The present study was conducted to determine effect of different processing and extrusion method on in vitro digestibility of organic matter (OOM), metabolizable energy (ME) and net energy for lactation (NEL) values. Commercial products containing extruded linseed including Nutex Compact@ (containing 56% extruded linseed) and LINOMAX@, and a pure extruded linseed (155-160 °C for 15-20 s) sample were evaluated. Samples grounded to pass through a I-mm screen and subjected to in vitro gas production technique. Mixed rumen micro-biota obtained from four ruminally fistulated Holstein steers (420% 13 kg. body weight) fed twice daily a diet containing 5.8 kg alfalfa hay and 3.0 kg concentrate mixture). Approximately 200 mg of each sample was weighed into a 125 ml flask (n=9) and then 50 ml rumen fluid-buffer mixture (in a 1:2 ratio) added into each bottle under C02 flush, followed by incubation in a water bath at 38.6 qc. Gas volume was recorded at 24 h of incubation. Metabolizable energy (ME), NEL and OOM values of the samples were calculated using following equations: ME (MJlkg OM) = 1.56 + 0.1390 GP + 0.0074 XP + 0.0178 XL: N~ (MJ/kg OM) = 0.10 I0 GP + 0.0051 XP + 0.0 I1 XL: OOM (glkg OM) = 14.88 + 0.8893 GP + 0.0448 XP + 0.065IXA. Where GP is net gas produced after 24 h of incubation (ml/0.2 g OM), and XP, XL and XA are crude protein, crud fat and ash content of the feed (glkg OM), respectively. The results showed that gas production for Nutex Compact@, LINOMAX@ and pure extruded linseed samples at 24 hours were 21.4\". 14.8b and 12.7c m1/0.2 g: respectively (P<0.05). The OOM of samples were 49.06\". 39.6b and 31.28%c: respectively. The ME contents were 10.47\", 10.62\" and 9.llb MJlkg OM, respectively and the NEL contents were 5.97\", 5.92\" and 4.87b MJ/kg OM. respectively (P<0.05) Session

Keywords