Endogenous N-excretion and minimal protein requirement for maintenance of the common marmoset (Callithrix jacchus)

The protein requirement for maintenance of the marmoset Callithrix jacchus was investigated by factorial calculation via the N balance technique. Six adult male marmosets were fed a protein-free pelleted diet for 22 days. When a low protein diet (6%) was fed in the preperiod, only 7 days were necessary and when fed a higher protein diet (18%) 10 days were necessary to reach a minimum of N excretion during protein depletion. Body weight losses averaged 11% and food intake was 21% lower in the protein free period. The average endogenous urine N (EUN) was 62.1 mg N and endogenous fecal N (EFN) 49.2 mg N/kg W0.75. Body surface losses (BSN) were assumed to be 20 mg N/kg W0.75. The total endogenous loss of 131.3 mg N/kg W0.75 is similar to that of other species. Net protein utilization (NPU) of well balanced proteins, determined near the N equilibrium, was 51.8%. The calculated net protein requirement amounts to 313.6 mg N/kg W0.75, which corresponds to a dietary protein content of 6% in a diet of high caloric density, (about 19-20 MJ/kg dry matter) when the food intake is 3.3% of body weight.     

Effects of a high soy protein diet on intestinal polyamines and ornithine decarboxylase activity in rats

This study was performed to determine whether intestinal luminal polyamine concentrations are affected by a high soy protein diet when compared with a high casein diet or a normoprotein casein diet. We also determined the effects of these diets, with differences in polyamines content, on mucosal polyamines and ornithine decarboxylase (ODC) activity to assess cell proliferation. Three groups of eight male Wistar rats were fed either a 50% soy protein diet, a 50% casein diet, or an 18% casein diet as a control. After 4 weeks of feeding, both intestinal content and mucosa were recovered. Polyamines were assayed by high performance liquid chromatography. ODC activity was measured by the release of (14)CO(2) from (14)C-L-ornithine. Luminal putrescine and cadaverine concentrations were higher in the jejunum than in the ileum, suggesting an absorptive process. The highest concentrations of intestinal polyamines were observed in rats fed the soy protein diet (P < 0.05). Only minor differences were observed in mucosal polyamines according to the diets. ODC activity was also higher in the intestinal mucosa of rats fed the high soy protein diet (P < 0.05). These results suggest that intestinal luminal polyamine concentrations and ODC activity are modulated by the dietary protein source.     

Quality of eggs from Lohmann Brown Classic laying hens fed black soldier fly meal as substitute for soya bean

Soya bean is the main protein source in poultry feed but rising prices make an alternative protein source necessary. Insects, such as the black soldier fly (Hermetia illucens), may be an attractive solution for hens, although little information is available on their effect on egg quality. The present study aims to fill this gap by testing the effect of 100% replacement of soya bean with H. illucens larva meal in the diet of Lohmann Brown Classic laying hens for 21 weeks. At the end of the trial, the eggs were characterized for parameters such as weight, colour, proximate composition of albumen and yolk, and content of carotenoids, tocopherols and cholesterol. The fatty acid profile of yolks was also determined. Hens fed the insect-based diet produced eggs (HIM group) with a higher proportion of yolk than the group fed the soya bean-based diet (SBM group). HIM was associated with redder yolks (red index 5.63 v. 1.36) than SBM. HIM yolks were richer in γ-tocopherol (4.0 against 2.4 mg/kg), lutein (8.6 against 4.9 mg/kg), β-carotene (0.33 against 0.19 mg/kg) and total carotenoids (15 against 10.5 mg/kg) than SBM yolks. The fatty acid composition of HIM yolks was almost identical to that of SBM yolks. Finally, HIM yolks contained 11% less cholesterol than SBM yolks. These results suggest that H. illucens larva meal is a suitable total substitute for soya bean meal in the diet of Lohmann Brown Classic laying hens. A sustainable alternative to the plant protein source therefore seems feasible.     

