Dried-Atella as an affordable supplementary feed resource for a better sheep production: in the case of Washera lambs in Ethiopia.

Ethiopia has a huge livestock population that includes sheep, which can be considered as a significant potential for the advancement of the country's economy. However, due to a shortage of appropriate supplementary feed and its escalating price, the production and productivity of sheep fattening in Ethiopian smallholder farmers are below its potential. Moreover, the use of Dried-Atella as an affordable supplementary feed resource for a better sheep production is not investigated and well documented. The aim of this study was to assess the comparative supplementation effects of Dried-Atella and Niger seed cakes (NSCs) on total dry matter and nutrient intake, body weight change, and carcass characteristics of Washera lambs. The experiment was conducted using a completely randomized design with three treatments replicated five times. The treatments are described as follows: Treatment 1 = Natural pasture hay (NPH) (800 g/d) + Wheat bran (WB) (160 g/d) + salt and water (ad libitum); Treatment 2 = NPH (800 g/d) + WB (160 g/d) + NSC (163 g/d) + salt and water (ad libitum); and Treatment 3 = NPH (800 g/d) + WB (160 g/d) + Dried-Atella (330 g/d) + salt and water (ad libitum). The finding elucidated that the crude protein (CP) content of Dried Atella, WB, NPH, and NSC were about 25.07%, 16.57%, 4.48%, and 38.04%, respectively. The result also indicated that the average mean value of the feed and CP intake of the sheep fed Dried-Atella was significantly higher than the other treatments (P-value = 0.000). With regard to the CP digestibility and dry matter digestibility, animals supplemented with Dried-Atella were significantly higher than the control group with P-value = 0.000 and P-value = 0.028, respectively. The body weight gain of the sheep is significantly higher (P-value = 0.008) for feeds supplemented with Dried-Atella than feeds without any supplement. In terms of economic profitability, a slightly better benefit was recorded in feed supplements with Dried-Atella than supplements with NSC, animal feed without any supplement exhibited loss. Considering its effect on feed intake, CP intake, and its digestibility, body weight gain, and carcass characteristics of lambs, Dried-Atella is a promising affordable supplementary feed resource for better sheep production in Ethiopia.

Starch and Cellulose Degradation in the Rumen and Applications of Metagenomics on Ruminal Microorganisms.

Carbohydrates (e.g., starch and cellulose) are the main energy source in the diets of dairy cows. The ruminal digestion of starch and cellulose is achieved by microorganisms and digestive enzymes. In order to improve their digestibility, the microbes and enzymes involved in starch and cellulose degradation should be identified and their role(s) and activity known. As existing and new analytical techniques are continuously being developed, our knowledge of the amylolytic and cellulolytic microbial community in the rumen of dairy cows has been evolving rapidly. Using traditional culture-based methods, the main amylolytic and cellulolytic bacteria, fungi and protozoa in the rumen of dairy cows have been isolated. These culturable microbes have been found to only account for a small fraction of the total population of microorganisms present in the rumen. A more recent application of the culture-independent approach of metagenomics has acquired a more complete genetic structure and functional composition of the rumen microbial community. Metagenomics can be divided into functional metagenomics and sequencing-based computational metagenomics. Both approaches have been applied in determining the microbial composition and function in the rumen. With these approaches, novel microbial species as well as enzymes, especially glycosyl hydrolases, have been discovered. This review summarizes the current state of knowledge regarding the major amylolytic and cellulolytic microorganisms present in the rumen of dairy cows. The ruminal amylases and cellulases are briefly discussed. The application of metagenomics technology in investigating glycosyl hydrolases is provided and the novel enzymes are compared in terms of glycosyl hydrolase families related to amylolytic and cellulolytic activities.

Glucogenic and lipogenic diets affect in vitro ruminal microbiota and metabolites differently.

