Transit time and digestibility of two experimental diets in the maned wolf (Chrysocyon brachyurus) and domestic dog (Canis lupus)

Recent research involving nutritional management of clinical disease secondary to cystinuria in captive maned wolves (Chrysocyon brachyurus) in the United States resulted in the production of a commercially manufactured maintenance diet and subsequently, a further modified experimental diet. These two diets differed only in their protein sources and sodium concentrations. The purpose of this study was to further investigate these diets by determining their digestibility and transit time in maned wolves, and also to compare these results to the digestibility and transit time of the diets in domestic dogs. The experiment consisted of two diets (maned wolf commercial maintenance diet and experimental diet) and two species (maned wolf and domestic dog [beagle]) arranged as a 2 × 2 factorial design. For the transit time study, titanium dioxide (TiO₂, 5 g/kg diet) was administered as a pulse dose and total collection of feces was carried out for 50 hr. There was no effect of diet or species on initial Ti recovery time (IRT), the amount of Ti recovered at IRT, or the time to reach 50% of Ti excretion in the feces. Maned wolves had lower total percent recovery (P<0.01) of Ti than dogs and shorter time to last recovery of Ti in the feces (P<0.05), however, marker excretion in the maned wolves may not have been complete. For the digestibility study, in which chromic oxide was used as a marker, fecal samples were collected on 2 consecutive days immediately after 12 days of being fed the diets and then analyzed for dry matter, energy, protein, and minerals. Crude protein, calcium, phosphorus, and zinc apparent digestibilities were unaffected by species or diet (P>0.05). Apparent digestibility of dry matter (P<0.05) and energy (P<0.01) were higher in the experimental diet and in the dogs. Both dogs and maned wolves fed the maintenance diet exhibited a greater apparent retention of copper, iron, and magnesium (P<0.01). Dogs had a higher apparent retention of magnesium and sodium than the maned wolves. Zoo Biol 0:1–13, 2006. © 2006 Wiley‐Liss, Inc.     

Taurine deficiency in maned wolves (Chrysocyon brachyurus) maintained on two diets manufactured for prevention of cystine urolithiasis

This study assesses the long‐term effects of an experimental diet vs. a commercially available manufactured diet, intended to reduce clinical disease related to cystinuria, on the taurine status of captive maned wolves. For 13 weeks, two pairs of maned wolves were maintained on the commercially available maintenance diet, whereas two individually housed wolves were maintained on the experimental diet. All six wolves, at the beginning and at the end of the diet trial, had severely decreased plasma concentrations of taurine (as compared to the normal canine reference range of 60–120 nmol/ml) (National Research Council [2003] National Academies Press) with average taurine concentrations of 16 nmol/ml at the beginning of the study and 3 nmol/ml at the end of the study. There was no statistically significant difference in the taurine concentrations between animals on the maintenance vs. experimental diets. Both diets were supplemented subsequently with taurine at a concentration of 0.3%. All study animals were eventually switched to the taurine‐supplemented version of the commercially manufactured maintenance diet and subsequent samplings were carried out to monitor plasma taurine concentrations. A final sampling, carried out approximately 5 months after the initiation of taurine supplementation, showed an average taurine concentration within the target canine reference range (90.25 nmol/ml). There are numerous physiologic (e.g., possible unique metabolism and requirements for taurine in this species as compared to other canids) and dietary factors (e.g., effects of the types and concentrations of fiber and protein on nutrient availability, taurine metabolism, and enterohepatic circulation of taurine‐conjugated bile salts; impaired taurine synthesis secondary to low cysteine availability) that could be potential contributors to the development of taurine deficiency in the maned wolves in this study. Taurine supplementation should be considered in maned wolves maintained on diets intended for reduction of cystinuria‐related complications. Zoo Biol 0:1–14, 2005. © 2005 Wiley‐Liss, Inc.     