Effect of a high protein diet on glucose tolerance in the rat model

The purpose of this study was to determine the effects of a high protein diet on glucose tolerance. Nine Sprague Dawley rats received a high protein (HP) diet (65% protein, 35% fat) and eight rats consumed a standard chow (SC) diet over eight weeks. Oral glucose tolerance tests (OGTT) were performed at the end of the third and the seventh week. The diet did not effect glucose tolerance in the first (SC=10357+/-294 mg/dl/120 min; HP=9846+/-300 mg/dl/120 min) or the second OGTT (SC=10134+/-395 mg/dl/120 min; HP=10721+/-438 mg/dl/120 min) as reflected by the area under the glucose concentration curve. Similarly, the area under the insulin concentration curve was not effected by the high protein diet during the first (SC=49.21+/-8.46 ng/ml/120 min; HP=41.75+/-10.54 ng/ml/120 min) or the second OGTT (SC=96.63+/-13.68 ng/ml/120 min; HP=92.77+/-17.44 ng/ml/120 min). The high protein diet group experienced a delayed glucose response for the first (SC=30 min at 112+/-7 mg/dl; HP=60 min at 101+/-5 mg/dl) and second OGTT (SC=15 min at 117+/-5 mg/dl; HP=60 min at 95+/-7 mg/dl). Body mass increased to the same extent in each diet group from the initial to final weighing (SC=159+/-2 g to 254+/-7 g; HP=157+/-2 g to 242+/-7 g). Despite a delay in peak glucose response, these findings suggest that glucose tolerance and body mass were neither adversely nor positively affected by a high protein diet.     

The use of Balanites kernel cake in a diet for fattening sheep

Balanites kernel cake (BKC) is produced from the fruit of Balanites aegyptiaca, a tree which is widely and densely distributed along the tropical belt of the African continent. The cake is characterized by high protein (36.8%) and low crude fibre (5.9%) contents. In this work the value of BKC as a source of crude protein in ruminant diets was compared with cotton seed cake (CSC), a conventional source of protein. Two groups of 10 and 11 lambs having an average liveweight of 20.5 ± 0.9 kg were used. For a 3-week preliminary period animals of both groups were fed ad libitum on a diet containing 30% CSC as a major source of protein. During the following 13 weeks the group of 10 lambs continued on the same diet, whereas the other group was fed ad libitum on a Balanites cake diet (20% BKC). All lambs were slaughtered at about 40 kg liveweight. No significant differences were detected between the two groups of lambs in feedlot performance or carcass analysis.It is concluded that BKC is non toxic to sheep and its addition at the rate of 20%, together with 10% straw, can replace 30% CSC in the diet. The Balanites cake diet was also found to be substantially cheaper.     

Bioavailability studies of a new iron source by means of the prophylactic-preventive method in rats

The bioavailability of iron from a new commercial source containing ferric gluconate stabilized with glycine sold under the trade name Bioferrico™ was studied in this work by means of the prophylactic-preventive test in rats. NaFeEDTA was also studied by the same methodology for comparative purposes and ferrous sulfate was used as the reference standard. The test was conducted for 4 wk with male weaned rats, which were randomized into four groups of at least eight animals each. A control group received a basal diet of low-iron content, whereas the other groups received the same diet with iron added at a dose of 20 mg/kg as FeSO₄·7H₂O, NaFeEDTA, and Bioferrico, respectively. Individual hemoglobin concentrations (HbC) and weights were determined at the beginning and at the end of the study and food intake was daily registered. The iron bioavailability (BioFe) of each source was calculated as the ratio between the amount of iron incorporated into hemoglobin during the treatment (HbFe) and the total iron intake per animal (ToFeIn). A relative biological value (RBV) was obtained for each iron source under study as the ratio between the BioFe of the tested compound and that of the reference standard. The RBVs were 98% and 86% for Bioferrico and NaFeEDTA, respectively. Bioferrico showed a high bioavailability and behaved inertly in relation to the sensorial properties of the fortified food when it was added to flour. These qualities emphasize Bioferrico as a promising source for iron fortification.     

High and low responding strains of laboratory opossums differ in sterol 27-hydroxylase and acyl-coenzyme A:cholesterol acyltransferase activities on a high cholesterol diet

