High-protein Pellets Research Articles

Dietary protein restriction modulates ‘dessert’ intake after a meal, via fibroblast growth factor 21 (FGF21)

Pharmacological administration of fibroblast growth factor 21 (FGF21) alters food choice, including that it decreases the consumption of sucrose and other sweet tastants. Conversely, endogenous secretion of FGF21 by the liver is modulated by diet, such that plasma FGF21 is increased after eating foods that have a low dietary protein: total energy (P: E) ratio. Together, these findings suggest a strategy to promote healthy eating, in which the macronutrient content of a pre-load diet could reduce the consumption of sweet desserts in sated mice. Here, we tested the prediction that individuals maintained on a low P: E diet, and offered a highly palatable sweet ‘dessert’ following a pre-load meal, would eat less of the sugary snack compared to controls—due to increased FGF21 signaling. In addition to decreasing sweet intake, FGF21 increases the consumption of dietary protein. Thus, we predicted that individuals maintained on the low P: E diet, and offered a very high-protein pellet as ‘dessert’ or snack after a meal, would eat more of the high protein pellet compared to controls, and that this depends on FGF21. We tested this in C57Bl/6J, and liver-specific FGF21-null (FGF21ΔL) null male and female mice and littermate controls. Contrary to expectation, eating a low protein pre-load did not reduce the later consumption of a sweet solution in either males or females, despite robustly increasing plasma FGF21. Rather, eating the low protein pre-load increased later consumption of a high protein pellet. This was more apparent among males and was abrogated in the FGF21ΔL mice. We conclude that physiologic induction of hepatic FGF21 by a low protein pre-load diet is not sufficient to reduce the consumption of sweet desserts, though it effectively increases the subsequent intake of dietary protein in male mice.

Diet Protein Content and Individual Phenotype Affect Food Intake and Protein Appetence in Rats

BackgroundA low-protein diet can induce compensatory intake of excess energy. This must be better evaluated to anticipate the obesogenic risk that may result from the dietary recommendations for reducing animal protein consumption. ObjectivesWe aimed to further characterize the behavioral and physiological responses to a reduction in dietary protein and to identify the determinants of protein appetite. MethodsThirty-two male Wistar rats [4 wk old, (mean ± SEM) 135 ± 32 g body weight] were fed a low-protein (LP; 6% energy value) or normal-protein (NP; 20%) diet for 8 wk. Food intake and body mass were measured during the entire intervention. During self-selection sessions after 4 wk of experimental diets, we evaluated rat food preference between LP, NP, or high-protein (HP; 55%) pellets. At the end of the experiment, we assessed their hedonic response [ultrasonic vocalizations (USVs)] and c-Fos neuronal activation in the olfactory tubercle and nucleus accumbens (NAcc) associated with an LP or HP meal. ResultsRats fed an LP diet had greater food intake (24%), body weight (5%), and visceral adiposity (30%) than NP rats. All LP rats and half of the NP rats showed a nearly exclusive preference for HP pellets during self-selection sessions, whereas the other half of the NP rats showed no preference. This suggests that the appetite for proteins is driven not only by a low protein status but also by individual traits in NP rats. LP or HP meal induced similar USV emission and similar neuronal activation in the NAcc in feed-deprived LP and NP rats, showing no specific response linked to protein appetite. ConclusionsProtein appetite in rats is driven by low protein status or individual preferences in rats receiving adequate protein amounts. This must be considered and further analyzed, in the context of current recommendations for protein intake reduction.

Dietary choices in a generalist herbivore, the eastern cottontail Sylvilagus floridanus, in urban landscapes

Abstract We tested for dietary choices of foods varying in nutrient composition by cottontail rabbits on two college campuses in midwestern USA. We quantified choices among pellets of varying nutritional quality at artificial food patches. Dietary choices differed between seasons and locations. Spring giving-up densities (GUDs: food left behind) did not show differences in food choices and were lower than summer GUDs. In Appleton, the cottontails favoured both high protein and fibre pellets, whereas the medium protein and fibre pellets were favoured in Chicago. The cottontails maintained their choice of high protein, high fibre pellets at three spatial scales. The cottontails varied food intake to balance their protein, salt and fibre needs at different times and locations. Studying dietary choices and the effect of resource quality on foraging responses by urban wildlife provides a useful tool to study ecological interactions and can help minimize damage in urban environments such as parks.

