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Digestive Capacity (digestive + capacity)
Selected AbstractsCauses and consequences of post-growth age-dependent differences in small intestine size in a migratory sandpiper (Calidris mauri, Western Sandpiper)FUNCTIONAL ECOLOGY, Issue 1 2006R. W. STEIN Summary 1Calidris mauri Cabanis (Western Sandpiper) exhibits a pronounced post-growth age-dependent difference in small intestine size during southward migration, such that the later-migrating juveniles have larger small intestines than do the adults. Potential causes and consequences of this age-dependent difference are examined. 2Premigrant juveniles of full structural size had small intestines that were 10% longer than those of the premigrant adults, even though the juveniles had not attained asymptotic body mass. The elongated small intestines of premigrant juveniles appear to be growth-related. 3Adults and juveniles exhibited parallel increases in intestinal length (7·0%) and circumference (9·5%) in association with the initiation of migration; these effects are consistent with migratory hyperphagia. 4Refuelling juveniles had small intestines that were 8·5% longer than those of the refuelling adults. Retaining an enlarged small intestine during migration confers increased digestive capacity to the juveniles, which may be under selection to minimize stopover duration. 5Refuelling juveniles had a higher prevalence of cestode infection than refuelling adults in one of two years, and the length-corrected mass of the small intestine was 9·7% heavier in infected individuals. Cestode infection may be an important determinant of migration-related mortality for juveniles, by compromising their health and increasing stopover duration. [source] Phenotypic compromise in the face of conflicting ecological demands: an example in red knots Calidris canutusJOURNAL OF AVIAN BIOLOGY, Issue 1 2010François Vézina Phenotypic flexibility is a phenomenon where physiological functions in animals are reversibly adjusted in response to ecological constraints. Research usually focuses on effects of single constraints, but under natural conditions animals face a multitude of restrictions acting simultaneously, and potentially generating conflicting demands on the phenotype. We investigated the conflicting demands of low temperatures and a low quality diet on the phenotype of a shorebird, the red knot Calidris canutus. We tested the effects of switching diet from a high quality trout food to low quality hard-shelled bivalves in captive birds acclimated to temperatures reflecting natural winter conditions. Feeding on bivalves generated a digestive constraint forcing the birds to increase the height and width of their gizzard by 66% and 71%, respectively, over 30 days. The change in gizzard size was associated with an initial 15% loss of body mass and a reduction in size of the pectoral muscles by 11%. Because pectoral muscle size determines summit metabolic rate (Msum, an indicator of cold endurance), measured Msum declined by 9%. Therefore, although the birds were acclimated to cold, gizzard growth led to a loss of cold endurance. We propose that cold-acclimated knots facing a digestive constraint made a phenotypic compromise by giving-up cold hardiness for digestive capacity. Field studies suggest that phenotypic compromises occur in free-living red knots as well and help improve survival. [source] Atlantic salmon (Salmo salar) postsmolts adapt lipid digestion according to elevated dietary wax esters from Calanus finmarchicusAQUACULTURE NUTRITION, Issue 1 2009A.S. BOGEVIK Abstract Wax esters (WE) in copepods constitute huge natural marine lipid resources, which can contribute as future lipid source in formulated diets in aquaculture, and thereby reduce the pressure on use of marine resources at higher trophic levels. The present study was undertaken to investigate factors affecting WE digestibility, including production of bile and lipases in Atlantic salmon fed diets containing high proportions of oil derived from copepods. Individually tagged postsmolt Atlantic salmon (initial weight 250 g) were distributed into three dietary groups in triplicate tanks and fed either a fish oil supplemented diet or diets where 50% or 100% of the fish oil was replaced with oil extracted from Calanus finmarchicus. WE accounted for 30.7% or 47.7% of the lipids in these latter diets, respectively. Over the 100 day feeding period, the salmon fed the fish oil diet displayed a significantly higher specific growth rate (SGR; 0.74) than fish fed the 100%Calanus oil diet (SGR; 0.67). The apparent digestibility coefficient of total lipid and