Lysine reactivity and starch gelatinization in extruded and pelleted canine diets

Fifteen dry adult canine diets (i.e., dinners, extrudates, pellets) were collected from retailers in Wageningen, The Netherlands, and chemically and physically characterized. Quality measurements were lysine O-methylisourea (OMIU) reactivity and starch gelatinization degree (SGD). In general, extruded diets had a higher crude fat and starch content than pellets. Mean values for starch gelatinization were higher in pellets and ranged between 0.78 and 0.91. The mean reactive/total lysine ratio in extrudate samples was about 5–10% higher than in pellet samples, suggesting the presence in commercial diets of about 200 g bound lysine/kg in pellets and 120 g/kg in extrudates with bound lysine levels of canine dinners about 170 g/kg. Variation of analysed nutrients in pellets was larger than in extrudates. Inclusion of animal or vegetable ingredients, and the process variables during extrusion or pelleting, are the likely causative factors for the variation in lysine reactivity and starch gelatinization.     

Proper energy evaluation of commercial laboratory animal diets based on digestibility and metabolizable energy values

The energy values of commercial laboratory animal diets have been customarily calculated by applying physiological fuel values (PFV) in this country. In order to ascertain accuracy of this application, apparent digestibility of crude protein, crude fat, nitrogen-free extracts (NFE), carbohydrate (NFE + crude fiber) and nitrogen-corrected metabolizable energy (MEn) of 10 commercial diets were determined using rats, dogs, rabbits and guinea pigs, respectively, and true digestibility of crude protein and crude fat of 12 feed ingredients was determined using rats. Apparent digestibility of the nutrients in the diets decreased with an increase in the crude fiber content of the diets. MEn values of the diets ranged between 2.18 and 3.75 kcal per g dry matter depending upon the crude fiber content of the diets. The energy values of the 10 diets calculated using PFV values of 4 kcal/g for protein and carbohydrate and 9 kcal/g for fat were compared with each MEn. The calculated values were 1.04 to 1.39 times higher than those of the respective MEn. All of the diets and most feed ingredients did not show high digestibility of nutrients assumed for the application of PFV. Therefore, it is concluded that application of PFV to the diets results in over-estimation of energy values and use of PFV for commercial laboratory diets in our country is not warranted. It is advisable to use MEn to evaluate energy value of commercial laboratory animal diets.     

Concentration of animal blood by ultrafiltration

Pilot-scale investigations into the application of ultrafiltration (UF) for concentrating bovine blood or a mixture of bovine and ovine blood are described. Tests were carried out in an Iopor 6CL UF system and a Romicon (hollow fiber) UF system. Optimal operating conditions for these two system were evaluated. Starting from a 18–20% TS lood concentration final concentrations of 28–30% TS were achieved. The lopor system was found to be more suited for processing blood and the average flux values obtained indicated UF to be a more economical process for concentrating blood than vacuum evaporation.     

How isoflavone levels in common rodent diets can interfere with the value of animal models and with experimental results

Phytoestrogens are a diverse group of plant-derived compounds structurally or functionally mimicking mammalian oestrogens. A variety of effects, in vitro, in animal models and in humans, have been attributed to these compounds. It is generally not appreciated that many commercial rodent diets are formulated with soy as a source of protein and thus large daily doses of phytoestrogens in the form of isoflavones are delivered to the animals. The content of isoflavones in laboratory diets depends on a number of factors and, therefore, varies considerably, both between different formulations, and also from batch to batch of the same formulation. Dietary isoflavones can influence a number of different endpoints, rendering the dietary levels of such compounds an important experimental factor to consider. The levels of isoflavones in common laboratory diets are reviewed in relation to the dietary levels influencing different endpoints.     

