Energy intake and milk production in mink (MUSTELA vison)‐effect of litter size

Energy intake and milk production were measured in 12 mink dams raising litters of 3, 6 and 9 kits one to four weeks post partum by means of balance experiments and measurements of milk intake of the kits by the water isotope dilution technique. The dams were fed ad libitum on a conventional wet mink diet (DM: 323 g/kg; CP: 173 g/kg; ME: 4.4 MJ/kg). Milk samples collected from dams with corresponding litter sizes and lactation weeks, and body composition of kits nursed by these dams, were analysed for content of DM, ash, N and fat. The ME and drinking water consumption were higher in dams nursing 9 kits than in dams nursing 3 kits. The N and water balances as well as the live weight of dams were not affected by litter size. Daily milk production was higher in dams nursing 9 kits than in dams nursing 3 kits. The DM, N and fat content of the milk increased during lactation, but were not affected by litter size. Individual kit live weight was higher in litters of 3 than in litters of 6 and 9 kits four weeks post partum. The DM and fat content of the kits were lowest in kits from litters of 9 kits, whereas these kits had the highest protein content. Daily ME for maintenance of kits and the efficiency of utilisation of ME in milk for body gain were estimated to 356 kJ/kg^0.75, k_p ≈0.53 and k_f ≈0.71, respectively. In conclusion, daily milk production increased with increasing litter size, but not in proportion to the number of kits, indicating that milk production limits the growth rate of the young. In the fourth week of lactation, milk production was not different between dams nursing 6 or 9 kits, indicating a maximum capacity.     

Utilization of milk energy by suckling mink kits

A total of 36 mink dams and their litters of 3, 6 or 9 kits were used for determination of milk intake of the suckling young by means of deuterium dilution technique, and chemical composition of milk and of kit bodies. Measurements were performed during lactation weeks 1?–?4, each week with 3 dams with each litter size. Milk intake was determined over a 48?h measurement period, and by the end of this milk samples were collected and 2 kits (litters of 6 and 9) or 1 kit per litter (litters of 3) were killed for body chemical composition. Based on the results, different models were applied for calculation of the energetic efficiency of milk. Dam milk yield increased steadily from week 1 until week 3 but only slightly from week 3 to 4. The increase declined with increasing litter size, and for dams suckling 9 kits the increment from week 3 to week 4 was only 2?g. The dry matter content of milk increased significantly as lactation progressed, being reflected in crude protein increasing from 6.9% in lactation week 1 to 8.1% in week 4. Milk fat increased concomitantly from 5.6% to 8.0%. In kit bodies, crude protein content increased from 9.4% in week 1 to about 12% in weeks 3 and 4. Body fat content increased from week 1 (4.1%) to week 3 (8.4%) and then declined in week 4 (7.1%). Animals suckled in litters of 3 kits had the highest milk intake and live weight and kits suckled in litters of 9 had the lowest milk intake, live weight and daily gain. In terms of milk intake per g gain kits in litters of 6 were the most efficient, with 4.1?g milk per g body gain. The metabolizable energy requirement for maintenance (MEm) was estimated to 448 kJ/kg^0.75 and the efficiency of utilization of ME for body gain (k_g) to 0.67, the estimates being higher (MEm) or in good agreement with previous findings (k_g) in suckling mink kits.     

Milk intake,growth and energy consumption in pups of ice-breeding grey seals (Halichoerus grypus) from the Gulf of St. Lawrence,Canada

