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Ileal endogenous nitrogen recovery (ENR) in pigs (9 [+ or -] 0.6 kg body weight) was estimated simultaneously using the [sup.15]N-isotope dilution technique ([sup.15]N-IDT) and the peptide alimentation ultrafiltration (UF) method. Diets were cornstarch, enzyme-hydrolyzed casein with no (control) or high (4%) content of quebracho extract (Schinopsis spp.) rich in condensed tannins. The amino acid (AA) pattern of the ENR was also determined. The ENR of pigs fed the quebracho diet was higher (P = 0.0001) than that of pigs fed the control diet [6.00 vs. 1.95 g/kg dry matter intake (DMI) for the [sup.15]N-IDT and 5.18 vs. 1.49 g/kg DMI for the UF method, respectively]. With the [sup.15]N-IDT, ENR values were 0.44-0.79 g/kg DMI (24%) higher (control P = 0.0032, quebracho P = 0.0002) than for the UF method. Apparent nitrogen digestibility depended on diet (69.0% quebracho vs. 86.0% control, P = 0.0001). Real nitrogen digestibility (RD-N) determined by the UF method was higher (P = 0.0001) for the control than for the quebracho diet (91.4 vs. 88.2%). Corresponding values for the [sup.15]N-IDT did not differ (P = 0.0569) between diets (92.8 vs. 91.4%). The [sup.15]N-IDT gave higher values for RD-N of both diets (control P = 0.0030, quebracho P = 0.0002) compared with the UF method. Endogenous AA recoveries (g/kg DMI) were increased 300% (P = 0.0001) and the AA-pattern of ENR was changed (P from 0.0001 to 0.7530 for different AA) by the quebracho diet. A constant AA-pattern of ENR cannot be assumed. Despite limitations of both techniques, the [sup.15]N-IDT and the UF method gave similar results with respect to ENR. J. Nutr. 134: 3076-3082, 2004. KEY WORDS: * quebracho extract * [sup.15]N-isotope dilution technique * peptide alimentation ultrafiltration * endogenous amino acids * condensed tannin

The [sup.15]N-isotope dilution technique ([sup.15]N-IDT), with either pulse-dose oral administration or continuous i.v. administration of [[sup.15]N]-L-leucine (carotid artery), both at 5 mg/(kg body weight, d), was used to measure ileal (postvalve T-cecum cannuia) endogenous nitrogen recovery (ENR) in pigs (9 [+ or -] 0.6 kg). Diets were cornstarch, enzyme-hydrolyzed casein with no (control) or high (4%) content of quebracho extract (Schinopsis spp.) rich in condensed tannins. Blood was sampled from a catheter in the external jugular vein. Mean plasma [sup.15]N-enrichment at d 8-10 was higher (P = 0.0009) after i.v. than after oral administration [0.0356 vs. 0.0379 atom% excess (APE)]. Plasma [sup.15]N-enrichment for i.v. infused pigs was 0.01117 APE higher (P < 0.0001) and for orally dosed pigs 0.0081 APE lower (P < 0.0001) at 11 h postprandial compared with 1 h postprandial. Apparent ileal N digestibility was higher (P < 0.0001) for the control (85.5%) than for the quebracho diet (69.5%). ENR was calculated from the ratio of [sup.15]N-enrichment of plasma and digesta. The ENR for the quebracho diet was ~300% higher than for the control diet (6.03 vs. 1.94 g/kg dry matter intake, P < 0.001). The real N digestibility (92.2 [+ or -] 0.4%) was equal for both diets (P = 0.1030) and both tracer methods (P = 0.9730). We concluded that oral administration of [[sup.15]N]leucine provides reasonable estimates of ENR in pigs fed semipurified diets with high or low content of tannins; however, one must be careful in extrapolating this conclusion to studies with other protein sources or feeding frequencies. J. Nutr. 134: 3068-3075, 2004. KEY WORDS: * [sup.15]N-isotope dilution technique * oral label administration * first-pass uptake * endogenous N * quebracho tannin

Abstract: Reproduction in dairy cattle is negatively affected by a negative energy balance (NEB), a combination of the deposition or mobilisation of fat and protein. The mode of action of NEB on fertility is not always clear, but the severity, length, and probably also the nature of the NEB may be involved. Extensive mobilisation of fat is expected to have detrimental effects on liver function due to the accumulation of non-esterified long chain fatty acids, impairing the detoxification of ammonia into urea. Protein evaluation systems nowadays use the concept of metabolisable protein (MP) and distinguish between rumen degradable protein (RDP) and rumen undegradable protein (RUP). Mobilisation of protein itself does not seem to have negative effects on reproduction. However, when protein is extensively degraded in the rumen or used as an energy source, metabolic residues like ammonia and urea will result. Such residues may exert metabolic effects that are often detrimental to reproduction and fertility. Ammonia is believed to play a role starting before ovulation, whereas urea mainly interferes negatively after fertilisation. But, urea is also believed to aggravate the severity of NEB and its effect on fertility by preventing or delaying the start of cyclicity. Besides, urea has been shown to lower the pH in the uterine fluid, giving rise to disturbances in follicular development and embryonic growth. It is recommended to limit the level of rumen degradable protein in the diet to 10% in the DM. [Copyright &y& Elsevier]

Provides information on two studies which examined the effect of protein and protein-like energy on the degradation rate of myofibrillar protein in preruminant calves. Materials and methods; Effect of dietary treatments on muscle protein turnover; Conclusions.

