Effect of low protein and low energy diet on physiological status and digestibility of F344 rats.

A long-term raising study was carried out on male F344/DuCrj rats with three low protein (Crude Protein (CP); 14.5, 11.5, 8.5%) and low energy (Digestible Energy (DE); 2.0 kcal/g) diets from 4 to 104 weeks of age. In rats fed the 8.5% CP diet, body weight and digestible crude protein (DCP) consumption at 10 weeks of age were lower (P < 0.05) but the body weight at 50 weeks of age was higher (P < 0.05) than in the other groups. In rats fed the 8.5% CP diet the crude fat digestibility was higher (P < 0.05), and the CP/nitrogen-corrected metabolizable energy (MEn) ratio was low. On the other hand, the mean survival time at 80 weeks of age was shorter in rats fed the 8.5% CP diet (P < 0.05).     

Establishment and characteristics of four sub-strains of F344 rats reared on various low protein and low energy diets.

Four sub-strains, reared by sib-mating and having for their origin the F344/DuCrj strain of rats, were established by feeding with different levels of low protein and low energy diets, and their characteristics investigated. The amounts of crude protein (CP) and digestible energy (DE) in the four diets were 17.6%-3.0 kcal, 10.5%-2.5 kcal, 8.4%-2.0 kcal, and 10.5%-2.5 kcal, respectively, and the four sub-strains established here were provisionally designated as F344/Tig1, F344/Tig2, F344/Tig3 and F344/Tig4, respectively. Intakes of nitrogen-corrected metabolizable energy (MEn) did not differ, and a large intake of digestible crude protein (DCP) was observed in F344/Tig1 rats. The body weight of rats provided with lower-nutrient diets showed a tendency to decrease until the F2 generation, but no change among the generations was seen subsequently, and the same compiled differences in protein content were maintained. Similar transitions were observed in the lifetime rearing test. Though F344/Tig3 rats, which were reared on minimum nutrients, showed a tendency to delayed puberty, we were easily able to breed four pairs in every generation using procedures similar to those used for other strains of rats. There were no differences among the F344/Tig1 to -3 strains of rats in body length, digestive tract length, or organ weight per body weight, and all the rats had a normal range of biochemical values. But the F344/Tig4 showed a high glutamic-oxaloacetic transaminase (GOT), and a tendency to decreased liver function and a shorter lifespan. These sub-strains of F344 rats clarified differences in fatty acid compositions, such as docosahexaenoic acid (DHA) in serum, liver and the brain. The rats were intended to be useful animal models for the study of nutritional environments and their influence on the memory and learning.     

Indices for physiological assessment of nutritional condition in pregnant collared peccaries (Tayassu tajacu)

Hematological and serum biochemical responses to two levels of dietary energy (high energy [HE], 3300 kcal digestible energy [DE]/kg; moderate energy [ME], 2300 kcal DE/kg) and protein (high protein [HP], 16.0% crude protein; moderate protein [MP], 8.4% crude protein) during gestation in 15 collared peccaries (Tayassu tajacu) were examined. Dietary energy and protein levels influenced body weight gain during gestation. Red blood cell counts and lymphocyte concentrations were higher and neutrophil concentrations were lower among females fed an HP diet compared to those fed an MP diet. Alkaline phosphatase and alpha-2 globulin concentrations were higher among females fed an MP diet. Aspartate aminotransferase and cholesterol concentrations were higher and calcium and thyroxine concentrations were lower among females fed ME diets compared to those fed HE diets. These results suggest that physiological indices used in combination with morphological measurements can be useful in assessing collared peccary nutritional health during gestation.     