In this study we document growth, milk intake and energy consumption in nursing pups of icebreeding grey seals (Halichoerus grypus). Change in body composition of the pups, change in milk composition as lactation progresses, and mass transfer efficiency between nursing mothers and pups are also measured. Mass transfer efficiency between mother-pup pairs (n=8) was 42.5±8.4%. Pups were gaining a daily average of 2.0±0.7 kg (n=12), of which 75% was fat, 3% protein and 22% water. The total water influx was measured to be 43.23±8.07 ml·kg^-1·day^-1. Average CO₂ production was 0.85±0.20 ml·g^-1·h^-1, which corresponds to a field metabolic rate of 0.55±0.13 MJ·kg^-1·day^-1, or 4.5±0.9 times the predicted basal metabolic rate based on body size (Kleiber 1975). Water and fat content in the milk changed dramatically as lacation progressed. At day 2 of nursing, fat and water content were 39.5±1.9% and 47.3±1.5%, respectively, while the corresponding figures for day 15 were 59.6±3.6% fat and 28.4±2.6% water. Protein content of the milk remained relatively stable during the lactation period with a value of 11.0±0.8% at day 2 and 10.4±0.3% at day 15. Pups drank an average of 3.5±0.9 kg of milk daily, corresponding to a milk intake of 1.75 kg per kg body mass gained. The average daily energy intake of pups was 82.58±19.80 MJ, while the energy built up daily in the tissue averaged 61.72±22.22 MJ. Thus, pups assimilated 74.7% of the energy they received via milk into body tissue. The lactation energetics of ice-breeding grey seals is very similar to that of their land-breeding counterparts.Abbreviations bm body mass - BMR basal metabolic rate - FMR field metabolic rate - IU international unit - RQ respiration quotient - HTO tritiated water - HT¹⁸O doubly labeled water - TBW total body water - VHF very high frequency     

Utilization of milk energy by suckling mink kits

A total of 36 mink dams and their litters of 3, 6 or 9 kits were used for determination of milk intake of the suckling young by means of deuterium dilution technique, and chemical composition of milk and of kit bodies. Measurements were performed during lactation weeks 1-4, each week with 3 dams with each litter size. Milk intake was determined over a 48 h measurement period, and by the end of this milk samples were collected and 2 kits (litters of 6 and 9) or 1 kit per litter (litters of 3) were killed for body chemical composition. Based on the results, different models were applied for calculation of the energetic efficiency of milk. Dam milk yield increased steadily from week 1 until week 3 but only slightly from week 3 to 4. The increase declined with increasing litter size, and for dams suckling 9 kits the increment from week 3 to week 4 was only 2 g. The dry matter content of milk increased significantly as lactation progressed, being reflected in crude protein increasing from 6.9% in lactation week 1 to 8.1% in week 4. Milk fat increased concomitantly from 5.6% to 8.0%. In kit bodies, crude protein content increased from 9.4% in week 1 to about 12% in weeks 3 and 4. Body fat content increased from week 1 (4.1%) to week 3 (8.4%) and then declined in week 4 (7.1%). Animals suckled in litters of 3 kits had the highest milk intake and live weight and kits suckled in litters of 9 had the lowest milk intake, live weight and daily gain. In terms of milk intake per g gain kits in litters of 6 were the most efficient, with 4.1 g milk per g body gain. The metabolizable energy requirement for maintenance (MEm) was estimated to 448 kJ/kg(0.75 and the efficiency of utilization of ME for body gain (kg) to 0.67, the estimates being higher (MEm) or in good agreement with previous findings (kg) in suckling mink kits.     

Energy intake and utilisation by nursing bearded seal (Erignathus barbatus) pups from Svalbard,Norway

In this study we measure energy intake via milk in nursing bearded seal (Erignathus barbatus) pups and determine how this energy is allocated into metabolism and storage of new tissues. This was accomplished using longitudinal mass gain records and the doubly labelled water technique on nursing pups in combination with cross-sectional data on changes in milk composition from bearded seal mothers. The pups (n=3) were all less than a week old at the start of the experiments. Pups gained 3.3±0.4 kg·day^-1 of which 50% was fat, 14% protein and 36% water. Average daily water influx for the pups was 69.5±9.0 ml · kg^-1· day^-1. Average CO₂ production during the study period was 0.99±0.10 ml·g^-1·h^-1, which corresponds to a field metabolic rate of 642±67 kJ·kg^-1· day^-1, or 6.0±0.5 times the predicted basal metabolic rate according to Kleiber (1975). The pups drank an average of 7.6±0.5 kg of milk daily. This corresponds to a daily energy intake of 154±8 MJ, 47±14% of which was stored as new body tissue. Despite this high energy intake bearded seal pups do not get as fat as do other nursing phocids. This is in part due to their larger body size but also due to their very active aquatic lifestyle and the lower and more consistent fat content of the milk compared to other phocid species. Bearded seal mothers forage during lactation and may also be involved in teaching their pups to feed independently. All these data suggest that the lactation strategy of bearded seals differs from the phocid norm.     