Two partially inbred strains of laboratory opossums exhibit extremely high or low levels of VLDL+LDL cholesterol concentrations, respectively, when challenged with a high cholesterol and high fat diet. The present studies were conducted to determine whether the high and low responding strains differ in activities of important enzymes that have been shown to affect lipemic responsiveness to diet. We measured plasma 27-hydroxycholesterol and hepatic activities of 27-hydroxylase and 7-hydroxylase in high and low responding opossums while consuming the basal diet and cholesterol-enriched diets. Plasma 27-hydroxycholesterol concentration and 27-hydroxylase activity in liver did not differ between groups on the basal diet, but both were significantly higher in low responders than in high responders on the cholesterol-enriched diet with unsaturated fat (10.79 ± 0.56 in low vs. 7.31 ± 0.50 μg/dl in high responders for 27-hydroxycholesterol and 14.14 ± 0.79 in low vs. 10.07 ± 0.80 pmol/mg protein/min in high responders for 27-hydroxylase activity). On the other hand, 7-hydroxylase activity was significantly higher in high responding opossums (75.72 ± 6.81 pmol/mg protein/min) than in low responding opossums (51.39 ± 6.18 pmol/mg protein/min) on the basal diet, but it did not differ on the high cholesterol and high fat diet. We measured hepatic ACAT and extrahepatic hepatic 27-hydroxylase activities in high and low responding opossums on the cholesterol enriched diet. Hepatic ACAT activity was significantly higher in high responding opossums (137.00 ± 18.33 pmol/mg protein/min) than in low responding opossums (47.67 ± 2.71 pmol/mg protein/min), whereas extrahepatic 27-hydroxylase activity was higher in low responding opossums (33.00 ± 2.10 pmol/mg protein/min in lungs and 3.69 ± 0.20 in kidneys) than in high responding opossums (21.17 ± 1.54 pmol/mg protein/min in lungs and 2.82 ± 0.31 in kidneys). We also compared the composition of bile between high and low responders. The concentration of taurine conjugates of cholic acid in bile of both groups was similar, but concentration of taurine conjugates of chenodeoxycholic acid in bile of low responding animals was higher than in high responding animals (124.9 ± 17.3 in low vs. 59.2 ± 13.2 μmol/ml in high responders). The results of these studies suggest two enzymes may affect the lipemic response to diet in laboratory opossums: sterol 27-hydroxylase and ACAT. Each of these enzymes may influence diet-induced hyperlipidemia at a different step of lipoprotein metabolism.     

The pH dependence of siliconiron interaction in rats

A 2 x 2 x 3 factorial experiment was conducted to study the pH dependence of a silicon-iron interaction in vivo. The dietary treatments used in the factorial design were the following (mg/kg of diet): silicon, 0 and 500; iron, 35 and 187; acid-base, ammonium chloride as 0.5% of total diet (acidic), sodium bicarbonate as 1.0% of total diet (basic), or no supplementation of acid or base (control). The supplementation of 500 mg silicon/kg of diet increased plasma-iron concentration in rats fed the acidic or control diets, but not in rats fed the basic diet. A high dietary-iron level suppressed copper absorption and utilization and subsequently imposed a negative effect on its own utilization. An increase in the plasma total-cholesterol concentration caused by high dietary-iron level was likely a consequence of the antagonistic effect of iron on copper absorption and utilization. The use of cupric sulfate pentahydrate as the dietary-copper source in this study resulted in plasma copper concentrations that were approximately twice those obtained in a related study using cupric carbonate. Also, a 42% coefficient of variation (C.V.) for plasma-copper concentrations of rats fed cupric sulfate in this study was greatly reduced from the C.V. = 108% previously associated with the dietary cupric carbonate.     

Nutritive value of leaf-protein concentrate from potato haulm for rats and chicks

A leaf-protein concentrate (LPC), containing approximately 45% protein, was prepared from potato haulm by standard methods. Its content of essential amino acids was similar to that recommended for chicken diets, except for the sulphur-containing amino acids, especially cystine. The biological value estimated in rats was high (64), almost as high as that of soya protein (65), but its true digestibility was lower (82 and 91, respectively). The concentrate contained carotenoids (295 mg/kg), but these were not converted into vitamin A in chicks. Leaf-protein concentrate may be a usable protein source for chicks, provided that not more than 25% of it is included in their diet.     

The effect of dietary protein on the excretion of alpha2u, the sex-dependent protein of the adult male rat.