Prediction of the energy value of rabbit feeds varying widely in fibre content

Digestibility trials of 23 pelleted diets, with one or two ingredients and having 8.7–53.5% acid detergent fibre (ADF) on a dry matter (DM) basis, were carried out in adult rabbits fed ad libitum. Using a step-wise linear regression approach, the relationship between the digestible energy content (DE) or the coefficient of digestibility of gross energy (dGE) and the chemical composition of diets was established. Excluding beet pulp, with a very high crude fibre digestibility (54.8%), the prediction equations obtained were: DE (MJ kg⁻¹ DM) = 14.2 − 0.205 ADF + 0.218 EE + 0.057 CP (R² = 0.965, RSD = 0.494) and dGE (%) = 83.2 − 1.07 ADF (R² = 0.951, RSD = 3.15) where ADF, ether extract (EE) and crude protein (CP) are expressed as a percentage on a DM basis. When diets with level of EE or CP higher than 6% or 18% respectively (grape marc, olive oil cake, brewer's grains, sunflower meal) were also removed, the prediction equations became: DE = 15.9 − 0.219 ADF (R² = 0.974, RSD = 0.391) and dGE = 85.6 − 1.20 ADF (R² = 0.977, RSD = 2.02). The contents in DE, digestible crude protein and undigestible crude fibre of 21 ingredients are presented and discussed in comparison with other studies.     

Energy/protein ratio in natural-ingredient diets for weanling rats. II. Energy and protein retention and efficiency of retention

A 3 x 3 factorial experiment was carried out, in which natural ingredient diets formulated at 3 digestible energy levels (DE) (100, 90 and 80% of NRC, 1978 recommendations) and at 3 energy: protein ratios (EPR) (63, 71 and 79 kJ DE/g crude protein (CP)) were fed to 8 weanling male Wistar rats/group. Half of these animals were sacrificed at the end of the 6-week experimental period and their body composition analyzed. Retentions of protein and energy were assessed by difference from a similar group of 8 rats killed and analyzed at the beginning of the experiment. No interaction was found between the 2 factors studied. Main results showed a decrease in intake and retention of both energy and protein, without affecting the efficiency of retention when energy level of diets was reduced by 20%. An increase in the EPR of the diets led to a decrease in protein intake and to an increase in efficiency of protein retention, without affecting the amount retained. No changes in body composition, nor in composition of live weight gains were found as a result of treatments. It is concluded that a 10% reduction in DE level of the diet is of no consequence, and that an EPR of 79 kJ/g leads to more efficient use of the dietary protein without detrimental effects over any other nutritional indicator.     

Effect of the energy density of non-purified diets on growth, gestation and lactation in mice

The effects of dietary energy density on the performance of growing, gestating and lactating C57BL/6J mice were determined in order to develop pelleted non-purified practical diets for use in all stages of the mouse life cycle. Experimental diets with 4 levels of energy at 24% crude protein (CP) were pelleted and the nutritional values were determined using adult rats. The nitrogen-corrected metabolizable energy (MEn) values ranged from 2.86 to 3.73 kcal/g and the digestive CP (DCP) contents ranged from 20.5 to 22.6% on a dry matter (DM) basis. Mice responded to decreased dietary energy by increasing their feed intake to maintain MEn intake levels, except for 1 week after weaning and during lactation periods. During these periods, mice fed lower energy diets could not consume as much MEn as those fed higher energy diets. The lowest energy diet, in comparison with the highest energy diet, resulted in approximately a 33% lower weaning weight of pups at 3 weeks of age, a 13.2 to 34.4% slower growth at 3 to 4 weeks of age, and a 9.3 day delay in the onset of vaginal opening in young females. Lower energy diets, however, did not affect the litter size or the birth weight of pups. The DCP intake usually increased with decreases in dietary energy but apparently this did not affect the performance of the mice. It was concluded that an optimal diet should have an MEn value of 3.73 kcal/g DM or more for both the one week post weaning growth period and during lactation, but a diet with an MEn value of 2.86 kcal/g DM was sufficient for growth after 4 weeks of age and during gestation.     

