Nonfaecal and faecal losses of Pomadasys commersonni (Teleostei: Pomadasyidae) feeding on the surf clam, Donax serra

1. The nonfaecal and the faecal production of Pomadasys commersonni, a marine teleost, were investigated at 15, 20 and 25 degrees C. 2. Nonfaecal nitrogen excreted by starved and fed P. commersonni consisted mainly of ammonia-N. 3. The mass component b of the equation, AE = aMb (AE, ammonia-N in Mg-N/hr; M, fish mass in g) ranged from 0.68-0.72 and 0.71-0.75 for starved and fed fish, respectively, and was temperature-independent. 4. The mean percentage of the food energy lost as nonfaecal energy (exogenous plus endogenous) was 4.38 +/- 2.68%. 5. The faeces had a low energy content and ranged from 2.09 to 4.25 kJ/g. 6. Assimilation efficiencies showed some variation and ranged from 7.34 to 99.34% for dry matter and from 96.02 to 99.89% for energy. 7. The mean combined energy loss was 11.77% of the ingested energy.     

Nitrogen and energy loss in the marine teleost Lithognathus mormyrus (Linnaeus)

Nitrogen excretion and assimilation efficiencies in Lithognathus mormyrus (Linnaeus), a marine teleost present in high-energy surf zones in Algoa Bay, South Africa, were determined under controlled laboratory conditions at 15, 20 and 25 °C. Ammonia was the major form of nonfaecal nitrogen excreted by starved and fed L. mormyrus. Urea and amino acids were secondary excretory products. Ammonia excretion rates were temperature independent and the excretion rates of fed fish were significantly higher than starved fish at 20 and 25 °C but not at 15 °C. The mass component (b) of the mass/ammonia excretion equation was temperature independent and ranged from 0.590 to 0.669 and from 0.670 to 0.767 for starved and fed fish, respectively. The mean percentage of food energy lost via the dissolved nonfaecal excretory products (exogenous plus endogenous) was 4.12%. Assimilation efficiencies ranged from 71.89 to 98.78% for dry matter and from 96.89 to 99.88% on an energy basis. The combined nonfaecal and faecal energy loss was calculated at 10.11% of the ingested energy. The omnivorous ichthyofauna present in the surf zone ecosystem recycle 33 g N · m strip · yr⁻¹. This constitutes < 1 % of total phytoplankton nitrogen requirements.     

Energy budget of juvenile fat snook Centropomus parallelus fed live food

The fat snook Centropomus parallelus is a tropical estuarine species with importance for recreational and commercial fisheries and further aquaculture potential. Considering ingested energy (C) is channeled into growth (P), metabolic expenditure (R), excretion (U) and feces (F), a balanced energy budget was established for isolated and grouped juvenile C. parallelus (5.18 to 10.25 g wet mass) by experimental quantification of each of these parameters. Fish were fed live prawn (Macrobrachium sp.) at 25 degrees C and 20 per thousand for 19 days and daily energy budgets could be calculated. Energy content of food (live prawn), fish whole body and feces were 17.7, 14.5 and 6.1 KJ g(-1) dry mass (DW), respectively. Mass-specific rates of oxygen consumption and ammonia-N excretion were 0.271 and 0.0082 mg of O(2) or NH(3)-N g(-1) wet mass (WW) h(-1), respectively, resulting in O:N=23.4. Daily ingestion (C) was dependent on the amount of food offered and ranged between 4.9% to 7.4% of initial wet weight. Growth (P) was positively correlated with initial mass varying from 0.008 to 0.104 g day(-1). Feces release also correlated to fish mass and averaged 9.53 mg dry mass day(-1). The components of energy budget showed mean values of 2.39 (C), 0.24 (P), 1.96 (R), 0.11 (U) and 0.06 (F) KJ ind(-1) day(-1). As percentage of ingested energy, C. parallelus channeled 10% in growth (P), 82% in metabolism (R), 4.6% in excretion (U) and 2.5% in feces (F). Gross (K(1)) and net (K(2)) growth efficiencies were 9.2% and 9.9%, respectively. On the course of this period of juvenile development, K(1) and K(2) increased significantly. Partitioning of ingested energy in P, R, U and F was significantly different in individually and group maintained fish (P<0.05). Energy budget of C. parallelus fed a highly digestible diet (live prawn) revealed poor growth and growth efficiencies (K(1) and K(2)) possibly associated with an elevated metabolic demand and a high channeling of metabolized energy (P+R) into metabolism (R) in both isolated and grouped fish. Data can be applied to ecosystem modeling and may contribute to identify species potential to aquaculture.     