This study was conducted to evaluate the effects of two glucogenic diets (C: ground corn and corn silage; S: steam-flaked corn and corn silage) and a lipogenic diet (L: sugar beet pulp and alfalfa silage) on the ruminal bacterial and archaeal structures, the metabolomic products, and gas production after 48 h in vitro fermentation with rumen fluid of dairy cows. Compared to the C and S diets, the L dietary treatment leaded to a lower dry matter digestibility (DMD), lower propionate production and ammonia-nitrogen concentration. The two glucogenic diets performed worse in controlling methane and lactic acid production compared to the L diet. The S diet produced the greatest cumulative gas volume at any time points during incubation compared to the C and L diet. The metabolomics analysis revealed that the lipid digestion especially the fatty acid metabolism was improved, but the amino acid digestion was weakened in the L treatment than in other treatments. Differences in rumen fermentation characteristics were associated with (or resulting from) changes in the relative abundance of bacterial and archaeal genera. The rumen fluid fermented with L diet had a significantly higher number of cellulolytic bacteria, including the genera of Ruminococcus, Butyrivibrio, Eubacterium, Lachnospira, unclassified Lachnospiraceae, and unclassified Ruminococcaceae. The relative abundances of amylolytic bacteria genera including Selenomonas_1, Ruminobacter, and Succinivibrionaceae_UCG-002 were higher in samples for diets C and S. The results indicated that the two glucogenic diets leaded to a higher relative abundance of bacteria which functions in succinate pathway resulting in a higher propionate production. The steam-flaked corn diet had a higher gas production and lower level of metabolites in fatty acids and amino acids. Most highly abundant bacteria were observed to be not sensitive to dietary alterations of starch and fiber, except for several amylolytic bacteria and cellulolytic bacteria. These finding offered new insights on the digesting preference of ruminal bacteria, which can assist to improve the rumen functioning.

ß-Glucan-Induced Immuno-Modulation: A Role for the Intestinal Microbiota and Short-Chain Fatty Acids in Common Carp.

Dietary supplementation of fish with ß-glucans has been commonly associated with immunomodulation and generally accepted as beneficial for fish health. However, to date the exact mechanisms of immunomodulation by ß-glucan supplementation in fish have remained elusive. In mammals, a clear relation between high-fibre diets, such as those including ß-glucans, and diet-induced immunomodulation via intestinal microbiota and associated metabolites has been observed. In this study, first we describe by 16S rRNA sequencing the active naive microbiota of common carp intestine. Based on the abundance of the genus Bacteroides, well known for their capacity to degrade and ferment carbohydrates, we hypothesize that common carp intestinal microbiota could ferment dietary ß-glucans. Indeed, two different ß-glucan preparations (curdlan and MacroGard®) were both fermented in vitro, albeit with distinct fermentation dynamics and distinct production of short-chain fatty acids (SCFA). Second, we describe the potential immunomodulatory effects of the three dominant SCFAs (acetate, butyrate, and propionate) on head kidney leukocytes, showing effects on both nitric oxide production and expression of several cytokines (il-1b, il-6, tnfα, and il-10) in vitro. Interestingly, we also observed a regulation of expression of several gpr40L genes, which were recently described as putative SCFA receptors. Third, we describe how a single in vivo oral gavage of carp with MacroGard® modulated simultaneously, the expression of several pro-inflammatory genes (il-1b, il-6, tnfα), type I IFN-associated genes (tlr3.1, mx3), and three specific gpr40L genes. The in vivo observations provide indirect support to our in vitro data and the possible role of SCFAs in ß-glucan-induced immunomodulation. We discuss how ß-glucan-induced immunomodulatory effects can be explained, at least in part, by fermentation of MacroGard® by specific bacteria, part of the naive microbiota of common carp intestine, and how a subsequent production of SFCAs could possibly explain immunomodulation by ß-glucan via SCFA receptors present on leukocytes.

Sainfoin (Onobrychis viciifolia) silage in dairy cow rations reduces ruminal biohydrogenation and increases transfer efficiencies of unsaturated fatty acids from feed to milk.