A high protein meal affects plasma insulin concentrations and amino acid metabolism in horses with equine metabolic syndrome

Equine metabolic syndrome (EMS) is characterized by an abnormal insulin response to a glycemic challenge but despite the known insulinotropic effects of certain amino acids, there is a paucity of data evaluating the impact of dietary protein on insulin dynamics in these horses. The objective was therefore to assess insulin and amino acid responses following intake of a high protein meal in healthy horses and those with EMS. Six mature horses diagnosed with EMS and six age-matched control horses without EMS were used. Horses were fed 2g/kg body mass (BM) of a high protein pellet (31% crude protein) at time 0 and 30min, for a total of 4g/kg BM, following an overnight fast. Blood samples collected during a 4h period were analysed for plasma glucose, insulin, amino acids and urea concentrations.Glucose concentrations were not different between groups (P=0.2). Horses with EMS had a 9-fold greater insulinemic response to the consumption of a high protein meal compared with controls (P=0.046). Post-prandial levels of histidine, citrulline, tyrosine, valine, methionine, isoleucine, leucine and ornithine were higher in horses with EMS (P<0.05). Baseline urea nitrogen concentrations were not significantly different between groups (P=0.1). Knowing that certain amino acids are insulin secretagogues, these results illustrate that consumption of a high protein meal caused a hyperinsulinemic response and affected amino acid dynamics in horses with EMS. These findings suggest that dietary protein content should be taken into consideration in the management of horses with insulin dysregulation.

Tasting novel foods and selecting nutrient content in a highly successful ecological invader, the common myna

Invasion success is dependent on the ability of a species to discover and exploit novel food resources. Within this context, individuals must be willing to taste novel foods. They must also be capable of evaluating the nutritional content of new foods, and selecting their relative intake in order to fulfil their nutritional needs. Whereas the former capacity is well studied, little is known about the latter capacity. First, using the common myna as a model avian invader species, we quantified the willingness of mynas to taste novel foods relative to familiar ones. Mynas readily tasted high protein (HP) novel foods and consumed them in higher quantities compared to a familiar food. Data showed that at three different levels – mixes, ingredients and macronutrients – intake could not be explained by a random model. In experiment 2, we confirmed that mynas were making their selection based on protein (P) content rather than a selection for novelty per se. When given the choice of three equally unfamiliar foods, mynas again ate disproportionately from the high protein relative to high lipid and high carbohydrate foods. Analysis revealed that mynas consumed amounts of protein that were closer to the ones in their natural diet. Finally, in experiment 3, we measured inter‐individual variation in innovation and exploration propensities, and examined associations with inter‐individual variation in consumption of specific macronutrients. This analysis revealed that individuals that selected HP pellets were more exploratory and individuals that selected HC pellets were quicker to solve the innovative foraging task. These findings indicate that not only the willingness to taste novel foods, but also the capacity to evaluate their nutritional content, might be central to the myna's substantial ecological success.

Effect of dehydrated alfalfa on equine gastric and faecal microbial ecosystems

Disturbances of the gastric and hindgut ecosystems can lead to damage of the mucosa in the stomach and to intestinal colic. Some studies suggested that alfalfa could have preventive and healing capacities against gastric ulcerations. Preliminary data suggest that buffering capacity of alfalfa could also be beneficial for the hindgut ecosystem. The objective of this study was thus to assess the effect of dehydrated alfalfa pellets on the bacterial composition and the microbial activity of the equine gastric and faecal ecosystems. Six adult horses allotted in three pairs were studied in a 3 diets x 3 periods Latin square design experiment. During the 18-days experimental period, horses were fed grass hay (57% of total DMI) plus rolled barley and high-protein pellets (27% and 16% of total DMI) that represented a total intake of 1.8% BW / day. High-protein pellets consisted of alfalfa (obtained from 2 different processes, ALF – 2.35mcal/kg DM, 16.9% DM CP, 27.2% DM NFC, 10.8% DM ash, 2.1% DM Ca) and sunflower meal (SFM – 2.26 mcal/kg DM, 29.1% DM CP, 13.8% DM NFC, 7.2% DM ash, 0.5% DM Ca) pellets. Daily starch intake (289g) was divided into 2 equal meals. During the 5-day wash-out period, horses were fed grass hay and rolled barley (93% and 7% of total DMI respectively). On day 18 of the experimental period, faeces and gastric content were collected 3:00 and 3:30h respectively after morning barley + high-protein pellets meal to assess microbial ecosystem parameters. Horses fed ALF had significantly lower gastric concentrations of amylolytic bacteria than the ones fed SFM (P=0.04). On the contrary, amylolytic bacterial concentrations were higher in the faeces of horses fed ALF (P=0.01) compared to SFM diets, as well as lactate-utilizing and pectinolytic bacterial concentrations (P=0.05 and P=0.04 respectively). However, no significant modification of the pH, VFAs proportions, VFAs and lactic-acid concentrations were measured in gastric content and faeces. Regarding gastric health, minimizing carbohydrate fermentation could be beneficial, although VFAs concentrations were not different in this study between ALF and SFM diets. In the hindgut, higher lactate-utilizing concentrations could be advantageous to limit hindgut acidosis. Further work is required to understand the mechanisms that altered gastric and faecal bacterial ecosystems in horses fed the alfalfa diet and to investigate whether other proportions or processed forms of alfalfa in the diet would be more beneficial.