Composition of amino acids in feed ingredients for animal diets

Dietary amino acids (AA) are crucial for animal growth, development, reproduction, lactation, and health. However, there is a scarcity of information regarding complete composition of “nutritionally nonessential AA” (NEAA; those AA which can be synthesized by animals) in diets. To provide a much-needed database, we quantified NEAA (including glutamate, glutamine, aspartate, and asparagine) in feed ingredients for comparison with “nutritionally essential AA” (EAA; those AA whose carbon skeletons cannot be formed by animals). Except for gelatin and feather meal, animal and plant ingredients contained high percentages of glutamate plus glutamine, branched-chain AA, and aspartate plus asparagine, which were 10–32, 15–25, and 8–14% of total protein, respectively. In particular, leucine and glutamine were most abundant in blood meal and casein (13% of total protein), respectively. Notably, gelatin, feather meal, fish meal, meat and bone meal, and poultry byproduct had high percentages of glycine, proline plus hydroxyproline, and arginine, which were 10–35, 9.6–35, and 7.2–7.9% of total protein, respectively. Among plant products, arginine was most abundant in peanut meal and cottonseed meal (14–16% of total protein), whereas corn and sorghum had low percentages of cysteine, lysine, methionine, and tryptophan (0.9–3% of total protein). Overall, feed ingredients of animal origin (except for gelatin) are excellent sources of NEAA and EAA for livestock, avian, and aquatic species, whereas gelatin provides highest amounts of arginine, glycine, and proline plus hydroxyproline. Because casein, corn, soybean, peanut, fish, and gelatin are consumed by children and adults, our findings also have important implications for human nutrition.     

Performance, gut morphology and carcass characteristics of fattening rabbits as affected by particle size of pelleted diets

A review of past literature revealed inconsistencies in recommended feed particle size for optimal growth and productive performance of rabbits. Changing diet formulation and subsequent processing conditions may improve pellet texture and potentially affect rabbit performance. In the current study, two isoenergetic and isonitrogenous pelleted diets were formulated, which varied in the particle size of the concentrates (2 and 8 mm, respectively). The objective was to evaluate the effect of different particle sizes of compound diets on performance, nutrient utilisation, gut morphology, and carcass characteristics of fattening Italian White breed rabbits. The finely ground diet led to a significant improvement in feed efficiency and apparent digestibility of crude protein, ether extract, crude fibre and NDF, without any negative effect on gut morphology. Furthermore, a smaller particle size of concentrates in pelleted diets improved carcass traits. Meat colour parameters showed significant differences in longissimus lumborum and biceps femoris due to dietary treatments, but in both muscles pH values 1 h and 24 h after slaughter remained unchanged. It is concluded that a finely ground pelleted diet can be used to improve growth performance of rabbits without affecting carcass parameters.     

Performance,gut morphology and carcass characteristics of fattening rabbits as affected by particle size of pelleted diets

A review of past literature revealed inconsistencies in recommended feed particle size for optimal growth and productive performance of rabbits. Changing diet formulation and subsequent processing conditions may improve pellet texture and potentially affect rabbit performance. In the current study, two isoenergetic and isonitrogenous pelleted diets were formulated, which varied in the particle size of the concentrates (2 and 8 mm, respectively). The objective was to evaluate the effect of different particle sizes of compound diets on performance, nutrient utilisation, gut morphology, and carcass characteristics of fattening Italian White breed rabbits. The finely ground diet led to a significant improvement in feed efficiency and apparent digestibility of crude protein, ether extract, crude fibre and NDF, without any negative effect on gut morphology. Furthermore, a smaller particle size of concentrates in pelleted diets improved carcass traits. Meat colour parameters showed significant differences in longissimus lumborum and biceps femoris due to dietary treatments, but in both muscles pH values 1 h and 24 h after slaughter remained unchanged. It is concluded that a finely ground pelleted diet can be used to improve growth performance of rabbits without affecting carcass parameters.     

Glycosyl-transferase activities in pancreas: comparison between semi-synthetic and commercial diets

The glycosyl-transferase activities in the rat pancreas have been previously demonstrated to be modified by the quantity of different dietary components (lipids or proteins). To evaluate the role of the qualitative composition of the diet on such enzymic systems, two groups of rats were fed either a semi-synthetic diet or a commercial diet of very similar quantitative composition but differing in the quality of their components. The two diets induce a quite similar growth of animals, although the pancreas weight of the commercial-diet-fed rats is slightly higher. The galactosyl-, fucosyl- and mannosyl-transferase activities are more or less highly enhanced by the commercial diet according to the enzyme studied. The highest increase is observed for the biosynthesis of mannosyl-phosphoryl-dolichol. This enhancement by the commercial diet disappears when exogenous phosphoryl-dolichol is added. Such results indicate that the mannose transfer is probably modified by an increased level of the pancreatic lipidic acceptor.     

