETRA BLANCA white egg layers), which were chosen from altogether 45 TETRA SL and 45 TETRA BLANCA hens based on their CT (computer tomography) predicted body fat content at 20 weeks of age (hens with the highest (n=5), hens with the lowest (n=5) and hens with average (n=5) body fat content in both genotype). For the in vivo determination of changes in the body composition of these hens, computer tomography (CT) measurements were carried out at every fourth week between the 20th and 72nd week of age. During the CT measurements hens were fixed with belts in a special plexiglass container without using any anaesthetics. The measurements covered the whole body of the hens using overlapping 10 mm slice thickness on a Siemens Somatom Emotion 6 multislice CT scanner. After collecting, weighing and breaking the eggs produced by the experimental birds on the days of the CT measurements their yolk ratio was determined. Based on the results, it was established that the body fat content of the hens increased continuously in both of the genotypes in the first phase of the experimental period, while it did not change further in the second phase of the experiment. It was also observed at all examination days, that the body fat content of the white egg layers was higher than that of the brown egg layers. Hens with the highest starting body fat content had the highest body fat content in both genotypes during the whole egg laying period. The egg production of the hens was not influenced by the body fat content of the birds, but it was affected by the genotype. The TETRA SL hens produced significantly more eggs than the TETRA BLANCA hens. The hens with average body fat content produced lighter eggs than the hens with low or high body fat content

Effect of genotype and hens' starting body fat content on the changes in the body fat content of the hens and on the weight and composition of the eggs produced in the first egg laying period

The aim of this study was to examine the effect of genotype and hens’ starting body fat content on the changes in the body fat content of the hens and on the weight and composition of the eggs produced in the first egg laying period. The experiment was carried out with altogether 30 hens (15 TETRA SL brown egg layers and 15 TETRA BLANCA white egg layers), which were chosen from altogether 45 TETRA SL and 45 TETRA BLANCA hens based on their CT (computer tomography) predicted body fat content at 20 weeks of age (hens with the highest (n=5), hens with the lowest (n=5) and hens with average (n=5) body fat content in both genotype). For the in vivo determination of changes in the body composition of these hens, computer tomography (CT) measurements were carried out at every fourth week between the 20th and 72nd week of age. During the CT measurements hens were fixed with belts in a special plexiglass container without using any anaesthetics. The measurements covered the whole body of the hens using overlapping 10 mm slice thickness on a Siemens Somatom Emotion 6 multislice CT scanner. After collecting, weighing and breaking the eggs produced by the experimental birds on the days of the CT measurements their yolk ratio was determined. Based on the results, it was established that the body fat content of the hens increased continuously in both of the genotypes in the first phase of the experimental period, while it did not change further in the second phase of the experiment. It was also observed at all examination days, that the body fat content of the white egg layers was higher than that of the brown egg layers. Hens with the highest starting body fat content had the highest body fat content in both genotypes during the whole egg laying period. The egg production of the hens was not influenced by the body fat content of the birds, but it was affected by the genotype. The TETRA SL hens produced significantly more eggs than the TETRA BLANCA hens. The hens with average body fat content produced lighter eggs than the hens with low or high body fat content

Two possible source regions for Central Greenland last glacial dust

Dust in Greenland ice cores is used to reconstruct the activity of dust-emitting regions and atmospheric circulation. However, the source of dust material to Greenland over the last glacial period is the subject of considerable uncertainty. Here we use new clay mineral and <10 µm Sr–Nd isotopic data from a range of Northern Hemisphere loess deposits in possible source regions alongside existing isotopic data to show that these methods cannot discriminate between two competing hypothetical origins for Greenland dust: an East Asian and/or central European source. In contrast, Hf isotopes (<10 µm fraction) of loess samples show considerable differences between the potential source regions. We attribute this to a first-order clay mineralogy dependence of Hf isotopic signatures in the finest silt/clay fractions, due to absence of zircons. As zircons would also be absent in Greenland dust, this provides a new way to discriminate between hypotheses for Greenland dust sources

High Risks of Losing Genetic Diversity in an Endemic Mauritian Gecko: Implications for Conservation

Genetic structure can be a consequence of recent population fragmentation and isolation, or a remnant of historical localised adaptation. This poses a challenge for conservationists since misinterpreting patterns of genetic structure may lead to inappropriate management. Of 17 species of reptile originally found in Mauritius, only five survive on the main island. One of these, Phelsuma guimbeaui (lowland forest day gecko), is now restricted to 30 small isolated subpopulations following severe forest fragmentation and isolation due to human colonisation. We used 20 microsatellites in ten subpopulations and two mitochondrial DNA (mtDNA) markers in 13 subpopulations to: (i) assess genetic diversity, population structure and genetic differentiation of subpopulations; (ii) estimate effective population sizes and migration rates of subpopulations; and (iii) examine the phylogenetic relationships of haplotypes found in different subpopulations. Microsatellite data revealed significant population structure with high levels of genetic diversity and isolation by distance, substantial genetic differentiation and no migration between most subpopulations. MtDNA, however, showed no evidence of population structure, indicating that there was once a genetically panmictic population. Effective population sizes of ten subpopulations, based on microsatellite markers, were small, ranging from 44 to 167. Simulations suggested that the chance of survival and allelic diversity of some subpopulations will decrease dramatically over the next 50 years if no migration occurs. Our DNA-based evidence reveals an urgent need for a management plan for the conservation of P. guimbeaui. We identified 18 threatened and 12 viable subpopulations and discuss a range of management options that include translocation of threatened subpopulations to retain maximum allelic diversity, and habitat restoration and assisted migration to decrease genetic erosion and inbreeding for the viable subpopulations