Effect of fulvic and humic acids on performance, immune response and thyroid function in rats.

Effect of humic acid (HA) and fulvic acid (FA) on production parameters, immune response and thyroid function of rats were investigated in two experiments. First experiment: control or 0.1%, 0.2%, 0.4%, 0.8% HA- or FA-supplemented diets. Second experiment: control and 0.4% HA- or FA-supplemented diets. The feeding period lasted 26 days in both trials. No significant changes were observed in production parameters. Ovalbumine antibody titre of rats on HA- or FA-supplemented diets showed dose-dependent (at 0.4% supplementation) and significant (p < 0.05) increase (350 and 418% respectively) over the control (100%). Dose-related increase of plasma TSH (r = 0.99), and decrease of the T(4)/T(3) ratio (r = -0.97) was observed in FA-supplemented rats. Second experiment: both FA and HA stimulated the immune response by the 14th day (mean values: control: 685.79; FA: 1131.37; HA: 1055.6099) and 26th day (control: 544.31; FA: 1969.83; HA: 1600.00). No significant differences were noted with lymphocyte stimulation test. Diameter of the 'B'-dependent lymphoid tissues in the ileum and spleen were significantly (p < 0.05) larger in both the FA- and HA-treated animals. Humic acid and FA supplementation resulted in strong humoral immune stimulation. Our data also indicate that FA content is responsible for the mild hypothyroid effect of humic substances.

Investigations on the effects of Ca-soap of linseed oil on rumen fermentation in sheep and on milk composition of goats.

Six rumen-cannulated wethers were fed by a diet composed of alfalfa hay and concentrate and supplemented by 75 g Ca-soap of linseed oil (5.4% in dry matter, DM) daily. A model trial was performed to detect the effects of the Ca-soap on rumen fermentation parameters and on fibre digestion. Approximately 3 h after feeding Ca-soap, ratio of C2:C3 decreased (from 4.33 to 4.02) and the production of i- and n-butyrate and i- and n-valeriate increased by 28, 5.3, 11.76% and 6.80% respectively. Total volatile fatty acid concentration in rumen fluid did not change (126.1 vs. 126.4 mm) as a result of Ca-soap supplementation. The in vitro trial showed no detrimental influence of Ca-soap on the acid detergent fibre (ADF) degradation. Using feed samples containing Ca-soap to be incubated in tubes, ADF digestion proved to be significantly higher (p < 0.001). Approximately 14 goats (Saanen breed, 30-70 days in lactation) were used to test the effects of Ca-soap on milk composition. Their ration contained alfalfa hay, millet straw and a concentrate. In the experimental group (seven goats) the diet was supplemented with Ca-soap of linseed oil (75 g/animal/day). The milk composition was changed (slightly reduced solid content, sometimes significantly reduced milk fat contents), when Ca-soap was included in the diet of lactating goats.

Comparison of feed preference and digestion of three different commercial diets for cats and ferrets.

Diet preference and digestibility experiments were conducted using a total of 10 cats and 10 ferrets. The composition of the three different kinds of dry cat feed was as follows (each data are given in dry matter, DM): (i) normal diet (N): 95.3% DM, 33.7% crude protein (CP), 20.4% ether extract (EE), 37.6% nitrogen-free extract (NFE); (ii) 'light diet' (L): 94.2% DM, 31.6% CP, 10.7% EE, 52.2% NFE; (iii) 'veterinary diet' (D): 94.57% DM, 38.7% CP, 9.6% EE, 47.2% NFE. During the period of the preference test, the average daily dry matter intake (calculated with the mean of the three diets: 94.7% DM) was 98.0, 15.0 and 16.7 g DM in cats and 25.0, 7.3 and 8.1 g DM in ferrets. The preference rates of the three different diets, expressed in percentage of their total consumption, were as follows: 60.4% N (54.4 g DM), 12.4% L (12.1 g DM) and 27.2% D (26.6 g DM) in cats, and 46.2% N (11.6 g DM), 29.9% L (7.5 g DM) and 23.9% D (6.0 g DM) in ferrets. This indicates that cats and ferrets have a clear preference for diets of higher fat content. In all three diets, the digestibility of CP was significantly (p < 0.05) lower (70.1 +/- 5.4 vs. 75.9 +/- 5.8) while that of EE was significantly (p < 0.05) higher (95.6 +/- 1.5 vs. 89.4 +/- 5.3) in ferrets than in cats. The average digestible/metabolizable energy (DE/ME) ratio of feeds turned to be 95.6% for cats and 90.6% for the ferrets. From the data one can conclude that the ferret cannot be used as a model animal for cats either for preference or digestibility studies.