Dietary protein selection in a free-ranging urban population of common myna birds

Anthropogenic environments can offer rich sources of energy to urban wildlife, but little is known about how they impact on nutritional balance and food selection. Common mynas (Sturnus tristis) provide a powerful model system for testing the nutritional constraints and priorities of an invasive species that has successfully adapted to urban environments. Here, we use behavioral observations, field-based feeding trials, videography, and the right-angled mixture triangle model (RMT) to examine the macronutrient preferences of these invasive birds. Our behavioral observations showed that mynas consumed insects (40.6%), worms (33.2%), human discards (17.6%), and plants (8.6%). Our feeding trials using nutritionally defined foods showed that mynas had a clear preference for food dishes containing only high-protein (HP) pellets over high-lipid (HL) or high-carbohydrate (HC) pellets. In addition, mixed feeders were also presented in 2 combinations: 1) contained equal proportions of HP and HC pellets and 2) equal proportions of HP and HL pellets. HP pellets were selectively consumed from both mixed feeders, this involving an increase in feeding time. Overall, the RMT showed that mynas consumed a higher proportion of protein from the feeders than in their natural diet. Furthermore, the majority of our observations of birds feeding at the dishes containing HP foods ended in intraspecific aggression, suggesting that protein is a contestable resource. These results suggest that mynas at our urban study site are deficient in protein relative to fats and carbohydrates.

The effect of palatability of protein source on dietary selection in dairy calves

Evidence has shown that soybean meal is perceived as more palatable than canola meal by dairy calves in short-term preference tests. This study evaluated the effect of protein source on longer-term dietary selection of dairy calves. In experiment 1, 40 Holstein bull calves (11.4±4.3d of age) were randomly assigned to 1 of 2 choice diets for 6wk: base starter pellet (S; 12% crude protein; CP) and high-protein pellet (40% CP) containing either (1) soybean meal (SB) or (2) canola meal (CM). In wk 7 to 8, all calves were offered a single pelleted diet containing the protein source to which they were previously exposed. In experiment 2, 22 Holstein bull calves (9.9±4.6d of age) were offered, for 6wk, a choice of 2 mixed pelleted diets: (1) 70% S and 30% SB (SB mix), or (2) 70% S and 30% CM (CM mix). In wk 7 to 8, calves were randomly assigned to 1 of 2 choice diets, as in experiment 1: (1) SB + S, or (2) CM + S. All feeds were provided ad libitum. Calves received 6 L/d of milk replacer [0.75kg/d of dry matter (DM)] for the duration of both experiments. Feed intake was recorded daily and calves were weighed every 14d. Feeds were sampled weekly to analyze DM and nutrient intake. Mixed diets in experiment 2 were analyzed for CP in wk 4 and 6 to assess feed sorting (calculated as actual CP intake as a percentage of predicted intake). In experiment 1, calves offered SB + S in wk 1 to 6 consumed more high-protein pellet than calves offered CM + S [73 vs. 42% of DM intake (DMI)] and, consequently, more CP (168 vs. 117g/d). Solid feed DMI and average daily gain were similar between treatments. When offered a single diet in wk 7 to 8, calves offered starter containing soybean meal increased intake to a greater extent than calves offered the starter containing canola meal. In experiment 2, calves preferred the SB mix to CM mix (preference ratio: 0.7). Calves consumed more CP than predicted from SB mix in wk 4 and 6 (108±2.0%), indicating that they were sorting in favor of SB. In contrast, calves consumed less CP than predicted from CM mix in wk 4 (81.48±4.1%), indicating that they were sorting against CM. When assigned to choice treatments in wk 7 to 8 of experiment 2, calves offered SB + S consumed more protein pellet than calves offered CM + S (81 vs. 31% DMI) and consumed more CP (378 vs. 196g/d). Average daily gain was greater for calves offered SB + S but DMI was similar. Overall, these results suggest that dietary selection was influenced by innate feed preferences, and milk-fed calves may not be sensitive to protein imbalances in their diet.

