Concentration of indoles and other rumen metabolites in sheep after a meal of fresh white clover,perennial ryegrass or Lotus corniculatus and the appearance of indoles in the blood

The objective of this study was to determine the effect of feeding three fresh forage diets, white clover (WC), perennial ryegrass (PRG) and Lotus corniculatus (LC), on the formation of indole and skatole in the rumen of sheep. The formation of indole and skatole in the rumen and their appearance in the blood were also compared. Peak rumen indole and skatole concentrations per kg crude protein intake (CPI) were significantly higher when feeding WC compared with PRG and LC (P < 0.05) and this was associated with a significantly higher rumen concentration per kg CPI of ammonia, branched chain volatile fatty acids, total nitrogen and soluble nitrogen (P < 0.05). Greater indole and skatole concentrations when feeding WC can be attributed to high solubility and rapid degradation of the forage protein. LC had a similar nutrient composition to WC, but the condensed tannins in LC slowed protein degradation and reduced indole and skatole formation. Indole and skatole concentrations peaked in the plasma 1–2 h after the end of feeding, indicating that skatole and indole are rapidly absorbed from the rumen into the blood. High indole and skatole formation with low intakes of WC indicates that the WC component of traditional New Zealand pastures may be the primary cause of undesirable pastoral flavours that result from the presence of indoles in meat. To ameliorate undesirable flavours, producers reliant on pastoral systems will need to consider using alternative forages such as LC to reduce protein solubility and degradation rate. Copyright © 2007 Society of Chemical Industry     

Controlling the formation of indole and skatole in in vitro rumen fermentations using condensed tannin

Indole and skatole are formed in the rumen from the fermentation of tryptophan and have been correlated to the presence of undesirable pastoral flavours in meat from grazing ruminants. A series of four in vitro rumen fermentation experiments was carried out to determine the effectiveness of condensed tannin (CT) for reducing the formation of indole and skatole. Experiment 1 utilised fresh white clover (WC; Trifolium repens) in ratios with the CT‐containing forage Lotus pedunculatus (LP; 97 g CT kg^?1 dry matter (DM)). Increasing the ratio of LP to WC decreased the formation of indole and skatole. Experiments 2 and 3 used extracts of CT from LP and grape seed added to incubations of fresh non‐CT‐containing WC or perennial ryegrass (PRG; Lolium perenne). Including the CT extracts in incubations at 40 and 80 g kg^?1 DM was more effective at reducing indole and skatole formation than lower concentrations of CT extract (P < 0.05). Including fresh LP in ratios with WC gave a linear decrease in indole and skatole concentration (indicating dilution), while including a CT extract in the incubations gave an exponential decrease in indole and skatole concentration (suggesting binding). Experiment 4 elucidated the mechanisms behind the action of CT by delayed addition of tryptophan and polyethylene glycol (PEG) to incubations of LP. Rumen microbes that were exposed to CT of LP in planta for up to 6 h and then provided with tryptophan were still able to convert tryptophan to indole and skatole. Adding PEG to incubations of LP after 6 h inhibited the activity of plant CT and increased the availability of substrate for indole and skatole formation. These studies have shown that a higher concentration of CT is more efficient for reducing indole and skatole formation and that CT contained within plants acts differently in in vitro rumen fermentations than additions of extracted CT. Under the conditions of these experiments, there was no evidence that CT contained in LP affected the protein present in WC in a mixed fermentation. Copyright © 2007 Society of Chemical Industry     

The effect of supplementation of a white clover or perennial ryegrass diet with grape seed extract on indole and skatole metabolism and the sensory characteristics of lamb

