Digestibility measurements in juvenile tench [Tinca tinca (L.)] by using a continuous filtration device for fish faeces

Effective pond production of tench [Tinca tinca (L.)] requires the use of formulated diets. However, insufficient information is available regarding the nutrition of this species. Therefore, for the first time, the digestibility of macronutrients by tench was investigated using a sieving method of faeces collection and chromic oxide. A pelleted experimental diet rich in untreated wheat starch revealed the following mean apparent digestibility coefficients (ADCs): dry matter 77.2%, crude protein 89.4%, crude fat 94.3%, ash 30.5%, nitrogen‐free extracts 78.2%, organic matter 83.3% and energy 85.1%. Generally, these ADCs indicate that the ability of tench to digest the macronutrients from pelleted feed correlates with reports of other fish species. However, the tench is more able to digest untreated wheat starch than are carnivorous and coldwater fish species. Compared with carp (Cyprinus carpio L.), the digestibility of untreated wheat starch is less in tench. The faeces sieving method as described in this paper is a useful procedure for further digestibility trials with tench. However, compared with the approach presented here, several adaptations are recommended, e.g. long adaptation times to the rearing facility, high stocking densities, usage of more waterproof food pellets and the addition of formalin to the collection pans.     

Digestion of cereals in the equine gastrointestinal tract measured by the mobile bag technique on caecally cannulated horses

The mobile bags procedure was used to measure the disappearance of starch and proteins in the precaecal as well as in the total intestinal tract of four caecally cannulated horses. Experimental grains were oats, barley and maize, each in four different forms: ground, pelleted, extruded and micronized. The horses had 16 to 20 mobile nylon bags containing one of the experimental cereals intubated through a nasogastric tube together with the morning meal. Some of the bags were captured with a magnet through the caecal cannula and analysed for contents of starch and protein. The remaining bags were captured from the faeces and underwent the same analysis, and the digestibilities in the different parts of the gastrointestinal (GI) tract were calculated. Oats had a high degree of starch digestibility (0.949 precaecally and 0.990 totally), considerably higher (P<0.05) than barley (0.705 precaecally and 0.960 totally) and maize (0.663 precaecally and 0.910 totally). However, oats had a higher precaecal digestibility of protein (P<0.10), but a lower total tract digestibility than the other grains (P<0.01). The high-temperature treated cereals (extruded and micronized) had a higher total tract digestibility of protein than the untreated cereals (P<0.01). The pelleted and micronized cereals had the highest precaecal digestibility of protein. Differences in digestibility should be considered when formulating rations for the athletic horse.     

Relationship between hydroxycinnamic acid content,lignin composition and digestibility of maize silages in sheep

Cell wall-bound hydroxycinnamic acids and the composition of lignin were studied in relation to the digestibility of a collection of 91 maize silages in wethers. Total lignin and guaiacyl content showed the highest correlation coefficients with digestibility. Using the above-mentioned chemical parameters, eight equations were also developed to predict digestibility. The prediction of organic matter digestibility produced a high adjusted R ² value (0.487) using total lignin, guaiacyl, esterified ferulic acid and esterified p-coumaric acid content as predictors. The prediction of in vivo dry matter digestibility produced a higher adjusted R ² value (0.516) using the same variables as predictors. Cell wall digestibility depends on a multiplicity of factors and it is not possible to attribute a causal effect on in vivo digestibility to any single factor. However, total lignin, guaiacyl and p-coumaric acid content emerge as good predictors of digestibility.     

Digestion in the hippopotamus

The hippopotamus (Hippopotamus amphibius Linn.) has an enlarged stomach, divided into: (a) two anterior diverticula; (b) a large median chamber, and (c) a posterior chamber, secreting gastric juice. Fermentative digestion occurs in (a) and (b). The anatomy and function of the stomach are discussed. Two experiments were performed to compare digestive efficiency with that of ruminants. Exp. 1. In a total collection experiment, chopped grass wasfedtoahippopotamusand five ruminants. Overall digestibility was lower in the hippopotamus, but this may have been due to keeping the animal out of water. Exp. 2. A hippopotamus and two sheep were fed chopped elephant grass (Pennisetum purpureum), digestibility being measured by total collection (in the sheep) and the chromogen ratio method. Dry matter digestibility was similar in all three animals, while digestibility of crude protein was higher in the hippopotamus.     

