Effect of protected and non-protected corn oil supplementation on in vitro rumen fermentation

This study aimed to determine the effect of supplementation of corn oil (CO) and protected corn oil (PCO) mixture using formaldehyde on rumen fermentation. Protection of corn oil was carried out by mixing skim milk powder and CO (2:1) using formaldehyde 1.5. Rumen fluid for in vitro dry matter digestibility (IVDMD), in vitro organic matter digestibility (IVOMD) as well as for in vitro gas production was collected from rumen fistulated Bali cattle which has been adapted with elephant grass and wheat bran (60:40). The combination of CO and PCO in several rations was added as the supplement to feed substrate (dry matter basis). Ratios of CO: PCO supplementation that given were T0 (0:0) as a control, T1 (5:0), T2 (3.75:1.25), T3 (2.5:2.5), T4 (1.25:3.75), and T5 (0:5). The T1 and T2 had lower (P<0.05) total gas production at 48 hours incubation and fewer protozoa compared to the other treatments. The T1 had lower (P<0.05) NH₃ and IVDMD. It is concluded that supplementation with the ratio of 3.75 CO and 1.25 PCO reduced the production of total gas and the number of protozoa, but did not decrease the pH, NH₃, IVDMD, and IVOMD.