The effects of replacing grass silage by sainfoin silage in a total mixed ration (TMR) based diet on fatty acid (FA) reticular inflow and milk FA profile of dairy cows was investigated. The experiment followed a crossover design with 2 dietary treatments. The control diet consisted of grass silage, corn silage, concentrate and linseed. In the sainfoin diet, half of the grass silage was replaced by a sainfoin silage. Six rumen cannulated lactating multiparous dairy cows with a metabolic body weight of 132.5 ± 3.6 kg BW0.75, 214 ± 72 d in milk and an average milk production of 23.1 ± 2.8 kg/d were used in the experiment. Cows were paired based on parity and milk production. Within pairs, cows were randomly assigned to either the control diet or the sainfoin diet for 2 experimental periods (29 d per period). In each period, the first 21 d, cows were housed individually in tie-stalls for adaptation, then next 4 d cows were housed individually in climate-controlled respiration chambers to measure CH4. During the last 4 d, cows were housed individually in tie stalls to measure milk FA profile and determine FA reticular inflow using the reticular sampling technique with Cr-ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) and Yb-acetate used as digesta flow markers. Although the dietary C18:3n-3 intake was lower (P = 0.025) in the sainfoin diet group, the mono-unsaturated FA reticular inflow was greater (P = 0.042) in cows fed the sainfoin diet. The reticular inflow of trans-9, trans-12-C18:2 and cis-12, trans-10 C18:2 was greater (P ≤ 0.024) in the sainfoin diet group. The cows fed sainfoin diet had a lower (P ≤ 0.038) apparent ruminal biohydrogenation of cis-9-C18:1 and C18:3n-3, compared to the cows fed the control diet. The sainfoin diet group had greater (P ≤ 0.018) C18:3n-3 and cis-9, cis-12-C18:2 proportions in the milk FA profile compared to the control diet group. Transfer efficiencies from feed to milk of C18:2, C18:3n-3 and unsaturated FA were greater (P ≤ 0.0179) for the sainfoin diet. Based on the results, it could be concluded that replacing grass silage by sainfoin silage in dairy cow rations reduces ruminal C18:3n-3 biohydrogenation and improves milk FA profile.

Evaluation of equine rectal inoculum as representative of the microbial activities within the horse hindgut using a fully automated in vitro gas production technique system.

The in vitro gas production technique (IVGPT) has been a valuable tool in ruminant nutrition research for decades and has more recently been used in horse nutrition studies to investigate fermentation activities of the equine hindgut though primarily using feces as inoculum. This study was conducted to evaluate the use of equine rectal content in the IVGPT system as a viable inoculum that can be considered representative of the activities throughout the equine hindgut. Additionally, the study was conducted to measure the effects on fermentation kinetics and end-product production using inoculum from horses fed supplemental levels of coated sodium butyrate in an IVGPT system. Eight warmblood horses were fed a diet consisting of haylage (1% DM intake based on ideal body weight [BW]) and a mash concentrate formulated to provide 2.5 g nonstructural carbohydrate (NSC)/kg BW per meal. The diet was intended to create a NSC challenge to the microbial populations of the hindgut. The horses were randomly assigned to treatment or control group and after a 1-wk diet-adaptation period, the treatment group received 0.4 g/kg BW per day of a coated sodium butyrate supplement, while the control group received a placebo (coating only). After a 3-wk treatment period, the animals were sacrificed and digesta from the cecum, left ventral colon, right dorsal colon, and the rectum were collected within 30 min postmortem and used as inocula for the IVGPT trial. Haylage and concentrates fed to the test animals were also used as substrates in vitro. Sodium butyrate supplementation was not significant for gas production parameters or VFA measured suggesting no effect of sodium butyrate supplementation on the extent or kinetics of gas production or microbial end-product production (P ≥ 0.073). Differences in inocula were significant for organic matter corrected cumulative gas production (P = 0.0001), asymptotic gas production of the second phase (A2) (P < 0.0001); and maximal rate of OM degradation of the second phase (Rmax2) (P = 0.002). Inocula had a significant effect on total VFA (P = 0.0002), butyrate (Bu) (P = 0.015), branched chain fatty acids (P < 0.0001), pH (P < 0.0001), and ammonia (NH3) (P = 0.0024). In conclusion, based on observed results from this study, total tract digestibility may be overestimated if using rectal content inoculum to evaluate forage-based feeds in an IVGPT system.