Apparent and true digestibility of the Weende components, cell content and cell wall of ryegrass

For 14 samples of ventilated hay and 6 of fresh grass, digestibility was determined with young wethers. The contribution to the digestibility was calculated for the Weende components (crude protein, crude fibre, nitrogen-free extractives + fat) and for cell content and cell wall (Van Soest) components. For the cell content and crude protein, a hyperbolic relationship, y' = a − b/x between the digestibility coefficient of the components (y') and the percentage component in dry matter (DM, x) can be accepted with a sufficient degree of certainty. This means that the apparent digestibility of the cell content and crude protein increase with increasing concentration. The latter formula can be transformed into a linear regression y = ax − b where y = percentage digestible component in DM, a being an estimate of the true digestibility of the component and b an estimate of the endogenous excretion of the component. From these relationships some important practical conclusions can be drawn. For other dry matter components, such as crude fibre, nitrogen free extractives + fat and cell wall, the relationship between the digestibility coefficient and the percentage of the component in DM cannot be expressed by a simple regression line. The advantages of splitting the digestibility into a contribution from cell content and cell wall components versus splitting into contributions from the Weende components are discussed.By determination of the cell wall and its digestibility in vitro, a very good prediction for the dry matter digestibility of grass can be given, which is of great importance for plant breeding and grassland research.     

Consumption of sugars, hemicellulose, starch, pectin and cellulose by the grasshopper Arcris flavolineata

Adults (0.61 g, fresh-weight) of Abracris flavolineata De Geer (Orthoptera: Acrididae) feeding on Brassica oleracea acephala leaves ingest 21 mg dry-weight/day with an approximate digestibility of 42%. Chemical determinations performed on the leaves ingested and on the feces expelled led to the determination of the approximate digestibilities (%) of the major carbohydrates of leaves as follows: soluble carbohydrates, 91; pectin, 32.1; hemicellulose, 0; starch, 66; cellulose, 15. The results are not sufficient to disregard the possibility that digestible hemicellulose polymers contaminate the pectin and the cellulose fraction. Thus, it is possible that the digestibility of hemicellulose is different from zero, and that the digestibility of pectin and cellulose are somewhat lower than reported. The data are used to propose physiological roles of the enzyme activities previously found in the A. flavolineata midgut.     

Variation in the Nutritional Value of Primate Foods: Among Trees, Time Periods, and Areas

The study of nutritional ecology has proven to be useful for understanding many aspects of primate behavior and ecology and is a valuable tool in primate conservation. However, to date this approach has had limited application since chemical analyses of food items is very time-consuming and collections of perishable food material are often made in remote field locations. Such logistic difficulties have led to plant material being collected in a variety of fashions, and it is not known how variation in collection method might influence our understanding of the chemical basis of dietary selection. A standardization of collection methods is greatly needed to allow for direct comparison among studies. To develop an appropriate standardized method and to evaluate past research, it is necessary to understand along what dimensions plant chemistry varies. We evaluated variation in nutritional value—protein, fiber, digestibility, alkaloids, saponins, cyanogenic glycocides, and minerals—of leaf material from species eaten by red colobus (Piliocolobus tephrosceles) and black-and-white colobus (Colobus guereza) of Kibale National Park, Uganda. We consider variation at 3-levels: among trees, time periods, and areas. While there was considerable variation among species with respect to protein, digestibility, and saponins, there was also variation among individuals of the same species; in fact, individuals may vary by as much as 20%. The average coefficients of variation (CV) among individuals of the same species are 13.4 for protein, 12 for digestibility, and 43 for saponins, while the average CV among species are 35, 31.3, and 82.4, respectively. No species showed a variable response with respect to testing for the presence or absence of cyanogenic glycocides, while 2 of 11 species tested for alkaloids showed a variable response. Over 2 years there was evidence of variation among time periods in the chemical composition of the same food items. The protein-to-fiber ratio of mature leaves of the same species collected from 4 sites separated by 12 km within Kibale was also variable and in some cases the variation among sites was greater than the differences among species. For example, while Funtumia latifolia had little variation in protein-to-fiber ratio at 3 sites (0.44 at all sites), the remaining site was 28% greater. Because temporal variation is less than variation among individuals, it is likely more important to sample from multiple trees at a single point in time than to sample across time. However, the most accurate assessment of nutrient intake is obtained by collecting plant material from the specific trees selected for consumption.     