Adult male rats were maintained on normal (20% casein), protein-free (0% casein), high protein (50% casein), decicient protein (20% zein), and a supplemented, deficient protein (20% zein plus L-lysine and L-tryptophan) diets. Rats on a protein-free diet excreted approximately 1 mg alpha2u/24 h compared with a normal of 10-15 mg/24 h. Depleted rats placed on a 20% casein diet showed a rapid restoration of the normal alpha2u excretion as well as total urinary proteins. Accumulation of alpha2u in the blood serum was measured in nep-rectomized rats. Rats on a 0% casein diet accumulated only 30% of the alpha2u compared to normals. On a 50% casein diet, rats excreted 30-50 mg alpha2u/24 h. However, the accumulation was normal in the serum of nephrectomized rats. A high protein diet did not stimulate alpha2u synthesis but probably increased the renal loss of all urinary proteins. The excretion of alpha2u on a zein diet was reduced to the same degree as with the protein-free diet. Supplementation with lysine and tryptophan restored the capacity to eliminate alpha21 to near normal levels. Accumulation of alpha2u in the serum of nephrectomized rats kept on the zein diets showed that the effect to suppress the synthesis of the ahpha2u. Supplementation restored the biosynthesis of alpha2u. We conclude that the effect of dietary protein on the excretion of urinary proteins in the adult male rat is caused in large part by an influence on the hepatic biosynthesis of alphay2u. The biosynthesis of this protein, which represents approximately 30% of the total urinary proteins, is dependent on an adequate supply of dietary protein.     

Clonidine increases food and protein consumption in rats

Rats were given clonidine or its diluent, and allowed to eat freely from two isocaloric diets that differred in protein or carbohydrate content. Low clonidine doses (25–50 μg/kg) significantly increased total food and protein intake by rats given access to a high and a low protein diet. Several pairs of diets, differing in protein contents, were tested; clonidine's effect was greatest when a diet containing 30–45% protein was paired with one that was very low (5%) in protein. Higher clonidine doses (200 μg/kg) failed to modify either total food or protein intake. Clonidine had no effects on food or nutrient intake among animals given access to diets that differed in carbohydrate content (25 or 70% carbohydrate, plus 25% protein). In rats given access to only one diet, clonidine administration decreased food consumption when the diet was low in protein (5%), but increased consumption when the diet contained 25 or 50% protein. These data suggest that central noradrenergic synapses participate in the mechanisms controlling appetites for proteins. Clonidine may enhance protein intake by stimulating presynaptic alpha receptors, thus diminishing central noradrenergic tone. This effect on noradrenergic transmission is probably partly overcome by protein consumption, which increases brain tyrosine levels and thus can accelerate norepinephrine synthesis. Clonidine or related drugs may be useful clinically in treating diseases characterized by impaired appetite or increased need for protein.     

High-yield expression of a viral peptide animal vaccine in transgenic tobacco chloroplasts

The 2L21 peptide, which confers protection to dogs against challenge with virulent canine parvovirus (CPV), was expressed in tobacco chloroplasts as a C-terminal translational fusion with the cholera toxin B subunit (CTB) or the green fluorescent protein (GFP). Expression of recombinant proteins was dependent on plant age. A very high-yield production was achieved in mature plants at the time of full flowering (310 mg CTB-2L21 protein per plant). Both young and senescent plants accumulated lower amounts of recombinant proteins than mature plants. This shows the importance of the time of harvest when scaling up the process. The maximum level of CTB-2L21 was 7.49 mg/g fresh weight (equivalent to 31.1% of total soluble protein, TSP) and that of GFP-2L21 was 5.96 mg/g fresh weight (equivalent to 22.6% of TSP). The 2L21 inserted epitope could be detected with a CPV-neutralizing monoclonal antibody, indicating that the epitope is correctly presented at the C-terminus of the fusion proteins. The resulting chimera CTB-2L21 protein retained pentamerization and G(M1)-ganglioside binding characteristics of the native CTB and induced antibodies able to recognize VP2 protein from CPV. To our knowledge, this is the first report of an animal vaccine epitope expression in transgenic chloroplasts. The high expression of antigens in chloroplasts would reduce the amount of plant material required for vaccination (approximately 100 mg for a dose of 500 microg antigen) and would permit encapsulation of freeze-dried material or pill formation.     

Effect of Dietary Composition on Lipids in Serum and in Liver of Rats Fed a Cystine-excess Diet

The effects of dietary composition on lipids in serum and in liver of rats fed with a cystine- excess diet were investigated.