Isolipidic replacement of krabok oil by whole krabok seed reduces in vitro methanogenesis, but negatively affects fermentation.

The background of the current in vitro study involves the issue of methane (CH4 ) production inherent to rumen fermentation. One of the dietary strategies to reduce enteric CH4 production by ruminants involves the supplementation of medium-chain fatty acids in diets. As such, oils containing high amounts of MCFA, such as coconut, palm kernel and krabok oil, are of much interest to formulate energy efficient and environmentally friendly rations for ruminants. Krabok oil (KO) reduces methanogenesis, but the appropriate inclusion level of dietary KO is unclear. We therefore investigated the dose-response relationship between krabok oil and CH4 production. In practice, the use of whole krabok seed (WKS), instead of KO, is easier, but the efficacy of WKS to inhibit methanogenesis was hitherto unknown. Thus, we also investigated whether WKS provides an alternative tool to inhibit CH4 production. The experimental substrates contained either KO, WKS, the residue of WKS after fat extraction residue (FER) or FER + KO. Appropriate amounts of WKS or its derivatives were added to a basal substrate so as to attain either a low, medium or high content of KO, that is, 37-46, 90-94 and 146-153 g/kg dry matter respectively. The experimental substrates were formulated to keep the amounts of incubated fat-free OM, crude protein, neutral detergent fibre and acid detergent fibre constant in order to avoid biased results through potential differences in fermentability between WKS and its derivatives, and the basal substrate. The latter resembled the ingredient composition of a total mixed ration commonly used in Thai dairy cows. Fully automated gas production (GP) equipment was used to measure gas- and CH4 production. Irrespective of the type of substrate (p ≥ .115), both the absolute (ml/g fat-free OM) and relative (% of total GP) CH4 production was reduced at the highest inclusion level of WKS or its derivatives (p ≤ .019). Total GP (ml/g fat-free OM), however, was reduced after incubation of FER, FER + KO, and WKS, but not KO, at the highest inclusion level of the respective substrates (p = .019). Volatile fatty acids were likewise affected (p ≤ .001). Krabok oil can inhibit CH4 production but only when the dietary KO content is at least 9.4% (DM). Supplementation of KO in the form of WKS, however, is considered not opportune because the fat extracted residue of WKS is poorly degraded during fermentation.

Laminaria digitata phlorotannins decrease protein degradation and methanogenesis during in vitro ruminal fermentation.

BACKGROUND: Phlorotannins (PhTs) are marine tannins consisting of phloroglucinol subunits connected via carbon-carbon and ether linkages. These have non-covalent protein binding properties and are, therefore, expected to be beneficial in protecting protein from hydrolysis during ruminal fermentation. In this study, the effectiveness of a methanolic PhTs extract from Laminaria digitata (10, 20, 40, 50, 75 and 100 g kg-1 tannin-free grass silage, with or without addition of polyethylene glycol (PEG), was investigated in vitro on protection of dietary protein and reduction of methane (CH4 ) in ruminal fluid. RESULTS: Addition of PhTs had linear (P < 0.0001) and quadratic (P = 0.0003) effects on gas and CH4 production, respectively. Optimal dosage of PhTs was 40 g kg-1 as at this point CH4 decreased (P < 0.0001) from 24.5 to 15.2 mL g-1 organic matter (OM), without affecting gas production (P = 0.3115) and total volatile fatty acids (P = 1.000). Ammonia trended (P = 0.0903) to decrease from 0.49 to 0.39 mmol g-1 OM, indicating protection of protein. Addition of PEG inhibited the effect of tannins at all dosage levels, and none of the fermentation parameters differed from the control. CONCLUSION: PhTs effectively protected protein from fermentation and reduced ruminal methanogenesis. © 2017 Society of Chemical Industry.