Influence of daylength on metabolic rate and daily water loss in the male prosimian primate Microcebus murinus

In its natural habitat, Microcebus murinus, a small malagasy prosimian primate, is exposed to seasonal shortage of water and resources. During the winter dry season, animals enter a pronounced fattening period with concurrent decrease in behavioural/physiological activities, whereas the breeding season is restricted to the rainy summer months. To determine the role of daylength on metabolic rate and water loss in this nocturnal primate, we measured body mass, oxygen consumption at 25°C (RMR), circadian water loss through urine output (UO) and evaporation (EWL) in eight males exposed to either short days (8L:16D SD) or long days (14L:10D LD), under controlled captive conditions. Exposure to SD led to a ponderal increase (maximal body mass: 125±4 g, N=8), and to significant changes in RMR and water loss, both reaching lowest values after 3 months under SD (0.84±0.04 ml O₂ h⁻¹ g⁻¹ and 38±0.3 mg H₂O g⁻¹ day⁻¹, respectively). Following exposure to LD, body mass decreased to 77±3 g (N=8), whereas both RMR and water loss, mainly through EWL, significantly increased (P<0.001), the highest value occurring after 2 months (1.51±0.08 ml O₂ h^.−1 g⁻¹ and 87±7 mgH₂O g⁻¹ day⁻¹, respectively). Moreover, independent of daylength, circadian changes in EWL were characterized by significantly reduced values during the diurnal rest. The results demonstrate that daylength variations affect the physiology of this tropical primate, allowing anticipatory adaptation to seasonal environmental constraints.     

Activity,milk intake and energy consumption in free-living ringed seal (Phoca hispida) pups

Measurements of growth, activity and energy consumption and estimates of milk intake were made in free-living, nursing ringed seal (Phoca hispida) pups. This was accomplished through the simultaneous use of time-depth recorders and the doubly labelled water technique. The pups spent an average of 52±7% of their time hauled out on the ice, 37±5% of the time in the water at the surface, and 11±5% of the time diving. Average daily mass gain of the pups (n=3) throughout the duration of the study period was 0.35±0.08 kg. The composition of the mass gain was 76% fat, 6% protein and 18% water. The total water flux was measured to be 52±10 ml·kg^-1·day^-1. Average CO₂ production was 0.85±0.16 ml·g^-1·h^-1, corresponding to a field metabolic rate of 0.55±0.10 MJ·kg^-1·day^-1, or 3.8±0.6 times the predicted basal metabolic rate based on body size (Kleiber 1975). Average daily milk intake was estimated to be 1379±390 ml. The field metabolic rate for the different components of seal pup activity budgets were calculated to be FMR_{haul out}=1.34 BMR, FMR_surface=6.44 BMR, and FMR_diving=5.88 BMR.Abbreviations BMR basal metabolic rate - FMR field metabolic rate - HTO tritiated water - HT¹⁸O doubly labelled water - RQ respiration quotient - SDA specific dynamic action - TDR time-depth recorder     

Ionic and osmotic regulation capabilities of juvenile Gulf of Mexico sturgeon, Acipenser oxyrinchusde sotoi