Nutritional evaluation of the white-rot fungus Sporotrichum pulverulentum as a feedstuff to rats,pigs, and sheep

The production of single-cell protein (SCP) based on cheap carbon sources such as spent liquor from paper mills is of interest for different reasons. The White-rot fungus (Sporotrichum pulverulentum) has earlier been shown to degrade cellulose and lignin. The nutritive value of this fungus was investigated with rats, pigs, and sheep. The effect of different drying process was evaluated on rats. Experiments with piglets, growing pigs, and sheep were aimed at getting primary information on nutritive parameters with domestic animal species, Chemical analysis of S. pulverulentum showed that the sum of the amino acids corresponded to 70% and ammonia, GABA, and glucosamine to 20% of its crude protein content. Differences between drying treatments in their effect on protein digestibility were not noted. From a protein quality viewpoint, a tendency toward superiority was noted for two of the drying processes. The amino acid digestibility of S. pulverulentum was inferior to values for soybean oil meal given in textbooks. The piglet experiment confirmed the lower nutritive value of S. pulverulentum compared with soybean oil meal. in the piglet stage a content of metabolizable energy of S. pulverulentum was found which corresponded to 60% of that for soybean oil meal. With increasing age the ability of pigs to utilize the fungus increased. The limited nutritive value for monogastric animals is most certainly caused by the cell-wall structure of S. pulverulentum with poor digestibility of the carbohydrates. The experiment with sheep showed more satisfactory results than with monogastric species, with digestibility of crude protein of 82% and a content of metabolizable energy of 70% of soybean oil meal.     

Effects of Fusarium Toxin Contaminated Wheat and of a Detoxifying Agent on Performance of Growing Bulls,on Nutrient Digestibility in Wethers and on the Carry Over of Zearalenone

Experiments were carried out to examine the effects of a Fusarium contaminated wheat (10mg deoxynivalenol and 0.76mg zearalenone, ZON, perkg dry matter) and of a detoxifying agent (Mycofix ®Plus, Biomin GmbH, Herzogenburg, Austria) on the growing performance of bulls, carry-over of ZON and its metabolites into body fluids and tissues, and on nutrient digestibility in wethers. The experiments were designed according to a complete two by two factorial approach which meant that both the uncontaminated control wheat and the Fusarium toxin contaminated wheat were tested both in the absence and presence of Mycofix ®Plus. The growing experiment with bulls (n = 14 per treatment) covered the live weight range between 244kg and 460kg. The respective wheat batches were included in the concentrate portion at 65%. Concentrates were fed according to plan whereas maize silage was offered for ad libitum consumption. Daily dry matter intake and live weight gain [kg per animal and day] were 7.40, 7.52, 7.51 and 7.49 and 1.367, 1.296, 1.380 and 1.307 for bulls fed the unsupplemented control wheat, the supplemented control wheat, the unsupplemented and Fusarium toxin contaminated wheat and the supplemented Fusarium toxin contaminated wheat, respectively. ZON and its metabolites were not detected in edible tissues. The most striking effects of feeding the Fusarium toxin contaminated wheat on carcass characteristics were a reduced dressing percentage, an increased weight of the emptied gastro-intestinal tract and a reduced weight of the testicles. No effect of the detoxifying agent was seen for these parameters whereas heart weight increased independently of Fusarium toxin contamination of the concentrates. Nutrient digestibility of the two wheat batches, unsupplemented or supplemented with Mycofix ®Plus was evaluated according to the difference method using wethers. Presence of Fusarium toxins in wheat did not influence its feeding value. The effects of the addition of the detoxifying agent were mycotoxin unspecific and resulted in an increase in apparent digestibility of crude protein and a decrease in crude fiber digestibility. It is concluded that feeding of Fusarium toxin contaminated wheat did not adversely affect performance of growing bulls (approximately 2.2mg DON and 0.1mg ZON perkg complete ration at a reference dry matter content of 88%) or nutrient digestibility in wethers. The effects of the detoxifying agent Mycofix ®Plus on growing performance and on nutrient digestibility were rather Fusarium toxin unspecific. The slightly negative effects on growing performance needs to be examined further.     