Arsenic species excretion after controlled seafood consumption

Influence of controlled consumption of marine fish on the urinary excretion of arsenite, arsenate, dimethylarsinic and monomethylarsonic acid (DMA, MMA) was investigated in two experiments. Arsenic species were separated by anion-exchange chromatography and detected with hydride-technique atomic absorption spectrometry (detection limit 1, 10, 2, 2 microg/l). Firstly, 13 probands ate different types of seafood after having refrained from any seafood for 1 week. DMA levels rose from 3.4+/-1.3 microg/g creatinine (n=12; a day before seafood) to a mean peak level of 28.2+/-20.6 microg/g (n=13; 10-23 h after; P<0.001; max. 77.7 microg/g). No other species were excreted before the meal, but small amounts of arsenite (8.5% positive; max. 1.7 microg/g) and MMA (1.2%; 1.6 microg/g) within 2 days after it (n=82). Consumption of white herring caused the highest DMA levels. Secondly, eight probands ingested white herring (dose 3.5 g/kg; DMA content 32.1+/-15.3 ng/g wet weight; n=36). No arsenite, arsenate and MMA was found in the urine or in the herring tissues. The mean DMA mass excreted after the meal (65.3+/-22.0 microg/24 h) was about 6-fold higher than the sum of base DMA excretion (3.0+/-1.7 microg/24 h) and the ingested DMA mass (7.9+/-2.7 microg). This indicates that the elevated DMA excretion after herring consumption is not caused by the metabolism of inorganic arsenic but of other arsenic species present in the fish tissue, e.g. arsenobetaine or fat-soluble arsenic species.     

Endectocide exchanges between grazing cattle after pour-on administration of doramectin, ivermectin and moxidectin

Self-licking behaviour in cattle has recently been identified as a determinant of the kinetic disposition of topically-administered ivermectin. In the present study, we document the occurrence and extent of transfer between cattle of three topically-administered endectocides, as a consequence of allo-licking. Four groups of two Holstein cows each received one pour-on formulation of doramectin, ivermectin, or moxidectin, or no treatment. The cows were then kept together in a paddock. Systemic exposure to each topically-administered endectocide was observed in at least five of six non-treated cattle. Plasma and faecal drug concentration profiles in non-treated animals were highly variable between animals and within an animal, and sometimes attained those observed in treated animals. Drug exchanges were quantified by measuring plasma and faecal clearances after simultaneous i.v. administration of the three drugs as a cocktail. Plasma clearances were 185+/-43, 347+/-77 and 636+/-130ml/kg/day, faecal clearances representing 75+/-26, 28+/-13, and 39+/-30% of the plasma clearance for doramectin, ivermectin and moxidectin, respectively. The amount of drug ingested by non-treated cattle attained 1.3-21.3% (doramectin), 1.3-16.1% (ivermectin), 2.4-10.6% (moxidectin) of a pour-on dose (500 microg/kg). The total amount of drug ingested by all non-treated cattle represented 29% (doramectin), 19% (ivermectin), and 8.6% (moxidectin) of the total amount of each drug poured on the backs of treated animals. The cumulative amounts of endectocide ingested by each non-treated cow ranged from 1.3 to 27.4% of a pour-on dose. Oral bioavailability after drug ingestion due to allo-licking was 13.5+/-9.4, 17.5+/-3.5 and 26.1+/-11.1% for doramectin, ivermectin and moxidectin, respectively. The extent of drug exchange demonstrated here raises concerns for drug efficacy and safety, emergence of drug resistance, presence of unexpectedly high residue levels in treated and/or untreated animals and high environmental burdens. Moreover, scientific and regulatory aspects of clinical and bioequivalence trials for topical drug administration in cattle should be explored.     

NaHCO(3) and KHCO(3) ingestion rapidly increases renal electrolyte excretion in humans.