When starch was used as the carbohydrate source, the addition of excess-cystine caused an increase in serum cholesterol and phospholipids, and hepatomegaly. Phospholipids in serum of rats fed with a cystine-excess diet containing 5% corn oil were higher than those with a cystine-excess diet that was low in corn oil (0.1 %). The addition of konjac mannan and pectin prevented hypercholesterolemia, and the rise in phospholipids in serum was prevented by the addition of konjac mannan.

Liver cholesterol (mg/liver/100 g of body wt.) increased in rats fed with a cystine-excess diet.

The addition of excess cystine to a diet containing sucrose as the carbohydrate source resulted in a marked increase of cholesterol in serum and liver, and a decrease of serum triglycerides.

The replacement of starch by sucrose in the cystine-excess diet increased liver cholesterol.

Lipids, cholesterol, phospholipids and triglycerides in the liver, but not phospholipids, when expressed as mg per g of liver for rats fed with the diets containing sucrose, increased when compared to those for rats fed with the diets containing starch. In contrast, serum triglycerides increased.     

The concentration of cyclic AMP and the activity of cyclic AMP dependent protein kinase and an inhibitor in the adipose tissue of rats fed lard or glucose diets.

Measurements of tissue cyclic AMP (cAMP) concentration, the activity of cAMP-dependent protein kinase and the level of the enzyme's thermostable, macromolecular inhibitor were made on preparations of rat epididymal fat pad from animals fed high fat or high carbohydrate diets. The cAMP concentration from rats adapted to a high lard diet for 14-15 days was 153 +/- 17.8 pmoles/mg protein as opposed to 76 +/- 6.0 found with high glucose diet. No significant difference in total cAMP-dependent protein kinase activity was observed among rats fed high glucose, high lard or laboratory chow, although the enzyme's activity ratio (-cAMP)(+cAMP) was significantly elevated with lard feeding (0.49 +/- 0.02) as opposed to glucose feeding (0.43 +/- 0.01). Crude preparations from lard and glucose fed animals were equivalent in inhibitory activity when tested with enzyme from chow fed animals. Agarose column chromatography separated holoenzyme and C subunit forms of the protein kinase when 500 mM NaCl was present in the elution buffer. Absence of the salt allowed subunit reassociation to occur. Direct addition of NaCl greater than or equal to 75 mM significantly inhibited protein kinase activity. The results indicate that the adipose tissue of rats fed a high lard diet has a higher concentration of cAMP and an increased protein kinase activity ratio than tissue from rats fed a fat free, high glucose diet. Total cAMP-dependent protein kinase activity and the level of a thermostable macromolecular inhibitor remained unchanged.     

The relationship between specific dynamic action and growth in grass carp, Ctenophavyngodon idella (Val.)

Individual grass carp, Ctenopharyngodon idellu , were maintained in a respirometer for a month and fed pelleted diets containing various proportions of carbohydrate, fat and protein at different ration levels. Oxygen consumption was measured continuously, allowing the effects of consecutive daily feeding on respiration to be studied. The relationships established between daily food intake and oxygen consumption showed that, on average, 23.3% (high protein diet), 15.3% (high carbohydrate diet), 20.7% (high lipid diet) and 7.0% ( Lemnu diet ) of the absorbed energy was partitioned into specific dynamic action (SDA). (Here the term SDA is used to describe the oxygen consumption of a feeding fish in excess of the routine metabolic rate.) In terms of the overall energy budgets of growing fish, SDA represented between 12 and 58% of the total heat lost over the experimental period and was equivalent to between 14 and 33% of the consumed energy. Ration was positively correlated with heat loss due to total respiration ( r = 0.881) and with heat loss due to SDA ( r = 0.762). As ration increased, the size of SDA relative to total respiration increased. Significant positive correlations were found between oxygen consumption (total or due to SDA) and specific growth rate, and between oxygen consumption and the deposition of protein and energy. However, growth rate had a minimal influence on daily oxygen consumption when compared with food intake.     

