Biological treatment of cereal straw for ruminant nutrition purposes might present an environmentally friendly option of valorizing a widely available by-product of grain production for farming ...systems with low external input. Several strains of white-rot fungi have been selected in the past under mostly controlled laboratory conditions for their capacity of lignin degradation. The study adapted to conditions on farm for upscaling purposes. The development of the in vitro straw digestibility with two different moistening pre-treatments and inoculated with three different fungi species, namely Pleurotus ostreatus, Ceriporiopsis subvermispora and Volvariella volvacea, was determined up to 42 days of fermentation with five sampling times. The effect of physical straw pre-treatments on nutritional parameters was evaluated. The neutral detergent fiber digestibility (NDFD
), enzymatically soluble organic substance (ELOS) and the gas production (Hohenheim Feed value Test, HFT) as indicators for in vitro ruminal degradability decreased over time independent of the fungus: HFT, ELOS and NDFD
by up to 50, 35 and 30% of the original straw. Remoistening and autoclaving the straw increased the gas production significantly by 2.6 mL/200 g dry matter (DM), and ELOS and NDFD
by 45 and 51 g/kg DM compared to the original straw (34.9 mL/200 mg DM, 342 g/kg DM, 313 g/kg NDF).
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The development of strategies to overcome the shortage of forage due to persistently low rainfall is becoming a central task for animal nutrition in research and practice. In this study, it was ...investigated how the treatment of straw with NaOH or feed urea in a practicable procedure for modern farms affects rumen fermentation (gas production and greenhouse gas concentration) as well as the digestibility of feed energy and nutrients. For this purpose, the treatments were tested individually and in different proportions in a total mixed ration (TMR) in ruminal batch cultures in vitro and in a digestibility trial with sheep. In order to explain the observed effects at the molecular level, descriptive data from
C solid state nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy were obtained. NaOH treatment of straw increased crude ash (CA), non-fibrous carbohydrates, digestible energy (DE), and metabolizable energy (ME) concentration, whereas the proportion of neutral detergent fibre (aNDFom) and hemicellulose decreased. In urea treated straw, NH
-N and crude protein increased, whereas acid detergent lignin (ADL), DE, and ME decreased. The physically effective fibre (peNDF
) concentration increased in TMR containing 18% of NaOH or urea treated straw (p < 0.01). The application of straw treatments as pure substrates (not as part of a TMR) increased gas production and decelerated ruminal fermentation (p < 0.05). In vitro organic matter digestibility (IVOMD) of the straw (0.31) increased after NaOH (0.51; p < 0.05) and urea treatment (0.41; p > 0.05). As part of a TMR, straw treatments had no distinct effect on gas production or IVOMD. Concentrations of CH
and CO
were likewise not affected. Apparent total tract digestibility of aNDFom, acid detergent fibre (ADFom), hemicellulose, and cellulose increased in the TMR by approximately 10% points following NaOH treatment (p < 0.05). The inclusion of urea treated straw did not affect apparent digestibility. Calculated true digestibility of aNDFom was 0.68, 0.74, and 0.79, of ADFom 0.58, 0.57, and 0.65, and of ADL 0.02, 0.13, and 0.08 in TMR including untreated, NaOH treated, and urea treated straw, respectively.
C NMR and FTIR analyses consistently revealed that the global structure and crystallinity of the carbohydrates (cellulose and hemicellulose) was not altered by treatment and the concentration of lignin was likewise not affected. Depolymerisation of lignin did not occur. However, NMR signals assigned to acetyl groups were significantly altered indicating that straw treatments disrupted linkages between hemicelluloses and lignin. Moreover, the acetates signal was affected. This signal can be assigned to linkages between ferulic acids and hemicelluloses (arabinoxylans). FTIR spectra of straw treatments mainly differed at a wavelength of 1730 cm
and 1240 cm
. Disappearance of the 1730 cm
peak suggests removal of hemicelluloses or lignin related compounds by treatment. The disappearance of the lignin peak at 1240 cm
could be due to conjugated ketone (phenyl-carbonyl) removal or the removal of ferulic and p-coumaric acid acetyl groups. Both treatments are supposed to release fermentable cell wall components (hemicelluloses) from lignin-associated bonds and as a result, straw fibre can be better fermented in the rumen. This contributes to energy supply and increased fibre digestibility at least in the TMR that contained NaOH treated straw. The alkaline straw treatments probably induced a release of phenolics such as ferulic acid and p-coumaric acid, which can be metabolised in the gut and the liver and metabolites might be excreted with the urine. This could notably contribute to metabolic energy losses.