This paper describes and quantifies acute responses of the kidneys in correcting plasma volume, acid-base, and ion disturbances resulting from NaHCO(3) and KHCO(3) ingestion. Renal excretion of ions and water was studied in five men after ingestion of 3.57 mmol/kg body mass of sodium bicarbonate (NaHCO(3)) and, in a separate trial, potassium bicarbonate (KHCO(3)). Subjects had a Foley catheter inserted into the bladder and indwelling catheters placed into an antecubital vein and a brachial artery. Blood and urine were sampled in the 30-min period before, the 60-min period during, and the 210-min period after ingestion of the solutions. NaHCO(3) ingestion resulted in a rapid, transient diuresis and natriuresis. Cumulative urine output was 44 +/- 11% of ingested volume, resulting in a 555 +/- 119 ml increase in total body water at the end of the experiment. The cumulative increase (above basal levels) in renal Na(+) excretion accounted for 24 +/- 2% of ingested Na(+). In the KHCO(3) trial, arterial plasma K(+) concentration rapidly increased from 4.25 +/- 0.10 to a peak of 7.17 +/- 0.13 meq/l 140 min after the beginning of ingestion. This increase resulted in a pronounced, transient diuresis, with cumulative urine output at 270 min similar to the volume ingested, natriuresis, and a pronounced kaliuresis that was maintained until the end of the experiment. Cumulative (above basal) renal K(+) excretion at 270 min accounted for 26 +/- 5% of ingested K(+). The kidneys were important in mediating rapid corrections of substantial portions of the fluid and electrolyte disturbances resulting from ingestion of KHCO(3) and NaHCO(3) solutions.     

Non-invasive faecal steroid monitoring of ovarian and adrenal activity in farmed blue fox (Alopex lagopus) females during late pregnancy, parturition and lactation onset

In the semi-domesticated blue fox, handling stress may influence reproductive performance and increase perinatal pup loss. Ovarian and adrenal steroids were analysed in faecal samples collected from mid-gestation through the first week of lactation in 40 female blue foxes to characterize hormone patterns during this important reproductive period. Daily faecal samples were collected from 40 foxes during 30 pregnancies, one late abortion and nine bred-matched non-pregnancies. Mean concentrations of faecal progestagens over the 10 days before birth were significantly higher in pregnant compared to non-pregnant females (51+/-1.50 microg/g versus 36+/-3.72 microg/g, respectively; P < 0.01). From 10 to 3 days before whelping, total faecal oestrogen concentrations also were higher (P < 0.01) in pregnant (1082+/-41.69 ng/g) than non-pregnant (628+/-72.43 ng/g) foxes, before declining to non-pregnant values (402+/-24.88 ng/g) after parturition. Overall mean faecal corticoid concentrations from 3 to 20 days before whelping differed between pregnant and non-pregnant foxes (128+/-3.11 ng/g versus 103+/-5.86 ng/g, respectively; P < 0.01). Furthermore, in pregnant foxes, corticoid excretion increased further from 2 days before to 3 days after whelping (216+/-13.71 ng/g; P < 0.01). Thereafter, corticoid concentrations were similar between pregnant and non-pregnant females (P > 0.05). In sum, the faecal steroid hormone patterns for oestrogens and progestagens were similar to those previously obtained by analyses of fox serum hormones, with both steroids being higher in pregnant than non-pregnant foxes at the end of gestation. The elevation in corticoid concentrations in pregnant females suggests that adrenal activation is involved in the initiation of parturition in the blue fox. Thus, faecal steroid analyses can be used to monitor ovarian activity during pregnancy and pseudopregnancy in farmed blue fox females.     