Symposium mit internationaler Beteiligung vom 27.-29. Oktober 1981 in Dresden

Two feeding trials were performed on rainbow trout of mean initial weights of 40 and 50 g and lasting for 12 and 14 weeks, respectively. In trial 1, diets contained per kg 300 g fish meal and varying proportions of gelatinized maize starch plus either casein or hydrolyzed feather meal. Dietary crude protein content varied from about 27 to about 53%. In trial 2, all diets had about 45% crude protein. Fish meal (300 g/kg) was replaced in 3 steps by hydrolyzed feather meal either without or with supplementation of L‐ lysine‐HC1 and/or DL‐methionine.

In trial 1, efficiency of utilization of digestible energy (DE) rose from 38 to 50% when the ratio digestible crude protein (DCP)/DE was increased from about 11 to 17 g/MJ irrespective of the source of additional DCP, but did not further increase at higher ratios DCP/DE. Efficiency of utilization of DCP was about 50% as long as the ratio DCP/DE did not exceed 17 g/MJ.

With progressing replacement of fish meal by hydrolyzed feather meal, efficiencies of utilization of DE as well as of DCP were reduced, the respective rates of reduction being about halved by supplementing lysine with no effect of supplementing methionine.     

The effect of exposure to oestrous ewes on rams' sexual behaviour, plasma testosterone concentration and ability to stimulate ovulation in seasonally anoestrous ewes

Ruminants eat a variety of foods from different locations in the environment. While water, cover, social interactions, and predators are all likely to influence choice of foraging location, differences in macronutrient content among forages may also cause ruminants to forage in different locations even during a meal. We hypothesized that lambs forage at locations containing foods that complement their basal diet and meet their nutritional needs. Based on this hypothesis, we predicted that lambs (n=12) fed a basal diet low in protein and high in energy would forage where a high-protein food (Food P) was located, and that lambs (n=12) fed a basal diet low in energy and high in protein would forage where a high-energy food (Food E) was located. Food P was a ground mixture of blood meal (50%), grape pomace (30%), and alfalfa (20%) that contained 47% crude protein (CP) and 2.211 Mcal/kg digestible energy (DE). Food E was a ground mixture of cornstarch (50%), grape pomace (30%), and rolled barley (20%) that contained 6% CP and 3.07 Mcal/kg DE. Food P provided 212 g CP/Mcal DE, whereas Food E provided 20 g CP/Mcal DE. Lambs growing at a moderate rate require 179 g CP and 3.95 Mcal DE. During Trial 1, we determined if lambs foraged to correct a nutrient imbalance, and if they preferred a variety of foods (Foods P and E) to only one food at a location (Food P or E). During Trial 2, we determined if nutrient-imbalanced lambs foraged in the location with the food that corrected the imbalance when the location of the foods changed daily. During Trial 3, lambs were offered familiar foods (Foods P and E) at the location furthest - and novel foods (wheat and soybean meal) at the location nearest - the shelter of their pen. During all three trials, lambs foraged most at the location with the food that contained the highest concentration of the macronutrient lacking in their basal diet, but they always ate some of both foods. Lambs did not feed exclusively at the location with a variety of foods (P and E). Rather, they fed at the location nearest the shelter that contained the macronutrient lacking in their diet. As availability of the food with the needed macronutrient declined in one location, lambs moved to the nearest location that had food with the needed macronutrient. When food that complemented their basal diet was moved to a different location, lambs foraged in the new location. Collectively, these results show that lambs challenged by imbalances in energy or protein selected foods and foraging locations that complemented the nutrient content of their macronutrient imbalanced basal diets.     

