title: Effects of supplemental fat source on nutrient digestion and ruminal fermentation in steers.
abstract: Five Holstein steers (235 kg of BW) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 5 Latin square design experiment to determine the effects of supplemental fat source on site and extent of nutrient digestion and ruminal fermentation. Treatments were diets based on steam-flaked corn containing no supplemental fat (control) or 4% (DM basis) supplemental fat as tallow, dried full-fat corn germ (corn germ), corn oil, or flax oil. Fat supplementation decreased (P < 0.08) ruminal starch digestion but increased (P < 0.03) small intestinal starch digestion as a percentage of intake. Feeding corn germ decreased (P < 0.09) ruminal starch digestion and increased (P < 0.03) large intestinal starch digestion compared with steers fed corn oil. Large intestinal starch digestion was less (P < 0.04), and ruminal NDF digestion was greater (P < 0.09) for steers fed tallow compared with steers fed other fat sources. Small intestinal (P < 0.08) and total tract NDF digestibilities were greater (P < 0.02) for steers fed corn germ than for those fed corn oil. Feeding tallow increased total ruminal VFA (P < 0.03) and NH(3) (P < 0.07) concentrations compared with steers fed the other fat sources. Feeding corn germ led to a greater (P < 0.02) rate of ruminal liquid outflow compared with corn oil. A diet x hour interaction (P < 0.04) occurred for ruminal pH, with steers fed corn oil having the greatest ruminal pH 18 h after feeding, without differences at other time points. Fat supplementation increased (P < 0.09) ruminal concentrations of Fusobacterium necrophorum. Duodenal flow of C18:3n-3 was greater (P < 0.01) for steers fed flax oil compared with those fed corn oil. Feeding corn germ led to less (P < 0.01) ruminal biohydrogenation of fatty acids compared with corn oil. Steers fed tallow had greater small intestinal digestibility of C14:0 (P < 0.02) and C16:1 (P < 0.04) than steers fed the other fat sources. Fat supplementation decreased (P < 0.06) small intestinal digestibility of C18:0. Feeding corn germ decreased (P < 0.10) small intestinal digestibility of C18:1 compared with corn oil. It appears that source of supplemental fat can affect the site and extent of fatty acid and nutrient digestion in steers fed diets based on steam-flaked corn.
authors.affiliation: Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-1600, USA.
authors.forename: S P
authors.initials: SP
authors.lastname: Montgomery
authors.forename: J S
authors.initials: JS
authors.lastname: Drouillard
authors.forename: T G
authors.initials: TG
authors.lastname: Nagaraja
authors.forename: E C
authors.initials: EC
authors.lastname: Titgemeyer
authors.forename: J J
authors.initials: JJ
authors.lastname: Sindt
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002404:Catheterization; D002417:Cattle / Q000378:metabolism*; D015169:Colony Count, Microbial; D004032:Diet / Q000662:veterinary*; D004041:Dietary Fats / Q000008:administration & dosage* / Q000032:analysis; D004063:Digestion / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism; D005285:Fermentation / Q000502:physiology*; D005673:Fusobacterium / Q000254:growth & development / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D012417:Rumen / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology; D013997:Time Factors
chemical_list: D004041:Dietary Fats; D005227:Fatty Acids