Condensed tannin in the form of a grape seed extract (GSE) was dosed to weaned wether lambs fed white clover (WC) or perennial ryegrass (PRG) over a 9‐week period to determine whether the ‘pastoral’ flavour and odour of meat could be altered. The concentrations of the pastoral flavour compounds indole and skatole were determined in the rumen fluid, blood plasma and intermuscular fat. The odour and flavour of fat and meat from the slaughtered lambs was assessed by a trained panel. The rumen fluid and blood plasma concentrations of indole and skatole were higher in those lambs fed WC compared to PRG (P < 0.05) and the overall meat flavour intensity was greater when feeding WC (P < 0.01). The observed concentration of indole and skatole in the fat between WC and PRG feeding treatments was not statistically different. Power analysis indicated that increasing the number of lambs per treatment group from 20 to 65 would result in a higher fat skatole concentration (P < 0.05) being detected in lambs fed WC compared to PRG. Dosing with GSE gave a small reduction in skatole concentration in the rumen fluid and reduced plasma concentration of indole and skatole (P < 0.001). Odour and flavour scores of the fat and meat samples were not particularly high however, dosing with GSE lowered the overall and sweet odour and the sheepy, camphor, faecal and barnyard flavour (P < 0.05). Although the plasma concentration of indole and skatole suggests that GSE reduced indole and skatole formation, the intermittent supply of the GSE to the rumen environment was not sufficient to reduce their concentration in the fat. Hence, the small difference in the scores for pastoral odour and flavour attributes associated with GSE treatment may arise from other unknown factors. From a primary investigation, there was no difference in the concentration of indole and skatole in fat samples collected from carcasses before and after chilling. Further investigations into meat pastoral flavour are warranted through feeding condensed tannin‐containing forages. Copyright © 2007 Society of Chemical Industry     

Spatial variation of intestinal skatole production and microbial community in Jinhua and Landrace pigs

BACKGROUND: An excessive accumulation of skatole in pigs is a major contributor to boar taint. Intestinal skatole concentrations may vary among different pig segments and breeds. The objective of this study was to evaluate the spatial variation of intestinal skatole production and the microbial community in local Jinhua and exotic Landrace pigs. RESULTS: For both breeds, skatole concentration increased towards the rectum and segment had a significant effect on skatole (P < 0.001). The caecal skatole concentration in Landrace was significantly lower than proximal, distal colonic and rectal skatole levels (P < 0.05). Compared with Jinhua pigs, the rectal skatole and proximal and distal colonic indole levels were significantly higher in Landrace pigs (P < 0.05). Volatile fatty acids were significantly affected by breed except for isobutyrate and isovalerate (P < 0.05), with higher butyrate level and lower pH in Landrace pigs (P < 0.05). There were no significant differences in mitosis and apoptosis for the two breeds. The denaturing gradient gel electrophoresis profile showed differences between breeds and segments within one breed, though some bands were common to all samples. CONCLUSION: The higher skatole levels in Landrace pigs may be not associated with higher intestinal apoptosis. The results suggested that pig genotype plays a role in the establishment of the host‐specific microbiota and that the variations in fermentation patterns are more likely to explain differences in intestinal skatole production. Copyright © 2009 Society of Chemical Industry     

Determination of extractable and bound condensed tannin concentrations in forage plants,protein concentrate meals and cereal grains

A procedure was developed for extraction of ‘free’ condensed tannins (CT) using a mixture of acetone/water/diethyl ether (4.7:2.0:3.3), followed by extraction of protein-bound and fibre-bound CT using boiling sodium dodecyl sulphate containing 2-mercaptoethanol (SDS). CT concentrations in all three fractions were determined by a modified butanol-HCI procedure. Separate standard curves using purified CT in water or SDS solution were utilised for analysis of extractable CT (water standards) and protein-bound and fibre-bound CT (SDS standards). The method accurately predicted the concentration of CT added to forage extracts. CT extractable in acetone/water/diethyl ether comprised, on average. 68% of total CT in a range of freeze dried forage legume samples, with most of the remainder being bound to protein. When total CT concentration was low (0.6-3.0% DM), a lower proportion was extractable (33-35%). In protein concentrate meals containing CT, the extractable, protein-bound and fibre-bound components comprised 15, 60 and 25% respectively of total CT. Total CT concentration in the forages Lotus corniculatus and Coronilla varia was considered appropriate for ruminant nutrition (2.1 and 3.0% DM). whilst CT concentration in the forage of Dorycnium spp (13–19% DM) was more suitable for soil conservation purposes. The substantial CT concentration in cottonseed meal (1.6% DM) may be involved in the high resistance of proteins in this product to ruminal degradation. CT concentration was indistinguishable from zero in perennial ryegrass forage, in barley and triticale grains and in soya bean meal (0.1% DM).     

