title: Effects of lauric acid on ruminal protozoal numbers and fermentation pattern and milk production in lactating dairy cows.
abstract: The objectives of this study were to evaluate lauric acid (LA) as a practical ruminal protozoa-suppressing agent and assess effects of protozoal suppression on fermentation patterns and milk production in dairy cows. In a pilot study, 6 lactating Holstein cows fitted with ruminal cannulae were used in a randomized complete-block design trial. Cows were fed a basal total mixed ration (TMR) containing (DM basis) 15% alfalfa silage, 40% corn silage, 30% rolled high moisture shelled corn, and 14% solvent soybean meal, and assigned to 1 of 3 treatments: 1) control, 2) 160 g/d of LA, or 3) 222 g/d of sodium laurate, which is equimolar to 160 g/d of LA, all given as a single dose into the rumen via cannulae before feeding. Both agents showed high antiprotozoal activity when pulse dosed at these amounts via ruminal cannulae, reducing protozoa by 90% (P<0.01) within 2 d of treatment. Lauric acid reduced ruminal ammonia concentration by 60% (P<0.01) without altering DMI. Both agents reduced ruminal total free AA concentration (P<0.01) and LA did not affect ruminal pH or total VFA concentration. In a large follow-up feeding trial, 52 Holstein cows (8 with ruminal cannulae) were used in a randomized complete-block design trial. Cows were assigned to 1 of 4 diets and fed only that diet throughout the study. The TMR contained (DM basis) 29% alfalfa silage, 36% corn silage, 14% rolled high moisture shelled corn, and 8% solvent soybean meal. The 4 experimental diets were similar, except part of the finely ground dry corn was replaced with LA in stepwise increments from 0 to 0.97% of dietary DM, which provided (as consumed) 0, 83, 164, and 243 g/d of LA. Adding these amounts of LA to the TMR did not affect DMI, ruminal pH, or other ruminal traits, and milk production. However, LA consumed at 164 and 243 g/d in the TMR reduced the protozoal population by only 25% and 30% (P=0.05), respectively, showing that these levels, when added to the TMR, were not sufficient to achieve a concentration within the rumen that promoted the antiprotozoal effect of LA.
authors.affiliation: Department of Dairy Science, University of Wisconsin, Madison, WI 53706, USA. afaciola@cabnr.unr.edu
authors.forename: A P
authors.initials: AP
authors.lastname: Faciola
authors.forename: G A
authors.initials: GA
authors.lastname: Broderick
authors.forename: A
authors.initials: A
authors.lastname: Hristov
authors.forename: M I
authors.initials: MI
authors.lastname: Leão
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D005260:Female; D005285:Fermentation; D007774:Lactation / Q000187:drug effects* / Q000502:physiology; D007850:Lauric Acids / Q000008:administration & dosage / Q000494:pharmacology*; D008892:Milk; D012417:Rumen / Q000469:parasitology*
chemical_list: D007850:Lauric Acids; C030358:lauric acid