Effect of diet composition and lysine supply on growth and body composition in juvenile turbot (Psetta maxima)

A 10-week feeding trial was conducted to study the effect of feeding level and dietary lysine concentration on growth, protein and lysine retention, and body composition in juvenile turbot. Maintenance requirement for lysine and the efficiency of lysine utilisation were determined as well. Two experimental diets were formulated based on fishmeal or wheat gluten as main protein sources, containing 6.4 g (Diet A, control) and 4.5 g lysine per 100 g CP (Diet B), respectively. Diets were fed once daily at six feeding levels (per day 0.3%, 0.6%, 0.9%, 1.2%, and 1.5% of body weight [BW] and ad libitum) to a total of 432 fish of 48 g initial BW. No differences in the growth parameters were observed between diets at the same feeding level, except a lower feed to gain ratio (p < 0.05) at the highest feeding level at Diet B. Whole-body composition was not affected by diet, whereas muscle protein concentration was significantly lower for fish fed Diet B. Amino acid concentration in whole-body protein was affected by dietary treatment and fish fed Diet B showed lower concentrations of all essential amino acids. In fish muscle protein, lysine, methionine, leucine, isoleucine, and valine concentrations were significantly lower in Diet B. Efficiency of lysine utilisation for growth (k_lys) was determined by linear regression analysis and amounted for 0.69 for Diet B. The maintenance lysine requirement defined at zero lysine retention was 6.5 mg · kg^?0.8 · d^?1. Lysine intakes at zero protein retention were 13.0 mg and 12.9 mg · kg^?0.8 · d^?1 for Diet A and B, respectively. Growth and nutrient retention were similar for both diets and, therefore, a lysine deficiency in Diet B did not occur. In conclusion, a proportion of 330 g wheat gluten per kg feed did not influence growth performance and maintenance requirement for lysine in juvenile turbot. However, the effect of diet composition on the amino acid profile of body protein might be relevant for the derivation of the amino acid requirement from protein retention.     

Effect of bacterial protein meal on protein and energy metabolism in growing chickens

Abstract

This experiment investigates the effect of increasing the dietary content of bacterial protein meal (BPM) on the protein and energy metabolism, and carcass chemical composition of growing chickens. Seventy-two Ross male chickens were allocated to four diets, each in three replicates with 0% (D0), 2% (D2), 4% (D4), and 6% BPM (D6), BPM providing up to 20% of total dietary N. Five balance experiments were conducted when the chickens were 3 – 7, 10 – 14, 17 – 21, 23 – 27, and 30 – 34 days old. During the same periods, 22-h respiration experiments (indirect calorimetry) were performed with groups of 6 chickens (period 1), 5 chickens (period 2), and one chicken (periods 3 – 5). After each balance period, one chicken in each cage was killed and the carcass weight was recorded. Chemical analyses were performed on the carcasses from periods 1, 3, and 5. Weight gain, feed intake, and feed conversion rate were found to be similar for all diets. Chickens on D0 retained 1.59 g N · kg^?0.75 · d^?1, significantly more than chickens on D2, D4, and D6, which retained 1.44 g, 1.52 g, and 1.50 g N · kg^?0.75 · d^?1, respectively. This was probably caused by the higher nitrogen content of D0. Neither the HE (p = 0.92) nor the retention of energy (p = 0.88) were affected by diet. Carcass composition was similar between diets, in line with the values for protein and energy retention found in the balance and respiration experiments. It was concluded that the overall protein and energy metabolism as well as carcass composition were not influenced by a dietary content of up to 6% BPM corresponding to 20% of dietary N.     

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.     

Food habits of three carnivores in a mosaic landscape of São Paulo state,Brazil

São Paulo is the most developed state in Brazil, but despite intense land use changes, some mammal species still inhabit remnant fragments of native vegetation of the state. We used fecal analyses to investigate prey diversity, trophic niche breadth, and trophic niche overlap of pumas, ocelots, and maned wolves in protected and non-protected areas in São Paulo state. During 18 months, we inspected more than 10,000 km of roads and trails and collected 233 fecal samples. Maned wolves showed generalist food habit, ocelots were predominantly carnivores, and pumas were strict carnivores. The European hare, an exotic species which had not yet been reported in the study area, was identified in the feces of a puma. Trophic niche breadth was the lowest for maned wolves (BA?=?0.339) and the highest for pumas (BA?=?0.723). Trophic niche overlap was high between maned wolves and ocelots (O_jk?=?0.765) and between pumas and ocelots (O_jk?=?0.639). Significantly different diets of maned wolves and ocelots were observed between dry and rainy seasons. Our findings indicate that these three species may adapt their diets to the disturbed landscapes. This is the second study characterizing food habits of ocelots in Cerrado areas but the first considering a large number of samples.     