Validation of water flux and body composition in glaucous gulls (Larus hyperboreus)

Water influx rates (WIR) measured with tritiated water dilution were compared with direct measures of water and energy intake in glaucous gulls (Larus hyperboreus). Total body water (TBW) measured isotopically was also compared with TBW determined by body composition analysis (BCA) of the same birds. Seventeen wild gulls were captured and studied in outdoor enclosures at Ny-Alesund, Svalbard, in July 2002. Gulls were hand-fed known quantities of Arctic cod (Boreogadus saida) or given water on the basis of one of four experimental treatments: (A) fasting, (B) fish only, (C) water only, or (D) fish and water. Water and energy content of Arctic cod was also determined. WIR of gulls (after subtracting metabolic water production) in treatments A, B, C, and D were 0, 101 +/- 5, 62 +/- 19, and 122 +/- 21 SD g d(-1), respectively. Measured water intake in each group was 0, 111 +/- 2, 64 +/- 3, and 134 +/- 15 SD g d(-1), respectively. On average, WIR underestimated measured water intake in each group. Errors were lowest but most variable for gulls fed water only (-2.2% +/- 32.8%) compared with gulls fed fish only (-9.0% +/- 5.4%) or fish and water (-9.0% +/- 7.0%). Compared with measured water intake, errors in WIR were relatively low overall (-6.9% +/- 17.4%) and comparable to previous validation studies. The difference in TBW determined by BCA versus isotopic dilution ranged between -1.02% and +8.59% of mass. On average, TBW measured isotopically (632 +/- 24 g kg(-1)) overestimated true body water by a factor of 1.033.     

The effect of dietary protein level and ration level on excretion of ammonia in common carp,Cyprinus carpio

• 1.1. Nitrogenous excretion in the form of ammonia was determined in common carp of 65.0 ± 8.0 g body weight in metabolism chambers. The fish were fed with 20, 35 and 50% dietary protein at 1, 2 and 3% body weight per day ration level.
• 2.2. Nitrogenous excretion as a percentage of ingested food increased with an increase of dietary protein but decreased with an increase of ration level.
• 3.3. The energy lost in excretion ranged from 4.19% with 20% dietary protein at 3% ration level to 8.74% with 50% dietary at 1% ration level.

     

Absorption,retention and tissue distribution of radiocaesium in reindeer: effects of diet and radiocaesium source

Radiocaesium absorption and retention in reindeer (Rangifer tarandus) calves was compared in groups fed diets containing different proportions of lichen and concentrates, and different chemical forms of radiocaesium ((134)CsCl in solution or fallout from the Chernobyl accident). Daily intakes of fallout radiocaesium were 15-23 kBq, while daily intakes of (134)CsCl ranged from 70 kBq to 1,160 kBq. The half-life for radiocaesium in red blood cells (RBC) in animals fed with a pure lichen diet exceeded that in animals fed with a combined diet of lichen and concentrates by 40% (17.8+/-0.7 days vs. 12.7+/-0.4 days). Corresponding differences in the half-lives for urinary and faecal excretion were about 60% and 40%, respectively. Transfer coefficients (F(f)) to reindeer meat were estimated to be 0.25+/-0.01 days kg(-1) for fallout radiocaesium and 1.04+/-0.03 days kg(-1) for (134)CsCl, reflecting differences in both radiocaesium bioavailability and retention. The bioavailability of the Chernobyl radiocaesium in lichen in 1988 was estimated at ca. 35% compared to (134)CsCl.     

Protein synthesis, RNA concentrations, nitrogen excretion, and metabolism vary seasonally in the Antarctic holothurian Heterocucumis steineni (Ludwig 1898)

Seasonal changes in protein and nitrogen metabolism have not previously been reported in any Antarctic suspension-feeding species that ceases feeding for extended periods in winter. To provide comparison with data reported on Nacella concinna, a species that continues to feed in winter, we have measured feeding activity; oxygen consumption; ammonia, urea, and fluorescamine-positive substance (FPS) excretion; O : N ratios; body wall protein synthesis; RNA to protein ratios; and RNA activity at three times during the year in an Antarctic suspension-feeding holothurian. Feeding activity ceased for 4 mo during winter, and oxygen consumption rates decreased from 8.79+/-0.43 micro mol h(-1) to 4.48+/-0.34 micro mol h(-1). Ammonia excretion also decreased during winter from 2,600+/-177 nmol N h(-1) to 974+/-70 nmol N h(-1), but urea excretion rates increased from 178+/-36 nmol N h(-1) to 281+/-110 nmol N h(-1), while FPS excretion rates remained unchanged throughout the year with a seasonal mean of 88+/-13 nmol N h(-1). Oxygen to nitrogen ratios ranged between 6 and 10, suggesting that proteins were used as the primary metabolic substrate. Body wall protein synthesis rates decreased from 0.35%+/-0.03% d(-1) in summer to 0.23% d(-1) in winter, while RNA to protein ratios decreased from 33.10+/-1.0 microg RNA mg(-1) protein in summer to 27.88+/-1.3 microg RNA mg(-1) protein in winter, and RNA activity was very low, ranging between 0.11+/-0.01 mg protein mg(-1) RNA d(-1) in summer and 0.06+/-0.01 mg protein mg(-1) RNA d(-1) in winter. Heterocucumis steineni shows a larger seasonal decrease in oxygen consumption and ammonia excretion between February (summer) and July (winter) than N. concinna, while the proportional decrease in protein synthesis rates is similar in both species.     