Effect of different fibre types on the digestibility of nutrients in cats.

In this study the effect of different fibre types was investigated on the acceptance of foods (in a short-term study) and on the nutrients' digestibility by using 10 adult, castrated cats. Peanut hull (PH, source of lignin), dried sugar beet pulp (SBP, source of hemicelluloses and pectin) and alfalfa meal (ALF, source of cellulose) were mixed to a poultry meat based cat food in 10% on dry matter (DM) basis. The average DM intake did only slightly differ according to the type of fibre added. Supplementation of basal food by dried SBP did not influence the digestibility of DM and crude protein (CP) significantly. Using ALF as a fibre source decreased the digestibility of DM (85.8% vs. 78.6%) and CP (93.8% vs. 92.0%) significantly. More severe decline could be observed in the digestibility of DM (85.8% vs. 63.4%) and CP (93.8% vs. 83.7%) when using PH as a fibre source. Fibre sources also influenced the stool DM content significantly. While application of PH increased the DM content of the faeces (45.0% vs. 49.6%), the use of dried sugar beet or ALF reduced the faecal DM content (45.0% vs. 24.1% and 39.0%, respectively). According to these results the less digestible fibre source (PH) increased the DM content of the faeces while by improving the digestibility of the fibre sources the DM content of the faeces decreased. It can be concluded, that not only the absolute fibre content of the food but also the type of fibre must be taken into account when evaluating its possible role as a component of weight loss products.

Reduction of the energy density of cat foods by increasing their fibre content with a view to nutrients' digestibility.

Indigestible compounds are useful for reducing the energy density of food for obese cats, but the acceptance and digestibility of such components must also be taken into consideration. In this trial, dried apple pomace was investigated as a compound having sweet taste, aromatic flavour and high fibre content (207 g/kg dry matter). It was mixed in a meat-based diet at a ratio of 10, 20, and 40%. These diets were fed to adult cats in digestibility trials. As could be predicted, by increasing the percentage of apple pomace in the mixtures the digestibility of nutrients significantly decreased (p < 0.01; p < 0.001). However, the digestibility of ether extract decreased much less than that of the other nutrients. The addition of apple pomace to the diets at an inclusion rate of 10 or 20% reduced their energy density but only slightly changed the digestibility of fat. However, the digestibility of crude protein decreased considerably. According to the present findings, the energy density of mixed diets decreases proportionally to the percentage of apple pomace added. However, due to the much lower digestibility, the protein supply to the cat will be worse. It was concluded that the addition of palatable fibrous components is the best method for reducing the energy content of food for obese cats, as it maintains a normal level of food intake. When calculating the required protein content of a diet supplemented with a fibrous component, in addition to the degree of dilution the reduced protein digestibility must be taken into account.

Factors influencing the food preference of cats.

Four individual preference tests were carried out using the same 10 castrated adult cats. The main questions investigated were: (i) do the cats prefer diets having one dominant taste or diets made from a relatively wide range of compounds of animal origin and (ii) can the preference be connected to one taste? In test 1 a dry diet (K) made by a world-renowned company having a beef taste was compared with four others (I, II, III, IV) dry foods prepared at the authors' institute in order to prevent any one of the mixtures having a predominant taste. In test 2 diets I, II, III and IV were compared with each other in the absence of diet K. In test 3 another four diets with different dominant tastes (fish, liver, poultry with fat addition and poultry without fat addition) were investigated. In test 4 the same three tastes (beef, fish and poultry) were compared with each other by using diets of three world-renowned companies. From the results the following conclusions can be drawn. Cats undoubtedly use smell in the detection and selection of food. If cats find the odour of a certain food is significantly more attractive than that of the other, they will consume it exclusively and without tasting the less attractive food. If none of the diets are especially attractive, according to smell, cats will also taste the foods and make their decision on the basis of both senses. Diets having one dominant taste result in a higher feed intake than that reached by diets without a dominant taste. If a diet is manufactured well, its dominant taste may have less effect on diet consumption. Food preference does not seem to be connected to one exclusive taste but is significantly influenced by other factors connected to the manufacturing of the diets.

Alteration of body composition in rats: effect of organic chromium and L-carnitine.