Effect of dietary copper on the growth performance,non-specific immunity and resistance to Aeromonas hydrophila of juvenile Chinese mitten crab,Eriocheir sinensis

An 8-week feeding trial was conducted to determine the dietary copper (Cu) on growth performance and immune responses of juvenile Chinese mitten crab Eriocheir sinensis. Six semi-purified diets with six copper levels (1.88, 11.85, 20.78, 40.34, 79.56 and 381.2 mg kg^?1 diet) of CuSO₄·5H₂O were fed to E. sinensis (0.45 ± 0.01 g). Each diet was fed to the crab in five replicates. The crab fed diets with 20.78 and 40.34 mg Cu kg^?1 diet had significantly greater weight gain and hemolymph oxyhemocyanin content than those fed diets with 1.88 and 381.2 mg Cu kg^?1 diet. Survival rates of crab were not significantly different between all treatment groups. The activities of copper–zinc superoxide dismutase (Cu–Zn SOD), phenoloxidase (PO), and total hemocyte count (THC) significantly increased when the supplementation of dietary copper reached 20.78–40.34 mg Cu kg^?1 diets. In the bacteria challenge experiment with Aeromonas hydrophila, survival rates significantly increased and reached a plateau when the dietary copper increased from 1.88 to 40.34 mg kg^?1, whereas significantly decreased when the dietary copper increased from 40.34 to 381.2 mg kg^?1. This study indicates that the level of dietary copper is important in regulating growth and immune response in crab.     

Comparative analysis of the digestive efficiency and nitrogen and energy requirements of the phyllostomid fruit-bat (Artibeus jamaicensis) and the pteropodid fruit-bat (Rousettus aegyptiacus)

Nitrogen (N) and energy (E) requirements of the phyllostomid fruit bat, Artibeus jamaicensis, and the pteropodid fruit bat Rousettus aegyptiacus, were measured in adults that were fed on four experimental diets. Mean daily food intake by A. jamaicensis and R. aegyptiacus ranged from 1.1–1.6 times body mass and 0.8–1.0 times body mass, respectively. Dry matter digestibility and metabolizable E coefficient were high (81.1% and 82.4%, respectively) for A. jamaicensis and (77.5% and 78.0%, respectively) for R. aegyptiacus. Across the four diets, bats maintained constant body mass with mean metabolizable E intakes ranging from 1357.3 kJ · kg^−0.75 · day⁻¹ to 1767.3 kJ · kg^−0.75 · day⁻¹ for A. jamaicensis and 1282.6–1545.2 kJ · kg^−0.75 · day⁻¹ for R. aegyptiacus. Maintenance E costs were high, in the order of 3.6–5.4 times the basal metabolic rate (BMR). It is unlikely that the E intakes that we observed represent a true measure of maintenance E requirements. All evidence seems to indicate that fruit bats are E maximizers, ingesting more E than required and regulating storage by adjusting metabolic output. We suggest that true maintenance E requirements are substantially lower than what we observed. If it follows the eutherian norm of two times the BMR, fruit bats must necessarily over-ingest E on low-N fruit diet. Dietary E content did affect N metabolism of A. jamaicensis. On respective low- and high-E diets, metabolic fecal N were 0.492 mg N · g⁻¹ and 0.756 mg N · g⁻¹ dry matter intake and endogenous urinary N losses were 163.31 mg N · kg^−0.75 · day⁻¹ and 71.54 mg N · kg^−0.75 · day⁻¹. A. jamaicensis required 332.3 mg · kg^−0.75 · day⁻¹ and 885.3 mg · kg^−0.75 · day⁻¹ of total N on high- and low-E diets, respectively, and 213.7 mg · kg^−0.75 · day⁻¹ of truly digestible N to achieve N balance. True N digestibilities were low (29% and 49%) for low- and high-E diets, respectively. For R. aegyptiacus, metabolic fecal N and endogenous urinary N losses were 1.27 mg N · g⁻¹ dry matter intake and 96.0 mg N · kg^−0.75 · day⁻¹, respectively, and bats required 529.8 mg · kg^−0.75 · day⁻¹ (total N) or 284.0 mg · kg^−0.75 · day⁻¹ (truly digestible N). True N digestibility was relatively low (50%). Based on direct comparison, we found no evidence that R. aegyptiacus exhibits a greater degree of specialization in digestive function and N retention than A. jamaicensis. When combined with results from previous studies, our results indicate that all fruit bats appear to be specialized in their ability to retain N when faced with low N diet. Accepted: 24 November 1998     