FABP3 and FABP10 in Atlantic salmon (Salmo salar L.)--general effects of dietary fatty acid composition and life cycle variations

The increased use of dietary plant oil supplementation combined with high dietary lipid loads challenges the lipid transport systems of cultivated fish species. Fatty acid binding proteins (FABPs) have been thoroughly studied as intracellular fatty acid transporters in vertebrates, but no data have been reported in Atlantic salmon. In the present study, comparative characterizations were performed, and dietary influence of plant oil supplementation on FABP3 and FABP10 expression was studied for several tissues in two separate dietary trials. In trial I, groups (6 fish each) were fed diets for 42 weeks (body mass 142+/-1 to 1463+/-83 g) (mean+/-S.D.), containing graded levels of rapeseed oil substituting for fish oil using a linear regression design. In trial II, groups (3 fish each) were fed 100% fish oil or 100% plant oil for 22 months (0.160+/-0.052 to 2523+/-590 g) (mean+/-S.D.) and sampled at regular intervals. Liver and muscle tissues appeared to express several FABPs possibly linked to different metabolic functions. FABPs mRNA expression did not change with dietary inclusion of 75% rapeseed oil, whereas FABP3 protein expression seemed to be affected by dietary rapeseed oil inclusion. Significant changes in red muscle FABP3 mRNA expression correlate to significant changes in total beta-oxidation capacity during the energy consuming process of smoltification.     

粪便收集时间和饲料中肉骨粉含量对异育银鲫(Carassius auratus gibelio) 消化率的影响

本研究探讨了通过收集器不同粪便收集时间和饲料中肉骨粉(MBM)含量对异育银鲫干物质、蛋白、能量、磷的表观消化率 (ADC) 影响.不同梯度(0, 20, 40, 60, 80 ,100%)的肉骨粉替代鱼粉(FM) 蛋白配制成六种等氮 (粗蛋白: 410 g/kg) 等能 (总能: 18 kJ/g) 的饲料,通过11周的饲养实验,实验开始后2周开始收集粪便,收集时间分别是:排粪后 1 min, 投喂后4h和16h. 结果表明,干物质、蛋白、能量、磷的消化率明显随粪便收集时间增加而升高(p<0.05),但在高肉骨粉替代饲料中差异不显著(p>0.05). 干物质、蛋白、能量、磷的消化率随饲料中肉骨粉含量的增加呈线性或近线性下降.因此,在消化率测定中应该尽快收集排出的粪便以保证消化率的真实性.消化率是影响肉骨粉利用一个因素.     

建鲤和异育银鲫摄食不同质量饲料时的氮收支和能量收支比较

实验探讨了建鲤和异育银鲫摄食低质和高质饲料时氮和能量的收支情况.低质饲料以豆粕为主要蛋白源,饲料蛋白含量为33.91%,高质饲料以鱼粉为主要蛋白源,饲料蛋白含量为45.59%.55d的生长结果显示,氮收支和能量收支受到饲料质量和鱼类种类的显著影响:摄食低质饲料时,建鲤的生长氮和生长能比例显著低于异育银鲫,排泄氮、排泄能和代谢能比例显著高于异育银鲫;摄食高质饲料时,两种鱼的氮收支和能量收支无显著差异;建鲤的氮收支和能量收支受饲料质量的显著影响,摄食低质饲料时,其生长氮和生长能比例均显著低于摄食高质饲料时,而排泄氮、粪能和代谢能比例均显著高于摄食高质饲料时;异育银鲫的氮收支、生长能和代谢能比例不受饲料质量的显著影响.结果表明,在低质饲料条件下,建鲤利用氮和能量的能力弱于异育银鲫,在高质饲料条件下,两种鱼没有显著差异.与异育银鲫相比,建鲤利用氮和能量的能力受饲料质量的影响更为显著.       