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Hypoglycin A (HGA) originating from soapberry fruits (litchi, and ackee) seeds or seedlings from the sycamore maple (SM) tree (related to Sapindaceae) may cause Jamaican vomiting sickness in humans ...and atypical myopathy in horses and ruminants. A possible transfer into dairy cow’s milk cannot be ruled out since the literature has revealed HGA in the milk of mares and in the offal of captured deer following HGA intoxication. From a study, carried out for another purpose, bulk raw milk samples from four randomly selected dairy farms were available. The cows were pastured in the daytime. A sycamore maple tree was found on the pasture of farm No. 1 only. Bulk milk from the individual tank or milk filling station was sampled in parallels and analyzed for HGA by LC-ESI-MS/MS. Measurable concentrations of HGA occurred only in milk from farm No. 1 and amounted to 120 and 489 nmol/L. Despite low and very variable HGA concentrations, the results indicate that the ingested toxin, once eaten, is transferred into the milk. However, it is unknown how much HGA the individual cow ingested during grazing and what amount was transferred into the bulk milk samples. As a prerequisite for a possible future safety assessment, carry-over studies are needed. Furthermore, the toxins’ stability during milk processing should also be investigated as well.
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Atypical myopathy (AM) in horses is caused by ingestion of seeds of the Acer species (Sapindaceae family). Methylenecyclopropylacetyl-CoA (MCPA-CoA), derived from hypoglycin A (HGA), is currently the ...only active toxin in Acer pseudoplatanus or Acer negundo seeds related to AM outbreaks. However, seeds or arils of various Sapindaceae (e.g., ackee, lychee, mamoncillo, longan fruit) also contain methylenecyclopropylglycine (MCPG), which is a structural analogue of HGA that can cause hypoglycaemic encephalopathy in humans. The active poison formed from MCPG is methylenecyclopropylformyl-CoA (MCPF-CoA). MCPF-CoA and MCPA-CoA strongly inhibit enzymes that participate in β-oxidation and energy production from fat. The aim of our study was to investigate if MCPG is involved in Acer seed poisoning in horses. MCPG, as well as glycine and carnitine conjugates (MCPF-glycine, MCPF-carnitine), were quantified using high-performance liquid chromatography-tandem mass spectrometry of serum and urine from horses that had ingested Acer pseudoplatanus seeds and developed typical AM symptoms. The results were compared to those of healthy control horses. For comparison, HGA and its glycine and carnitine derivatives were also measured. Additionally, to assess the degree of enzyme inhibition of β-oxidation, several acyl glycines and acyl carnitines were included in the analysis. In addition to HGA and the specific toxic metabolites (MCPA-carnitine and MCPA-glycine), MCPG, MCPF-glycine and MCPF-carnitine were detected in the serum and urine of affected horses. Strong inhibition of β-oxidation was demonstrated by elevated concentrations of all acyl glycines and carnitines, but the highest correlations were observed between MCPF-carnitine and isobutyryl-carnitine (r = 0.93) as well as between MCPA- (and MCPF-) glycine and valeryl-glycine with r = 0.96 (and r = 0.87). As shown here, for biochemical analysis of atypical myopathy of horses, it is necessary to take MCPG and the corresponding metabolites into consideration.
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For protein evaluation of feedstuffs for ruminants, the Streptomyces griseus protease test provides a solely enzymatic method for estimating ruminal protein degradation. Since plant proteins are ...often structured in carbohydrate complexes, the use of carbohydrase during the test might improve its accuracy. It is advisable to co-incubate protease and carbohydrase, risking that the carbohydrase activity is reduced under the influence of the protease. The present study was conducted to investigate this impact by using α-amylase or the multi-enzyme complex Viscozym® L as carbohydrase. The detection of active protease was determined fluorescence photometrically using internally quenched fluorogenic substrates (IQFS). Cellulose, pectin, and starch degradation were determined spectrophotometrically using 3,5-dinitro salicylic acid as a colorimetric agent. The Streptomyces griseus protease mixture proved to be active for the selected IQFS immediately after the start of measurements (p < 0.05). Starch hydrolysis catalyzed by α-amylase or Viscozym® L, respectively, was decreased by co-incubation with protease mixture by maximal 3% or 37%, respectively, at 5 h incubation time (p > 0.05). Pectin and cellulose hydrolysis catalyzed by Viscozym® L, respectively, was not significantly influenced by co-incubation with a protease mixture (p > 0.05). Although a decrease in carbohydrase activity during co-incubation with Streptomyces griseus protease occurred, it was only numerical and might be counteracted by an adapted carbohydrase activity.