In vitro degradability of three forages: fermentation kinetics and gas production of NDF and neutral detergent‐soluble fraction of forages

The fermentation of the neutral detergent‐soluble (NDS) fraction of three forages (alfalfa hay, Italian ryegrass + oats hay and corn silage) was measured using a curve subtraction technique with in vitro gas production data from the whole forage (WF) and the isolated neutral detergent fibre (NDF). NDF disappearance and volatile fatty acid (VFA) production were determined. There was no significant difference between the VFA patterns from the whole forage and the isolated NDF. There were significant (P < 0.001) linear correlations between the volume of gas and moles of VFA produced and the mass of fibre digested in the NDF samples. Using the monophasic curve model, maximum gas production rates (R_M) for the whole forages and the isolated NDF and NDS fractions can be calculated. For all three forages we obtained R_M‐NDS > R_M‐WF > R_M‐NDF. Trends in the rates of gas and VFA production were similar in the whole forages. The NDF showed a high superimposition between substrate degradability and VFA production. Our experiment confirmed the curve subtraction technique as a simple method to obtain information on the size and digestion kinetics of the NDS fraction, which helps in understanding the nutritional significance of this important fraction of the forages studied. © 2001 Society of Chemical Industry     

Effect of breed type,housing and feeding system on performance of growing pigs managed under organic conditions

BACKGROUND: There is a need for information on the performance and carcass quality of pigs under different organic management systems. This study compared Duroc‐sired progeny from three maternal breed types when kept either at pasture or in housing with an outdoor run and offered ad libitum concentrate either alone or with fodder beet or grass/clover silage as additional forage. RESULTS: Liveweight gain, feed intake and the proportion of forages consumed did not differ between genotypes. Carcass fatness of progeny was lowest for a ‘modern’ genotype (Camborough 12) and highest for a ‘traditional’ purebred genotype (Saddleback), with a ‘crossbred traditional’ genotype (Saddleback × Duroc) being intermediate (11.4, 14.3 and 13.4 mm P₂ respectively, standard error of mean (SEM) 0.27, P < 0.001). With a cereal‐based concentrate available ad libitum, intake of forages was low (<2% of dry matter intake). Although growth rate did not differ between housing systems, daily feed intake was greater at pasture (2.47 vs 2.22 kg meal equivalent, SEM 0.05, P < 0.001), giving poorer feed efficiency (P < 0.01). Pastured animals consumed less additional forage and had a higher killing‐out % but similar carcass fatness. CONCLUSION: For organic pig production to be financially sustainable, disadvantages arising from the genotype and/or rearing system chosen need to be offset by a market premium for the pigs produced. Copyright © 2007 Society of Chemical Industry     

Effect of applying formic acid,heterolactic bacteria or homolactic and heterolactic bacteria on the fermentation of bi‐crops of peas and wheat

