Scope for growth and dietary needs of Mediteranean Pinnids maintained in captivity.

BACKGROUND: The measurement of the energy available for growth (scope of growth, SFG) can be used in bivalves to make a long-term prediction in a short-term experiment of the condition of the individual. In order to tackle the best conditions for captive maintenance of Mediterranean Pinnids, a SFG study was conducted using Pinna rudis as a model species. Three diets were examined to test the viability of live microalgae and commercial products: i) a control diet using 100% of live microalgae based on the species Isochrysis galbana (t-ISO), ii) a 100% of commercial microalgae diet based on the product Shellfish Diet 1800®, and iii) a 50/50% mix diet of I. galbana (t-ISO) and Shellfish Diet 1800®. RESULTS: SFG results showed significant differences among diets in the physiological functions measured and suggested lower acceptability and digestibility of the commercial product. Negative SFG values were obtained for the commercial diet which indicates that it should be rejected for both Pinnid maintenance. The mixed diet showed improved physiological performance compared to the commercial diet, resulting in a higher SFG that had no significant differences with the control diet. However, in the long-term, the lower digestibility of the mixed diet compared to the control diet could lead to a deterioration of individuals' conditions and should be considered cautiously. CONCLUSIONS: This work represents the first case study of SFG in Pinna spp. and provides fundamental data on dietary needs for the critically endangered species, P. nobilis.

Evaluation of the effects of cage height and stocking density on the behaviour of laying hens in furnished cages.

1. Limited information is available on how changes in horizontal and vertical space within enriched or furnished layer cages (as defined by Directive 1999/74/EC) influence hen behaviour. This study evaluated the effects of varying minimum cage heights and space allowances on the behaviour of laying hens housed in furnished cages. It was conducted on two flocks of medium brown hybrid hens housed in furnished cages with access to perches and nest boxes on a semi-commercial scale at ADAS Gleadthorpe. 2. Flock 1 consisted of two layer strains (ISA Brown and Babcock 380), housed at two minimum cage heights (38 and 45 cm) and 5 stocking densities between 609 and 870 cm2/bird, with 12 replicates of each of the 20 strain/cage height/stocking density treatment combinations. Stocking density was varied by varying the number of birds per cage from 10 to 7 in standard full-width cages or housing 7 hens in a narrower cage. As a consequence stocking density, group size and trough width per bird co-varied for 4 out of 5 stocking density treatments. 3. Behaviour of flock 1 was sampled at 33 to 36, 46 and 68 weeks of age. At each age one top-tier, one middle-tier and one bottom-tier cage was sampled for each treatment. 4. Few behavioural differences due to cage treatments were detected. Hens at 870 cm2 had shorter feeding bouts than hens at 609 and 762 cm2. Yawning was more common in the cages with greater cage height. 5. Video recordings of flock 1 examined cage height effects on hens' use of vertical space and provided additional data on stretching and self-maintenance activities. No differences in behaviour between 38 and 45 cm cages were found except that scratching head was more common in cages with greater cage height. 6. Flock 2 consisted of two layer strains (Shaver Brown and Hy-Line Brown), housed at 38 and 45 cm and 609, 762 and 1016 cm2/bird, with 18 replicates of each of the 12 strain/cage height/stocking density treatment combinations. Stocking density was varied by housing 10, 8 or 6 hens in standard full-width cages. Behaviour of flock 2 was sampled at 30, 48, 60 and 67 weeks from video recordings. Three cages per treatment from middle-tiers only were sampled at each age. 7. Hens housed at 609 cm2/hen had the longest mean feeding bout, greater than for hens at 762 cm2/hen but not hens at 1016 cm2/hen. More unsuccessful attempts to reach the feeder and sideways and backwards displacements from the feeder occurred at 762 and 609 cm2/hen than at 1016 cm2/hen. A maximum of 8 hens were observed feeding synchronously. 8. These results suggest that changes in horizontal and vertical space over the ranges we studied had little effect on behaviour other than feeding behaviour. Specifying a minimum useable trough space per hen, rather than calculating feeder space from total length of feeder per cage, irrespective of accessibility, might help avoid crowding at the feeder and associated disturbance of feeding bouts.

