Influence of protein supplementation on site and extent of digestion, forage intake, and nutrient flow characteristics in steers consuming dormant bluestem-range forage.
Four multicannulated Holstein steers (initial BW 424 +/- 16 kg) were used in a 4 x 4 Latin square to determine the influence of protein supplementation on forage intake, site and extent of digestion, and nutrient flow in steers consuming dormant bluestem-range forage (2.3% CP). Treatments were 1) control, no supplement; 2) 1.8 kg of low-protein supplement, 12.8% CP (Low-CP); 3) 1.8 kg of moderate-protein supplement, 27.1% CP (Mod-CP); and 4) 2.7 kg of dehydrated alfalfa pellets, 17.5% CP (Dehy). The Dehy supplement was fed to provide the same amount of CP/d as Mod-CP, and all supplements provided similar amounts of ME/d. Forage DMI was increased (P less than .05) by feeding Mod-CP and Dehy. Ruminal OM digestibility was 39% greater (P less than .05) for the Mod-CP and Dehy supplementations than for the Low-CP supplementation and control. Ruminal CP digestibility was negative for all treatments, and control (-326%) was less (P less than .05) than supplemented treatments (average -27%). Total tract OM digestibility was greatest (P less than .10) for steers fed Mod-CP and least for control steers; Low-CP and Dehy steers were intermediate. Total tract NDF digestibility tended (P = .15) to be less with Low-CP than with Mod-CP and Dehy. Duodenal N flow was greater (P less than .05) with Mod-CP and Dehy than with Low-CP and control. In summary, supplementation with Mod-CP increased forage intake, digestion, and duodenal N flow compared with Low-CP or control; however, the response was similar when Mod-CP and Dehy supplements were fed to provide equivalent amounts of CP and ME daily.
Hannah
S M
SM
Kansas State University, Manhattan 66506.
Cochran
R C
RC
Vanzant
E S
ES
Harmon
D L
DL
D000641:Ammonia / Q000032:analysis; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004044:Dietary Proteins / Q000494:pharmacology*; D004063:Digestion; D004435:Eating; D005232:Fatty Acids, Volatile / Q000032:analysis; D005285:Fermentation; D005746:Gastric Emptying; D006863:Hydrogen-Ion Concentration; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D006109:Poaceae; D012417:Rumen / Q000378:metabolism
D004044:Dietary Proteins; D005232:Fatty Acids, Volatile; D000641:Ammonia; D009584:Nitrogen