This work aimed to compare the effectiveness of bacterial inoculants or a chemical additive for preserving whole‐crop silages made from wheat, two pea varieties (cv Magnus or Setchey) or intercrops of wheat and both pea varieties. The forages were harvested when the wheat and peas were at the late milk and yellow wrinkled stages respectively, and conserved in five replicate mini silos without treatment (control) or after treatment with 2.5 g kg^?1 of formic acid (FA) or 1 × 10⁶ cfu g^?1 fresh forage of either of two bacterial inoculants (WholeCrop Gold (WCG) or WholeCrop Legume (WCL), Biotal Ltd, Cardiff, UK). WCG contained Lactobacillus buchneri, while WCL contained L buchneri, L plantarum and Pediococcus pentosaceus. Chemical composition, fermentation characteristics and in vitro digestibility were measured after 65 days of ensiling. Additive‐treated bi‐crops had lower (P < 0.05) concentrations of soluble N, ammonia N and lactic acid than the controls. Inoculant‐treated bi‐crops had higher (P < 0.001) acetic acid and lower (P < 0.001) residual water‐soluble carbohydrate (WSC) concentrations than FA‐treated bi‐crops. WCL‐treated bi‐crops had similar residual WSC concentrations to and higher (P < 0.05) starch concentrations than WCG‐treated bi‐crops. Unlike Magnus pea bi‐crops, Setchey pea bi‐crops treated with WCL had lower concentrations of ammonia N (P < 0.01) and acetic acid (P < 0.001) and higher concentrations of starch (P < 0.001) and lactic acid (P < 0.05) than those treated with WCG. For both bi‐crops, FA‐treated bi‐crops were more stable (P < 0.05) than inoculant‐treated or untreated silages, and the stability of inoculant‐treated and untreated silages was similar. Formic acid treatment was also the most effective at reducing WSC losses in the bi‐crop and pea silages. Inoculant treatment reduced proteolysis in these forages but did not prevent spoilage in the bi‐crops. Additive treatment reduced yeast counts but did not improve the fermentation in wheat silages. Copyright © 2004 Society of Chemical Industry     

Drying method and origin of standard affect condensed tannin (CT) concentrations in perennial herbaceous legumes using simplified butanol‐HCl CT analysis

BACKGROUND: Several factors affect condensed tannin (CT) levels in plants and accuracy of the butanol‐HCl assay for total CT. Six native, perennial, herbaceous legumes from Texas were harvested at three stages of growth over a growing season; young vegetation, initial flowering, and late season. The samples were subjected to oven‐drying and freeze‐drying and analyzed for extractable (ECT), protein‐bound (PBCT), and fiber‐bound (FBCT) CT using a butanol‐HCl procedure, comparing several types of purified CT as standards. RESULTS: There was a wide range of CT concentration in the legumes, but little change in ECT and total (TCT) tannin concentrations over the growing season. Oven‐drying decreased (P < 0.05) ECT and increased (P < 0.05) PBCT and FBCT concentrations compared with freeze‐drying, but both methods ranked the forages similarly throughout the growing season relative to TCT. Quebracho tannin as a standard increased CT values for the forages compared with purified legume CT standards, but all standards ranked the forages similarly relative to tannin concentration. Modifications to the procedure increased speed and ease of using the CT analysis method. CONCLUSION: Quantitative CT values have limited value except to allow a relative ranking of forages. Selection of appropriate standards is important in providing realistic CT values. Improvements in the total (extractable + bound) CT analysis method will allow wider use of this procedure. Although ECT and TCT values changed little in native legumes over a growing season, biological activity and potential nutritional/medicinal benefits of CT in these plants needs further evaluation. Copyright © 2008 Society of Chemical Industry     

Comparison of sheep and red deer rumen fluids for assessing nutritive value of ruminant feedstuffs