Response of two species of clams, Ruditapes decussatus and Venerupis pullastra, to starvation: physiological and biochemical parameters.

Adult specimens of two species of clams, Ruditapes decussatus and Venerupis pullastra, were starved for 84 days to determine the effect of starvation on their metabolism. The energy cost of metabolism in starvation was assessed using the oxygen consumption rates (respiration rates) of the clams and assessing the type of fuel used to provide this energy by analyzing their biochemical composition. Respiration rates decreased in both species after 15 days of starvation and remained at basal levels throughout the rest of the experimental period. Both during the first period and also after the metabolism had slowed down, the amount of energy consumed in respiration was higher in V. pullastra than in R. decussatus. The energy needed to maintain vital functions in both species is obtained from catabolism of body components, with a reduction in dry mass of the specimens, and consequently their energy content, in both species. This reduction was greater in V. pullastra given that energy demand is higher in this species. In both species carbohydrates made the largest contributions to energy output, followed by lipids in males and proteins in females. However, the energy contribution of each biochemical component differs according to species: R. decussatus obtains its energy from the catabolism of carbohydrates and proteins in equal proportion, while V. pullastra obtains it from proteins and lipids. In both species, albeit to a greater extent in R. decussatus, we observed that female specimens conserved their lipids until the later stages of the period of starvation (day 70), after which they started to metabolise their lipid components more intensely. The interspecific differences are interpreted in relation to the different habitat occupied by the two species.

Lipid composition of Ruditapes philippinarum spat: effect of ration and diet quality.

This study investigates the influence of the lipid composition of microalgal and commercial flour diets on the lipid classes and fatty acids of Ruditapes philippinarum spat. Aspects of the nutritional role of the diets and the feeding ration are discussed with regard to previously published spat growth data. Our results demonstrated that clams showed the best growth rates when fed with diets that supplied a larger quantity of lipids, further characterised by a high content of phospholipids and triacylglycerols. We observed a significant correlation between the amount of triacylglycerols (r=0.929, p<0.05) and phospholipids (r=0.781, p<0.05) supplied and spat growth. In addition, R. phillipinarum spat reached the highest percentages of triacylglycerols (about 12%) and the lowest percentages of phospholipids (about 60%) and sterols (about 4%) with these growth-promoting diets. Spat fed with the other diets and/or rations showed lower growth rates and significantly lower quantities of triacylglycerols. In the present study, the alternative essentiality of 20:5n-3 and/or 22:6n-3 is confirmed. The diminishing supply of 22:6n-3 without an increase of 20:5n-3 has an effect on the growth of the spat. The dietary composition of fatty acids influenced the fatty acid profiles in bivalves. The results of our study would suggest that R. philippinarum is incapable of transforming 18:3n-3 to 20:5n-3 and then to 22:6n-3. Accordingly, although diets contained 18:3n-3, the spat reflected the low content of 20:5n-3 of the diets. With respect to 22:6n-3, given that this fatty acid is present in high quantities in Isochrysis, the spat content of this fatty acid was relative to its content in the diet. This study showed that clams with the lowest growth rates presented an increase in 20:4n-6. In the spat fed with the microalgal diets, 18:2n-6 scarcely reached 2% whereas in spat fed with wheat germ 18:2n-6 amounted to 18% of the total fatty acids. This fatty acid, by means of elongation, transforms to 20:2n-6, which also appeared in important quantities in the lipids of the spat fed totally or partially by wheat germ. We note that 20:2n-6 did not originate from the diet since it is absent in the microalgae and the flour. The desaturation of 20:2n-6 to 20:3n-6 has not been observed (low levels of 20:3n-6 in all cases) and therefore it can be assumed that the observed levels of 20:4n-6 were diet-related.

Strain and age differences in behaviour, fear response and pecking tendency in laying hens.