Effects of variety and storage duration on the nutrient digestibility and the digestible and metabolisable energy content of maize fed to growing pigs

The objective of this research was to determine the effects of variety and storage duration on the nutrient digestibility and the digestible (DE) and metabolisable (ME) energy content in maize when fed to growing pigs. Four maize varieties (LS1, LS2, LS3 and LS4) were hand-harvested from the same growing area in China in early October of 2012. The samples were sun dried to about 14% moisture content and then stored in the warehouse of the Fengning Pig Experiment Base at China Agricultural University for 0, 3 or 10 months. Twenty-four barrows of about 33 kg body weight were used and allotted to a completely randomised block design with four diets and six replicate pigs per diet. Pigs were individually housed in metabolic crates. The four experimental diets were formulated by mixing 96.8% of each variety of maize with 3.2% vitamins and minerals. A 5-day collection period followed a 7-day diet acclimation period. The results indicated that the DE and ME contents of maize and the apparent total tract digestibility (ATTD) of organic matter (OM), dry matter, gross energy (GE), neutral detergent fibre, acid detergent fibre (ADF), crude protein (CP) and ether extract (EE) were significantly (p < 0.05) influenced by maize variety and storage duration. With an extension of storage duration from 0 to 10 months, the DE and ME of maize and the ATTD of OM, GE, ADF, CP and EE changed in a quadratic manner (p < 0.05), and 3 months of storage exceeded 0 months of storage by 1.84%, 1.43%, 0.31%, 0.32%, 15.37%, 2.11% and 5.02%, respectively. The DE, ME of maize and the ATTD of OM, GE, ADF, CP and EE decreased by 3.67%, 6.00%, 0.97%, 1.40%, 30.54%, 3.92% and 20.93%, respectively, at 10 months of storage compared to 3 months of storage. No interaction was observed between maize variety and storage duration in DE and ME contents in maize. In conclusion, under the conditions of this study, most of the nutrient digestibility and the DE and ME contents of maize increased from 0 to 3 months and decreased from 3 to 10 months.     

Studies on limiting essential amino acids in grieves as source of dietary protein for rainbow trout (oncorhynchus mykiss)

Diets were computed to contain equal concentrations of digestible crude protein either of wheat gluten (diet 1) or of grieves (diets 2–8). Per kg dry diet, 41 g crystalline amino acids were supplemented. All diets contained at least 1.2 g Lys per MJ digestible energy (DE). In diet 2, ratios of Met + Cys, Trp, Leu, Ile and Phe to Lys were about equal to those in diet 1. In each of diets 3–7, one of the respective amino acids, in diet 8 all five were replaced by Glu in the supplemented mixture of amino acids.

Each diet was fed to triplciate groups of 20 trout during a trial lasting 66 days. Trout fed the diet containing wheat gluten consumed more dry matter and showed higher growth rates as well as higher protein contents in their gained body mass than trout fed diets based on grieves. Supplementing Met plus Trp significantly improved dry matter intake, growth rate and protein content of gain, though not to the level of trout fed the wheat gluten diet, whereas Leu, Ile and Phe showed no such effect. When grieves were not supplemented with both Met and Trp, gain in body mass contained significantly more lipids. DE required per kg gain by trout fed wheat gluten, grieves + Met + Trp or grieves without supplementation of Met and Trp was 20.1, 21.2 and 29.9 MJ, respectively.     

生长期实验兔日粮消化能、蛋白质、粗纤维适宜水平和氨基酸模式的研究

以日本大耳白断奶仔兔为试验动物 ,试验分两期。第一期 ,以 55日龄、健康、体重相近、来源一致的 90只大耳白仔兔随机分为 9组。试验日粮采用L9( 34)正交试验设计与 9组试验动物相对应的 9个日粮配方及其营养水平组合 ,进行 45d的饲养试验 ,研究试验日粮能量 (DE)、蛋白质 (CP)、粗纤维 (CF)适宜水平和必需氨基酸 (EAA)模式。以生长速度和血液生理指标为试验观察指标。试验结果 ,45d平均日增重以第 2组 34.5g为最高 ,比最低的第 9组2 7.5g提高 2 5.45% ,差异极显著 (p <0 .0 1 ) ,表明第 2组日粮配方及其营养水平组合为优。第二期 ,对一期第 2组日粮进行重复试验 ,以验证一期饲养试验效果的重现性。选用一期同源的 40日龄健康体重相近的 60只大耳白断奶仔兔进行 60d饲养试验。试验结果 ,60d平均日增重 34.0g,与一期结果相似 ,全部血液生理指标均在正常范围。两期试验结果表明 ,第 2组日粮DE1 2 .0MJ.kg- 1 、CP1 5.0 %、CF1 4.0 %的水平组合和必需氨基酸模式适宜于生长阶段大耳白兔的营养需要。     