Relationship between bronchopulmonary nematode larvae and relative abundances of Spanish ibex (Capra pyrenaica hispanica) from Castilla-La Mancha, Spain

The excretion of bronchopulmonary nematode infective larvae was evaluated in 160 faecal samples of Spanish ibex (Capra pyrenaica hispanica) collected from 13 populations in Castilla-La Mancha, south-central Spain in September 2003. Intensities and prevalences were compared with pasture availability, abundances of wild and domestic ungulates at both levels, i.e. for populations and for faeces in a two-step procedure. Protostrongylid larvae showed similar infection rates (mean intensity: 1.56+/-0.12, n=94; mean prevalence: 25.62+/-6.86%, n=160) to Dictyocaulus spp. (mean intensity: 1.03+/-0.11, n=48; mean prevalence: 30.00+/-7.11%, n=160). At the population level, positive correlations were found between the prevalences of both bronchopulmonary taxa. The prevalence in both groups, but not intensity, also correlated positively with Spanish ibex abundance indexes both for the populations and individual faeces. These findings suggest that: (i) parasite spreading across Spanish ibex populations in Castilla-La Mancha could respond to host density-dependent processes; and (ii) these populations may have similar exposition and/or susceptibility to both bronchopulmonary taxa resulting in similar host-parasite patterns, despite their different life cycles. Bronchopulmonary outputs in the Spanish ibex from Castilla-La Mancha seems not to represent a health risk for this endemic wild ungulate but may be useful in any health surveillance scheme for the increasing populations of Spanish ibex.     

The influence of circadian rhythms on pre- and post-prandial metabolism in the snake Lamprophis fuliginosus

Measuring standard metabolic rate (SMR) and specific dynamic action (SDA) has yielded insight into patterns of energy expenditure in snakes, but less emphasis has been placed on identifying metabolic variation and associated energy cost of circadian rhythms. To estimate SMR, SDA, and identify metabolic variation associated with circadian cycles in nocturnally active African house snakes (Lamprophis fuliginosus), we measured oxygen consumption rates (VO2) at frequent intervals before and during digestion of meals equaling 10%, 20% and 30% of their body mass. Circadian rhythms in metabolism were perceptible in the VO2 data during fasting and after the initial stages of digestion. We estimated SMR of L. fuliginosus (mean mass=16.7+/-0.3 g) to be 0.68+/-0.02 (+/-SEM) mL O2/h at 25 degrees C. Twenty-four hours after eating, VO2 peaked at 3.2-5.3 times SMR. During digestion of meals equaling 10-30% of their body mass, the volume of oxygen consumed ranged from 109 to 119 mL O2 for SMR, whereas extra oxygen consumed for digestion and assimilation ranged from 68 to 256 mL O2 (equivalent to 14.5-17.0% of ingested energy). The oxygen consumed due to the rise in metabolism during the active phase of the daily cycle ranged from 55 to 66 mL O2 during digestion. Peak VO2, digestive scope, and SDA increased with increasing meal size. Comparisons of our estimates to estimates derived from methods used in previous investigations resulted in wide variance of metabolic variables (up to 39%), likely due to the influence of circadian rhythms and activity on the selection of baseline metabolism. We suggest frequent VO2 measurements over multiple days, coupled with mathematical methods that reduce the influence of undesired sources of VO2 variation (e.g., activity, circadian cycles) are needed to reliably assess SMR and SDA in animals exhibiting strong circadian cycles.     

How important is milk for near-weaned red kangaroos (<Emphasis Type="Italic">Macropus rufus</Emphasis>) fed different forages?