A growth trial was carried out to test the effect of organic, trivalent chromium and L-carnitine on the body composition of growing rats. At the same time, an evaluation of different measurement methods (weight of epididymal fat pad, adipocyte morphometry, total body electrical conductivity) was performed. Outbred Wistar rats of 30 days of age were fed diets of different (0, 10 and 20%) protein level. The diets were supplemented with 4 mg/kg Cr as chromium nicotinate, and 100 mg/kg L-carnitine. The experimental feeding lasted 15 days, after a 5-day-long adjustment period. It was found that Cr addition increased feed intake. Both treatments caused changes in body composition, increasing fat and protein deposition. Organic chromium had no effect at either protein level, while L-carnitine improved the protein retention only at an optimum (20%) protein supply. No statistically significant correlation was found between total body electrical conductivity (TOBEC) and body composition, which could be attributed to the great individual differences. A close correlation was found among total body fat percentage, weight of epididymal fat pad and the adipocyte surface. The data suggest that there is an interaction between dietary protein supply and the effect of repartitioning agents.

Influence of feeding intensity on corporeal development, body composition and sexual maturity in female rabbits.

Twenty-six 6-week old female New Zealand White rabbits were divided into two groups: ad libitum (AL) and 70% restricted (RS) feeding. At the beginning of the experiment the liveweights were practically the same: 0.99 +/- 0.08 vs. 1.01 +/- 0.08 kg in group AL and RS, respectively. At 18 weeks of age the body weight of Group RS rabbits was 84.7% (3.14 +/- 0.24 kg) of the group AL (3.71 +/- 0.31 kg). The apparent digestibility of crude protein was significantly (p < 0.001) higher in Group RS than in Group AL (76.5 +/- 1.4 vs. 73.0 +/- 2.7%). The daily water consumption was significantly (p < 0.05) higher (3.5 ml/g DM intake) in Group RS as compared to Group AL (1.9 ml/g DM). Since the average body weight in Group RS at 18 weeks was the same as that of Group AL at 14 weeks of age (3.14 kg), the comparison of the live body measures and indices was based on these ages. Animals fed ad libitum or restricted show no differences at the defined age in most live body measurements except in heart girth and rump width, which were significantly (p < 0.05) shorter in Group AL than in Group RS (29.3 +/- 0.8, 5.7 +/- 0.5 and 30.7 +/- 1.0, 6.2 +/- 0.3 cm, respectively). Body capacity was significantly (p < 0.05) smaller in Group AL, as the head capacity-body capacity proportion was significantly (p < 0.05) higher in Group AL than in Group RS (1653.1 +/- 134.5, 22.0 +/- 2.5 and 1913.7 +/- 168.7, 17.7 +/- 1.9, respectively). Due to restricted feeding the growth of the head proved to be less intensive than that of the body at the same body weight. The body in these does tended to be wider. Since the head in comparison to length or capacity of the body was smaller in does fed 70% of ad libitum, it could be concluded that the development of body parts of restricted-fed does was unequal (allometric growth). The effect of feed restriction reflected in lower dry matter and fat, and a higher ash and protein content both in total body and in dry matter composition of rabbits at 18 weeks of age. Restricted feeding delayed sexual maturity (69 vs. 92% of rabbits) with later starting ovarian activity, weaker ovarian responsiveness, and a smaller number of tertiary follicles on the ovarian surface.

Effect of methionine and its derivatives on the weight gain and protein utilisation of growing rats.

Methionine and its derivatives are used as feed supplements. The objective of this study was to compare the effectiveness of DL-methionine (MET), DL-methionine-hydroxy-analogue (2-hydroxy-4-methylthio-butyric acid, MHA), and DL-S methyl-methionine-sulphonium-chloride (SMM) in rats using low- (10 g/100g, BD10), medium-(15g/100g, BD15) and high-protein (20 g/100 g, BD20) diets. In a 10-day growth assay with weaning male rats (Wistar, SPF, LATI, Gödöllo, Hungary, 6 rats/group) methionine-deficient basic diets (BD10, BD15, BD20) were supplemented with 0, 1.5 ad 3.0 g/kg MET, MHA OR SMM. Extracted soybean meal was used as sole protein source. A protein-free diet was used for determining net protein ratio (NPR) indices. The weight gain of rats fed test diets fortified with 1.5 and 3.0 g/kg MET, MHA, or SMM was significantly higher (p < 0.05) than that obtained with the unfortified diets. The NPR index of the diets was increased by MET, MHA or SMM supplementation, which increase was significant (p < 0.05) at 3.0 g/kg fortification level. However, there were no significant differences between the efficiencies of methionine derivatives on the same dietary protein levels. The weight gains of the rats were higher and the NPR indices of the diets were lower at a higher dietary protein level.