Effects of Acomastylis rossii tannins on a mammalian herbivore,the North American pika,Ochotona princeps

 I investigated the effects of tannin consumption, using plant tannins naturally occurring in the diet, on a herbivorous mammal, the North American pika, Ochotona princeps. The objectives were to determine if a high-tannin diet influenced protein and dry matter apparent digestibility, fiber digestibility and production of detoxification by-products. Additionally, I examined the possibility that pikas produce salivary tannin-binding proteins, a potential mechanism for avoiding detrimental effects of tannins. My results demonstrate that although pikas constitutively produce salivary tannin-binding proteins, animals consuming a high-tannin diet of Acomastylis rossii exhibited lower dry matter, protein and fiber digestion and excreted higher concentrations of detoxification by-products. Thus, A. rossii tannins are potential toxins as well as digestibility reducers. I propose a hypothesis coupling detoxification to reduced fiber digestion that is applicable to pikas as well as other mammalian herbivores consuming phenolic-rich diets. Received: 31 July 1995 / Accepted: 9 July 1996     

Indigestibility of plant cell wall by the Australian plague locust, Chortoicetes terminifera

The plant cell wall may play an important role in defence against herbivores since it can be both a barrier to, and nutrient diluter of, the easily digested cell contents. The aim of this study was to investigate the digestibility of the cell wall of three grasses, Triticum aestivum L., Dactyloctenium radulans (R. Br.) Beauv., and Astrebla lappacea (Lindl.) Domin, by the Australian plague locust, Chortoicetes terminifera Walker (Orthoptera: Acrididae, Acridinae) as determined by the Van Soest method [ Van Soest PJ, Robertson JB & Lewis BA (1991) Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. Journal of Dairy Science 74: 3583–3597]. Determination of plant cell wall digestion by locusts required a precise methodological procedure to determine both the exact intake and the concentration of cell wall in the diet and the faeces. Plant cell wall determination is affected by the particle size distribution of the dried plant material. All three grasses differed in the percentage of cell wall per gram dry matter and the proportions of hemicellulose, cellulose, and acid‐detergent sulphuric lignin within the cell wall. The locust was unable to digest the cell wall of any of the grasses. Thus, plant cell walls are a mechanical barrier hindering locusts assimilating nutrients. That is, access, rather than nutrient concentration per se, may be limiting nutrient factor.     

Intake,feeding behaviour,digestibility, performance,carcass characteristics and meat quality of lambs fed different levels of semi-purified glycerine in the diet

The aim of this study was to evaluate the effect of different inclusion levels of semi-purified glycerine in the diet of feedlot lambs on feeding behaviour, nutrient intake and digestibility, carcass characteristics, meat quality and in vitro degradability. Thirty-two Dorper × (Texel × Suffolk) crossbred intact male lambs (22.2 ± 5.51 kg) were fed glycerine (90% purity) at 0, 120, 240 or 360 g/kg dry matter (DM) in a total mixed ration with a roughage to concentrate ratio of 40:60 for 84 d. In vitro degradability was not affected by glycerine supplementation. Feeding behaviour and digestibility of DM, crude protein and fibre and production performance were similar among treatments. Ether extract digestibility was lower at the highest inclusion level. Glycerine level had no effect on ruminal pH, carcass characteristics and meat quality, except for subcutaneous fat thickness which was lower for lambs fed glycerine at 240 and 360 g/kg DM. Scores for unpleasant taste, unpleasant odour, succulence and softness of meat were not affected by dietary glycerine level. These data suggest that there are no adverse effects on carcass quality and performance when semi-purified glycerine is provided up to 360 g/kg DM in the diet of growing lambs fed a forage to concentrate ratio of 40:60.     

Effects of Saccharomyces cerevisiae supplementation on ruminal parameters, nutrient digestibility and growth in sheep: A meta-analysis

Despite the increased use of dry active Saccharomyces cerevisiae yeast supplementation in ruminant feeding, inconsistent results among studies hamper the prediction of its effects on animal performance. A meta-analysis has been conducted to quantify the magnitude of yeast supplementation effects on ruminal parameters, total tract nutrient digestibility, growth and feed conversion across different studies with sheep. Different methodologies and small numbers of studies necessitated the use of the classical effect size method, in which a unitless standardised effect size (Hedges's g) was used to calculate differences obtained in outcomes between supplemented and non-supplemented sheep. Summary statistics across studies were calculated with fixed and random effects models, whereas subgroup-analysis and meta-regression were applied to identify possible interfering factors that could be responsible for between-study variability. Possible publication bias was evaluated with graphical and statistical tests. Effect sizes for ruminal ammonia nitrogen (33 comparisons), pH (42 comparisons) and total volatile fatty acids (38 comparison) did not (P > 0.10) present heterogeneity among studies, and was not affected by yeast supplementation. No effects (P > 0.05) were detected on the stoichiometry of volatile fatty acids or protozoa counts. Effects sizes calculated for digestibility of dry matter, organic matter, crude protein, acid-detergent fibre and neutral-detergent fibre, which included from 17 to 28 comparisons, showed considerable (>50%) between-study variability. This variability could not effectively be explained by the categorical variables (1) mode of yeast application, (2) feed intake (ad lib versus restricted) or (3) faeces collection method, or the continuous independent variables (1) adaptation period, (2) study period, (3) dietary roughage concentration and (4) dietary crude protein concentration. According to random effects models, digestibility of dry matter, organic matter and crude protein were increased by yeast supplementation, with no effects found for digestibility of fibre components. Substantial unexplained between-study variability (50–90%) was found for growth (13 comparisons) and feed intake (9 comparisons). This meta-analysis presented evidence that addition of dry active S. cerevisiae yeast to diets did not have any effect on growth, feed conversion, ruminal parameters or fibre digestibility in sheep.     

