The study was conducted to assess the impact of protected fat on rumen fermentation. Rumen fistulatcd cattle (4; 2 yrs old of 295 kg BW) were fed concentrate containing mustard oil (MO), crushed mustard seed (CMS), heat treated crushed mustard seed (HTCMS) and Calcium salts of mustard oil (CaMO) to provide 4% supplemental fat in the ration in 4 x 4 latin square switchover design. All the animals were fed a basal ration comprising of wheat straw, maize fodder and concentrate mixture in 40:20:40 proportion on DM basis. There was no effect of different sources of fat supplementation on nutrient intake, rumen pH, or N-fractions in the strained rumen liquor (SRL). TVFA concentration in SRL was higher by 21.5% in group fed CaMO and 5.8% in group fed HTCMS over that of group fed MO. Concentration of total fatty acids (mg/g) in SRL were higher (P<0.05) in group fed CMS as such or after heat treatment (49.6, 53.8) than group fed MO or Ca MO (33.8 vs 26.1). Similarly EFA and NEFA in SRL as percent of total fatty acids were not effected by dietary treatments except that linoleic (C18:2) acid was higher (P<0.05) in group fed CaMO than that in other groups. The ruminal biohydrogenation of individual C18 fatty acids showed a declining trend in animals fed CMS, HTCMS, CaMO. Biohydrogenation of total C18 fatty acid was 14.5 per cent lower (P<0.05) in group fed CaMO than those fed MO. The results indicated that supplementation of Ca salts of mustard oil showed better response as bypass fat as compared to caished or heat treated mustard seed.
Bypass fat, Fatty acid biohydrogenation, Rumen metabolites, Cows