Evaluation of the nutritional value of the amaranth plant. I. Raw and heat-treated grain tested in experiments on growing rats.

Two experiments were carried out on rats to determine the nutritional value of raw and autoclaved amaranth (Amaranthus retroflexus) seeds. The test groups of the first experiment were fed only ground amaranth seed. The control group received pure maize meal. Both test groups showed higher growth rate than the control group, due to the higher protein content of amaranth. The final body weight of rats fed autoclaved amaranth seed significantly exceeded that of rats fed raw amaranth seed. The Net Protein Utilisation (NPU) index of raw and autoclaved amaranth was determined in the second experiment. The diets had 10% crude protein concentration and the only protein source was the meal of raw and autoclaved amaranth seed. It was found that the heat treatment of amaranth increased the body weight gain of rats even when the animals consumed diets containing only 10% crude protein. The feed consumption was also higher with the diet containing autoclaved seeds. Despite the finding that there was no significant difference in the NPU index, data suggest the presence of a heat-labile antinutritive compound.

Assessment of nutritional adequacy of the protein in dog foods by trials on growing rats.

In order to offer methods for assessing the protein quality of dog foods, eight commercial dry-type complete dog foods were analysed by in vitro chemical methods (crude protein, amino acid composition, in vitro pepsin digestibility) and rat growth trial (weight gain = WG, feed efficiency = FE, protein efficiency ratio = PER, net protein ratio = NPR, and net protein utilisation = NPU). Three individual samples were taken from each dog food and their homogenous mixture was used as an ingredient for the test diets fed to six rats per diet. All dog food samples were used as a single protein source in isonitrogenous (10% crude protein) and isoenergetic (ME = 14.9 MJ/kg) complete diets. Rat weight gains showed significant differences among most of the test diets as a consequence of the differences in protein quality of the dog food samples. The protein quality indices of the dog food products showed significant variations. The measured ranges of protein quality indices of the samples were as follows: WG = -5.4-21.4 g; FE = 0-0.25 g/g; PER = 0-2.54 g/g; NPR = 1.06-3.52 g/g; NPU = 19.93-65.93%. The limiting amino acid, the sum of essential amino acids and the chemical scores were calculated from gross amino acid composition. Tryptophan was the first limiting amino acids in all samples but one. Methionine was found to be the second limiting amino acid. The crude protein content of the samples showed no correlation with indices of protein quality, indicating that the declaration of crude protein is not a sufficient information to judge the protein quality of dog foods. The declaration of NPR, or NPU indices may be recommended for labelling the protein quality of premium-type dog foods.

Relationship of dietary fat and lysine level with body composition in broiler chickens.

The effect of dietary fat and/or lysine supplementation on the body composition of broiler chickens was studied. Body composition was measured by computed tomography (CT) and direct chemical analysis. Cockerel chicks from a previous experiment (Fekete et al., 1992) were used in this study. Ten chickens from each treatment group were euthanised, deep frozen and subjected to CT. Subsequently the bodies were dissected and ground to obtain homogeneous samples for chemical analysis. Supplementation of the diet with 6 g/kg lysine did not change total body composition but positively influenced the final body weight. In the treatment group receiving 40 g/kg added fat and 3 g/kg feed lysine (F-LYS-I) the higher body weight ran parallel with a higher fat content. The difference between the frozen body weight and final live body weight shows that lysine supplementation increased the water-holding capacity of muscle, which was the best in groups receiving a diet of normal energy content plus high lysine supplementation.

Effect of methionine and its related compounds on rumen bacterial activity.

The effect of several methionine sources (L-methionine = L-MET; DL-methionine = DL-MET, DL-S-methyl-methionine-sulphonium-chloride = SMM; N-hydroxymethyl-DL-methionine-Ca = NHM; methionine-hydroxy-analog free acid = MHA; methionine-sulphoxide = MSO) on rumen bacterial growth was studied using a new methodical approach which utilises a methionine free assay medium (Bacto Methionine Assay Media, Difco) supplemented by increasing quantities of the methionine sources and inoculated with one drop of diluted rumen bacteria. The optical density was measured after 18 h incubation on 39 degrees C. L- and DL-MET promoted the highest growth response, while SMM and NHM exerted significantly (p < 0.05) lower optical densities. MHA and MSO showed no growth response. The methodical approach and the possible bacterial strains, which might have contributed to the growth response have been discussed.