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Background
Hypoglycin A (HGA) and methylenecyclopropylglycine (MCPrG) from seeds/seedlings of Sycamore maple (SM, Acer pseudoplatanus) causes atypical myopathy (AM) in horses. AM was not known to ...occur in wild ruminants until several fatalities in milus (Elaphurus davidianus) following the ingestion of HGA in SM seeds. However, a role for MCPrG has not previously been evaluated.
Objectives
To test the hypothesis that MCPrG is also a major factor in AM in milus, three milus (M1, M2, M3) from the Zoo Dresden (aged 7–11 years, 2 females and 1 male, in good nutritional condition) that developed AM were studied.
Methods
Serum, urine and methanol extracts from the liver, kidney, rumen digesta and faeces were analysed by ultrahigh‐performance liquid chromatography‐tandem mass spectrometry for HGA, MCPrG and for conjugates of carnitine (C) and glycine (G): Methylenecyclopropylacetyl (MCPA)‐G, MCPA‐C, Methylenecyclopropylformyl (MCPF)‐G, MCPF‐C, butyryl‐C and isobutyryl‐C.
Results
HGA in serum was high (M2 480 nmol/L; M3 460 nmol/L), but MCPrG was not. HGA and MCPrG were found in rumen and faeces extracts, and MCPrG was also identified in the liver. Metabolites of HGA and MCPrG were high in serum, urine and liver, but not in the rumen or faeces.
Conclusions
This study shows that MCPrG is involved in the pathophysiology of AM in milus. The metabolism of MCPrG is considered to be faster because, after ingestion, the specific metabolites appear highly concentrated in the serum. The high toxin concentration in the liver suggests that a possible transfer into products for human consumption may pose a risk.
In humans and equines, the intoxication with Methylenecyclopropylglycine (MCPrG) and Hypoglycin A (HGA) from Sapindaceae fruits or seeds is well‐known with a high fatality rate, whereas in horses the common ingestion of both toxins was firstly described in 2019. This study shows for the first time, that also in ruminants both toxins present a major hazard. A possible transfer to the food chain following the consumption of products from affected ruminants by humans should be taken into consideration.
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Weather extremes in parts of Europe have led to a renewed search for alternative feeds for ruminants. Cereal straw presents one source of fibre, which is hard to digest due to its lignin-carbohydrate ...complexes. Chemical and biological treatments have been investigated to improve digestibility. Here, the applicability of alkaline treatments for farming conditions under EU legislation and their efficacy were checked. Thus, we tested caustic soda (60, 120 g kg-1straw) and urea (15, 30, 45, 60 g kg-1 straw without and with urease addition) applications both at laboratory scale and using a mixer-wagon. The nutritive value was evaluated analyzing chemical parameters including fibre components and estimating in vitro digestibility. The in vitro digestibility indicated by gas production, enzymatically soluble substrate and neutral detergent fibre digestibility (30h) was highest for the NaOH treatments, which did not differ by dose. Remoistening the straw to 600 g DM kg-1 was a precondition for the effectiveness of both treatments. Urease addition enhanced the intended ammonification when urea was applied at ≥ 30 g kg-1. An ambient temperature for urea treatment ≥ 25 °C was necessary and had to be maintained for at least 14 d post treatment. The determination of crude ash in NaOH treated feeds by the standard procedure and time overestimated the mineral fraction and had to be modified. This systematic approach provides guidance for feasible straw treatments for EU farmers. However, trials for feed acceptance and in vivo digestibility are needed to demonstrate the real effect in animals.