The amino acid concentrations of cornstarch-based guanidinated unprocessed (UGM) and autoclaved (AGM) Nutrisoy (defatted soy flour) protein test meals were compared with the respective unguanidinated Nutrisoy diets. Endogenous ileal recoveries and true digestibilities of amino acids were determined in six growing pigs, fitted with a simple T-cannula at the distal ileum, fed the guanidinated protein test meals. The UGM and AGM contained 13.4 (high) and 3.0 (low) g/kg dry matter of soybean trypsin inhibitors (SBTI), respectively. The experiment was a two-period cross-over design with each period lasting 15 d. On d 14 of each period, the pigs were fed the guanidinated test meals followed by 24 h continuous collection of digesta. Concentrations of crude protein and most of the amino acids in the test meals were higher than in the respective diets. Apparent ileal amino acid digestibilities of the test meals did not differ (P > 0.05) from reported values for the respective diets and were higher (P < 0.05) by 22.7 (cysteine) to 61.3 (tyrosine) percentage units for AGM compared with UGM. The ileal recoveries of endogenous amino acids in AGM-fed pigs were lower (P < 0.05) than UGM-fed pigs. Values ranged from -0.10 (arginine) to 0.64 (aspartate + asparagine) and from 0.84 (histidine) to 2.61 (tyrosine) g/kg dry matter intake for AGM- and UGM-fed pigs, respectively. True ileal amino acid digestibilities for AGM were higher (P < 0.05) than UGM with differences ranging from 12.7 (tyrosine) to 38.3 (leucine) percentage units. In conclusion, ileal recoveries of endogenous amino acids were increased in pigs fed guanidinated protein test meals with the higher concentration of SBTI. [ABSTRACT FROM AUTHOR]

Differences between the fermentation characteristics of cell contents (CC) and protease-treated cell walls (CW) of young leaves of Italian ryegrass (Lolium multiflorum Lam.) cultivar Multimo (tetraploid), were studied in vitro. Gas and volatile fatty acid (VFA) production rates were measured at regular intervals, as was the degradability of organic matter (OM) of CW. The measured VFA were used to predict the gas production and fermentable OM using stoichiometric calculations. For CW the volume and kinetics of measured gas production were the same as those predicted from the VFA formed. In contrast, the measured gas production for CC was consistently less than predicted, indicating that the stoichiometric equations were not valid for rapidly fermenting substrates. For both CC and CW, the relative rate of acetic acid production levelled off more slowly than for other VFA, resulting in an increasing gas yield (in ml/g fermentable OM) after 12 (CW)-24 (CC)h incubation. Consequently, the fermentation of OM was not linearly related to gas production kinetics. For CW, the kinetics of decline of degradable OM and fermentable OM were the same, after correction for a constant ‘lost fraction’ of degradable OM of 205 g/kg OM. This work indicates the value of detailed studies of fermentation processes to evaluate herbage quality. In particular, the role of CC and the difference between degradation and fermentation require further attention. [ABSTRACT FROM PUBLISHER]

A previously described mathematical model, that simulates the metabolic activities of rumen bacteria and protozoa, was used to examine the contribution of protozoa to neutral-detergent fibre (NDF) degradation in the rumen of cattle. Comparisons between predicted and experimentally observed NDF degradation showed general agreement. Further simulations were performed with diets containing variable proportions of concentrate (between 0 and 1 kg/kg diet DM) and at intake levels ranging between 5·3 and 21·0 kg DM/d. The simulated protozoal contribution to NDF degradation was 17–21% at the lowest intake level. Except for the all-concentrate diets, raising the feed intake level reduced this contribution to 5–3% at the highest intake level. The changes in contribution of protozoa to NDF degradation were related to variations in the fibrolytic bacteria: protozoa value and the NDF-degrading activities of protozoa predicted by the model. In simulations where dietary NDF levels were reduced and starch and sugar levels were increased independently, protozoal contribution to NDF degradation generally increased. These differences were reflected also in the generally increased protozoal contribution to NDF degradation predicted in response to a decreased roughage:concentrate value. The contribution of protozoa also generally declined in response to added N. These changes in predicted protozoal contribution to NDF degradation resulting from dietary variations provided possible explanations for the differences in rumen NDF degradation observed when animals are defaunated. [ABSTRACT FROM PUBLISHER]

