Authors : P. A. Davis, L. R. McDowell , W. E. Kunkle and J. D. Arthington
Abstract: Effects of lowering pH of molasses-based liquid supplements using phosphoric acid, sulfuric acid, or hydrochloric acid on free-choice liquid supplement intake of beef cows were evaluated in a 42 day trial. Seventy mature gestating Angus cows (ages 4-10 years; 568 kg initial weight; 120-180 days gestation) were randomly assigned to one of fourteen 1.62 ha bahiagrass (Paspalum notatum) pastures with free-choice mineral mixture shade (artificial or natural), and ad libitum water. Seven treatments were created from a 16% crude protein liquid supplement. Treatments were control (no additions to liquid supplement), pH 3.2 by adding 2.1% sulfuric acid, pH 3.2 by adding 3.2% hydrochloric acid, pH 3.2 by adding 5.7% phosphoric acid, pH 2.3 by adding 4.2% sulfuric, pH 2.4 by adding 6.3% hydrochloric acid, and pH 2.3 by adding 11.3% phosphoric acid. Each treatment was randomly assigned to two groups (5 cows/group) for a 21 day period in a randomized block design. After the first 21 day period, treatments were reassigned (treatments were not assigned to same pasture/group in second period) and another 21day consumption trial was conducted. Phosphoric acid added to achieve pH 3.2 lowered consumption 33% (3.58 kg) and the same acid added to achieve pH 2.3 lowered consumption 53% (2.55 kg) compared to control (5.38 kg). Sulfuric acid added to reach pH 3.2 reduced consumption 18% (4.39 kg) and sulfuric acid added to pH 2.3 reduced consumption 38% (3.36 kg). Hydrochloric acid added to create pH 3.3 tended to lower (P = 0.13) consumption by 9% (4.89 kg) and hydrochloric acid added to reach pH 2.3 reduced consumption 30% (3.76 kg). Variation in individual animal intake for control showed a 33% coefficient of variation (CV) and the six supplements with lower pH had similar variations (17% to 39% CV). Acidification of liquid supplements shows promise as a method of reducing liquid supplement consumption in beef cattle. In this experiment, lowering the pH of molasses-based liquid supplements reduced intake. The effectiveness of acid source varied, with phosphoric being most effective and hydrochloric being least effective when liquid supplements were adjusted to a similar pH.
Davis, P. A. , L. R. McDowell , W. E. Kunkle and J. D. Arthington , 2005. Liquid Supplement pH and Source of Added Acid Affects Liquid Supplement Intake of Mature Beef Cows . Journal of Animal and Veterinary Advances, 4: 135-139.