Diet Quality Limits Summer Growth of Field Vole Populations

Marked variation occurs in both seasonal and multiannual population density peaks of northern European small mammal species, including voles. The availability of dietary proteins is a key factor limiting the population growth of herbivore species. The objective of this study is to investigate the degree to which protein availability influences the growth of increasing vole populations. We hypothesise that the summer growth of folivorous vole populations is positively associated with dietary protein availability. A field experiment was conducted over a summer reproductive period in 18 vegetated enclosures. Populations of field voles (Microtus agrestis) were randomised amongst three treatment groups: 1) food supplementation with ad libitum high protein (30% dry weight) pellets, 2) food supplementation with ad libitum low protein (1% dry weight; both supplemented foods had equivalent energy content) pellets, and 3) control (no food supplementation), n = 6 per treatment. Vole density, survival, demographic attributes and condition indicators were monitored with live-trapping and blood sampling. Highest final vole densities were attained in populations that received high protein supplementation and lowest in low protein populations. Control populations displayed intermediate densities. The survival rate of voles was similar in all treatment groups. The proportion of females, and of those that were pregnant or lactating, was highest in the high protein supplemented populations. This suggests that variation in reproductive, rather than survival rates of voles, accounted for density differences between the treatment groups. We found no clear association between population demography and individual physiological condition. Our results demonstrate that dietary protein availability limits vole population growth during the summer growing season. This suggests that the nutritional quality of forage may be an underestimated source of interannual variation in the density and growth rates of widely fluctuating populations of herbivorous small mammals.

Neuropeptide Y Increases Both Ingestion of a Self-Selection Macronutrient Diet and Fos Expression in the Medial Amygdala of Rats

The rat posterodorsal medial amygdala (MePD) is responsive to the orexigenic neuropeptide Y (NPY) and is a putative candidate to participate in neural circuits that modulate feeding behavior. Here, we studied the effects of intracerebroventricular (icv) microinjection of NPY on the appetitive and food intake behaviors of rats under the paradigm of the self-selection macronutrient isolated diets [high-carbohydrate (high-CHO), high-protein and high-lipid food pellets]. At the same time, Fos expression was also evaluated in the MePD as a marker of local cellular activation. Adult male rats received icv microinjections of NPY (1mg and10mg/5mL, n = 10 and 8, respectively) whereas the control groups either received icv microinjection of artificial cerebrospinal fluid (5mL, n = 8) or underwent sham procedure (n = 8). The data were obtained after a fasting protocol. Feeding behavior was evaluated during a 2 h test period of free access to the selective diets. Rats in all groups preferred the high-CHO diet. Compared to controls, both doses of NPY increased the appetitive behaviors (searching for food and the frequency of attempts to eat any diet) and the percentage of animals eating high-CHO diet. However, only NPY at a dose of 1 μg led to a significant increase in food intake and showed a strong positive correlation with Fos expression in the MePD (p 0.05 in all cases). These new data reveal a biphasic effect of NPY on the appetite and food intake behaviors and suggest that the MePD participates in the NPY-induced feeding behavior in rats.