Effect of obesity per se on plasma lipid and aortic responses to diet in swine

Thirty-two genetically lean and obese Yorkshire X Duroc crossbred castrated male pigs were divided within genetic line into two groups at 7 weeks of age. Eight pigs within each line were fed a diet low in fat and cholesterol (maize-soybean meal diet fortified with minerals and vitamins). The other group was fed a similar diet containing added beef tallow (11%) and dried egg yolk (1%). All pigs were fed ad libitum for 4 months when one-half of each group was slaughtered. All other pigs were continued on their respective diets at a restricted level of intake for an additional 5 months at which time the protein source of two pigs in each diet group within each genetic line was changed from soybean meal to casein. After an additional 6 months on their respective diets (16 months total duration of experiment) these pigs were slaughtered. Blood samples were taken monthly or bimonthly for total plasma cholesterol and triglycerides. At slaughter, the aorta was opened, stained with Sudan IV, and the stained area traced and measured planimetrically. Only a moderate rise occurred in plasma cholesterol and triglycerides of pigs fed high fat-high cholesterol diets. Genetically obese pigs were no more susceptible to diet-induced hypercholesterolemia and to the percentage of the surface area of the aorta stained with Sudan IV than were lean pigs. It is concluded that obesity per se is not necessarily associated with development of atherosclerosis in pigs and that innate ability to metabolize high dietary cholesterol is of greater importance than body fatness in determining the response to diet.     

The bioenergetics of grass carp, Ctenopharyngodon idella (Val.): energy allocation at different planes of nutrition

Complete energy budgets were constructed for 19 grass carp, Ctenupharyngudon idella (Val.), held individually in a respirometer for a month. The fish were fed one of four diets or starved. Diets varying in the proportions of protein, lipid and carbohydrate were described as high protein (HP), high carbohydrate (HC) or high lipid (HL). A fourth diet (LM) was made from dried duckweed, Lemna spp., to provide a more natural diet. Fish were fed and faeces collected daily and oxygen consumption was measured continuously over the month that each experiment lasted. Excretion of ammonia and urea was measured on several days. The total energy lost via nitrogenous waste was calculated using an average daily ammonia quotient (AQ).
For growing fish between 50 and 61% of consumed energy was lost via respiration. Energetic losses via nitrogenous wastes were highest on the HP diet (4.7%) and lowest on the HC diet (3.1%). Faecal loss washigheston the HL diet (19.4%)and lowest on the HP diet (10.2%). Over a month of starvation, 32.5% of energy requirement was met by the respiration of protein and 3.2% of the total energy lost was via nitrogenous waste. Fish fed zero or sub-maintenance rations tended to respire lipid in preference to protein whereas fish fed super-maintenance rations accumulated lipid. Protein retention was proportionally highest on HP (48% of total energy retained as growth) and lowest on HC (32%) and HL (30%). This reflected the accumulation of lipid on both the high carbohydrate and high lipid diets. The partitioning of metabolizable energy (ME) was investigated and 0.45 (HL), 0.59 (HP) and 0-67 (HC) kJ ME.kJ^-1 retained were lost via respiration.     

Narrow-leaved lupine seeds as a dietary protein source for fattening rabbits: a comparison with white lupine seeds

Lupine seeds have the potential to be an alternative to imported dietary proteins. In rabbits, it has been indicated that White lupine seed (WLS) is a suitable protein source. Other lupine species, for example, narrow-leaved lupine seed (NLS), have not yet been tested in rabbit diets. Two experiments were carried out to evaluate the effect of the dietary inclusion of NLS on growth performance, sanitary risk index (SRI), coefficients of total tract apparent digestibility (CTTAD) and nitrogen output in fattening rabbits. Narrow-leaved lupine was compared with WLS as a main protein source. For Experiment I, a total of 198 Hyplus rabbits (37 days of age) were allocated into two groups (99 rabbits per group), fed the WLS I diet (120 g/kg of WLS cv. Amiga) or the NLS I diet (150 g/kg of NLS cv. Probor), and used for performance and carcass trait evaluations. In addition, the CTTAD of the diets and the nitrogen output were determined in 10 Hyplus rabbits per treatment (37 days of age). For Experiment II, a total of 180 Hyplus rabbits (32 days of age) were allocated into two groups (90 rabbits per group), fed the WLS II diet (120 g/kg of WLS cv. Amiga) or the NLS II diet (130 g/kg of NLS cv. Primadona), and used for performance and carcass trait evaluations. In addition, the CTTAD of the diets was determined in 10 Hyplus rabbits per treatment (32 days of age). Regardless of the treatment, the dietary inclusion of NLS had a negative effect on growth of the rabbits. The nitrogen excretion and coefficients of nitrogen retention of rabbits were not affected by the treatments. In Experiment I, SRI (37 to 80 days of age) was higher in rabbits fed the NLS I diet than in those fed the WLS I diet (38.4% v. 23.2%, respectively; P = 0.031). Similarly, in Experiment II (32 to 74 days of age), SRI was higher in rabbits fed the NLS II diet than in rabbits fed the WLS II diet (37.8% v. 23.3%, respectively; P = 0.052). In conclusion, regardless of the variety, the dietary inclusion of NLS had no negative effect on the nitrogen output or dressing-out percentage of rabbits when compared to those of rabbits fed the WLS diets. With respect to the SRI and performance, however, NLS did not provide a satisfactory outcome.     