The salinity tolerance, and hydromineral regulation capabilities of three size groups (small 110–170 g; medium 230–290 g, large 460–700 g; n=48 for each group) of 13-month-old juvenile Gulf of Mexico sturgeon were investigated. Fish (n=6 for each salinity) were transferred directly from freshwater (FW) to a series of experimental salinity treatments (0, 5, 10, 15, 20, 25, 30, and 35 parts per thousand (ppt)). Fish were also acclimated in brackish water (20 ppt) for 2 weeks and transferred to a salinity of 34 ppt. In this condition juvenile Gulf of Mexico sturgeon adapted to saltwater (SW) and maintained their hydromineral balance. FW adapted sturgeon (n=6) had an average blood hemotocrit of 28.2±0.8%, plasma osmolality of 260.7±1.6 mOsm kg⁻¹ H₂O, and plasma ion concentrations of 135.7±1.2 mM l⁻¹ Na⁺, 106.9±1.9 mEq l⁻¹ Cl⁻, and 2.9±0.1 mM l⁻¹ K⁺. In SW adapted sturgeon (n=8) blood parameters averaged 26.9±0.7% for hematocrit, 294.2±2.3 mOsm kg⁻¹ H₂O for osmolality, 152.0±1.7 mM l⁻¹ Na⁺, 149.2±1.4 mEq l⁻¹ for Cl⁻, and 3.1±0.1 mM l⁻¹ K⁺. The method of transfer (abrupt or slow acclimation) directly affected fish survival and the time they took to achieve ionic and osmotic regulation. This SW adaptation appears to be related to body size, the larger the fish the easier the adaptation process. A threshold size of about 170 g was apparent for the fish to adapt to saltwater after 2 weeks of acclimation. Chloride cells were present in both FW and SW adapted sturgeon with SW and brackish water fish having chloride cells significantly (P<0.05) more numerous (561±53 and 598±45 cells mm⁻²) and larger in size (41.0±3.85 and 34.2±4.49 μm²) than FW adapted sturgeon (10±1.0 cells mm⁻² and 22±2.53 μm²). Few chloride cells were observed in the opercular membrane, however, none were found in the pseudobranch and spiracle.     

Physiological energetics of the green abalone, Haliotis fulgens, fed on a balanced diet

A regression of different physiological responses against body size enables populations or stock cultures of various size ranges to be compared. Thus, the aim of the present work was to evaluate the physiological responses from juvenile green abalone (Haliotis fulgens), grouped according to size, in a standard controlled culture condition within their optimal range to create the balanced growth equation within an allometric relation, providing a basic framework for physiological research into H. fulgens. Feed intake, absorption efficiency, respiration and excretion were measured as functions of dry tissue weight (DTW) in juvenile abalone acclimated on a balanced diet. The daily feed intake (I) was related to body mass by the relationship I (mg day⁻¹)=24.25W^0.59. Absorption efficiency averaged 87% and was independent of body size. The equation relating daily respiration rate (R) to body mass was R (ml O₂ day⁻¹)=12.013W^0.704, including night correction. The rate of ammonia excretion (U) was related to dry tissue weight by the equation U (μmol N-NH₄ day⁻¹)=43.57W^0.85. The energetic value of food was 18.8 J mg⁻¹. The low feeding activity (<1% of abalone live weight per day) was compensated for by a relatively high absorption efficiency and a depression of 23% in the metabolic rate during diurnal activity. Gross and net growth efficiencies were constant throughout the size range, with average values of 36.4% and 41.5%, respectively. Values of the O/N ratio, with an average of 31.5, showed a higher use of proteins from the diet as an energy source for the size range studied.     

Interactions of feeding rates on growth,food conversion and body composition of the freshwater catfish Mystus vittatus (Bloch)

Food intake, growth, conversion efficiency and body composition of the non-air breathing catfish Mystus vittatus (Bloch) were studied in relation to different feeding levels. Fish weighing 817.9 ± 104.00 mg was found to consume a maximum of 156.0 mg live Tubifex worm/g day^-1. Geometrically derived feeding rates of 6.75, 23.00 and 26.00 mg dry food/g live fish day^-1 represent the maintenance, optimum and maximum levels respectively. The SDA increased from 6.75 mg/g day^-1 at maintenance to 13.50 mg/g day^-1 at maximum feeding rate. Starvation brougt about increase in body water content, while there was concomitant decrease in fat and crude protein.     