Digesta Passage Time,Digestibility, and Total Gut Fill in Captive Japanese Macaques (<Emphasis Type="BoldItalic">Macaca fuscata</Emphasis>): Effects Food Type and Food Intake Level

Digestion is an important process in understanding the feeding ecology of animals. We examined digesta passage time, digestibility, and total gut fill in Japanese macaques (Macaca fuscata; n = 4) under 4 dietary conditions representing the seasonal and regional variations in the diets of wild populations to determine the effects of food type and food intake on these digestive features. Food type is associated with mean retention time (MRT), digestibility, and total gut fill. Dry matter intake (DMI) of food correlates positively with total gut fill but not with MRT or digestibility. Conversely, indigestible DMI affected MRT negatively. Thus, when Japanese macaques consume high-fiber foods, MRT becomes shorter and digestibility is lower than when eating low-fiber foods. Moreover, macaques experience increases in total gut fill when they consume high-fiber diets or a large amount of food. Japanese macaques may excrete difficult-to-digest food components quickly; they nevertheless buffer an increase in food intake by an increase in gut fill. Our study offers new insights into the relationship between feeding ecology and nutritional physiology in primates by simultaneously examining the effects of food type and intake level on MRT and digestibility.     

The composition,nutritional status and digestibility of the diets of Sarotherodon mossambicus from nine man-made lakes in Sri Lanka

Synopsis The dietary composition and the nutritional status and the digestibility of the diets of Sarotherodon mossambicus from nine reservoirs in Sri Lanka were evaluated. The feeding habits of S. mossambicus were variable from reservoir to reservoir; they ranged from herbivory to total carnivory. The protein, total lipid, carbohydrate and total organic matter content of the ingested material were related to the dietary composition and ranged from 18.53% to 35.15% (x−24.18%), 5.94% to 9.84% (x−7.91%), 11.6% to 34.7% (x−22.34%) and 34.4% to 64.4% (x−45.71%), respectively. Irrespective of the feeding habits, the diet contained a significant proportion of organic material which cannot be accounted for by protein, total lipid and carbohydrate. As much as the ingested material was related to the feeding habit, the digestibility of the nutrient components was related to the food material devoured. For example, the mean digestibility of the total organic matter in S. mossambicus feeding on detritus, plants and animal were 36.85, 33.5 and 29.5 respectively, and compared well with observations from elsewhere. It is hypothesised that the favourable nutrient quality of the available dietary material in the reservoirs of Sri Lanka, which could be and is effectively utilized by S. mossambicus, may have been, at least partially, responsible for its almost unprecedented success in Sri Lanka.     

Food selection by the South Indian leaf-monkey,Presbytis johnii,in relation to leaf chemistry

Summary The leaf-monkey Presbytis johnii has been found to exhibit considerable selectivity in its dietary utilization of mature foliage in a rain-forest habitat. To investigate the basis of this selectivity and to examine the hypothesis that the observed selection is related to the digestibility and toxicity of the available foliage, chemical analyses have been made on 16 of the most important tree species in the monkey's habitat. It has been found that the most heavily used items, which form a staple part of the diet of P. johnii, are characterized by a low fibre content and a very low condensed tannin content. However, neither class of compound is an absolute feeding deterrent as minor, but still significant, mature leaf food items contain considerable amounts of both. It is suggested that the feeding deterrents in these minor items, which may be ingested to supply specific dietary requirements, can perhaps be tolerated because of their dilution in the gut by the dietary staples. An examination of the pepsin/cellulase digestibility of available mature foliage showed that the staple food items tended to be highly digestible. Little correlation has been found between alkaloid content and food selection and it is suggested that the colobine forestomach microflora has the ability to detoxify at least some alkaloids. Additional data on mature leaf petioles and young leaves suggest that the high ratio of cell-sap to cell-wall in these items, and their related high digestibility, explain the high relative abundance of these items in the P. johnii diet.     

