INFLUENCIA DA IDADE DE REBROTA SOBRE O POTENCIAL NUTRICIONAL DO FENO DE QUICUIO (PENNISETUM CLANDESTINUM) CONSUMIDO POR OVINOS / REGROWTH AGE INGLUENCE ON THE POTENTIAL NUTRITIONAL ASSESSMENT OF KIKUYU GRASS HAY (Pennisetum clandestinum) IN SHEEPS

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Two experiments were conducted to evaluate changes in chemical composition on kikuyu Pennisetum clandestinum hay cut with 50, 70 and 90 days of regrowth, and its effect on intake, digestibility, ruminal fermentation and passage kinetics of solid phase through gastrointestinal tract (Experiment 1) and oxygen utilization by the portal system (Experiment 2) in sheeps. Six and three castrated lambs, mean live weight of 35 3 kg and 33 3 kg were used, in a Double 3 X 3 Latin Square and in a Latin Square experimental design in experiment 1 and 2, respectively. These animals were chronically catheterized in portal and mesenteric veins. Experimental diets were hay fed twice a day ad libitum. Intake of hay components linearly decreased (P<0,05) with the increase of the regrowth age of the plant with the ecxeption of indigestible neutral detergent fiber (NDFi), acid detergent fiber (ADF) and cellulose that were similar between treatments (P<0,05). Aparent digestibility of dry matter (DM), organic matter (OM) and neutral detergente fiber (NDF) were similar between treatments (P<0,05). Nitrogen intake and retention linearly decreased (P<0,05) with the increase of regrowth age of kikuyu but N digestibility and urinary excretion were similar between treatments. Protein synthesis and eficiency were quadratically related (P<0,05) with the regrowth age of kikuyu with maximum values on hay of 70 days. Aminoacids concentrations were similar while N-amonia concentration linearly decreased and (P<0,05) sugar and peptides concentrations were quadratically related (P<0,05) with the regrowth age of kikuyu. The kinetic of solid phase and retention time through the astrointestinal tract were similar between treatmens. Of the parameters that defines the nutritional value of the forage, only intake was correlationated with regrowth age. However, this relationship was not explained for the rate of passage of the solid phase or the hay digestibility. Around 4 5 % of the consumption of energy metabolic was liberated as heat by the organs that compose the portal system, but there was not relation between oxygen consumption and regrowth age. These results indicates that other than dietetic factors, like oxygen disponibility, also can affect oxygen utilization by the tissues.

ASSUNTO(S)

oxygen consumption maturity tropical forage gramínea tropical zootecnia maturidade digestibility digestibilidade gasto de oxigênio

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