Dietary fibers may have positive impact on health and wellbeing of pigs. The study examined physicochemical properties of two lignocelluloses (including and excluding bark), powdered cellulose,
...mycelium, lucerne chaff, soybean shells, wheat bran, and sugar beet pulp in relation to fermentability and digestibility using in vitro batch-culture incubation. Maize starch and a purified cellulose were used as standardized substrates for classification of the test substrates. The substrates covered a wide range regarding their physicochemical properties. Swelling capacity (SC) was 9-411%, water binding capacity (WBC) was 4.4-14.3 g/g dry matter (DM), and water holding capacity (WHC) was 4.1-10.6 g/g DM. Gas production and other fermentation parameters-namely post-incubation pH, CH
, NH
, and short chain fatty acids (SCFA) concentrations-revealed a significant fermentation of sugar beet pulp, soybean shells, lucerne chaff, wheat bran,
mycelium, and powdered cellulose, whereas the lignocelluloses were not fermented. Significant correlations were found between the physicochemical properties and the fermentation parameters (
< 0.05). Enzymatic pre-digestion mostly reduced gas, NH
, and SCFA production. In vitro digestibility of DM (IVDMD) and organic matter (IVOMD) was mostly negligible after enzymatic pre-digestion. Fermentation alone led to only 0.10-0.15 IVDMD and 0.14-0.15 IVOMD in lignocelluloses and powdered cellulose, respectively, but 0.44-0.37 IVDMD and 0.46-0.38 IVOMD in the remainder of substrates (
< 0.05). In vitro digestibility was again correlated with the physicochemical properties of the substrates and the fermentation parameters (
< 0.05). The fiber preparations and fiber-rich byproducts were fermented to a relevant extent. In contrast, lignocelluloses were not fermented and can be used rather as bulk material.
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The provision of NaCl, according to current recommendations, to horses in moderate work has been shown to induce immediate postprandial acidosis. The present study aimed to clarify whether this NaCl ...induced acidosis i) persists beyond the immediate postprandial period, and ii) is still present after a 2 week adaptation period. Six adult warmblood mares in moderate work received daily 1.00 kg hay per 100 kg body weight (bwt) only together with 0.64 kg unprocessed cereal grains/100 kg bwt.d as fed basis. Using a 3x3 Latin Square, either 0 (NaCl-0), 50 (NaCl-50) or 100 (NaCl-100) g NaCl/d were fed together with the concentrates in two equal doses for 3 weeks. During the final week, a mineral digestibility trial was undertaken. The middle sodium and chloride intake (NaCl-50) at least met the most common recommendations for moderate work. Morning (7:00 AM) urine and venous blood samples were collected on days 0, 1-4, 8, and 15, and analysed for pH, acid-base status, creatinine and electrolyte concentrations. Fractional electrolyte clearances (FC) were determined. Mean apparent sodium digestibility ranged between 60-62% whereas chloride digestibility was consistently above 94%. Supplementing 100 g but not 50 g of NaCl resulted in significant reduction of blood pH and base excess as well as urinary pH and urine acid excretion. Both 50 g and 100 g NaCl supplementation caused a significant reduction in base and net acid-base excretion, urine density and potassium concentration, but increased urine sodium concentration and the FC of sodium and chloride (P < 0.05). This suggests that a high proportion of the recommended salt doses is excreted renally. The above effects of NaCl supplementation persisted over the 2 week measurement period. Results suggest that feeding 100 g NaCl to moderately exercising horses results in mild metabolic acidosis, whereas feeding 50 g according to current recommendations resulted in compensated acidosis.
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Horses suffering from equine asthma must consume low-dust forage, with soaking and steaming being suitable methods of hay treatment. The impacts of this treated hay’s subsequent storage and effects ...on the horses’ chewing activity are largely unknown. Meadow hay was soaked (10–15 °C, 15 min) or steamed (100 °C, 60 min). Microbial counts (colony forming units (CFU)) were determined by culture before and after soaking or steaming, and subsequent storage at 10 and 25 °C for 6, 12 and 24 h (three replicates each). Six horses were fed native, soaked and steamed hay, according to a cross-over design, and chewing parameters were measured. Steaming reduced (p < 0.05) typical mold vs. soaking (0 vs. 50 CFU/g) and yeasts vs. native and steamed hay (0 vs. 102 and 90 CFU/g). Storing soaked hay elevated bacteria, mold, and yeasts (p < 0.05). Within the first 60 min of hay intake, the steamed hay and soaked hay were eaten slower (19.5 and 21.5 g dry matter/min, respectively; p < 0.05) and the steamed hay was chewed more intensely (steamed hay: 3537; native: 2622; and soaked: 2521 chewing cycles/kg dry matter, p < 0.05). Steaming particularly improves the hygienic quality of hay. Soaked hay is not stable when stored and is less accepted by horses.
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