Use of the mobile nylon bag technique to determine the digestible energy content of traditional and non-traditional feeds for swine

The following experiment was conducted using the mobile nylon bag technique (MNBT) to determine dry matter and energy digestibility in traditional feeds as well as non-traditional feeds in order to calculate digestible energy (DE) values for use in ration formulation programmes. A total of 22 ingredients were tested in this experiment including the traditional cereal grains barley, corn, oats and wheat, as well as secondary cereal grains such as normal and low viscosity rye, low lignin and high fat oat groats, wheat heavies and # 1 wheat screenings and a new bread wheat designated as CDC Teal. Three legumes (lupines, peas and dehydrated alfalfa), three varieties of canary seed (CDC Maria, dehulled CDC Maria and Keet), and raw and micronized canola seed were tested as protein sources. Finally, three oilseed meals obtained from the Chinese feed industry (Chinese rapeseed meal, Chinese cottonseed meal and extruded full-fat soybean meal) were also included. After simulating gastric digestion the nylon bags were inserted into the duodenum of five barrows through simple duodenal T-cannulae. Eight bags were administered to each pig daily. Ten nylon bags were prepared for each feed with two bags being inserted into each of the five barrows. A total of 220 bags were inserted over a 7-day period. The overall results of this experiment indicate that the MNBT has great potential for use in determining the digestible energy content of swine feeds. For the most part, values obtained in the present experiment compared favourably with previously published values. Four feedstuffs produced digestible energy values that differed by greater than 5% from previously reported values. However, variation in chemical content provided a reasonable explanation for these discrepancies. The MNBT has several advantages compared with conventional digestibility methods in that many feeds can be tested in a relatively short duration of time with significantly fewer animals being used, only small amounts of feed are required and the test allows for energy measurements in feedstuffs that would not normally be fed to pigs as a single ingredient. Additional research on a wider variety of feedstuffs should be conducted to confirm the potential of the MNBT as a tool to accurately determine DE values for swine.     

Comparative digestibility of energy and nutrients in diets fed to sows and growing pigs

The objective of this research was to compare values for digestible energy (DE) and metabolisable energy (ME) and apparent total tract digestibility (ATTD) of nutrients in 11 diets fed to both growing pigs and gestating sows. Three diets were based on corn, wheat or sorghum and eight diets were based on a combination of corn and soybean meal, canola meal, conventional distillers’ dried grains with solubles, low-fat distillers’ dried grains with solubles, corn germ meal, corn bran, wheat middlings or soybean hulls. A total of 88 gestating sows (252 ± 24.2 kg BW; parity two to six) and 88 growing barrows (40 ± 4.7 kg BW) were used and randomly allotted to the 11 diets with eight replicate sows or pigs per diet. Faecal and urine samples were collected for 4 d following a 19 d adaptation period. The DE, ME and ATTD of gross energy (GE), acid detergent fibre (ADF), neutral detergent fibre (NDF) and crude protein (CP) in the 11 diets were calculated. Gestating sows had greater (p < 0.05) ATTD of GE and CP and DE values for all diets compared with growing pigs. Gestating sows also had greater (p < 0.05) ME values than growing pigs for the three grain diets and the diets containing wheat middlings and soybean hulls. No differences were observed in ATTD of ADF and NDF between gestating sows and growing pigs for any of the diets, except that gestating sows had greater (p < 0.05) ATTD of NDF than growing pigs when they were fed the four protein diets. The ATTD of GE and CP and DE values in gestating sows may be predicted by using equations generated from the values of ATTD of GE and CP and DE values obtained in growing pigs. Results of this research indicate that ATTD values of CP and GE obtained in gestating sows are greater than the values obtained in growing pigs, but values for ATTD of ADF obtained in growing pigs are not different from values in gestating sows.     