Bioavailability of methionine-hydroxy-analog free acid and S-methyl-methionine in the growing rat.

The biological utilization of DL-methionine (MET), DL-methionine-hydroxy-analog and DL-S-methyl-methionine-sulphonium-chloride (SMM) was tested in rat growth assay. Weight gain, feed efficiency, protein efficiency ratio (PER), net protein ratio (NPR) and net protein utilization (NPU) were applied as criteria. A test diet containing soybean meal as sole protein source was fortified with MET, MHA or SMM at 1.5 and 3.0 g/kg levels, respectively. All fortifications had a significant (p < 0.05) positive influence on weight gain, feed conversion and protein utilization. SMM showed the highest activity. MET and MHA were almost equally well utilized at 3.0 g/kg fortification level, however MHA proved slightly less efficient at 1.5 g/kg level than MET.

Optimizing protein quality of mixtures of blood meal, feather meal and bone meal.

The protein quality of two- or three-component mixtures of blood meal, feather meal and bone meal was characterized by amino acid scores and rat net protein utilization (NPU) values. A graphic method designed to find optimum levels of the limiting essential amino acids in the mixtures was suitable for predicting the optimum of NPU values determined by feeding rats with diets having 10% crude protein. The protein quality of mixtures of blood meal, feather meal and bone meal showed an optimum if blood meal constituted 60% of the protein content of the mixtures; however, poor feed intake and growth data were obtained.

Chemical composition and vitamin B content of abattoir by-product meals.

Chemical composition of meat-and-bone meals (n = 22), poultry by-product meals (n = 12), blood meals (n = 6), bone meals (n = 4) and feather meals (n = 8) indicated a slight degree of overdrying. Crude fat and ash contents were within the acceptable limits. Mineral elements of bones were determinative in the element pattern of meat-and-bone meals as indicated by the significant correlations between Ca, P and Mg. Crude protein was in negative regression and correlation with crude ash content (r = -0.81; P less than 0.001). This was more pronounced when the data were expressed in fatless dry matter (r = -0.94; P less than 0.001). Crude protein also showed significant negative correlations with Ca, P and Mg contents, offering the possibility to predict their levels from nitrogen content. Meat-and-bone meals and poultry by-product meals were relatively rich sources of riboflavin, niacin, pantothenic acid and biotin, whereas their pyridoxine and thiamine contents were low. Blood meals, bone meals and feather meals were found to be negligible vitamin B sources. Vitamin B and crude protein content of abattoir by-product meals showed uncertain correlations.

The value of crude protein content and in vitro pepsin digestibility of abattoir by-product meals in the prediction of their available protein content.

Amino acid composition of meat-and-bone meals, poultry by-product meals, blood meals, bone meals and feather meals showed characteristic differences. Meat-and-bone meals and blood meals had surplus in lysine, whereas poultry by-product meals and feather meals were relatively rich in cystine. Blood meals had high levels of branched-chain amino acids as compared to isoleucine. In vitro pepsin digestibility of meat-and-bone meals (79.9 +/- 17.7%; n = 24) and blood meals (95.8 +/- 4.2%; n = 11) was found to be higher than that of poultry by-product meals (65.3 +/- 7.7%; n = 14) or feather meals (44.7 +/- 9.2%; n = 16). Pepsin digestibility of poultry by-product meals showed a significant negative correlation with crude protein content (r = -0.73; P less than 0.05; n = 14). However, in vitro pepsin digestibility of poultry by-product meals as well as meat-and-bone meals, blood meals and feather meals, showed insignificant correlations with NPU indices as well as with available crude protein contents of the meals. The NPU values of meat-and-bone meals for rats (29.9 +/- 11.7; n = 100) were lower than those of poultry by-product meals (52.1 +/- 7.1; n = 14). The NPU values of blood meals (6.4 +/- 5.6; n = 11) and feather meals (23.5 +/- 10.0; n = 16), determined as sole sources of protein, were low and they did not elicit weight gain in rats. The available crude protein content of poultry by-product meals (34.3 g/100 g +/- 3.6; n = 14) was higher than that of meat-and-bone meals (17.0 g/100 g +/- 7.3; n = 100).(ABSTRACT TRUNCATED AT 250 WORDS)