Four forages (alfalfa hay, barley straw, maize silage and beet pulp), four cereal grains (barley, maize, sorghum and wheat) and four shrubs (Calluna vulgaris, Erica australis, Cytisus cantabricus and Genista occidentalis) were incubated using rumen fluids from sheep and red deer, to examine differences in in vitro fermentation rates and ruminal parameters. For the forages and cereal grains, results suggest few differences between species in parameters related to gas production, rates of fermentation, organic matter disappearance and extent of degradation. Deer showed slightly better results for shrubs than sheep did. Disappearance of neutral detergent fibre was generally greater when the rumen fluid was derived from red deer (P < 0.05). On the other hand, ammonia‐N concentration and total volatile fatty acids (VFAs) were higher in sheep (P < 0.05). Molar proportions of the major VFAs showed significant differences (P < 0.05) associated with the species of the inoculum donor and suggest that fermentation pathways might have been more efficient in red deer. The estimated amount of methane was higher in sheep, regardless of the substrate incubated (P < 0.001). The results indicate that although the sheep could be valid as a model to assess the nutritive value of good quality feedstuffs for red deer, it would fail to offer reliable information on non‐conventional, low‐quality feeds such as shrubs. Copyright © 2005 Society of Chemical Industry     

Effects of feeding salt-tolerant forage cultivated in saline-alkaline land on rumen fermentation, feed digestibility and nitrogen balance in lamb

BACKGROUND: Mixing salt‐tolerant plants with other plants may affect rumen fermentation, which could result in an increase of feed conversion rate. The objective of this study was to evaluate the effects of partially or entirely replacing the corn stover with a mixture of salt‐tolerant forage (Dahurian wildrye grass, weeping alkaligrass and erect milkvetch) in the diet of lambs on ruminal fermentation, feed digestibility and nitrogen (N) balance. Ratios of corn stover to the mixture of salt‐tolerant forages in the four experimental diets were 100:0, 67:33, 33:67 and 0:100, respectively, for control, low (LF), medium (MF) and high (HF). RESULTS: Ruminal pH was lower (P = 0.048) with LF and MF than with control and HF diets. Total VFA concentration was consistently higher (P = 0.039) for LF and MF than for control and HF with increasing amount of salt‐tolerant forage. Ratio of acetate to propionate was linearly (P = 0.019) decreased due to the decrease in acetate production. Digestibilities of OM, NDF and CP in the whole tract linearly (P < 0.002) decreased with increasing amount of salt‐tolerant forage. Similarly, retained N and ratio of retained N to digestible N also linearly (P < 0.005) decreased. CONCLUSION: Feeding salt‐tolerant forage cultivated in saline‐alkaline land improved rumen fermentation with increased total VFA production, and changed the rumen fermentation pattern to increased butyrate production. However, the decreased feed digestibility in the whole digestive tract of lamb may reduce nutrient availability to animals and thus adversely affect animal productivity. Additionally, feeding salt‐tolerant forages may require more protein supplement to meet animal requirements, because of the low protein content and low protein digestibility of the salt‐tolerant forages. Copyright © 2011 Society of Chemical Industry     

The nitrogen content of potato (Solanum tuberosum L.) tubers in relation to nitrogen application—the effect on amino acid composition and yields

The effect of nitrogen application on the nitrogen content and yield of amino acids from potato tubers was studied in one experiment in 1983 and two in 1984. Increasing fertiliser N over the range 0–250 kg ha^?1 raised tuber nitrogen concentrations from 0.68–0.81 to 1.27–1.49% DM. Applying half the fertiliser on the seedbed and half at tuber initiation did not increase tuber nitrogen concentrations compared with a single broadcast application at planting. Increasing tuber nitrogen concentrations had little effect upon the proportion recovered in amides or the different amino acids. Yields of some nutritionally essential amino acids were, therefore, substantially increased up to a maximum of 256 kg ha^?1 in 1982 and 308 and 384 kg ha^?1 in 1984 at the highest fertiliser level. These yields were significantly higher (P<0.01) than those found with the nitrogen application rate optimal for tuber dry matter production (213, 195 and 331 kg N ha^?1, respectively) in the same experiments. Methionine and cystine were the limiting essential amino acids. As the amount of each amino acid contained in a unit weight of fresh tuber increased with nitrogen supply, application of more nitrogen than is needed for maximal tuber dry matter production increased protein yields without decreasing the nutritional quality.     