Using Bayesian stable isotope mixing models to estimate wolf diet in a multi-prey ecosystem

Stable isotope analysis (SIA) of wolf (Canis lupus) tissues can be used to estimate diet and intra-population diet variability when potential prey have distinct δ¹³C and δ¹⁵N values. We tested this technique using guard hairs collected from 44 wolves in 12 northwestern Montana packs, summer 2009. We used hierarchical Bayesian stable isotope mixing models to determine diet and scales of diet variation from δ¹³C and δ¹⁵N of wolves and potential prey, white-tailed deer (Odocoileus virginianus), mule deer (Odocoileus hemionus), elk (Cervus canadensis), moose (Alces alces), snowshoe hare (Lepus americanus), and other prey. As a check on SIA results, we conducted a separate diet analysis with temporally matched scats (i.e., collected in summer 2008) from 4 of the same packs. Wolves were centered on the ungulate prey in the isotope mixing space. Both methods revealed differences among pack diets and that wolves may consume moose in greater proportions than predicted by available biomass. Stable isotope analysis, and scat results were not entirely concordant; assumptions related to tissues of use in SIA, hair growth period in wolves, and scat sampling may have contributed to a mismatch between methods. Incorrect fractionation values, insufficient separation of prey in the isotope mixing space, choice of prior information in the Bayesian mixing models, and unexplained factors may have distorted diet estimates. However, the consistently high proportion of moose in pack diets suggests that increased population monitoring would benefit management of moose and wolves. Our results also support suggestions of other researchers that species-specific fractionation values should be used whenever possible, and that SIA may sometimes only provide indices of use for general groups of prey (e.g., large ungulates). © 2012 The Wildlife Society.     

Effects of wild and farm-grown macroalgae on the growth of juvenile South African abalone Haliotis midae Linnaeus

The effect of various macroalgal diets on the growth of grow-out (>20 mm shell length) South African abalone Haliotis midae was investigated on a commercial abalone farm. The experiment consisted of four treatments: fresh kelp blades (Ecklonia maxima (Osbeck) Papenfuss) (c. 10% protein); farmed, protein-enriched Ulva lactuca Linnaeus (c. 26% protein) grown in aquaculture effluent; wild U. lactuca (c. 20% protein); and a combination diet of kelp blades + farmed U. lactuca. Abalone grew best on the combination diet (0.423 ± 0.02% weight d^?1 SGR [specific growth rate]; 59.593 ± 0.02 ?m d^?1 DISL [daily increment in shell length]; 1.093 final CF [condition factor]) followed by the kelp only diet (0.367 ± 0.02% weight d^?1 SGR; 53.148 ± 0.02 ?m d^?1 DISL; 1.047 final CF), then the farmed, protein-enriched U. lactuca only diet (0.290 ± 0.02% weight d^?1 SGR; 42.988 ± 0.03 um d”¹ DISL; 1.013 final CF) that in turn outperformed the wild U. lactuca only diet (-0.079 ± 0.01% weight d^?1 SGR; 3.745 ± 0.02 ?m d”^?1 DISL; 0.812 final CF). The results suggest that protein alone could not have accounted for the differences produced by the varieties of U. lactuca and that the gross energy content is probably important.     