In vitro methane and gas production with inocula from cows and goats fed an identical diet.

BACKGROUND: Fermentative capacity among ruminants can differ depending on the type of ruminant species and the substrate fermented. The aim was to compare in vitro cow and goat rumen inocula in terms of methane (CH4 ) and gas production (GP), fermentation kinetics and 72 h volatile fatty acids (VFA) production using the browse species Acacia etbaica, Capparis tomentosa, Dichrostachys cinerea, Rhus natalensis, freeze-dried maize silage and grass silage, and a concentrate as substrates. RESULTS: Total GP, CH4 and VFA were higher (P ≤ 0.008) in goat inoculum than cows across substrates. The half-time for asymptotic GP was lower (P < 0.0001) in phase 1 and higher (P < 0.012) in phase 2, and the maximum rate of GP was higher (P < 0.0001) in phase 1 and phase 3 (P < 0.0001) in goats compared to cows. Methane production and as a percentage of total GP was higher (P < 0.0001) and the half-time tended (P = 0.059) to be at a later time for goats compared to cows. CONCLUSION: Goat inoculum showed higher fermentative activity with a concomitant higher CH4 production compared to cows. This difference highlights the ability of goats to better utilise browse species and other roughage types. © 2017 Society of Chemical Industry.

Evaluation of an in vitro fibre fermentation method using feline faecal inocula: inter-individual variation.

The present study aimed to evaluate the inter-individual variability in fermentation of standard fibrous substrates by faecal inocula from ten healthy adult female cats. Substrates were citrus pectin (CP), fructo-oligosaccharides (FOS), guar gum (GG), sugar beet pulp (SBP) and wheat middlings (WM). Each substrate was incubated with faecal inoculum from each cat. Gas production was measured continuously during the 48 h incubation and SCFA and organic matter disappearance (only SBP and WM) after incubation. Out of ten cats, nine produced faeces on the days of inoculum preparation. The substrates contrasted in terms of fermentation parameters measured. The inter-individual variability was in general lower for the more simple and pure substrates (CP, FOS, GG) than for the more complex substrates containing mixtures of fibres (SBP, WM). Furthermore, for total SCFA and gas produced, inter-individual variability was lower than for proportions of butyrate and of branched-chain fatty acids and for the parameters of gas production kinetics. It is concluded that the variability in in vitro fermentation parameters is associated with the complexity of fibrous substrates. The presented data are instrumental for the calculation of number of faecal donors required for precise in vitro characterisation of the fermentability of dietary fibres. In addition, the number of faecal donors should be adjusted to the specific fermentation parameter(s) of interest.

Evaluation of an in vitro fibre fermentation method using feline faecal inocula: repeatability and reproducibility.

To gain knowledge on the precision of an in vitro method for characterisation of the fermentability of dietary fibres, this study aimed to evaluate the repeatability and reproducibility of such a method. Substrates used were citrus pectin (CP), fructo-oligosaccharides (FOS), guar gum (GG), sugar beet pulp (SBP) and wheat middlings (WM). Each substrate was incubated with faecal inoculum from five cats with three replicates for each substrate-cat combination. Gas production was measured continuously during the 48 h incubation and SCFA and organic matter disappearance (only SBP and WM) were determined after incubation. Four consecutive runs were performed. The within-run variability (repeatability) was generally lower for the more simple and pure substrates (CP, FOS, GG) than for the more complex substrates containing mixtures of fibres (SBP, WM). Replicates showed high variability, in particular for SCFA profiles and parameters of gas production kinetics. The between-run CV (reproducibility) for the measured parameters were, in general, below 10 % for CP, FOS and GG and higher values were obtained for SBP and WM. It is concluded that for precise dietary fibre characterisation, the number of replicates should be multiple and adjusted according to the variability of the parameters of interest and the complexity of fibres. The method yielded reproducible results with some variation in absolute values obtained, which may have an impact on the significance level of the differences among substrates.