Yield,nitrate levels and sensory properties of spinach as influenced by organic and mineral nitrogen fertiliser levels

Spinach was fertilised at two levels of nitrogen, 140 kg/ha (x) and 420 kg/ha (3x), using split applications of ammonium sulphate and dried blood as nitrogen sources. A single application of ammonium sulphate (x) 19 days prior to harvest was also tested. A no-nitrogen control was also employed. The x rate of mineral nitrogen produced statistically the same yield as the 3x organic source but at a lower tissue nitrate level. The 3x mineral fertiliser produced both the highest yield and nitrate concentration. Excluding late fertiliser application, nitrate levels were closely related to yield and dependent upon rate of nitrogen availability from each of the two sources. Late application of mineral nitrogen did not increase yield over a no-nitrogen application control, but resulted in an eight-fold increase in tissue nitrate. Triangle taste panels demonstrated significant differences in raw, cooked, and frozen samples when comparing the no-nitrogen application against both the 3x organic and mineral nitrogen applications and the late mineral application. No significant sensory differences resulted between organic and mineral fertilisers at either application level. Colour measurements revealed that higher nitrogen application darkened colour. Organic sources gave darker colours than corresponding mineral fertiliser levels. Late application of mineral nitrogen resulted in the darkest colour. Gas–liquid chromatography headspace scans demonstrated that increasing nitrogen rates from x to 3x approximately doubled total peak area. No qualitative differences were noted. Late application of mineral fertiliser resulted in a headspace scan similar to those obtained at the 3x nitrogen rates.     

Organic matter digestibility of poplar (Populus) and willow (Salix) forage trees and its in vitro prediction

Cuttings from poplar (Populus) and willow (Salix) trees are used increasingly as supplementary feed for livestock in summer‐dry and drought‐prone regions of New Zealand. The present experiment aimed to measure in vivo organic matter digestibility and digestibility of organic matter in the dry matter in tree fodder and investigated whether the in vitro system of Roughan and Holland can be used to predict in vivo organic matter digestibility and digestibility of organic matter in the dry matter in poplar and willow tree fodder, which contains high concentrations of secondary compounds, including condensed tannin. In vivo work showed that the digestibility of tree fodder declined from late spring to autumn (p < 0.05) and that this decline was much smaller than the decline in digestibility of grass‐based pastures in New Zealand over the same time period. Mean metabolizable energy concentrations and digestibilities were generally higher for willow than for poplar. The in vitro enzymatic system of Roughan and Holland can be used to predict in vivo digestibility of tree fodder. A standard curve using in vivo values determined with animals fed tree fodder would be preferable, owing to the very different chemical compositions of pasture and tree fodder, particularly the greater concentration of secondary compounds in willow and poplar. However, the accuracy and the range of prediction need to be improved. Willow and poplar had similar ME concentrations to high‐quality lucerne hay; willow cuttings also had similar ME and CT concentration to vegetative Lotus corniculatus, a high‐quality forage legume. Copyright © 2005 Society of Chemical Industry     

Factors affecting ANKOM™ fiber analysis of forage and browse varying in condensed tannin concentration

BACKGROUND: Browse species containing condensed tannins (CTs) are an important source of nutrition for grazing/browsing livestock and wildlife in many parts of the world, but information on fiber concentration and CT–fiber interactions for these plants is lacking. RESULTS: Ten forage or browse species with a range of CT concentrations were oven dried and freeze dried and then analyzed for ash‐corrected neutral detergent fiber (NDFom) and corrected acid detergent fiber (ADFom) using separate samples (ADFSEP) and sequential NDF‐ADF analysis (ADFSEQ) with the ANKOM^? fiber analysis system. The ADFSEP and ADFSEQ residues were then analyzed for nitrogen (N) concentration. Oven drying increased (P < 0.05) fiber concentrations with some species, but not with others. For high‐CT forage and browse species, ADFSEP concentrations were greater (P < 0.05) than NDFom values and approximately double the ADFSEQ values. Nitrogen concentration was greater (P < 0.05) in ADFSEP than ADFSEQ residues, likely due to precipitation with CTs. CONCLUSION: Sequential NDF‐ADF analysis gave more realistic values and appeared to remove most of the fiber residue contaminants in CT forage samples. Freeze drying samples with sequential NDF‐ADF analysis is recommended in the ANKOM^? fiber analysis system with CT‐containing forage and browse species. Copyright © 2010 Society of Chemical Industry     