Lysine requirements of imported European pigs in the humid lowland tropics from 23 to 62 kg liveweight

The responses of 144 Large White × Landrace pigs (72 castrated males and 72 females; mean initial liveweight approximately 23 kg) to graded additions of L-lysine monohydrochloride to a basal diet containing yellow maize and groundnut meal and 180 g crude protein per kg were studied. Total dietary lysine levels ranged from 5–12 g kg^?1. All diets contained digestible energy of 15.44–16.02 MJ kg^?1 DM. The pigs were individually fed from 23 to 33, 47 or 62 kg liveweight. Growth performance, carcass characteristics, nitrogen retention and plasma urea concentration were employed as response criteria. Influence of sex on lysine requirements for optimum growth, nitrogen retention and efficiency of essential amino acids utilization measured by minimum plasma urea concentration was also investigated.Supplementing the basal diet with L-lysine monohydrochloride significantly (P < 0.001) improved growth performance. Castrated male pigs grew faster and responded better to dietary lysine supplementation than gilts. No apparent decline in lysine requirements for optimum growth performance was observed for the two sexes of pigs as they got older. Optimum growth performance in castrated males was obtained with 9, 8 and 8 g lysine kg^?1 diets for the liveweight ranges 23–33, 23–47 and 23–62 kg, respectively. Optimum growth performance of the gilts for all three liveweight ranges was obtained at an estimated dietary lysine concentration of 11 g kg^?1.Optimum lean deposition, carcass leanness and other carcass measurements were obtained at 8 g lysine kg^?1 diet. Carcass data were not analysed for influence of sex.Plasma urea concentration showed further evidence of a quicker and cheaper indirect index of dietary amino acid adequacy in pigs. Minimal plasma urea concentration was obtained at 7–8 g lysine kg^?1 diet for the three liveweight ranges investigated.In a humid tropical environment, such as Ibadan, the dietary lysine requirement of Large White × Landrace pigs of 23–62 kg is about 9 g lysine kg^?1 diet for optimum growth performance and carcass quality, but nitrogen metabolism and plasma urea data suggest a lower level of to 7–9 g lysine kg^?1 diet.     

Effects of varying levels of dietary vitamin E (α‐tocopherol) on growth performance,proximate and fatty acid composition of juvenile silver pomfret (Pampus argenteus Euphrasen, 1788)

This study investigated the effects of elevated dietary levels of vitamin E (α‐tocopherol) on growth performance, proximate composition and fatty acid profiles of juvenile silver pomfret, Pampus argenteus. Three semi‐purified experimental diets were formulated to contain 49% protein and 16% lipid. High docosahexaenoic acid (DHA) tuna oil was added to the diets to supplement DHA. A graded level of vitamin E (0‐, 50‐, and 100 mg kg^?1) was added to experimental diets 1 to 3, respectively. Analyzed vit. E levels were 155.2, 195.3 and 236.4 mg kg^?1 in diets 1, 2 and 3, respectively. The experiment was conducted for 12 weeks with juvenile silver pomfret (29.6 ± 7.6 g) using a flow‐through system consisting of nine 1‐m³ tanks. Each treatment had three replicates and fish were stocked at the rate of 20 m^?3. Growth performance and feed utilization parameters of fish fed diets 2 and 3 were significantly (P < 0.05) higher than in fish fed diet 1, but the parameters in diets 2 and 3 did not differ significantly (P > 0.05). Although whole body protein levels were not influenced by the dietary vit. E levels, whole body lipid in fish fed diet 2 was significantly higher than in fish fed the other diets. The whole body vit. E levels in fish fed diet 2 (22.6 mg kg^?1) and diet 3 (24.1 mg kg^?1) were significantly (P < 0.05) higher than in those fed diet 1 (18.2 mg kg^?1). Whole body total saturated fatty acids were significantly lower, and DHA levels higher in fish fed diets 2 and 3 than those fed diet 1. The results of the present study suggest that increasing dietary supplementation of vit. E in high lipid diets enhances the growth performance of fish and that a dietary level of 196 mg kg^?1 vit. E is suitable for the growth of silver pomfret.     

