EFFECT OF CHOLINE IN ALL-CONCENTRATE DIETS OF FEEDLOT STEERS AND ON RUMINAL ACIDOSIS

Abstract

Four trials with beef steers were conducted to determine if choline supplementation of an all-concentrate diet improved performance and affected ruminal lactic acidosis. Trial 1 was a preliminary feeding trial with 12 individually fed steers averaging 356 kg initial body weight. Trials 2 and 3 were feedlot trials with 64 and 80 steers averaging 359 and 320 kg initial body weights, respectively. Trial 4 was an intensive trial with three ruminal-fistulated steers in a 3 × 3 Latin square design in which subacute ruminal acidosis was produced. Choline supplementation neither consistently affected feedlot performance and carcass merit measurements in the feeding trials, nor consistently affected end products of ruminal fermentation. Choline appeared to reduce total plasma amino acids and increase plasma urea (measurements made in Trials 2 and 3) and reduce serum glucose, triglycerides and glutamic pyruvic transaminase while increasing serum total lipids and cholesterol (measurements made in Trial 3). Choline did not affect ruminal volatile fatty acid, pH, ammonia and lactic acid isomer changes associated with subacute lactic acidosis. The results indicate that the levels of choline supplementation of an all-concentrate diet for beef steers used in this study did not affect ruminal acidosis and did not improve performance of feedlot steers. Key words: Choline, acidosis, lactic acid, rumen, steer, beef cattle