Effect of condensed tannins prepared from several forages on the in vitro precipitation of ribulose-1,5-bisphosphate carboxylase (Rubisco) protein and its digestion by trypsin (EC 2.4.21.4) and chymotrypsin (EC 2.4.21.1)

A series of in vitro experiments was undertaken to determine the extent to which Sephadex LH-20 treated extracts from a range of temperate forages precipitated ribulose-1,5-bisphosphate carboxylase (Rubisco) and affected the enzymatic hydrolysis of Rubisco protein by trypsin and chymotrypsin at a range of pH values. Rubisco was chosen because it represents the principal dietary protein for ruminants fed fresh forages. Condensed tannins (CT) or proanthocyanidins (PA) are routinely purified by chromatography using Sephadex LH-20 as a matrix. However, these extracts contained non-CT phenolics together with PA so the term ‘CT extract’ was preferred to ‘PA’ to describe the extracts. The in vitro precipitation of Rubisco provided a means to compare the reactivity of the CT extracts. The amount of CT extract required to precipitate all the Rubisco in 10 μg of total soluble leaf protein from white clover (Trifolium repens) when this protein was incubated with CT extracts of Lotus corniculatus, L pedunculatus and sainfoin (Onobrychis viciifolia) was similar, with between 25 and 50 μg of extract required. The CT extract of sulla (Hedysarum coronarium) also precipitated all the Rubisco, however this only occurred with 50 μg of the extract. The CT extract of dock (Rumex obtusifolius) precipitated all the Rubisco when 5 μg of extract or greater was incubated with total soluble leaf protein. However, the differences between the reactivity of all these CT extracts at a range of pH values appeared to be small. Condensed tannin extracts of L corniculatus and L pedunculatus partially inhibited the hydrolysis of Rubisco by trypsin and chymotrypsin to a similar extent, but the extent of the inhibition was affected by pH. The inhibition was greater at pH 6·0 than 7·0, whilst at pH 8·0, CT extracts had little or no affect on trypsin and chymotrypsin. It was concluded that, although the precipitation of Rubisco provided an ideal method for comparing CT extracts, reactivity alone was unlikely to account for the differences in nutritive value that occur with forages containing CT. © 1998 SCI.     

In vitro fermentation kinetics of carbohydrate fractions of fresh forage,silage and hay of Avena sativa

The objective of this experiment was to evaluate the influence of preservation methods on the fermentation kinetics of carbohydrate fractions of fresh forage, hay and silage of oats, which have been harvested at the milky stage of grain ripening. Samples of unfractionated forage (WF), residue insoluble in 90% ethanol (EIR) and isolated neutral detergent fibre (NDF) were fermented in vitro and the gas production was monitored. To obtain the gas production and fermentation kinetics of the ethanol‐soluble fraction (A fraction) the gas produced from the EIR fermentation was subtracted from the WF gas at each time point. The same approach was used to obtain the gas production and fermentation kinetics of the fraction insoluble in 90% ethanol but soluble in neutral detergent solution (B₁ fraction), by subtracting the isolated NDF gas curve from the corresponding EIR curve. The fractional maximum rate of gas production (R_M) was lower for both preserved forages (p < 0.01 for silage; p < 0.05 for hay) than for fresh forage. Ensiling did not change the size of the A fraction but reduced by 40% its R_M (p < 0.01) compared with fresh forage. The potential gas production from the B₁ fraction and its R_M were reduced by 19% (p < 0.01) and 44% (p < 0.05), respectively. R_M of both A and B₁ fractions was the same for hay and fresh forage. The curve subtraction technique may be used to obtain an estimation of the rate for neutral detergent‐soluble fractions and to determine changes due to ensiling and haymaking on the rate of gas produced. Copyright © 2005 Society of Chemical Industry     