Soybean oil and beef tallow in dry extruded diets for adult dogs

The aim of the study was to determine the effects of two different fat sources (soybean oil (SO) and beef tallow (BT)) in dry extruded dog diets on the intake of food and metabolizable energy (ME), on faecal characteristics and apparent total tract digestibility (ATTD) of nutrients and energy. Ten adult dogs of different breeds were used in a Latin square design. Five experimental diets were designed from a basal diet. A Control diet was coated with 1% SO and four other diets were obtained by coating the basal diet with 6.5% and 13% of SO or BT. The Control, 6.5% and 13% coated diets contained approximately 8.5%, 15% and 20% fat, respectively. The dogs had similar dry matter (DM) intakes and, consequently, higher ME intakes with an increased fat content for both sources (p < 0.05). Fat digestibility was highest for Diet SO13% (p < 0.05). The ATTD of DM and organic matter was highest (p < 0.05) for Diets SO13% and BT13%. Fat coating improved the faecal score, especially for Diet BT13%. The dietary ratios of protein:fat:carbohydrate [% of ME] were close to AAFCO’s estimates. For SO a higher ATTD (99.1%) and ME content (38.88 MJ/kg) was estimated than for BT (ATTD 92.9% and 36.37 MJ ME/kg). Both SO and BT can comprise up to 13% of the diet. However, SO was more susceptible to leaking from the kibbles with the coating method applied.     

Assessment of anadromous salmon resources in the diet of the Alexander Archipelago wolf using stable isotope analysis

The Alexander Archipelago wolf (Canis lupus ligoni) is unique to southeast Alaska, occurring on islands south of Frederick Sound and along the mainland between Dixon Entrance and Yakutat Bay. Sitka black-tailed deer (Odocoileus hemionus sitkensis) are an important prey species for wolves across the southern part of the region. Spawning salmon (Onchorynchus sp.) are seasonally available but their presence in wolf diets has not previously been quantified. We examined the range of bone collagen δ¹³C and δ¹⁵N values for wolves throughout southeast (n = 163) and interior (n = 50) Alaska and used a dual-isotope mixing model to determine the relative contribution of salmon-derived marine protein in the diet. Southeast Alaska wolves consumed significantly more salmon (mean ± SE: 18.3 ± 1.2%) than did wolves from interior Alaska (9.1 ± 0.6%, P<0.001). Wolves on the southeast Alaska mainland appeared to have higher marine isotopic signatures than island wolves, although this difference was not significant. Variation among individual wolf diets was higher for southeast than for interior Alaska wolves, and variation was highest in coastal mainland wolf diets (P<0.001). Marine resources may augment the diet of southeast Alaska wolves during seasonal or annual fluctuations in the availability of deer, particularly in those areas on the mainland where densities of terrestrial ungulates are relatively low. Received: 1 July 1998 / Accepted: 23 February 1999     

Growth Performance,Hemato-Immunological Responses,and Digestive Enzyme Activities in Silvery-Black Porgy (<Emphasis Type="Italic">Sparidentex hasta</Emphasis>) Fed Dietary Bovine Lactoferrin

An 8-week study was conducted to evaluate three different diets supplemented with bovine lactoferrin (LF) at 0 (control), 800, and 1200 mg LF kg^?1 diet on somatic growth, hemato-immunological parameters, antioxidant status, and digestive enzyme activities in silvery-black porgy (Sparidentex hasta) juveniles. Fish fed the 800 mg LF kg^?1 diet had higher growth performance and feed utilization parameters than the other groups. Hematological and liver antioxidant parameters were not affected by dietary LF supplementation. Fish fed the 800 mg LF kg^?1 diet had higher plasma lysozyme activity values than the other groups. Total protease activity was higher in fish fed LF-supplemented diets than the control group. Results indicated that diet supplemented with 800 mg kg^?1 for 8 weeks enhanced somatic growth performance, lysozyme activity, and proteolytic digestive enzyme activities in S. hasta, as well as improving feed efficiency parameters like the protein efficiency and feed conversion ratios.     