The commercial and agricultural applications of animal transgenesis

The potential for commercial application of transgenic technologies in domestic animals is discussed in relation to the areas where a significant impact on agriculture might be expected. These are the endocrine system, novel biochemical pathways, structural proteins of milk and of textile fibers, and the immune system. Manipulation of the endocrine system has been investigated for some years and it is clear that very accurate control is needed over gene expression if this approach is to prove commercially useful. The area most advanced in commercial application is the production of high-value pharmaceutical proteins in the mammary glands of domestic animals. Other applications that are discussed remain to be proven in larger animals despite being demonstrated laboratory test animals. These include a functional cysteine biosynthetic pathway and a functional glyoxylate cycle transferred from bacteria to mice, and alterations to the proteins of hair that change the physical properties of the resultant fibers. Research is also actively directed toward novel approaches for providing domestic animals with resistance to insects.     

Factors limiting the commercial application of animal cells in culture

The application of quality control and assurance procedures to the components of animal cell cultures has transformed what was an art to a viable industrial technology. This results in the successful large scale operation of such cultures. However it is clear that the cost of obtaining a license to produce materials from animal cells in culture severely impedes the movement of products into the market place. It is therefore necessary to examine in more detail the reasons for the reluctance of the regulatory authorities to issue product licences and in particular to appreciate the way ethical issues influence this process. This paper reviews these issues and indicates a way ahead.     

Variation in exocrine pancreatic secretion in rats due to different commercial diets

The diet fed to laboratory animals is one of many variables that can confound research results. The authors investigated the effect of the composition of commercial standard rodent diets on exocrine pancreatic function in rats. They compared two widely used commercial animal diets and found that diet composition greatly influences pancreatic secretion. Their results indicate that commercial diets should conform to the recommended composition requirements to avoid alterations in physiological functions that would eventually affect the results of biomedical research and that investigators should be keenly aware of the composition of the diets being fed to their animals.     

Irradiated laboratory animal diets: Dominant lethal studies in the mouse

In 4 separate dominant lethal experiments groups of mice of either Charles River CD1 or Alderley Park strains were fed laboratory diets (Oakes, 41B, PRD, BP nutrition rat and mouse maintenance diet No. 1). The diets were either untreated (negative control diets) or irradiated at 1, 2.5 and 5 megarad and were freshly irradiated, or stored. The animals were fed their test diets for a period of 3 weeks prior to mating. Groups of mice given a single intraperitoneal injection of 200 mg cyclophosphamide per kg body weight served as the positive controls.

Freshly irradiated PRD diet fed to male mice of both strains caused an increase in early deaths in females mated to the males in week 7 and to a lesser extent in week 4. The increase due to irradiation was small by comparison with that produced by the positive control compound. The responses for the other irradiated diets showed no significant increases in early deaths although some values for Oakes diet were high. The effect of storage was examined with PRD and BPN diet on one occasion and produced conflicting results.

Thus there was some evidence that irradiated PRD diet has weak mutagenic activity in the meiotic and/or pre-meiotic phase of the spermatogenic cycle which appeared to be lessened on storage; the inclusion of such a diet in toxicological studies would therefore need to be carefully considered.     

Maintenance of cotton-top tamarins fed an experimental pelleted diet versus a highly diverse sweetened diet

The future study of colon disease in captive callitrichid colonies may require manipulation of diets. The limited knowledge of the nutritional requirements for these species and the varied diets and supplementations fed to these animals in various colonies suggest the importance of testing the palatability and acceptability of diets for these primates. Individually housed cotton-top tamarins (Saguinus oedipus) were given either the regular Oak Ridge Associated Universities (ORAU) diet (monkey chow slurry, canned diet and supplements), a similar slurry using an experimental natural ingredient diet plus supplements, or the experimental diet without supplements. Neither dry food consumption, body weight, fecal output, nor the histological evaluation of the colons were affected by these diets. Daily intake of protein and calories were higher than previously reported estimates for the species. These results demonstrate that a natural ingredient non-sweetened pelleted diet is palatable for cotton-top tamarins for a period of 3.5 months, however, further testing over longer time periods is necessary. The nonnutritional (e.g. psychological) advantages of providing a highly diverse diet to primates housed in a relatively monotonous environment should be considered before adopting such a diet for an entire colony.     