Simple phenols and indoles in anaerobically stored piggery wastes

Phenol, p-cresol, 4-ethylphenol, indole and skatole, which contribute to a large extent to the bad smell of piggeries, were estimated in anaerobically stored piggery wastes. p-Cresol, indole and skatole were also found in freshly voided faeces. Phenol, p-cresol and 4-ethylphenol are present in the urine as their glucuronides. It was shown that upon contact of urine and faeces, the urinary glucuronides are hydrolysed almost instantly liberating phenols. This hydrolysis is caused by the high β-glucuronidase activity of faeces. Protein degradation followed by transformation of tyrosine and tryptophane were found to be additional processes contributing to the accumulation of phenol, p-cresol, indole and skatole during the anaerobic storage of piggery wastes.     

Effect of lucerne preservation method on the feed value of forage

BACKGROUND: Natural climatic wilt (NCW) and induced industrial wilt (IIW) are widely used as preservation methods for lucerne. Both of these methods reduce the quality of green forage due to respiration under NCW and heat damage under IIW. We compared the influence of these two preservation methods on nutritive value across a wide range of harvest conditions. RESULTS: Cell wall content and cell wall‐linked nitrogen values were higher (P < 0.05) in IIW than NCW. The preservation methods differed significantly (P < 0.05) in terms of soluble fraction, insoluble potentially degradable fraction of dry matter and effective degradability of dry matter. Nitrogen disappearance kinetics showed that the interactions of preservation by cut and preservation by phenological state were significant for the effective degradability of nitrogen. Organic matter digestibility was higher in lucerne preserved by NCW than IIW whereas cell wall digestibility was higher in lucerne preserved by IIW than NCW. Digestible organic matter intake did not differ between preservation methods (P > 0.05). CONCLUSION: Natural climatic wilt forage hay presents similar feed value to the induced industrial wilt alfalfa. Copyright © 2009 Society of Chemical Industry     

Skatole and indole concentrations in Longissimus dorsi and fat samples of pigs

A HPLC-NP (normal phase-high performance liquid chromatography) method for determining the concentration of skatole and indole in Longissimus dorsi samples is described. Lipids containing skatole and indole were extracted in chloroform:methanol (2:1) at room temperature and dehydrated by liquid-liquid extraction with an aqueous solution saturated with 10% of sodium chloride. The organic phase was evaporated to dryness and redissolved in 10 ml of hexane:2-propanol (92:8). Indolic compounds were separated on a Hypersil aminopropylsilica column (5 μm) (250×4.6 mm i.d.). The mobile phase was hexane:2-propanol (92:8) and detection was by fluorescence (excitation at 280 nm and emission at 360 nm). Linearity was found in the range of 0.05-0.4 μg/g and the coefficient of correlation was above 0.99 for both compounds. The within day (n=5) variation was at 0.05, 0.2 and 0.4 μg/g and the CV (coefficient of variation) values for relative areas determined at these concentrations were less than 13%. This method was used to compare the concentrations of skatole and indole in different samples: L. dorsi muscle, the fat covering the L. dorsi and subcutaneous fat. A correlation was observed between the concentration of indole and skatole in the back fat and fat covering the L. dorsi samples (P<0.001, r=0.99). No significant correlation was obtained in L. dorsi samples, between skatole and indole levels. In spite of the correlation shown between skatole and indole concentrations in the back fat and L. dorsi samples, the mean concentrations of these compounds were significantly higher (P<0.05) in the back fat samples.