Effect of feed restriction or feeding high-fibre diet during the rearing period on body composition, serum parameters and productive performance of rabbit does

This study evaluated the effect of different feeding regimes from 11 weeks of age to first parturition on feed intake, leptin, non-esterified fatty acids (NEFA) and total protein serum levels, as well as productive performance in young rabbit does. In addition, body composition was estimated by bioimpedance analysis. Thirty-six 11-week-old does were randomly distributed in three groups. The AL-C group was fed ad libitum a control diet containing 350 g neutral detergent fibre (aNDFom)/kg, 11.6 MJ digestible energy (DE)/kg and 173 g crude protein (CP)/kg, and the does were inseminated at 16 weeks of age. The R-C group was fed 150 g/d of the same diet until 16 weeks of age, one week before artificial insemination (AI) at 17 weeks of age, and then fed ad libitum. The AL-F group was fed a diet containing 475 g aNDFom/kg, 9.4 MJ DE/kg and 174 g CP/kg ad libitum, and was inseminated at 17 weeks of age. During rearing (11-16 weeks), does in the R-C group had the lowest DE (1.54 MJ/d; P<0.003) and digestible protein (DP, 17.9 g/d; P<0.001) intake, as well as the lowest protein (172 g/kg; P<0.05) and energy (5.9 MJ/kg) body contents, leptin concentration at 16 weeks of age (2.48 ng/ml; P<0.001) and fertility (P<0.02) at first AI. Daily feed intake during pregnancy and lactation, as well as prolificacy and litter weight, were similar among groups. The highest percentage of body fat was observed for all the does when were inseminated for the first time (135 g/kg; P<0.001), consistent with the highest leptin (4.48 ng/ml; P<0.001) and total protein serum levels (6.87 g/dl; P<0.001) at this time. Serum NEFA level around parturition was higher (P<0.05) in groups AL-C and R-C (1.11 and 0.85 mmol/l) than in group AL-F (0.71 mmol/l), suggesting a lower lipid mobilization that tended to improve fertility rate for AL-F does on day 11 post-parturition (P<0.09). In conclusion, feed restriction during the rearing period delays reproductive development in young rabbits. In nulliparous does, ad libitum feeding during rearing with a high-fibre diet allows a similar productive performance to that of feeding with a less fibrous diet. Nevertheless, the use of high fibre diets during rearing does not affect feed intake throughout the first pregnancy and lactation.     

Use of soybean flour (dehulled, solvent-extracted soybean) as a fish meal substitute in practical diets for African catfish, Clarias gariepinus (Burchell 1822): growth, feed utilization and digestibility

Growth and digestibility trials were conducted using African catfish, Clarias gariepinus (Burchell 1822): (1) to obtain apparent digestibility coefficient (ADC) values for capelin fish meal, soybean flour and corn meal; (2) to formulate diets based on ADC values of the protein feedstuffs; and (3) to evaluate the effects of replacing 25%, 50% and 75% of fish meal in control diets with soybean flour on growth, feed utilization efficiency and carcass composition. Supplemental methionine was added to the diet formulation in which soybean flour replaced 75% of the diet. Diets were formulated (400 g digestible protein kg⁻¹ and 15 kJ digestible energy g⁻¹ dry diet) and fed to catfish fingerlings (13.1 ± 0.5 g) to apparent satiation twice daily for 70 days. The protein and energy digestibilities of fish meal and soybean flour were high (>90% and >80%, respectively; P < 0.05). At 75% fish meal replacement with soybean flour (without methionine supplementation), growth and feed utilization efficiency indicators were depressed compared with other diet treatments which had a similar (P > 0.05) growth and feed utilization efficiency to those fed the control diet. The carcass compositions of catfish in all diets were similar (P > 0.05) and the liver histology of catfish fed any of the diets showed no alterations. The results obtained indicate that 50% of fish meal protein in practical catfish diets can be replaced with soybean flour and that catfish can effectively utilize supplemental methionine, thereby allowing up to 75% of the dietary fish meal protein to be replaced by soybean flour.     