On the effects of the concentrate proportion of dairy cow rations in the presence and absence of a fusarium toxin-contaminated triticale on cow performance

The aim of the present study was to investigate the effects of a deoxynivalenol (DON) contaminated ration with a concentrate proportion of 50%, on the performance of dairy cows (Period 1), and to examine the effects when the concentrate proportion was elevated to 60% compared to a ration with 30% concentrates (Period 2). In Period 1, 13 lactating German Holstein cows (Myco group, on average 29 days in milk) were fed the experimental diet (on average 5.3 mg DON/kg DM) as total mixed ration over 11 weeks, while another 14 cows (on average 33 days in milk) received a control diet. Both rations contained 50% concentrates (on DM basis). In Period 2 (18 weeks), the same 27 cows plus five additional cows were divided into four groups: Control-30 (30% concentrates), Myco-30 (30% concentrates, 4.4 mg DON/kg DM), Control-60 (60% concentrates), Myco-60 (60% concentrates, 4.6 mg DON/kg DM). The overall performance level was characterised by a mean daily DM intake of 17.9 kg and a mean daily milk production of 26.7 kg fat corrected milk (FCM) in Period 1 and 17.3 kg DM intake and 24.5 kg FCM in Period 2, respectively. In both periods cows fed the Fusarium toxin-contaminated diets consumed more DM (in Period 2 only significant for group Myco-30) resulting from stimulating effects on the ingesta passage rate of the natural contaminated Fusarium-infected triticale. In Period 1, cows fed the Fusarium toxin-contaminated diet had a significantly higher milk yield, milk urea and somatic cell count, whereas milk fat and protein concentration and fat-to-protein-ratio (FPR) were significantly lower. In Period 2, on a low concentrate level, FCM was significantly higher in group Myco-30. On a high concentrate level, group Myco-60 produced significantly more milk, but milk fat and protein concentration, FPR and milk urea were significantly lower. A concentrate proportion of 60% had a depressing effect on milk fat concentration but was significantly more pronounced in the presence of Fusarium toxin-contaminated and Fusarium damaged-triticale.     

Nutritive value of rumen contents for monogastric animals

Rumen contents were investigated as a possible feed for farm animals. Although their composition varied to some extent, an average sample contained 21.8% crude protein, 30.3% crude fibre, 6.1% fat and 11.5% ash in the dry matter. Of total crude protein, 73.4% was amino acids. The raw rumen material was dried using the “organic carrier method” by previous mixing with maize meal (3 parts raw rumen contents/1 part maize meal). The product, RM meal (12.5% crude protein, 10.8% crude fibre, 5% fat, 4.9% ash), was used for feeding broiler chicks.The nutritive qualities of dried rumen contents (DRC) were assessed by biological tests on rats. Two levels of DRC (10% and 24%) were included in diets containing blood meal as a protein source and maize (Experiment I). The lower level of DRC (10%) did not reduce the growth rate of young rats (2.4 g/day), but the food consumption was increased. The total body composition of the rats was not changed (55.3% crude protein, 34.1% fat, 9.6% ash). The higher concentration of DRC decreased the growth rates markedly, as well as the apparent digestibility of dry matter and protein, and changed the body composition of rats.The apparent digestibility by rats of rumen protein in a semi-synthetic diet containing 50% DRC (Experiment II) was 44.6% and of dry matter, 56%.The RM meal was given to broiler chicks (0–8 weeks of age) as 23% or 60% of the diet which also contained soya bean meal, blood meal and sunflower meal as protein supplements (Experiment III). The chicks consumed all diets readily. The diet containing 23% RM meal (corresponding to 6.4% DRC) supported a better performance than the control diet. The larger amount of RM meal (corresponding to 17% DRC) reduced the final body weights of chicks.