Abstract: Fermentable carbohydrates can lead to changes in the gut microflora, which may have positive consequences for health. However, often, ingredients are added to diets without prior investigating about their potential fermentability within the target animal. The experiment reported, was conducted to investigate the fermentation kinetics of some non-digestible carbohydrates (NDC) by the caecal microbial community of broiler chickens by an assessment of the cumulative gas production during fermentation of each substrate. It also aimed to study changes in the microbial community, following fermentation of these non-digestible carbohydrates, by use of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Four extracted non-digestible carbohydrates (ENC): soybean meal oligo- and water-soluble polysaccharides (SMO and SMP), alfalfa meal oligo- and water-soluble polysaccharides (AMO and AMP) were studied. Two pure sugars, raffinose (RAF) and stachyose (STA) were also included. To assess the fermentability of the substrates, cumulative gas pressure was monitored continuously, for 72h, and at the end of fermentation, pH, volatile fatty acid (VFA), and ammonia (NH3) concentrations were measured in the fermentation solution. The PCR-DGGE technique was applied to compare microbial DNA fingerprints between substrates at the end of the fermentation. The inoculum for the in vitro gas production was obtained from a mixture of caecal contents of forty 81-day-old broiler birds. Soy oligosaccharides led to significantly more butyric acid production (P<0.05) after fermentation compared with other ENC. The production of butyric acid was 155.2mg/g DM, 100.3mg/g DM, 84.5mg/g DM and 71.8mg/g DM for SMO, SMP, AMP and AMO, respectively. Soy oligosaccharides had the lowest pH (5.5) and ammonia–nitrogen concentration (199.3mg/l) after fermentation. This was significantly different from other ENC and the pure sugars. DGGE analysis revealed that, the fingerprint of caecal bacterial communities showed some variation (C, value >60–80%) between some of the substrates. It was concluded that SMO, SMP, AMO and AMP, as well as RAF and STA were significantly different, both in terms of their fermentation kinetics and end-products using caecal contents from adult broilers. The extent to which these non-digestible, but fermentable, carbohydrates could change the microbial community of the broiler caecum, either in terms of the species detected, or its activity, needs to be investigated further, and then related to its effect on gut health in the animal itself. [Copyright &y& Elsevier]

Abstract: Interest in fermentation within the monogastric digestive tract is growing, particularly relative to animal health. This is of particular importance in relation to the forthcoming European ban on inclusion of anti-microbial growth promotors in animal diets. Fermentable carbohydrates are recognized as having an important role in fermentation in the monogastric digestive tract, and are often added to diets without having been examined for their actual fermentability, particularly in relation to the target animal. We describe an in vitro method to assess feed ingredients, as potential components of monogastric diets, which stimulate a positive fermentation (i.e., ones which will be well fermented and produce more short-chain fatty acids (SCFA) and less ammonia). This technique requires use of a batch culture containing the test substrate and an inoculum of appropriate origin. During fermentation, cumulative gas production is measured at regular intervals, as an indicator of kinetics of the reaction. When fermentation is complete, organic matter losses and end-products such as SCFA and ammonia, are measured. This paper illustrates use of the technique with 45 carbohydrate-based ingredients using faeces from unweaned piglets as inoculum. By assessing potential fermentability of a large number of ingredients, it is possible to make an informed choice as to which substrates are most suited for inclusion in a diet. By combining results with information about transit time, diets can be designed which should stimulate desirable fermentation along the entire digestive tract. In vitro fermentability is a potentially valuable characteristic in diet design, in order to stimulate microbial activity in the digestive tract. [Copyright &y& Elsevier]

The pathway for oxidation of energy involves a balanced oxidation of C2 and C3 compounds. During early lactation in dairy cattle this C2/C3 ratio is out of balance, due to a high availability of lipogenic (C2) products and a low availability of glycogenic (C3) products relative of the C2 and C3 products required for milk production. This review compares studies which manipulated dietary energy source and shows that dietary energy source can affect the balance of the C2/C3 ratio, as indicated by plasma NEFA, beta-hydroxybutyrate (BHBA) and glucose levels. It is shown that glycogenic nutrients increase glucose and insulin concentrations and decrease NEFA and BHBA plasma levels. Extra lipogenic nutrients elevate NEFA and BHBA and decrease plasma glucose concentrations. Lipogenic nutrients generally increase milk fat percentage and decrease milk protein percentage, suggesting a surplus of C2 compounds. The inverse is the case for feeding extra glycogenic nutrients, implying reduced deamination and oxidation of glycogenic amino acids. Feeding extra glycogenic nutrients improved the energy balance (EB), in contrast to ambiguous results of lipogenic nutrients on EB. Moreover, glycogenic feed may reduce the severity of ketosis and fatty liver, but increased the incidence of (sub)clinical acidosis. Since studies are scarce, it seems difficult to draw conclusions on the effects of dietary energy source on reproduction. However, lipogenic nutrients decrease glucose and increase NEFA and BHBA plasma levels. High plasma NEFA and BHBA and low plasma glucose levels are associated with decreased reproductive performance, which might imply the C2/C3 compound balance to be important for reproductive function.