Abomasal infusion of an exogenous emulsifier improves fatty acid digestibility and milk fat yield of lactating dairy cows

摘要

The objective of our study was to determine the effectsof abomasal infusion of an emulsifier on fatty acid(FA) digestibility and production responses of lactatingdairy cows. Eight rumen-cannulated cows (109 ±18 d in milk) were randomly assigned to a treatmentsequence in replicated 4 × 4 Latin squares with 18-dperiods including 7 d of washout and 11 d of infusionwith sampling on the last 4 d. Treatments were abomasalinfusions of water carrier only (CON) and 3 levelsof increasing doses of Tween 80 (polysorbate 80, Tween80, Sigma-Aldrich, St. Louis, MO) delivering 15 (D-15),30 (D-30), and 45 (D-45) g/d. The Tween 80 was dissolvedin water before infusions, which were deliveredat 6-h intervals. Cows were fed the same diet, whichcontained (% dry matter) 31% neutral detergent fiber,17% crude protein, 25% starch, and 4% FA (2% drymatter from a saturated fat supplement containing 33%C16:0 and 51% C18:0). Increasing emulsifier infusiondose quadratically increased digestibility of total FA(60.7, 65.3, 70.9, and 66.8%), 16-carbon FA (61.7, 63.9,70.4, and 66.7%), and 18-carbon FA (59.8, 65.6, 71.1,and 66.6%, respectively). Increasing emulsifier infusiondose quadratically increased absorbed total FA (625,670, 744, and 658 g/d), 16-carbon FA (151, 157, 197,and 157 g/d, quadratic), and 18-carbon FA (420, 460,500, and 444 g/d). Increasing emulsifier infusion dosetended to quadratically decrease dry matter intake(29.0, 28.8, 29.6, and 27.6 kg/d). Increasing emulsifierinfusion dose quadratically increased milk fat content(3.23, 3.35, 3.45, and 3.35%), milk fat yield (1.54, 1.61,1.65, and 1.55 kg/d), ECM (45.7, 46.9, 47.5, and 45.3kg/d), and plasma nonesterified fatty acid concentration(95.6, 98.4, 101.2, and 98.6 μEq/L). On a yieldbasis, we observed that de novo, mixed, and preformedFA responded quadratically to Tween 80 infusion dueto FA yield increasing up to D-30. Treatments had noeffect on milk yield (47.9, 48.3, 48.0, and 46.6 kg/d).In conclusion, short-term infusion of an exogenousemulsifier improved FA digestibility and milk fat yieldresponses when cows were fed a diet containing a saturatedfat supplement. Most digestion and productionmeasurements responded quadratically because thehighest dose of exogenous emulsifier (45 g/d) decreaseddry matter intake and performance.