Resumen

GODOY, Susmira  y  CHICCO, Claudio F.. In vitro phytase activity of rumen microorganism and in situ degradation of fibrous substrate in sheep fed different feeding regimes. Zootecnia Trop. [online]. 2005, vol.23, n.1, pp.61-68. ISSN 0798-7269.

Summary Rams provided with rumen fistulae were fed diets containing three levels of forage/concentrate ratios: high (F, 100%)), medium (FC, 50%) and low forage level (FCC, 20%). An in vitro method was used to determine phytase activity, and an in situ suspension of nylon bags, containing grounded forage, to measure degradability of dry matter (MS), organic matter (MO) and residual crude protein (PC) and phosphorus (P). In addition, pH was measured in rumen content. Phytase activity increased with the addition of concentrate, with values of 0.232, 0.229 and 0.313 U/kg, respectively for F, FC and FCC, being the latter higher (P<0.05). No differences were found in MS and MO degradability. Proteolysis was enhanced with the addition on concentrate, being this higher (P<0.05) for FCC. Rumen pH was decreased by the addition of concentrate (P<0.05), reaching values of 6 approximately, at 8 hours of incubation. Residual P was higher (P<0.05) in FCC treatment. It is concluded that feeding forages with the addition on concentrate results in an increment o microbe phytase activity in the rumen, associated with changes in the fermentation pattern, apparently promoting microorganisms adapted to more acid ruminal environment.

Palabras clave : Phytase activity; rumen microbiota; substrate digestion fiber; sheep..