Effects of different protein and carbohydrate levels on growth performance and feed utilisation of brook trout,Salvelinus fontinalis (Mitchill, 1814), at two temperatures

A 12‐week feeding trial was conducted to determine the optimum dietary protein requirement of brook trout, Salvelinus fontinalis, at 15 and 19°C. Twelve iso‐energetic (22 MJ · kg^?1) and iso‐lipidic (23%) diets (36–58% protein at 2% increments) were prepared. Fish (29.45 ± 3.25 g · fish^?1) were fed 2% of body weight per day, divided into two equal rations. The specific growth rate (SGR, % · day^?1), feed efficiency ratio (FER), productive protein value (PPV), productive lipid value (PLV) and productive energy value (PEV), apparent digestibility of diet (AD_DM) and protein (AD_CP) were significantly higher at optimum temperature (15°C). Increasing PPV with increasing dietary carbohydrate and with decreasing dietary protein content was due to the protein‐sparing effect of carbohydrates. A piecewise regression (broken line) model between the SGR and digestible dietary protein level revealed that the digestible dietary protein requirement of brook trout was 44 and 40% at 15 and 19°C, respectively. When PPV (digestible protein retention basis) was modelled with a broken line, the digestible protein requirement of brook trout was 39 and 35% at 15 and 19°C, respectively. A reduction in dietary protein content balanced by increased gelatinised carbohydrate might be useful for improving the protein utilization efficiency for growth at 15 and 19°C; however, the growth and feed efficiency was lower at the elevated temperature.     

Effects of dietary l‐carnitine supplements on growth and body composition in beluga sturgeon (Huso huso) juveniles

The effects of dietary l ‐carnitine on growth performance, whole body composition and feed utilization were studied in beluga, Huso huso. Fish were randomly allocated in 15 tanks (30 fish per tank) and triplicate groups were fed to satiety during 84 days one of five isonitrogenous (41% CP) and isoenergetic (20 MJ kg^?1) diets, each differing in l ‐carnitine content [0 (control), 300, 600, 900 and 1200 mg kg^?1 diet]. At the end of the trial, fish grew from 19‐ to 23‐fold in weight, from 8.4 g to a maximum of 191 g. Fish fed 300–600 mg l ‐carnitine had the highest specific growth rate (SGR, 3.69 and 3.72% day^?1) and protein efficiency ratio (PER, 0.95 and 0.99), and the lowest feed conversion ratio (FCR, 1.4 and 1.3) than the other groups (P < 0.0001). SGR, PER and FCR were the poorest for fish fed 1200 mg l ‐carnitine, while fish fed the unsupplemented and 900 mg l ‐carnitine supplemented diet showed intermediate performance. Body lipid concentration decreased significantly from 5.8 to 5.1% (P < 0.0001) with dietary l ‐carnitine supplementation increasing from 0 to 300 mg. Energy content was significantly lower in fish fed the 900 and 1200 mg l ‐carnitine diet (5.8 MJ kg^?1), when compared with the other treatment groups (6.4–6.6 MJ kg^?1). The results indicated that feeding sturgeon on diets supplemented with 300 mg l ‐carnitine kg^?1 diet improved growth performance, and stimulated protein‐sparing effects from lipids.     

Atropine depresses release of neurotensin and its effect on the exocrine pancreas

In this study the effect of 10 and 20 μg · kg^?1 · h^?1 atropine sulfate on release and pancreatic effects of neurotensin was studied in 4 dogs. Neurotensin plasma levels rose significantly when a liquid fat preparation was infused intraduodenally. This rise was almost completely abolished by simultaneous infusion of atropine. Atropine further suppressed basal and fat-stimulated output of pancreatic volume, protein, and bicarbonate; it also reduced pancreatic secretion stimulated by an intravenous infusion of low doses (2.5 to 20 pmol · kg^?1 · min^?1) neurotensin. The effect of higher doses (80 and 240 pmol · kg^?1 · min^?1) of neurotensin was less affected.As neurotensin plasma levels in contrast to normal oral feeding did not rise after sham feeding, our findings suggest that release and action of neurotensin may at least in part be dependent on a cholinergic, non-cephalic mechanism.     