1. Behaviours associated with a high or low tendency to feather peck could be used as predictors of feather pecking behaviour in selective breeding programmes. This study investigated how strain and age at testing influenced responses in behavioural tests. 2. Four layer-type strains (ISA Brown, Columbian Blacktail, Ixworth and a high feather pecking (HP) and a low feather pecking (LP) line of White Leghorn) were reared in 6 same-strain/line pens of 8 birds from one day old. Birds in half the pens were given an open field test, a novel object test and a test with loose feather bundles between 4 and 12 weeks of age and a tonic immobility (TI) test at 13 weeks of age. All pens were tested with fixed feather bundles at 26 weeks, and undisturbed behaviour in the home pens was videoed at 1 and 27 weeks of age. Daily records of plumage damage were used as an indicator of feather pecking activity in the home pens. 3. Strain did not influence novel object test, open field test or loose feather test behaviour, although age effects in all three tests indicated a reduction in fearfulness and/or an increase in exploratory behaviour with increasing age. 4. White Leghorns showed longer TI durations than the other strains but less pecking at fixed feather bundles than ISA Browns and Columbian Blacktails. 5. There were few associations between behaviour in the 5 different tests, indicating that birds did not have overall behavioural traits that were consistent across different contexts. This suggests hens cannot easily be categorised into different behavioural 'types', based on their test responses and casts doubt on the usefulness of tests as predictors of feather pecking.

Effect of microalgal diets and commercial wheatgerm flours on the lipid profile of Ruditapes decussatus spat.

The influence of both the lipid composition of microalgal diets and commercial flours on the lipid classes and fatty acids of Ruditapes decussatus spat was studied. These aspects of the nutritional value of the diets were discussed in relation to the growth of the spat. Four diets were tested; Diet A, composed of 100% of the daily food ration of microalgae; Diet B, composed of 100% of wheatgerm; Diet C, composed of 50% of microalgae and 50% of wheatgerm; and Diet D, composed of 25% of microalgae and 75% of wheatgerm. The microalgal cells present a higher lipid content than that for wheatgerm. Tahitian Isochrysis cells have phospholipids and triacylglycerols as majority lipids, whereas in the wheatgerm particles, the lipids more abundant are triacylglycerols. Fatty acid content was higher in the microalgal cells than in the wheatgerm particles. The n-3 fatty acids were the most abundant acids in the microalgae, whereas the n-6 fatty acids were in the wheatgerm. The n-3 PUFA were not detected in wheatgerm. Phospholipids were the main lipids present in the clam spat, followed by triacylglycerols. Other lipid classes, detected in significantly lower amounts, included free fatty acids, sterols, and sterol ester + waxes. The composition of fatty acids in the spat was influenced by the fatty acid composition of the diet. Highest spat growth rates were observed with those diets that present a higher phospholipid/triacylglycerol relation. A negative correlation in the relation n-6/n-3 vs. growth has also been observed, with better growth rates in diets with a lower ratio. If the fatty acid 20:5n-3 and 22:6n-3 considered "essential" for marine animals were not present in the diet, they were not present in the spat either. Desaturation and elongation capabilities of R. decussatus spat were also discussed.

Micro-trabeculae, macro-plaques or mini-basement membranes in human term fetal membranes?

Immunocytochemical confocal laser scanning microscopy and ultrastructural analysis, including immunoelectron microscopy, reveals the distribution of structures in human term amniochorion similar in some respects to basement membranes but with unusually restricted dimensions. On the basis of their immunoreactivity, these trabecular structures, found on the fibroblast layer side of the spongy layer of human term amniochorion and adjacent reticular layer, have been shown to contain type IV collagen, laminin, and nidogen. The origin of these components may be from primitive epithelial structures which pumped fluid into the lakes that eventually coalesced to form the extraembryonic coelom separating the extraembryonic somatic mesoderm from the extraembryonic splanchnic mesoderm. Such a theory of their origin might link them with the mysterious 'cellular layer', a single-cell-thick layer of cells which is usually no longer present in fetal membranes at term. The similarity in composition but not in size of these structures to anchoring plaques for type VII collagen is possible support for the view that these structures are integrators of extracellular matrix polymeric proteins. The 'pseudobasement' membrane associated with the trophoblast layer, on investigation, appears to be typical by six criteria. 'Coiled' fibrous structures in the extracellular matrix of the spongy layer may aid adjustments under tension at this shear surface by a detachable 'Velcro' or 'two spring' fastening system. The coils are rich in fibronectin. The suggestion is made that the compact layer is a giant lamina reticularis associated with the amniotic epithelial basement membrane.