G. Getachew

Bio: G. Getachew is an academic researcher from University of California, Davis. The author has contributed to research in topics: Rumen & Forage. The author has an hindex of 23, co-authored 31 publications receiving 2390 citations. Previous affiliations of G. Getachew include University of Hohenheim.

Tropical browses: contents of phenolic compounds, in vitro gas production and stoichiometric relationship between short chain fatty acid and in vitro gas production

Abstract: The contents of phenolic compounds, protein precipitation capacity (PPC) and in vitro gas production of tropical browse species were evaluated The stoichiometric relationship between in vitro gas measured on incubation of tannin-containing browses in buffered rumen fluid and calculated from short chain fatty acid (SCFA) production was investigated Crude protein (CP) contents in the browses ranged from 54 to 300 g/kg dry matter (DM) Total phenol (TP), tannins (T) and condensed tannins (TP and T as tannic acid equivalent; CT, as leucocyanidin equivalent) ranged from 17-250, 7-214, and 0-260 g/kg DM respectively, and PPC from 0 to 1066 μg BSA precipitated/g DM CP content of browses was negatively correlated with TP T, CT and PPC A significant correlation was observed between per cent change in gas production on addition of polyethylene glycol (PEG) and the contents of phenolics (r = 076 for both TP and T) Addition of PEG to tannin-containing browses increased in vitro gas production PPC was significantly correlated with TP (r = 087; P 005) The relationship between in vitro gas measured on incubation of browse leaves and that calculated from SCFA allows prediction of SCFA from gas production

Effect of polyethylene glycol on in vitro degradability of nitrogen and microbial protein synthesis from tannin-rich browse and herbaceous legumes.

Abstract: Determination of microbial degradability of N is important in formulating a sound supplementation strategy for efficient utilisation of basal as well as supplementary diet components. In vitro degradability of N (IVDN) from tannin-containing browses (Acacia cyanophylla, Acacia albida, Acioa barteri and Quercus ilex) and two herbaceous legumes (Desmodium intortum and Desmodium uncinatum) was determined using the in vitro gas-production method coupled with NH 3 -N measurement in the presence and absence of a tannin-binding agent (polyethylene glycol (PEG), molecular mass 6000). Addition of PEG to tannin-containing feeds significantly (P < 0.05) increased in vitro gas and short-chain fatty acid (SCFA) production, and IVDN. The use of PEG as a tannin-binding agent increased IVDN from 28 to 59, 32 to 72, 19 to 40, 32 to 73, 40 to 80, and 26 to 77 % in A. cyanophylla, A. albida, A. barteri, D. intortum, D. uncinatum and Q. ilex respectively. There was significant correlation between total phenolic compounds (total phenol, TP; total tannin, TT) in leguminous forages and percentage increase in IVDN on addition of PEG (P < 0.05; R 2 070 and 0.82 for TP and TT respectively). The difference in IVDN observed in the absence and presence of PEG indicates the amount of protein protected from degradation in the rumen by tannins. When measured after 24 h incubation, tannin-containing feeds incubated in absence of PEG resulted in higher microbial protein synthesis than in the presence of PEG. Addition of PEG significantly (P < 0.05) reduced the efficiency of microbial protein synthesis expressed as μmol purine/mmol SCFA.

Voluntary food intake and diet selection in farm animals.

Abstract: Feeding behaviour feedback signals ruminant gastrointestinal tract metabolites and hormones central nervous control integrative theories of food intake control growth and fattening reproduction and lactation diet digestability and concentration of available energy specific nutrients affecting intake learning about food - preferences diet selection appetites for specific nutrients environmental factors affecting intake the intake of fresh and conserved grass prediction of voluntary intake. Appendices: particular features of poultry and ruminant animals outline programme to identify and store meals from the identities of animals and weights of food containers.

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

Abstract: 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.

Exploitation of dietary tannins to improve rumen metabolism and ruminant nutrition.

Abstract: Tannins (hydrolysable and condensed tannin) are polyphenolic polymers of relatively high molecular weight with the capacity to form complexes mainly with proteins due to the presence of a large number of phenolic hydroxyl groups. They are widely distributed in nutritionally important forage trees, shrubs and legumes, cereals and grains, which are considered as anti-nutritional compounds due to their adverse effects on intake and animal performance. However, tannins have been recognised to modulate rumen fermentation favourably such as reducing protein degradation in the rumen, prevention of bloat, inhibition of methanogenesis and increasing conjugated linoleic acid concentrations in ruminant-derived foods. The inclusion of tannins in diets has been shown to improve body weight and wool growth, milk yields and reproductive performance. However, the beneficial effects on rumen modulation and animal performance have not been consistently observed. This review discusses the effects of tannins on nitrogen metabolism in the rumen and intestine, and microbial populations (bacteria, protozoa, fungi and archaea), metabolism of tannins, microbial tolerance mechanisms to tannins, inhibition of methanogenesis, ruminal biohydrogenation processes and performance of animals. The discrepancies of responses of tannins among different studies are attributed to the different chemical structures (degree of polymerisation, procyanidins to propdelphinidins, stereochemistry and C-C bonding) and concentrations of tannins, and type of diets. An establishment of structure-activity relationship would be required to explain differences among studies and obtain consistent beneficial tannin effects.