In sacco NDF degradability and mineral release from selected forages in the rumen

Abstract

An in sacco technique was used to measure NDF degradability and release of Mg, Ca, Zn, Cu, Fe from six forages – lucerne hay from the 1<sup>st </sup>cut (LH<sub>1</sub>), from the 2<sup>nd </sup>cut (LH<sub>2</sub>), orchard grass (G), grass silage (GS), red clover silage treated with Feedtech (CS<sub>FT</sub>) and/or with Kofasil (CS<sub>KO</sub>). The forages differed in the content of NDF and minerals. There were large differences (P < 0.01) in element release in the rumen between experimental forages and the particular elements. The rate of release of elements was higher from LH<sub>1,</sub> LH<sub>2,</sub> CS<sub>FT</sub>,CS<sub>KO</sub> than from G and GS. The release of individual elements and NDF over all incubation times is very well expressed by cubic polynomials (R<sup>2</sup>> 0.9). Overall, across forages the release of mineral elements ranked as follows: Mg > Fe > Cu > Ca > Zn. The minimum and maximum disappeared portions of individual minerals from forages are as follows: Mg 74.7% from G and > 91.5% from LH<sub>1</sub>, Fe 29.7% from G and 99.9% from LH<sub>1</sub> and LH<sub>2,</sub> Cu 64.3% from G and 99.8% from LH<sub>1</sub> and LH<sub>2</sub>, Ca 28.4% from G and 75.4% from CS<sub>FT</sub>, Zn 12.0% from G and 38.2% from LH<sub>1</sub>, respectively. Calcium and zinc need a longer time for their maximum release. It can be concluded from the results of multiple regression analyses that only the Mg and Ca release is associated depending on NDF and time of observations, with a highly significant influence of forage on Zn and Cu.