Optimum dietary crude protein level for finishing Awassi lambs

Awassi is a multi-purpose sheep breed. Awassi lambs being finished are usually offered an 18% crude protein (CP) diet. The growth rate of Awassi lambs is lower than other meat breeds. Therefore, this high content of dietary CP is questionable. The objective of this study was to estimate the optimum CP level for finishing Awassi lambs. Fifty male Awassi lambs (23.0±1.2 kg) were fed five high concentrate isocaloric diets (10 lambs per diet) that contained 10, 12, 14, 16, and 18% CP in a totally mixed diets for 9 weeks using a completely randomized design. Lambs were fed twice daily, and feed offered and feed refusals recorded for each feeding. Individual lamb intakes were calculated using daily feed offered and feed refused averaged over the interval of the experiment. Digestibility estimates were measured by total fecal collection. Lambs fed diets that contained 10, 12, and 14% CP gained less weight than those fed the 16 and 18% CP diets (P<0.05). Dry matter and CP intakes increased (P<0.05) with increasing levels of dietary CP. No difference (P>0.10) was observed in feed-to-gain ratio between diets except for the diet that contained 10% CP (P<0.05) which had a lower ratio. Organic matter and CP digestibility were lowest in lambs fed the 10% CP diet. Results suggest that the optimum CP concentration is 16% and that any increase above this level will not result in any improvement in production.     

Comparative effects of feeding citrus pulp and grape pomace on nutrient digestibility and utilization in steers

Feedlot beef production in tropics and subtropics is being limited by shortage of feed ingredients due to prolonged droughts resulting in high prices of cereal grains and reduced profitability. To alleviate feed shortages and increase profitability for the feedlot industry, it is important to explore underutilized non-conventional resources such as fruit by-products. The current study compared the nutrient intake, digestibility and utilization effects of feeding either 150 g/kg of dried citrus pulp (DCP) or grape pomace (DGP) as alternative dietary fibre sources to 7 months-old Angus steers (281 ± 15.7 kg) under feedlot conditions. Twenty-four steers were assigned to three dietary treatments (8 steers/treatment) in a completely randomised design. Each steer was treated as an experimental unit. Steers were adapted to diets for 21 d followed by 7 d of sample collection during which nutrient intake, digestibility, rumen fermentation parameters, nitrogen retention and microbial N supply were determined. All the data were analysed using the GLIMMIX procedures. Overall, steers fed DGP had the greatest dry matter intake (DM), organic matter (OM) crude protein (CP), ash free neutral detergent fibre (aNDFom), ether extract (EE) and starch intake followed by DCP and control (CON) diets (P ≤ .05). Apparent digestibilities of DM, OM and aNDFom were higher (P ≤ .05) for DCP diet compared to DGP and CON diets. Feeding DCP and DGP diets increased ruminal concentrations of total volatile fatty acids, acetate and isovalerate, and acetate to propionate ratio, and reduced propionate concentrations compared to the CON diet (P ≤ .05). The steers fed the CON diet had the greatest urinary excretions of allantoin, uric acid and total purine derivatives followed by those fed the DCP and DGP diets (P ≤ .05). Nitrogen intake, faecal nitrogen (N), N retention and N efficiency utilization were in the order of DGP > DCP > CON diets (P ≤ .05). Overall, feeding DGP as alternative fibre source to wheat bran improved nutrient intake, retention and efficiency of N utilization but reduced apparent nutrient digestibility compared to DCP. Current finding suggests that DGP may be a better fibre substitute for wheat bran in beef diets than DCP.     