Extent and method of grinding of sorghum prior to inclusion in complete pelleted broiler chicken diets affects broiler gut development and performance

A broiler experiment was conducted to examine the effects of sorghum particle size and milling type on the performance, nitrogen corrected apparent metabolisable energy (AME_n), digestive tract development, digesta pH, duodenal digesta particle size and digesta passage rate. Complete pelleted diets with identical botanical and chemical composition containing 750 g/kg whole sorghum (WS), sorghum ground through hammer mill with 1 mm and 3 mm screen (HM1 and HM3) and sorghum ground on a roller mill with 0.15 mm spacing (RM0.15), were made. Sorghum for diets HM3 and RM0.15 were milled to approximately the same mean particle size. Diet WS resulted in poorer (P<0.05) weight gain and feed conversion ratio (FCR) than the other diets from 11 to 21 days of age, while diet RM0.15 resulted in improved FCR. Apparent ME_n determined between 25 and 28 days of age, however, was higher (P<0.05) for diet WS than for the other diets. This was possibly due to a longer adaptation time to a larger feed particle size, as indicated by a lower (P<0.05) pH in the gizzard and smaller duodenal digesta particle size for this diet. Diet HM1 gave similar performance as diet HM3, but resulted in a significantly smaller gizzard, a higher pH of the gizzard content, a lower pH of the duodenal content and larger particles in the duodenal contents, thus indicating that gizzard development and activity were compromised by this diet. Total tract passage rate of the liquid phase marker was slower (P<0.05) in the WS fed birds, but there were no differences in solid phase marker excretion rates.     

Imaging of experimental osteoarthritis in small animal models

Normally, tissue alterations in small animal models for osteoarthritis (OA) are assessed by time-consuming and destructive histology or biochemical assays. Some high resolution imaging modalities are used for longitudinal monitoring of the OA disease process in vivo. microCT is one of these imaging modalities, which is known for superb high-resolution imaging of bone architecture alterations. A major drawback of microCT is that it has low soft-tissue contrast, which makes direct imaging of cartilage impossible. The use of microCT in combination with negatively charged radiopaque contrast agents enables imaging of cartilage degeneration. We demonstrate the possibility of microCT to image cartilage degeneration as a consequence of experimental OA, by the use contrast enhanced microCT in vivo in a rat model for OA. Furthermore, for the assessment of alterations in molecular processes involved in OA we used the recently developed technique of multi pinhole SPECT. This enables us to assess molecular processes involved in experimental OA in a rat at sub-millimeter level. Here we show quantification of subchondral bone turnover in an OA rat knee. These new techniques demonstrate the possibilities of quantitative experimental OA assessment in small animal models such as mice and rats and might enable substitution of the conventional destructive methods.     

Practical aspects of experimental design in animal research

A brief overview is presented of the key steps involved in designing a research animal experiment, with reference to resources that specifically address each topic of discussion in more detail. After an idea for a research project is conceived, a thorough review of the literature and consultation with experts in that field are pursued to refine the problem statement and to assimilate background information that is necessary for the experimental design phase. A null and an alternate hypothesis that address the problem statement are then formulated, and only then is the specific design of the experiment developed. Likely the most critical step in designing animal experiments is the identification of the most appropriate animal model to address the experimental question being asked. Other practical considerations include defining the necessary control groups, randomly assigning animals to control/treatment groups, determining the number of animals needed per group, evaluating the logistics of the actual performance of the animal experiments, and identifying the most appropriate statistical analyses and potential collaborators experienced in the area of study. All of these factors are critical to designing an experiment that will generate scientifically valid and reproducible data, which should be considered the ultimate goal of any scientific investigation.