Effect of excessive dietary fluoride on nutrient digestibility and retention of iron, copper, zinc, and manganese in growing pigs

Ninety-six crossbred growing pigs were used to evaluate the effects of fluoride levels on growth performance, nutrient digestibility, and the retention of minerals in tissues. Four dietary treatments were formulated by supplementing fluorine (as NaF) to a corn-soybean basal diet (39.75 mg/kg F) to provide the following added fluorine levels: 0, 50 100, and 150 mg/kg fluorine. The results showed pigs of the 100 and 150 mg/kg fluorine-added groups had decreased average daily gain (ADG) and increased feed gain ratio (F/G) compared to the control (p<0.05). Apparent digestibility of protein and calcium in 100 and 150 mg/kg fluorinetreated groups was significantly lower than that of the control (p<0.05). On the other hand, iron, copper, zinc, and manganese levels in most tissues of the 100 and 150 mg/kg fluorine groups were markedly changed compared to the control (p<0.05). However, growth performance, nutrient digestibility, and mineral concentrations in all tissues of pigs were not significantly affected by the addition of 50 mg/kg fluorine (p>0.05). Thus, this study suggested that excess fluoride levels could decrease growth performance and change the retention of iron, copper, zinc, and manganese in pigs.     

Determination of endogenous faecal phosphorus loss in goats

Four black Liuyang wether goats were fed with corn stover and concentrate formulated to contain four levels of dietary phosphorus (P), including 0.129, 0.140, 0.162 and 0.180% of P. In a 4 × 4 Latin square experiment the endogenous faecal P loss was determined by the regression technique and the substitution method. Treatment effects on faecal and urinary P output, apparent P digestibility and P retention, and saliva P secretion were not significant. A linear relationship was observed between apparent faecal digestible P (Y, g/kg DMI) and P intake (X, g/kg DMI), which was described by the equation: Y = 0.4799X ?0.9209, r² = 0.9869, (p < 0.05). The true P digestibility determined by the regression technique and the substitution method amounted to 48.0 and 48.9%, respectively; the recorded endogenous faecal P losses were 0.92 and 0.93 g/kg DMI, respectively. The study demonstrated the potential of the regression method as well as the substitution method for estimation of true P digestibility and endogenous faecal P losses in goats.     

Effect of different diets on digestive enzyme activities,in vitro digestibility,and midgut gland structure in juvenile crayfish,Cherax quadricarinatus

This study investigated the effects of food quality on digestive enzyme activities, in vitro protein digestibility and histological traits of the midgut gland in juvenile crayfish Cherax quadricarinatus. Animals of a wide weight range were fed different diets: two commercial diets with high or low lipid content (high lipid and low lipid, respectively) and were compared with a reference diet (RF) previously formulated for this species. Proteinase, lipase and amylase activities were significantly influenced by diet and weight. Specific trypsin activity was significantly higher for crayfish fed with the HL diet. Trypsin activity depended on diet and weight. Protein digestibility showed that HL was the most digestible diet and RF the least. The weight of the animals did not affect protein digestibility. Structural disorganization, hypertrophy of B‐cells and presence of large vacuoles in R‐cells were mainly observed in juveniles fed with HL, indicative of malnutrition. Thus, our data suggest that the HL diet would not be the most appropriate for C. quadricarinatus, while RF diet would be more convenient for culture of this species.     

A method using solubility to predict dry matter digestibility of cellulosic materials.

A rapid chemical procedure based on the solubility of a holocellulose sample in a system of dimethyl sulfoxide with paraformaldehyde has been developed to provide a laboratory method for predicting dry matter digestibility of cellulose containing samples. The amount of dry matter solubilized by the chemical procedure was closely correlated with anaerobic, in vitro, rumen fluid digestion and with digestibility as measured by aerobic Cellulomonas, sp. bacteria. The quantity of solvent and dissolving time had little effect on solubility over a wide range. The method is rapid, well suited for various cellulosic materials, and may be carried out with simple equipment and facilities.