Effect of water exchange, salinity regime, stocking density and diets on growth and survival of domesticated black tiger shrimp Penaeus monodon (Fabricius, 1798) reared in sand-based recirculating systems

The effect of water exchange, salinity regime, stocking density and diets on growth and survival of domesticated Penaeus monodon juveniles was evaluated in two independent experiments. In the first experiment, 1g-domesticated P. monodon juveniles were stocked at 10 animals per m2 in 1-m3 tanks to test two feeding regimes (mono diet of high protein pellets and a combination diet of high protein pellets and a fresh-food combination) and two rearing systems (a sand-based recirculation system with low water exchange; and a sand-based system with high rates of flow-through water). In the second experiment, performance of the animals was assessed when reared under 2 different water salinities and 2 stocking density treatments.Results of the two experiments indicated that the sand-based recirculation system with a water exchange at a rate of 5–10% a day and a combination diet of high protein pellets (55%) and a fresh-food combination consisting of 75% squid, 15% oyster and 10% blood cockle were suitable for the indoor rearing of the grow-out phase of P. monodon. Water salinity of 20–23g·L−1 and low stocking density of 10 animals per m2 resulted in the best growth of the shrimp. Survival of P. monodon in the grow-out phase was significantly higher (P<0.05) at low salinity of 20–23g·L−1 as compared to high salinity of 32–33g·L−1 irrespective of stocking density. In conclusion, a sand-based recirculation system, high protein pellets and diversified fresh-food items, and water salinity of 20–23g·L−1 are suitable conditions for indoor grow-out phase up to 35g average of the black tiger shrimp P. monodon.

Effects of Supplementation and Stage of Lactation on Performance of Grazing Dairy Ewes

The majority of dairy sheep in the world are fed pasture and supplemental grain during lactation; however, no trials have reported the effects of supplementation of dairy ewes grazing improved pastures in North America. In trial 1, 56 three-year-old grazing dairy ewes in early [21±10 d in milk (DIM)] or late (136±9 DIM) lactation were fed 0 or 0.82kg of dry matter/d per ewe of supplement (16.5% crude protein mixture of corn and a soybean meal-based high-protein pellet) in a 2×2 factorial arrangement of treatments. There were no significant interactions between stage of lactation and supplementation treatments. Average test-day milk production was higher in early-lactation ewes than in late-lactation ewes (1.74 vs. 1.21kg/d, respectively). Although test-day milk protein percentage was higher in late-lactation ewes than in early-lactation ewes (5.02 vs. 4.86%, respectively), there was no difference in milk fat percentage between stages of lactation. Supplemented ewes had higher milk production (1.59 vs. 1.36kg/d, respectively), lower milk fat percentage (5.75 vs. 6.00%, respectively), and lower milk protein percentage (4.84 vs. 5.04%, respectively) than unsupplemented ewes. Milk urea N levels were similar between the 2 stages of lactation and between the 2 supplementation treatments and were above recommended levels for dairy sheep, indicating an excess intake or inefficient utilization of protein for both supplementation treatments. In trial 2, 96 two-, three-, and four-year-old grazing dairy ewes in midlactation (112±21 DIM) were randomly assigned to 4 treatments of 0, 0.41, 0.82, or 1.24kg of dry matter/d per ewe of whole corn. Average test-day milk production increased linearly and milk fat percentage decreased quadratically with increasing amounts of corn supplementation. Milk protein yield increased linearly, and milk urea N levels decreased quadratically with increasing amounts of corn supplementation, suggesting an improvement in the utilization of pasture protein with increasing dietary energy intake.

The effects of wintertime undernutrition on plasma leptin and insulin levels in an arctic ruminant, the reindeer

We examined the effects of prolonged undernutrition on plasma leptin and insulin levels and some serum protein metabolites in reindeer (Rangifer tarandus tarandus L.) during winter and spring. The reindeer (male <1 year) were fed their preferred winter feed, low-protein lichen ad libitum for 5 weeks, followed by 40% restriction of energy for 8 weeks and refeeding with high-protein pellets for 6 weeks. The control group received high-protein reindeer pellets ad libitum throughout the experiment. Plasma leptin decreased by 46% and insulin by 54% in the lichen group already during the ad libitum period between January and February, with parallel decreases in body weight, serum total proteins, albumin and urea. Leptin remained low during most of the energy restriction period in March and April, but increased at the end of April while body weight decreased. During the refeeding period in May and June, the body weight and insulin of the lichen group increased in parallel with total proteins and urea, but leptin remained unchanged. Similar significant reductions in plasma leptin (40%) as in the lichen group also took place in the control group fed high-protein pellets ad libitum in January and February, although their feed intake, serum total proteins and body weight remained unchanged. The results show that leptin decreases in reindeer during mid-winter, independent of food or protein intake, and suggest that the decrease may be cued by seasonal factors such as the short photoperiod.