Condensed Tannins in the Gastrointestinal Tract of Cattle after Sainfoin (Onobrychis viciifolia) Intake and Their Possible Relationship with Anthelmintic Effects.

Condensed tannins' (CTs) fate along the digestive tract of ruminants may account for the variable efficacy of CTs against gastrointestinal nematodes. We analyzed CTs in the digesta of cattle fed sainfoin. With the acetone-butanol-HCl assay, the total CTs concentrations in the digesta were close to those in the diets (6.3 and 1.5% of DM in experiments 1 and 2, respectively); thus, CTs remained potentially largely undegraded/unabsorbed. With the thiolysis assay, CTs concentration was much higher in the abomasum (2.3% of DM; expt 1) compared with the rumen and intestines, along with higher mean size and prodelphinidins percentage, corroborating CTs efficacy reported only against Ostertagia ostertagi in the abomasum. In expt 2, the dietary levels of CTs were probably too low to demonstrate anthelmintic effects in the rumen. Overall, the level of CTs accessible to thiolysis is favored under the acidic conditions of the abomasum, which seems critical for anthelmintic activity.

A study of the structure-activity relationship of oligomeric ellagitannins on ruminal fermentation in vitro.

The aim of this study was to investigate how the degree of oligomerization of ellagitannins (ET) influences their ability to alter ruminal fermentation. Dimeric to heptameric ET were isolated from rosebay willowherb (Epilobium angustifolium) flowers and purified. Ellagitannins were tested in vitro on a mixture of grass silage and buffered rumen fluid. Total gas production was measured in real time using an automated pressure evaluation system. Methane production was monitored at regular interval by gas chromatography for 72h. The effect of ET was evaluated on 2 sources of rumen fluid using a randomized block design. Ammonia nitrogen, volatile fatty acid concentration, and pH were measured at the end of the experiment. Results show that oligomeric ET decreased gas production and total volatile fatty acid concentration proportionally to their degree of oligomerization. Methane production was also decreased by all the tested compounds and dimer was less effective than the larger ET, which showed similar levels of activity. Additionally, willowherb's oligomeric ET decreased ammonia-nitrogen and branched-chain volatile fatty acid concentrations, thus indicating reduced protein degradation by ruminal bacteria. This effect showed a quadratic relationship with the degree of oligomerization and was maximal with the tetramer. In conclusion, this study shows that the degree of oligomerization of ET has more than a simple linear effect on fermentation parameters in vitro. Large oligomers, in fact, have more detrimental effects on volatile fatty acid and gas production than small ones, while being similarly effective at inhibiting methane production.

Stable isotope-labelled feed nutrients to assess nutrient-specific feed passage kinetics in ruminants.

Knowledge of digesta passage kinetics in ruminants is essential to predict nutrient supply to the animal in relation to optimal animal performance, environmental pollution and animal health. Fractional passage rates (FPR) of feed are widely used in modern feed evaluation systems and mechanistic rumen models, but data on nutrient-specific FPR are scarce. Such models generally rely on conventional external marker techniques, which do not always describe digesta passage kinetics in a satisfactory manner. Here the use of stable isotope-labelled dietary nutrients as a promising novel tool to assess nutrient-specific passage kinetics is discussed. Some major limitations of this technique include a potential marker migration, a poor isotope distribution in the labelled feed and a differential disappearance rate of isotopes upon microbial fermentation in non-steady state conditions. Such limitations can often be circumvented by using intrinsically stable isotope-labelled plant material. Data are limited but indicate that external particulate markers overestimate rumen FPR of plant fibre compared with the internal stable isotope markers. Stable isotopes undergo the same digestive mechanism as the labelled feed components and are thus of particular interest to specifically measure passage kinetics of digestible dietary nutrients.