Effects of feeding propylene glycol to mid-lactating dairy cows

Propylene glycol (PG) is a gluconeogenic precursor widely used to prevent and treat ketosis postpartum. The study has investigated the effects of PG administration to dairy cows at mid stage of lactation. According to a 3 × 3 latin square design, three Italian Brown lactating cows (125 ± 7 days in milk) fitted with rumen cannula were fed a corn silage based diet (CP 14.7%, NDF 41.1% DM) with 0, 200 or 400 g day⁻¹ PG added. Dry matter intake was increased by feeding PG with a significant quadratic component per dose (16.2, 17.2 and 16.5 kg day⁻¹ for 0, 200 and 400 g PG day⁻¹, respectively). Milk yield was not affected by PG, averaging 17.1 kg day⁻¹. Average daily gain increased from 64 to 206 and 302 g day⁻¹ when cows received 200 and 400 g day⁻¹ of PG (linear component per dose P < 0.05). Digestibility of the diet did not differ among treatments, whereas repeated rumen fluid samples, taken 0, 2, 4, 6 and 8 h after the meal, showed a consistently lower acetate to propionate ratio when feeding PG. Blood insulin was not affected by PG administration. Except for therapeutic treatments, PG administration to dairy cows at mid stage of lactation should be advised against. Despite the positive effect on intake, administration of the additive, increasing the molar percentage of rumen propionate, contributes to shift the energy partition from milk production to liveweight gain.     

Dietary Exposure to Lead and Cadmium in Sweden

Abstract

A duplicate diet study on male and female pensioners in 1970–71 showed mean daily dietary lead intakes of 30 μg and 19 μg respectively. The corresponding cadmium intakes were 10.5μg and 12.9 μg. Analysis of duplicate diets collected during seven consecutive 24-hour periods from 15 women in Stockholm in 1988 showed a mean daily lead intake of 26 μg (range 13–40 μg). The corresponding cadmium intake was 8.5μg (range 5.7–14 μg). Analysis of faeces samples corresponding to the duplicate diets showed similar lead and cadmium contents (mean lead content 24 μg day^?1, range 10–41 μg day^?1; mean cadmium content 8.9 μg day^?1 range 5.5–12 μg day^?1). The median lead and cadmium concentrations in human milk collected in Uppsala were 2 μg kg^?1 and 0.1 mg kg^?1 respectively. The median weekly intakes of lead and cadmium by the breast-fed infants were calculated to be 2 μg kg^?1 body weight and 0.1 μg kg^?1 body weight. Analysis of seven daily diets, together representing the weekly diet of an adult Swedish male, showed a mean lead content of 26 μg (range 15–45 μg), and a mean cadmium content of 10 μg (range 7–15 μg). The mean daily intakes of lead and cadmium found by analysing market baskets prepared in 1987 were 17μg and 12μg respectively. Calculations based on food balance sheet data and levels of lead and cadmium in individual foods showed mean daily intakes of 30 μg lead and 14 μg cadmium per person.     

Effect of farm and simulated laboratory cold environmental conditions on the performance and physiological responses of lactating dairy cows supplemented with bovine somatotropin (BST)

A study was conducted to evaluate the effect of bovine somatotropin (BST) supplementation in twelve lactating dairy cows maintained in cold environmental conditions. Six cows were injected daily with 25 mg of BST; the other six were injected with a control vehicle. Cows were maintained under standard dairy management during mid-winter for 30 days. Milk production was recorded twice daily, and blood samples were taken weekly. Animals were then transferred to environmentally controlled chambers and exposed to cycling thermoneutral (15° to 20° C) and cycling cold (–5° to +5° C) temperatures for 10 days in a split-reversal design. Milk production, feed and water intake, body weights and rectal temperatures were monitored. Blood samples were taken on days 1, 3, 5, 8 and 10 of each period and analyzed for plasma triiodothyronine (T³), thyroxine (T⁴), cortisol, insulin and prolactin. Under farm conditions, BST-treated cows produced 11% more milk than control-treated cows and in environmentally controlled chambers produced 17.4% more milk. No differences due to BST in feed or water intake, body weights or rectal temperatures were found under laboratory conditions. Plasma T³ and insulin increased due to BST treatment while no effect was found on cortisol, prolactin or T⁴. The results showed that the benefits of BST supplementation in lactating dairy cows were achieved under cold environmental conditions.     