Preliminary study on the use of synthetic substrate for juvenile stage production of the yabby, Cherax destructor (Clark) (Decapoda: Parastacidae)

Juvenile Cherax destructor (commonly called the yabby) (mean weight 48.3 mg) were cultured intensively (stocking density 360/m2) under controlled conditions for 48 days. The animals were provided with a combination of food (high protein pellets and/or natural feed organisms attached to a conditioned synthetic substrate) and refuge. Fastest growth and highest yield was recorded when both pellets and the conditioned synthetic material were provided. Although the yabbies sheltered in the synthetic substrate, it did not increase survival. Juvenile yabbies (< 200 mg) were able to graze on small organisms attached to the synthetic material but this ability appeared to decline as the yabbies grew to a larger size. The use of artificial substrates in the intensive nursery phase production of juvenile freshwater crayfish is discussed.

Improving the pre-weaning nutrition of calves by supplementation of the cow and/or the calf while grazing low quality pastures. 1. Cow production

Large numbers of weaner calves destined for meat production in Australia are born to cows grazing low quality pastures and have low growth rates to weaning. A study was undertaken in a New South Wales subtropical coastal area (Grafton, 29°38′S, 152°54′E) to increase these growth rates by supplementing cows to mid lactation and/or their calves up to weaning. This paper reports on the effects of these supplementation regimes on cow production. Cows were either not supplemented or supplemented with cottonseed meal twice-a-week at 4.2 kg/head over 145 days, commencing before the expected start of calving. Calves, depending on their treatment group, either had unrestricted access to a ‘creep’ containing a high-energy, high-protein pellet given from 75 or 150 days old, or had no access at all to ‘creep’ feed. However, all cows and their calves had access to mineral blocks. Cottonseed meal-supplemented cows were heavier (408 v. 362 kg) and had higher condition scores (3.3 v. 2.9 units) than non-supplemented cows when weighed and scanned in November 1996, after all cows had calved, and they maintained these differences until April 1997 when calves were weaned. There was a trend for cows, whose calves had access to a ‘creep’ from 150 days old, to gain weight towards the end of lactation whereas cows from other treatment groups lost weight. Non-supplemented cows had a 3-fold greater daily intake of mineral blocks than cottonseed meal cows (178 v. 61 g/cow) providing them with an additional 9.8 g phosphorus/cow. Cottonseed meal cows were observed to have fewer grazing incidences (60 v. 75% of activities) during supplementation than non-supplemented cows, with grazing instances increasing for all cows during lactation. Cottonseed meal cows whose calves had access to ‘creep’ feed continued to have fewer grazing incidences (74 v. 90%) than other cows 70 days post-supplementation. Milk yield was higher in cottonseed meal cows than in non-supplemented cows (4.8 v. 4.0 kg/day). Following a synchronised insemination program, at the end of cottonseed meal supplementation, the pregnancy rate of formerly cottonseed meal-supplemented cows was twice that (40 v. 20%) of non-supplemented cows. The combination of cottonseed meal supplements and macrominerals from blocks improved cow liveweight, condition score, milk yield and fertility, and was a successful strategy for increasing production from low quality pastures.

Operant Responding for Dietary Protein in the Golden Hamster ( Mesocricetus auratus)

D iBATTISTA, D. Operant responding for dietary protein in the golden hamster (Mesocricetus auratus). PHYSIOL BEHAV 67(1) 95–98, 1999.—Golden hamsters housed in operant chambers over a period of weeks had ad lib access to a maintenance diet that was either nutritionally complete (NCMD) or protein-free (PFMD), and they were required to press a lever on a fixed-ratio (FR) schedule to obtain 20-mg high-protein pellets. As the FR requirement increased, hamsters maintained on the NCMD made fewer lever presses and ate fewer pellets, and at the highest FR levels, they earned very few pellets. In contrast, hamsters maintained on PFMD increased the number of lever presses as the FR requirement increased, and they only slightly reduced the number of pellets eaten. Even at the highest FR requirement levels, PFMD hamsters still derived an average of 11–12% of total calories from protein, a level of intake that is either adequate for adult hamsters, or very nearly so. Previous research has shown that hamsters make adaptive behavioural adjustments in response to time-restricted access to dietary protein, and the present findings demonstrate that protein-restricted hamsters that must press a lever to obtain protein-rich pellets also make adaptive behavioural adjustments when challenged with increases in the FR requirement.