Stable isotope labeled n-alkanes to assess digesta passage kinetics through the digestive tract of ruminants.

We describe the use of carbon stable isotope ((13)C) labeled n-alkanes as a potential internal tracer to assess passage kinetics of ingested nutrients in ruminants. Plant cuticular n-alkanes originating from intrinsically (13)C labeled ryegrass plants were pulse dosed intraruminally in four rumen-cannulated lactating dairy cows receiving four contrasting ryegrass silage treatments that differed in nitrogen fertilization level (45 or 90 kg nitrogen ha(-1)) and maturity (early or late). Passage kinetics through the gastrointestinal tract were derived from the δ(13)C (i.e. the ratio (13)C:(12)C) in apparently undigested fecal material. Isotopic enrichment was observed in a wide range of long-chain n-alkanes (C27-C36) and passage kinetics were determined for the most abundant C29, C31 and C33 n-alkanes, for which a sufficiently high response signal was detected by combustion isotope ratio mass spectrometry. Basal diet treatment and carbon chain length of n-alkanes did not affect fractional passage rates from the rumen (K 1) among individual n-alkanes (3.71-3.95%/h). Peak concentration time and transit time showed a quantitatively small, significant (p≤0.002) increase with carbon chain length. K 1 estimates were comparable to those of the (13)C labeled digestible dry matter fraction (3.38%/h; r = 0.61 to 0.71; p≤0.012). A literature review has shown that n-alkanes are not fermented by microorganisms in the rumen and affirms no preferential depletion of (13)C versus (12)C. Our results suggest that (13)C labeled n-alkanes can be used as nutrient passage tracers and support the reliability of the δ(13)C signature of digestible feed nutrients as a tool to measure nutrient-specific passage kinetics.

Substantial Differences between Organ and Muscle Specific Tracer Incorporation Rates in a Lactating Dairy Cow.

We aimed to produce intrinsically L-[1-(13)C]phenylalanine labeled milk and beef for subsequent use in human nutrition research. The collection of the various organ tissues after slaughter allowed for us to gain insight into the dynamics of tissue protein turnover in vivo in a lactating dairy cow. One lactating dairy cow received a constant infusion of L-[1-(13)C]phenylalanine (450 µmol/min) for 96 h. Plasma and milk were collected prior to, during, and after the stable isotope infusion. Twenty-four hours after cessation of the infusion the cow was slaughtered. The meat and samples of the various organ tissues (liver, heart, lung, udder, kidney, rumen, small intestine, and colon) were collected and stored. Approximately 210 kg of intrinsically labeled beef (bone and fat free) with an average L-[1-(13)C]phenylalanine enrichment of 1.8±0.1 mole percent excess (MPE) was obtained. The various organ tissues differed substantially in L-[1-(13)C]phenylalanine enrichments in the tissue protein bound pool, the highest enrichment levels were achieved in the kidney (11.7 MPE) and the lowest enrichment levels in the skeletal muscle tissue protein of the cow (between 1.5-2.4 MPE). The estimated protein synthesis rates of the various organ tissues should be regarded as underestimates, particularly for the organs with the higher turnover rates and high secretory activity, due to the lengthened (96 h) measurement period necessary for the production of the intrinsically labeled beef. Our data demonstrates that there are relatively small differences in L-[1-(13)C]phenylalanine enrichments between the various meat cuts, but substantial higher enrichment values are observed in the various organ tissues. We conclude that protein turnover rates of various organs are much higher when compared to skeletal muscle protein turnover rates in large lactating ruminants.

Large intestinal fermentation capacity of fattening pigs on organic farms as measured in vitro using contrasting substrates.

