Doina Tarcau

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POLYPHENOLIC COMPOSITION OF A PERMANENT PASTURE UNDER INFLUENCE OF ORGANIC FERTILIZATION

Doina Tarcau, V. Vîntu, C. Samuil, Simona Cucu-Man

Abstract
Generally, tannins have a negative effect in animal feed intake, feed digestibility, and efficiency of production. These effects are depending on the content and type of tannin ingested and on the animal's tolerance, which in turn is dependent on characteristics such as type of digestive tract, feeding behavior, body size, and detoxification mechanisms. The study aimed to assess the influence of organic fertilization on the total polyphenols and tannins content in forages obtained from permanent grassland of Dorna Depression. The experience was monofactorial in three repetitions, located on grassland of Nardus stricta L. and Festuca rubra L., at an altitude of 940 m and 10% slope, to investigate the effect of fertilization with 20-50 t ha-1 manure, applied annually or every 2 years. Samples were collected in autumn 2010-2011 and were analyzed for total polyphenols and tannins content by Folin Ciocalteu method. It was observed that the fertilization with manure increase the total polyphenols and tannins content compared with the control variant. Concentration of the total polyphenols increased from 22.4 mg/g for the unfertilized variant to 40.3 mg/g for the variant fertilized with 50+0+40+0 t ha-1 manure. The tannins content also increased from 3.9 mg/g for the unfertilized variant to 13.1 mg/g for the variant fertilized with 50+0+40+0 t ha-1 manure. Phenolics contribute to the micronutrient composition of forages and assessment of these compounds is important because they could affect the quality of animal products.

Key words: tannins, polyphenols, forages, Nardus Stricta L, Festuca rubra L.