https://assets.publishing.service.gov.uk/media/57a08dc3ed915d622c001b6f/R4338b.pdf

A simple gas production method using a pressure transducer to determine the fermentation kinetics of ruminant feeds.

In situ and Other Methods to Estimate Ruminal Protein and Energy Digestibility: A Review

1. Chemical, Protein Precipitation and Bioassays for Tannins, Tannin Levels and Activity in Unconventional Feeds, and Efects and Fate of Tannins.- 2. Treatment of Plant Material, Extraction of Tannins, and an Overview of Tannin Assays Presented in the Manual.- 3. Measurement of Total Phenolics and Tannins Using Folin-Ciocalteu Method.- 4. Determination of Condensed Tannins (Proanthocyanidins).- 5. Gallotannin Determination by Rhodanine Assay.- 6. Gallotannin Determination Using HPLC.- 7. Determination of Hydrolysable Tannins (Gallotannins and Ellagitannins) after Reaction with Potassium Iodate.- 8. Determination of Protein-Precipitable Phenolics.- 9. Protein-Binding Capacity by Filter Paper Assay.- 10. Radial Diffusion Assay.- 11. Tannin Bioassay.- 12. Radiolabelled BSA Precipitation Method.- 13. Simplified Radiolabelled BSA Precipitation Method.- 14. Characterization of Phenolic Compounds by Thin Layer Chromatography (TLC).- 15. References.- 16. A Summary of Results from the First Phase of the Coordinated Research Project.- 17. List of Participants in the Co-Ordinated Research Project.

Quantification of Tannins in Tree and Shrub Foliage: A Laboratory Manual

Various tannin-complexing agents have been used to study the potential adverse effects of tannins on rumen metabolism. Using a method based on turbidity formation, the binding of various tannin-complexing agents (polyvinyl polypyrrolidone (PVPP), polyethylene glycol (PEG) of molecular weights 2000 to 35,000, and polyvinyl pyrrolidone (PVP) of molecular weight 10,000, 40,000 and 360,000) to tannins (tannic acid, purified tannins from quebracho (Aspidosperma quebracho) and leaves of trees and shrubs (Acioa barteri, Dichostachys cinerea, Guiera senegalensis, Piliostigma reticulatum)) was investigated at different pH values. The binding of all the tannins with PVPP was highest at pH 3-4 and lowest at pH 7. For all the pH range (3-7) studied, the binding of PEG was higher than that of PVP. For all the tannins except tannic acid, the binding to PVP was the same from pH 4.7 to 7. Similar results were observed for the PEG of molecular weight 6000 or higher for all the tannins except quebracho tannins for which the binding increased as the pH increased from 3 to 7. The binding with PEG 2000 decreased to a greater extent as the pH reached near neutral and for PEG 4000 this decrease was slightly lower. Addition of these tannin-complexing agents to the in vitro gas system resulted in higher gas production from tannin-rich feeds (increase varied from 0 to 135%). The PEG were the most effective followed by PVP and PVPP. The PEG 35,000 was least effective. The efficiency of other PEG was similar. The PEG 6000 was preferred to PEG 2000 or 4000 as its binding to tannins was higher at near neutral pH values. The gas production increased with an increase in the amount of PEG 6000 up to 0.6 g/40 ml rumen-fluid-containing medium containing 0.5 g tannin-rich feed, beyond which no increase was observed. The percentage increase in gas value at 24 h fermentation correlated significantly with tannin values, the highest correlation (r 0.95) being with protein precipitation capacity of tannins. The increase in gas production was associated with higher production of short-chain fatty acids with little change in their molar proportions, suggesting an increase in organic matter digestibility by inclusion of the PEG in tannin-rich feeds. However, apparent and true digestibilities were lower on addition of the PEG, due to the presence of PEG-tannin complexes in the residues. The use of this bioassay (percentage increase in gas production in the presence of PEG 6000) along with other tannin assays would provide a better insight into the nutritional significance of tannins.

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Formation of complexes between polyvinyl pyrrolidones or polyethylene glycols and tannins, and their implication in gas production and true digestibility in in vitro techniques

Comparison of in vitro gas production and nylon bag degradability of roughages in predicting feed intake in cattle

A rapid method for measuring gas production during incubation of feedingstuffs with rumen liquor in vitro is described. Gas production in 24 h from 200 mg feed dry matter was well correlated with digestibility of organic matter, determined in vivo with sheep. Multiple regression analysis, when it included data from proximate analysis, resulted in an equation ( R = 0·98) for prediction of metabolizable energy content, based on 30 experiments with rations varying in protein and crude fibre content, and 59 other experiments with concentrates. Energy content was in the range of 7·7–13·2 MJ ME/kg D.M. ( ± S.D. = 11·17 ± 1·08). The residual standard deviation of the equation was 0·25 MJ. Gas production was measured in calibrated syringes. The only chemical determinations needed are dry matter, protein and fat. Differences in activity between batches of rumen liquor are corrected by reference to gas production with standard feedingstuffs (hay meal and maize starch).

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A161917A7FD929D25DD3D9E6F21CFAF4/S0021859600086305a.pdf/div-class-title-the-estimation-of-the-digestibility-and-metabolizable-energy-content-of-ruminant-feedingstuffs-from-the-gas-production-when-they-are-incubated-with-rumen-liquor-span-class-italic-in-vitro-span-div.pdf

The estimation of the digestibility and metabolizable energy content of ruminant feedingstuffs from the gas production when they are incubated with rumen liquor in vitro

Forty respiration experiments with lactating cows were evaluated by multiple regression analysis. Protein content of the diet had a significant negative effect on the efficiency of utilization of metabolizable energy (ME), but metabolizability (q) had no significant effect in these experiments with diets of rather high metabolizability. Inclusion of results from other laboratories lead to square functions of q or M (MJ ME/kg) which showed maxima in the range of q = 0.6–0.7 and M = 11–12. The best fit was achieved with the function:

K. H. Menke

Papers

The estimation of the digestibility and metabolizable energy content of ruminant feedingstuffs from the gas production when they are incubated with rumen liquor in vitro

Effect of protein content and metabolizability of the diet on the efficiency of utilization of metabolizable energy in dairy cows