total fatty acids was significantly higher in salmon fed the fish oil and the mixed diet compared to fish fed the pure Calanus oil diet. However, the fish appeared to enhance the lipid digestive capacity by increasing bile volume and the lipolytic activity. It is concluded that the digestion of WE in Atlantic salmon is poorer than for triacylglycerols. However, the digestive capacity is increased by elevating the bile content and lipase activity. At very high levels however, WE of lipid between 37.5% and 47.7%, are there no more compensation and WE utilisation decreases. [source] Effects of dietary protein levels on the growth performance, digestive capacity and amino acid metabolism of juvenile Jian carp (Cyprinus carpio var. Jian)AQUACULTURE RESEARCH, Issue 9 2009Yong Liu Abstract This experiment was conducted to evaluate the effects of protein levels on the growth performance, digestive capacity and amino acid metabolism of juvenile Jian carp. Brown fish meal was used as the sole protein source in the present study. Six isoenergetic experimental diets containing 14.4 MJ kg,1 of digestible energy and 220,495 g crude protein kg,1 diets were fed to triplicate groups of 50 fish with a mean initial weight of 16.67 ± 0.01 g for 45 days. Per cent weight gain (PWG) and feed efficiency ratio (FER) improved with an increase in the dietary protein levels up to 330 g kg,1 diet. The condition factor, relative gut length, intestinal folds height, hepatopancreas and intestine protein content improved with an increase in the protein levels up to 330,385 g kg,1 diet. Trypsin, creatinkinase, Na+, K+ -ATPase and alkaline phosphatase activities generally followed the same tendency as that of growth parameters. Amylase and ,-glutamyl transpeptidase (,-GT) activities were negatively correlated with increasing protein levels from 220 to 330 g kg,1 diet, and no differences were found thereafter. Lipase activity was unaffected by protein levels. Lactobacillus amount was increased with protein levels up to 275 g kg,1 diet, while Aeromonas amount followed the opposite pattern. Escherichia coli amount was not influenced by dietary protein levels. Glutamate,oxaloacetate transaminase (GOT) activities in the hepatopancreas and plasma ammonia concentration (PAC) were not influenced by protein levels between 220 and 275 g kg,1 diet, but significantly increased with increasing protein levels from 275 to 440 g kg,1 diet, and remained similar thereafter. Glutamate,pyruvate transaminase (GPT) activities significantly increased with protein levels >275 g kg,1 diet. Based on the broken-line model, the dietary protein requirement for PWG of Jian carp (16.7,55.0 g) was estimated to be 341 g kg,1 diet with a digestible energy of 14.4 MJ kg,1 diet. [source] Growth, digestive capacity and intestinal microflora of juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of dietary inositolAQUACULTURE RESEARCH, Issue 8 2009Wei-Dan Jiang Abstract A 60-day feeding trial was carried out with juvenile Jian carp (Cyprinus carpio var. Jian) to study the effects of myo -inositol (MI) on the growth, digestive enzyme and intestinal microbial population. Diets with seven levels of inositol (163.5, 232.7, 384.2, 535.8, 687.3, 838.8 and 990.3 mg MI kg,1 diet) were fed to Jian carp (initial weight 22.28±0.07 g). Per cent weight gain (PWG) was improved with increasing inositol levels up to 535.8 mg MI kg,1 diet (P<0.05), and plateaued (P>0.05). The protein production value, lipid production value and ash production value were increased with increasing dietary inositol levels up to 384.2, 838.8 and 838.8 mg MI kg,1 diet respectively (P<0.05). Although intestinal protein content and trypsin activity were not affected by inositol levels (P>0.05), chymotrypsin, lipase and amylase activities in intestine were the lowest for fish fed the MI-unsupplemented diet (P<0.05). Alkaline phosphatase, Na+, K+ -ATPase, ,-glutamyl transpeptidase and creatinkinase activities in the intestine were increased with an increase in the inositol levels up to 384.2,687.3 mg MI kg,1 diet (P<0.05). Intestinal Aeromonas hydrophila and Escherichia coli decreased with an increase in the levels of dietary inositol up to 232.7 and 687.3 mg MI kg,1 diet respectively (P<0.05), while Lactobacillus in the intestine increased with an increase in inositol levels up to 990.3 mg MI kg,1 diet (P<0.05). In conclusion, inositol improved growth, digestive capacity and intestinal microbial population of juvenile Jian carp, and the dietary inositol requirement for PWG of juvenile Jian carp is 518.0 mg MI kg,1 diet. [source] Early weaning of winter flounder (Pseudopleuronectes americanus Walbaum) larvae