The influence of sulphur,molybdenum and cadmium exposure on the growth of goat,cattle and pig

A three factorial designed feeding experiment with common carp (Cyprinus carpio L.) was carried out in an intensive experimental rearing system. Fish (initial body weight 200 g) were fed on two different levels of dietary energy (16 and 18 MJ DE/kg DM), two different levels of protein (320 and 420 g CP/kg DM) and also two different feeding intensities (100% and 75% of the maximum intake). The experiment was terminated when fish reached a mean body weight of 1300 g.

Growth, feed utilization and nutrient composition of the whole body and fillet were observed. The highest growth was obtained when the fish were fed on the diet containing high dietary energy and high dietary protein with satiation feeding. High dietary energy, high dietary protein and restriction of feed intake improved feed conversion ratios. High dietary energy, low dietary protein and restrictive feeding increased energy utilization. Low dietary protein and restrictive feeding resulted in better protein utilization.

Fish fed with high dietary energy contained more fat and less protein in their carcasses. A lower fat content but higher protein and higher ash content in fish carcasses was shown when fish were fed with a diet high in protein and fed restrictively.     

Carnivorous mammals: nutrient digestibility and energy evaluation

Estimating the energy content is the first step in diet formulation, as it determines the amount of food eaten and hence the concentration of nutrients required to meet the animal's requirements. Additionally, being able to estimate the energy content of a diet empirically known to maintain body condition in an animal will facilitate an estimation of maintenance energy requirements. We collated data on nutrient composition of diets fed to captive wild canids, felids, hyenids, mustelids, pinnipeds, and ursids and the digestibility coefficients from the literature (45 species, 74 publications) to test whether differences in protein and fat digestibility could be detected between species groups, and whether approaches suggested for the estimation of dietary metabolizable energy (ME) content in domestic carnivores (NRC [2006] Nutrient requirements of dogs and cats. Washington, DC: National Academy Press.) can be applied to wild carnivores as well. Regressions of digestible protein or fat content vs. the crude protein (CP) or fat content indicated no relevant differences in the digestive physiology between the carnivore groups. For diets based on raw meat, fish, or whole prey, applying the calculation of ME using “Atwater factors” (16.7 kJ/g CP; 16.7 kJ/g nitrogen‐free extracts; 37.7 kJ/g crude fat) provided estimates that compared well to experimental results. This study suggests that ME estimation in such diets is feasible without additional digestion trials. For comparative nutrition research, the study implicates that highly digestible diets typically fed in zoos offer little potential to elucidate differences between species or carnivore groups, but research on diets with higher proportions of difficult‐to‐digest components (fiber, connective tissues) is lacking. Zoo Biol 29:687–704, 2010. © 2010 Wiley‐Liss, Inc.     

Effect of dietary energy intake on tubular reabsorption of urea in sheep

The aim of the experiment was to determine the effect of dietary energy intake on renal urea excretion in sheep with different nitrogen intakes. The control sheep, with a high nitrogen and energy intake, were given a daily feed dose of 21.18 g N and 15.2 MJ digestible energy (DE). The two experimental groups, with an equal, low nitrogen intake, were given diets with a different energy content. The high energy diet contained 3.63 g N and 14.18 MJ DE, the low energy diet 3.4 g N and 6.44 MJ DE. After nine weeks' adaptation to the diets, renal functions were measured by a standard clearance technique. It was found that, under stable urine flow conditions, both groups given the low nitrogen diet had a significantly lower glomerular filtration rate, fractional urea excretion and total urea excretion. A reciprocal comparison of these two groups showed that fractional urea excretion by the sheep with a high energy intake was significantly lower than in the group with a low energy intake. There were no differences in the glomerular filtration rate. A raised dietary energy intake in the presence of a low nitrogen intake caused marked natriuresis and kaliuresis. The results indicate that a raised dietary energy intake can be a significant factor in potentiating the renal effect of urea retention in sheep with a low nitrogen intake.