Poor Feed Conversion of Tawes (Puntius gonionotus) when Fed High Protein Pellets in Hapa Culture in Northeast Thailand

Tawes grew reasonably well but showed unfavorable feed conversion when reared in hapas on catfish pellets with a 35% protein content. Inefficient dietary protein digestion (fishmeal) in view of its herbivorous preference was suggested.

Scale Morphology as an Index of Developmental Stability and Stress Resistance of Tilapia (Oreochromis niloticus)

Growth and the stabilities of growth and development were examined in inbred, outbred, and interstrain hybrid lines of tilapia (Oreochromus niloticus) under two diet regimes. Developmental stability was quantified as the inverse of the number of deformed scale circuli (calcified ridges). Growth stability was measured as the inverse of the individual variability of circulus spacing (circulus spacing is an indirect measure of growth rate). Each line was fed an alternating diet of low-protein rice bran and high-protein commercial pellet or a constant diet of commercial pellet. Diet regime had a significant effect on growth, developmental stability, and growth stability. Genetic composition of line had a significant effect only on developmental stability. Inbred lines had lower developmental stabilities than outbred lines. Hybrid progeny had higher developmental stability than the average of the parent strain values. Faster growing individuals had higher developmental and growth stabilities and lower growth stabilities (only within the commercial pellet regime). Composite indices of "merit" can be constructed by combining the variables, according to the correlations among variables and breeding objectives.

Effects of supplementary hay in the diet of concentrate fed early weaned lambs

Early weaned lambs have been successfully reared to slaughter on ad libitum concentrate diets for many years, mainly in systems involving out of season lamb production where high market prices offset the comparatively high feed costs. In these systems maximum growth rates are required to enable lambs to reach acceptable slaughter weights before market prices fall.Feeding systems may be based on whole cereals supplemented with small, high protein pellets, a technique developed from Rowett studies (Orskov et al, 1974) or home made blends of processed cereals and by-products or proprietary concentrates. Component selection Is a common problem with diets based on whole grains and although this can largely be overcome by correct feeder design this incurs considerable expense. Diet selection can be reduced by processing grain (eg on farm rolling) or by pelleting. Cereal processing and pelleting however can have deleterious effects on rumen function as described by Orskov (1973), the effects being attributed to both inadequate saliva production and reduced rumen surface stimulation by roughage.

Effect of Protein Calorie Malnutrition and Cell Replication on Aflatoxin B&lt;sub&gt;1&lt;/sub&gt;-Induced Hepatocarcinogenesis in Rats

Malnourished and well-fed neonatal Holtzman rats 10 days of age were exposed to 3 doses of aflatoxin B1 [(AFB1) CAS: 1162-65-8] at intervals of 96 hours to study the combined effect of malnutrition and cell replication in AFB1-induced hepato-carcinogenesis. The neonatal model made use of the fact that cell replication persists in the liver for 3 weeks of postnatal life. Malnutrition during suckling was induced by adopting the techniques of Widdowson and McCance of increasing the litter size to 16. Following AFB1 administration, the malnourished animals were rehabilitated on a high-protein pellet diet given ad libitum. Preneoplastic lesions and neoplastic nodules were identified in the livers of the 2 groups. Alpha fetoprotein (AFP) was detected in the sera by immunoprecipitation. The preneoplastic lesions appeared earlier, and their progression was faster in the malnourished group as compared to the well-fed animals. By 65 weeks following AFB1 exposure, 6 of 17 (35%) animals from the malnourished group showed neoplastic nodules, whereas no such nodules were observed in the animals from the well-fed group. Neoplastic nodules showed a variable pattern of enzyme activities. Under the electron microscope the changes were again more marked in the animals of the malnourished group as compared to those of the well-fed group. In the former group serum AFP was detected as early as 46 weeks, and by 55-65 weeks almost 50% of the animals from the same group showed positivity for serum AFP. None of the animals from the well-fed group showed any positivity for serum AFP throughout the study. This study thus indicates that preneoplastic lesions-neoplastic nodules are enhanced when cell replication and malnutrition coexist during AFB1-induced hepatocarcinogenesis.