Differences in productive robustness in rabbits selected for reproductive longevity or litter size

The aim of this work was to evaluate the ability of a line selected for reproductive longevity (LP) to confront productive challenges compared to a line selected during 31 generations for litter size at weaning (V). A total of 133 reproductive rabbit does were used (72 and 61 from LP and V lines, respectively). Within each line, three groups with different levels of productive effort were planned: PP9, inseminated at day 4 after the first partum and with nine kits during the second partum, and inseminated after first weaning (30 days) and with nine (PW9) or five kits (PW5) during the second partum. The reproductive performance, body condition (perirrenal fat thickness (PFT)) and lipolytic response were controlled. LP does showed greater mean live weight (LW; +128 g; P < 0.05), PFT (+0.47 mm; P < 0.05) and estimated body energy (EBE; +0.29 MJ/kg; P < 0.01) than V does at second partum. However, LP does that mated at first post partum did not significantly differ in EBE relative to V does at second partum. During the first week of lactation, dry matter (DM) intake was similar for both lines (94 and 95 g DM/kg LW0.75 day for V and LP does, respectively). There was a significant difference in milk yield between both lines during the first week when litter size was nine (60 v. 54 g of milk/kg LW0.75 day for LP and V does, respectively; P < 0.01), but no difference when litter size was five. Consequently, when litter size was nine, LP does showed a lower recovery of PFT (0.6 mm less; P < 0.05) than V does during the first 10 days of lactation. However, when litter size was five, LP does showed a higher LW (+210 g; P < 0.05) than V does at 10 days of lactation and a similar recovery of PFT. During the last 3 weeks of the lactation, LP does showed a higher feed intake (+6 g DM/kg LW0.75 day; P < 0.05) and milk yield (+27 g/day; P < 0.001) than V does when litter size was nine, resulting in no significant differences in LW at 30 days of lactation. However, when litter size was five, both lines showed similar feed intake and milk yield, maintaining their differences in LW at 30 days of lactation (+206 g for LP does; P < 0.05). These results show that the rabbit line selected for reproductive longevity is more robust with respect to coping with productive challenges, than a line selected for reproductive intensity.     

Potential use of radiography for measuring feed intake of southern rock lobster (Jasus edwardsii)

The potential of using radiography for measuring feed intake in southern rock lobster Jasus edwardsii (Hutton) was evaluated. Lobsters (14-40 g) readily consumed feeds containing radio-opaque marker (400—450 μm). Marker particles were clearly identified in the stomach 90 min after feeding enabling feed intake to be estimated. Initially low estimates (15±17%; mean±S.D.) of feed intake (expressed as percentage of gravimetric estimates) were recorded due to loss of markers prior to ingestion. Radiographic estimates improved (100±23%; mean±S.D.) when changes to pellet diameter (1.5 mm), moisture content (11%) and binding agent (alginate) were made. Thus, estimates were dependent on pellet diameter and resistance to fragmentation prior to ingestion. To test for the presence of feeding hierarchies in groups of lobsters an experiment was conducted to examine the effect of ration level (high ration: 2.0% BW day⁻¹ and low ration: 0.2% BW day⁻¹) on intra-individual (measured as coefficient of variation for feed intake: CV_C) and inter-individual variation (measured as mean share of the group meal: MSM%). There was a significant (P<0.05) negative correlation between CV_C and MSM% for the low ration treatments which indicated that small lobsters (CV_C=114±19% and MSM%=22±10%: mean±S.D.) were less successful than large lobsters (CV_C 44±11% and MSM%=41±13%: mean±S.D.) at obtaining feed. This may be indicative of the formation of feeding hierarchies.     