on a commercial microencapsulated dietAQUACULTURE RESEARCH, Issue 6 2003I Ben Khemis Abstract Like most small marine fish larvae, the stomachs of winter flounder Pseudopleuronectes americanus are undeveloped at first feeding and have relatively reduced digestive capacity. This work was undertaken to test whether larvae at the onset of stomach differentiation (larval size about 5.5 mm) could be early weaned onto a commercial microencapsulated diet. We assessed the effect of early weaning by first comparing growth performance (standard length, total protein content and age at metamorphosis) of larvae fed enriched live prey from first feeding to a size of 5.5 mm and then reared on three different feeding regimes until metamorphosis: (1) live prey (LP) as a control group; (2) mixed feeding of live prey and microencapsulated diet (LP-ME); (3) exclusively microencapsulated diet (ME) after fast weaning over 4 days (to a larval size of 6.2 mm). No differences were observed between larval development in the two first groups, which began metamorphosis at 40 days old. The larvae of the third group showed significantly slower growth that resulted in a delay of 4 days in the onset of metamorphosis. Differences in live prey availability between the treatments and the short transition period to allow the larvae to adapt to the new diet were identified as possible contributing factors to the slower growth and to the delay in metamorphosis of early weaned larvae. In a second experiment, the transitional weaning period was increased until the larvae were 6.6 mm in length. Weaning at that size resulted in no slowing of growth or delay in metamorphosis, suggesting that the feeding schedule was adequate. [source] The integration of digestion and osmoregulation in the avian gutBIOLOGICAL REVIEWS, Issue 4 2009Todd J. McWhorter Abstract We review digestion and osmoregulation in the avian gut, with an emphasis on the ways these different functions might interact to support or constrain each other and the ways they support the functioning of the whole animal in its natural environment. Differences between birds and other vertebrates are highlighted because these differences may make birds excellent models for study and may suggest interesting directions for future research. At a given body size birds, compared with mammals, tend to eat more food but have less small intestine and retain food in their gastrointestinal tract (GIT) for shorter periods of time, despite generally higher mass-specific energy demands. On most foods, however, they are not less efficient at digestion, which begs the question how they compensate. Intestinal tissue-specific rates of enzymatic breakdown of substrates and rates of active transport do not appear higher in birds than in mammals, nor is there a demonstrated difference in the extent to which those rates can be modulated during acclimation to different feeding regimes (e.g. diet, relative intake level). One compensation appears to be more extensive reliance on passive nutrient absorption by the paracellular pathway, because the avian species studied so far exceed the mammalian species by a factor of at least two- to threefold in this regard. Undigested residues reach the hindgut, but there is little evidence that most wild birds recover microbial metabolites of nutritional significance (essential amino acids and vitamins) by re-ingestion of faeces, in contrast to many hindgut fermenting mammals and possibly poultry. In birds, there is some evidence for hindgut capacity to breakdown either microbial protein or protein that escapes the small intestine intact, freeing up essential amino acids, and there is considerable evidence for an amino acid absorptive capacity in the hindgut of both avian and mammalian hindgut fermenters. Birds, unlike mammals, do not excrete hyperosmotic urine (i.e. more than five times plasma osmotic concentration). Urine is mixed with digesta rather than directly eliminated, and so the avian gut plays a relatively more important role in water and salt regulation than in mammals. Responses to dehydration and high- and low-salt loads are reviewed. Intestinal absorption of ingested water is modulated to help achieve water balance in one species studied (a nectar-feeding sunbird), the first demonstration of this in any terrestrial vertebrate. In many wild avian species the size and digestive capacity of the GIT is increased or decreased by as much as 50% in response to nutritional challenges such as hyperphagia, food restriction or fasting. The coincident impacts of these changes on osmoregulatory or immune function of the gut are poorly understood. [source] | |||||||||||||