Red kangaroos (Macropus rufus) are large (>20 kg) herbivorous marsupials common to the arid and semi-arid regions of inland Australia, where drought is frequent. Young-at-foot (YAF) red kangaroos are the age/size class usually most affected by drought. Kangaroos at this YAF stage are making the transition from a milk-based diet to one of herbivory and an inability to adequately digest high-fibre feeds may contribute to their high mortalities during drought. We examined the role of milk in the nutrition of YAF red kangaroos fed forages of different fibre content and evaluated it as an extra energy and/or nitrogen source. Milk intake had little impact on the digestion of herbage by YAF red kangaroos fed low-fibre chopped lucerne (alfalfa) hay. Organic matter (OM) intake was 210+/-20 g day(-1) and 228+/-22 g day(-1), respectively, by YAF fed lucerne and lucerne with milk. Apparent digestibility of lucerne OM was ca. 55%, regardless of milk intake. Fed lucerne, with and without milk, YAF sustained growth rates of ca. 45 g day(-1). Conversely, even with a milk supplement, YAF red kangaroos ingested only 90+/-11 g day(-1) of high-fibre chopped oaten hay, of which they digested only ca. 36%. Despite milk intake, YAF fed chopped oaten hay lost between 0 and 75 g body mass day(-1) and were in negative nitrogen balance (-0.40+/-0.11 g N day(-1)). On all diets nitrogen loss was primarily as endogenous nitrogen (urinary and faecal) rather than as dietary nitrogen. Endogenous nitrogen losses were elevated in YAF fed chopped oaten hay, primarily as non-dietary faecal nitrogen. Overall, when high-quality feed was available, YAF were not markedly dependent on milk. However, YAF fed poor-quality chopped oaten hay would require up to 540 ml day(-1) of late-stage kangaroo milk to attain intakes of energy and nitrogen, and hence growth rates, comparable with those YAF fed lucerne.     

Blood-sucking bugs as a gentle method for blood-collection in water budget studies using doubly labelled water

During doubly-labelled water (DLW) experiments, blood collection by venous puncture may traumatize animals and consequently affect the animals' behaviour and energy budget. Recent studies have shown that blood-sucking bugs (Triatominae; Heteroptera) can be used instead of conventional needles to obtain blood from animals. In this paper, we validate the bug method in captive nectar-feeding bats, Glossophaga soricina, for water budget analysis by comparing the daily water flux estimated with the DLW method with values measured by an energy balance method. As the mean daily water flux of the DLW method was not significantly deviating from the expected value, blood-sucking bugs may substitute more invasive methods of blood collection in DLW experiments. Based on the DLW estimates, daily energy and water intake rates were calculated and compared to values measured with the energy balance method. The DLW method and the energy balance method yielded on average similar results regarding the daily energy intake (DLW method: 48.8+/-14.2 kJ d(-1) versus energy balance method: 48.1+/-9.9 kJ d(-1)) and daily water intake (DLW method: 13.7+/-2.4 mL d(-1) versus energy balance method: 14.7+/-3.0 mL d(-1)). Based on the calculated water and sugar intake per day, we estimated the sugar concentration of ingested nectar to equal on average 16.2+/-2.4% (mass/mass), which fell close to the measured sugar concentration of 17% (mass/mass) bats fed on during the experiment. We conclude that it is possible to extrapolate mean daily energy and water intake for animal groups, populations and species based on DLW estimates, but due to the large variance of results (low accuracy), it seems inadequate to calculate values for single individuals.     

Ingestion,egestion, excretion,growth, and conversion efficiency for the mummichog, Fundulus heteroclitus (L.)

The food conversion efficiency of Fundulus heteroclitus (L.) was measured in terms of calories and nitrogen for three diets: Palaemonetes sp., Nereis sp., and Uca pugnax. Fish were allowed to feed ad libitum for 30–60 min each day. Growth, ingestion, egestion, and excretion were measured for fish fed each diet. The growth rates of Fundulus heteroclitus fed two of the single item diets of invertebrates were higher than growth rates previously estimated for mummichogs from the natural population in Canary Creek marsh. In comparison with other fish species, F. heteroclitus was found to have a higher than average assimilation efficiency ($\text{X}\text{?}\text{= 87\%}$ for all three diets) and a lower than average gross growth efficiency (≈12% for two of the diets). Metabolic costs accounted for an average of 69% of ingested energy. Excretion rates were also large, with excretion accounting for more energy than egestion in two of the three diets.