Utilization of milk amino acids for body gain in suckling mink (Mustela vison) kits

The efficiency of utilization of milk amino acids for body gain in suckling mink kits from small (n = 3), medium (n = 6) and large litters (n = 9) was investigated by using 36 mink dams and their litters for measurements during lactation weeks 1 through 4. Measurements on each dam and litter were performed once, hence three dams per litter size each week (n = 9). Individual milk intake of kits was determined, milk samples were collected and kits were killed for determination of amino acid composition. The most abundant amino acids in milk were glutamate, leucine and aspartate making up about 40% of total amino acids. Branched chained amino acids made up slightly more than 20% and sulphur containing amino acids less than 5% of total milk amino acids. In kit bodies the sum of glutamate, aspartate and leucine made up about 32% of amino acids, branched chain amino acids about 16% and sulphur containing amino acids about 4%. The amino acid composition of both milk and bodies changed as lactation progressed with decreasing proportions of essential amino acids. The ratio between body and milk amino acids was constantly over 1 only for lysine, suggesting that it was the most limiting amino acid in mink milk. Milk amino acids were efficiently utilized during week 1, ranging from 74.7% (lysine) to 42.1% (leucine), with an average for essential amino acids of 58.4%. Tendencies for improved utilization of lysine (74.7-78.2%), phenylalanine (61.0-70.0%), histidine (62.4-68.8%), arginine (61.3-70.4%) and all essential amino acids (58.4-60.2%) from week 1 to week 2 were recorded. During weeks 3 and 4, the efficiency declined, and for all essential amino acids the average utilization was 38.1% during week 4.     

Transfer of Cl from herbage into tissues and milk products of dairy cattle and pigs

Cl-36 is an important component of nuclear waste. The concentrations of stable chlorine (Cl) in pig and cow tissues were measured to provide information which can be used to parameterize models of ³⁶Cl transfer into agricultural animals. The concentration of stable Cl in cows’ milk was 1.0 ± 0.2 g L⁻¹, in cow muscle it was 0.7 ± 0.2 g kg⁻¹ wet mass (wm) and in pig muscle 0.4 ± 0.1 g kg⁻¹ wm. The concentration of stable Cl in cow and pig liver was 0.9 ± 0.3 g kg⁻¹ wm, which was about two-fold higher than that in the kidney and lung. Due to homeostatic control, stable Cl concentrations in animal tissues are not related to the amount ingested daily in herbage at intake rates in the normal physiological range of up to 188 g day⁻¹ for cows and up to 40 g day⁻¹ for pigs. Therefore, the commonly used transfer coefficient is not suitable for use in quantifying the transfer of ³⁶Cl to milk and meat. Since the metabolism of stable Cl and ³⁶Cl in an animal’s body is identical, the average equilibrium ratios of ³⁶Cl to stable Cl in the daily ration (³⁶Cl (g kg⁻¹)/Cl (g kg⁻¹)) and animal tissues will be the same. We therefore conclude that the average equilibrium Cl isotopic ratio in the dietary daily intake should be used to predict the contamination of meat and milk with ³⁶Cl.     

Field metabolic rate and water turnover of the numbat (<Emphasis Type="Italic">Myrmecobius fasciatus</Emphasis>)