BACKGROUND: In accordance with the EU regulations, organic farms require pigs to be fed diets high in fibre, which may impact on the pigs' large intestinal fermentation capacity. The ability of pigs to ferment non-starch polysaccharides (NSP) depends on characteristics of the dietary NSP source and microbes present in the large intestine of pigs. Little information exists on the fibre fermentation capacity of organically raised pigs. The aim of this study was to determine the variation in fibre fermentation capacity of fattening pigs within and between organic farms using an in vitro batch culture method and three contrasting substrates: oligofructose, soy pectin and cellulose. RESULTS: Pigs from different organic farms showed varying fermentation capacities as assessed by gas production, kinetics and fermentation end-products formed (P < 0.01). Coefficients of variation between inocula within farms varied by up to 40% for gas production and kinetics, in particular for incubation with cellulose. No relationship between on-farm feeding practice and the pigs' fermentation capacity could be established. CONCLUSION: The fermentation capacity of pigs reared under organic conditions varies considerable between farms. Finishing pigs reared under organic farming conditions are fast fermenters of oligofructose and soy pectin. More than four donor animals should be used per inoculum to accurately assess in vitro fermentation capacity. Fermentation results could not be related to dietary management under on-farm conditions.

Repeated measurements of in vitro fermentation of fibre-rich substrates using large intestinal microbiota of sows.

BACKGROUND: Fibrous ingredients for pig diets can be characterized by in vitro fermentation. In vitro fermentation methods often use a one-time measurement of gas production during the incubation of test substrates with one faecal inoculum. The representativeness of this approach can be questioned as measuring time and number of animals from which inoculum originates may influence fermentation results. An in vitro fermentation trial was conducted incubating three fibrous substrates with three inocula in five replicates (different fermentation runs) to test the influence of run and origin of inocula. RESULTS: Total gas production and maximal rate of gas production differed (P < 0.05) between fermentation runs, but less than substrates (P < 0.01). The ranking order between substrates remained similar for each run. Fermentation of cellulose led to higher coefficients of variation between inocula compared to the fast fermentable substrates oligofructose and soy pectin. Differences ranged from 2% for total gas production up to 25% for maximal rate of gas production. CONCLUSION: One fermentation run can provide representative results for substrate ranking. Using multiple inocula mixed from four faecal samples each leads to high coefficients of variation for slow fermentable substrates like cellulose. Future studies should examine the optimal number of animals for inocula preparation to decrease variation.

Changes in fatty acid content and composition in silage maize during grain filling.

BACKGROUND: The stage of maturity at harvest has a major effect on the fatty acid (FA) content and composition of forage plants consumed by dairy cows. The present study investigated the dynamics of FA content and composition in stover (leaves and stem) and ears (cob, shank and husks) of two maize genotypes (G2 and G6) grown on sandy and clay soils and harvested at 14, 42, 56, 70 and 84 days after flowering (DAF). In addition, the FA content and composition of six maize genotypes (G1-G6) grown on the two soil types were compared at the normal harvest time of early genotypes in the Netherlands (70 DAF). RESULTS: The contents of total FAs and major individual FAs in both stover and ears changed significantly (P < 0.001) during the grain-filling period (14-84 DAF). In stover the contents of C16:0, C18:2, C18:3 and total FAs declined (P < 0.001) while those of C18:0 and C18:1 increased (P < 0.001) with progressive grain filling. The rate of decline in C18:3 and total FA contents was slower during 14-56 DAF as compared with 56-84 DAF. In ears, the contents of C16:0, C18:1, C18:2 and total FAs increased up to 56 DAF and then remained more or less constant until 84 DAF. At 70 DAF the content of polyunsaturated fatty acids (PUFAs) in both stover and ears did not differ among the six genotypes. However, the average contents of C16:0, C18:3 and total FAs in stover were higher (P < 0.05) on clay soil, whereas those of C18:0 and C18:1 were higher on sandy soil. CONCLUSION: The results demonstrate that the maximum PUFA content in silage maize is harvested around 56 DAF, in the present study at a T(sum) of 927 °C.d or at an ear dry matter content of 440 g kg(-1) , which is before the onset of rapid senescence. Any further delay in harvesting will cause a rapid decline in C18:3 content in maize silages.