Dietary total aromatic amino acid requirement and tyrosine replacement value for phenylalanine in Indian major carp: Cirrhinus mrigala (Hamilton) fingerlings

Two 8‐week growth trials were conducted to determine total aromatic amino acid requirement and tyrosine replacement value for phenylalanine in Cirrhinus mrigala fingerlings. To determine the phenylalanine requirement, 20 fish were randomly stocked in triplicate groups in 55‐L indoor polyvinyl flow‐through circular tanks and fed six experimental diets containing graded levels of phenylalanine (5.0, 7.5, 10.0, 12.5, 15.0 and 17.5 g kg^?1, dry diet) with 10 g kg^?1 tyrosine. Maximum weight gain (287%), best FCR (1.44) and PER (1.74) occurred at 12.5 g kg^?1 dietary phenylalanine. Quadratic regression analysis of weight gain, FCR and PER data indicated phenylalanine requirement at 13.5, 12.9 and 12.7 g kg^?1 of dry diet, respectively. Protein deposition was significantly (P < 0.05) higher at 12.5 g kg^?1 dietary phenylalanine. Based on the above results, phenylalanine requirement of C. mrigala is recommended at 13.0 g kg^?1 of dry diet, corresponding to 32.5 g kg^?1 of protein. On the basis of the above requirement, a second experiment with a similar design was conducted using six diets containing graded levels of tyrosine (2.1, 4.0, 6.0, 8.0, 10.0 and 12.0 g kg^?1) with 13.0 g kg^?1 phenylalanine fixed in all diets to determine the phenylalanine replacement value with that of tyrosine. Maximum weight gain (315%), best FCR (1.47) and PER (1.69) was at 8.0 g kg^?1 dietary tyrosine. Quadratic regression analysis of weight gain, FCR and PER data indicated tyrosine requirement at 9.0, 8.4 and 8.2 g kg^?1 of dry diet, respectively. Protein deposition was significantly (P < 0.05) higher at 8.0 g kg^?1 dietary tyrosine. On the basis of the above results, 8.5 g kg^?1 tyrosine, corresponding to 21.3 g kg^?1 of protein, is taken as the optimum requirement and the replacement value is 39.53% on a weight and 36% on a molar basis. Thus, the total aromatic amino acid requirement is 21.5 g kg^?1 of diet, corresponding to 53.8 g kg^?1 of protein for optimum C. mrigala growth.     

INTENSE GRAZING AND PREY‐DEPENDENT GROWTH OF PFIESTERIA PISCICIDA (DINOPHYCEAE)1

Grazing and growth of Pfiesteria piscicida (Pfiest) were investigated using batch and cyclostat cultures with Rhodomonas sp. (Rhod) as prey. Observed maximum growth rates (1.4 d^?1) and population densities (2 × 10⁵ cells·mL^?1) corresponded to values predicted by Monod functions (1.76 d^?1; 1.4 × 10⁵ cells·mL^?1). In batch cultures under a range of prey‐to‐predator ratios (0.1:1 to 180:1) and prey concentrations (1000–71,000 cells·mL^?1), Rhodomonas sp. was always depleted rapidly and P. piscicida concentrations increased briefly. The rate of Rhodomonas sp. depletion and the magnitude of P. piscicida population maxima depended on the prey‐to‐predator ratio and prey concentration. Starvation resulted in cell cycle arrest at G1 and G2+M and ultimately the demise of both P. piscicida and Rhodomonas sp. populations, demonstrating the dependence of P. piscicida on the supply of appropriate prey. The depletion of Rhodomonas sp. populations could be attributed directly to grazing, because P. piscicida did not exert detectable inhibitory effects on the growth of Rhodomonas sp. but grazed intensely, with maximum grazing rates>10 Rhod·Pfiest^?1·d^?1 and with no apparent threshold prey abundance for grazing. The results suggest that 1) the abundance of appropriate prey may be an important factor regulating P. piscicida abundance in nature, 2) P. piscicida may control prey population, and 3) high growth and grazing potentials of P. piscicida along with cell cycle arrest may confer survival advantages.