The numbat (Myrmecobius fasciatus) is a diurnal and exclusively termitivorous marsupial. This study examines interrelationships between diet, metabolic rate and water turnover for wild, free-living numbats. The numbats (488±20.8 g) remained in mass balance during the study. Their basal metabolic rate (BMR) was 3.6 l CO₂ day^–1, while their field metabolic rate (FMR) was 10.8±1.22 l CO₂ day^–1 (269±30.5 kJ day^–1). The ratio FMR/BMR was 3±0.3 for numbats. We suggest that the most accurate way to predict the FMR of marsupials is from the regression log FMR=0.852 log BMR+0.767; (r²=0.97). The FMR of the numbat was lower than, but not significantly different from, that of a generalised marsupial, both before (76%) and after (62–69%) correction for the significant effect of phylogeny on FMR. However the numbat's FMR is more comparable with that of other arid-habitat Australia marsupials (98–135%), for which the regression relating mass and FMR is significantly lower than for nonarid-habitat marsupials, independent of phylogeny. The field water turnover rate (FWTR) of free-living numbats (84.1 ml H₂O day^–1) was highly correlated with FMR, and was typical (89–98%) of that for an arid-habitat marsupial after phylogenetic correction. The higher than expected water economy index for the numbat (FWTR/FMR=0.3±0.03) suggests that either the numbats were drinking during the study, the water content of their diet was high, or the digestibility of their termite diet was low. Habitat and phylogenetic influences on BMR and FMR appear to have pre-adapted the numbat to a low-energy termitivorous niche.Abbreviations BMR basal metabolic rate - FMR field metabolic rate - EWL evaporative water loss - FWTR field water turnover rate - MR metabolic rate - PVR phylogenetic vector regression - RER respiratory exchange ratio - T_a ambient temperature - T_b body temperature - TBW total body water - CO₂ rate of carbon dioxide production - O₂ rate of oxygen consumption - WEI water economy index - WER water efflux rate - WIR water influx rateCommunicated by I.D. Hume     

Feeding, respiration and life history of the hyperiid amphipod Themisto libellula in the Arctic marginal ice zone of the Greenland Sea

Daily ingestion rates of the pelagic hyperiid amphipod Themisto libellula were studied in the marginal ice zone of the Arctic Fram Strait by feeding experiments, respiration measurements and an allometric approach based on body mass. Amphipods were collected by stratified multiple opening/closing net hauls and Rectangular Midwater Trawl (RMT 8) in August 2000 during the expedition ARK XVI/2 of R/V “Polarstern”. T. libellula occurred with abundances of 0.043 and 0.015 ind. m⁻³ in the upper 30 m of the water column at two RMT 8 stations. Based on respiration data, the daily ingestion necessary to cover metabolic energy demands measured 1.9±0.6% of body carbon per day. Actual prey consumption during feeding experiments with Calanus copepodids as prey was very similar and accounted for 1.9±1.5% day⁻¹, indicating that feeding on Calanus can meet the energy demands of T. libellula. In general, experimental results were slightly lower than the maximum potential ingestion (2% day⁻¹ for an individual of median body dry mass of 32 mg) estimated by an allometric equation based on body mass, but feeding experiments showed a strong variability. Reduced metabolism and low ingestion rates of T. libellula are consistent with low ambient temperature, large body size, slow growth and long life span of this polar species. The effect of the active pelagic life style of T. libellula on metabolism and ingestion rate is discussed in comparison to the sympagic (i.e. ice-associated) amphipod Gammarus wilkitzkii of similar body size living in the same environment. In relation to the mesozooplankton biomass in the investigation area, the predation impact by T. libellula was low. However, high-Arctic conditions also limit the secondary production of principal prey species, such as Calanus glacialis and Calanus hyperboreus, so that even low predation rates may affect the growth of prey populations.     

Cultivation of Chlorella pyrenoidosa in soybean processing wastewater

Chlorella pyrenoidosa was cultivated in soybean processing wastewater (SPW) in batch and fed-batch cultures without a supply of additional nutrients. The alga was able to remove 77.8 ± 5.7%, 88.8 ± 1.0%, 89.1 ± 0.6% and 70.3 ± 11.4% of soluble chemical oxygen demand (SCOD_Cr), total nitrogen (TN), NH₄⁺-N and total phosphate (TP), respectively, after 120 h in fed-batch culture. C. pyrenoidosa attained an average biomass productivity of 0.64 g L⁻¹ d⁻¹, an average lipid content of 37.00 ± 9.34%, and a high lipid productivity of 0.40 g L⁻¹ d⁻¹. Therefore, cultivation of C. pyrenoidosa in SPW could yield cleaner water and useful biomass.