Abstract

MONTIEL, M.D.; ELIZALDE, J.C.; SANTINI  and  GIORDA, L.. Deactivation of tannin in high-moisture sorghum grain with polyethylene glycol or urea. Arch. zootec. [online]. 2012, vol.61, n.234, pp.235-244. ISSN 1885-4494.  https://dx.doi.org/10.4321/S0004-05922012000200008.

An in vivo experiment was carried out to study the effect of polyethylene glycol-4000 (PEG-4000) or urea on apparent digestibility and ruminal fermentation characteristics in bovine fed high tannin high moisture sorghum grain. The treatments were generated as follows: sorghum untreated or control (T), sorghum treated with 1 g PEG/g CP of grain (P) and sorghum treated with 2% urea based on dry matter (U). Three ruminally fistulated steers (312 ± 38 kg BW) which consumed a diet with 70% sorghum grain were assigned according to treatment to a Latin square design (three animals and three experimental periods). In vivo apparent digestibility of the diet and ruminal and blood parameters were measured. The grain treatments with PEG-4000 or urea generated positive responses, increasing (p<0.05) in vivo total digestion of the diet. In addition, they decreased (p<0.05) ruminal pH and increased the concentration of NH₃-N in the rumen in accordance with a higher concentration of urea in plasma (p<0.05). The PEG-4000 increased (p<0.05) total VFA concentration; acetate/propionate ratio was lower (p<0.05) in animals under P and U treatments. The diets containing grains with PEG-4000 or urea modified molar ratios of propionic and valeric, without altering those of acetic, butyric and isovaleric. The use of substances such as PEG4000 and urea is effective in reducing the detrimental effects of condensed tannins in sorghum grain, increasing the digestibility of the diet and changing ruminal and blood parameters of the animals.

Keywords : Tannins inactivation; Apparent digestibility; VFA; Ammonia N.

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