Activated carbon supplementation of dairy cow diets: Effects on apparent total-tract nutrient digestibility and taste preference

The objectives of these studies were to determine whether the adverse effects of feeding poor-quality forages could be alleviated by adding activated carbon as a feed additive through observing the effect of activated carbon on apparent nutrient digestibility and taste preferences. In Exp. 1, 6 multiparous, late-lactation Holstein cows were assigned to a replicated 3 × 3 Latin square. All cows were fed a basal diet containing approximately 60% poor-quality corn silage containing the mycotoxin deoxynivalenol. The 3 treatments were 0, 20, or 40 g of activated carbon top-dressed once daily at the p.m. feeding. Cows fed activated carbon had increased DMI and apparent total-tract nutrient digestibilities of NDF, hemicellulose, and CP. Cows fed activated carbon also had increased milk fat content and showed increased BCS. In Exp. 2, 3 cannulated, primiparous, early-lactation Holstein cows were used in a 3 × 3 Latin square design. The cows were fed 0, 20, or 40 g of activated carbon per day using good-quality forage, which resulted in no differences in apparent total-tract nutrient digestibility or milk composition and yield. In Exp. 3, 6 early-lactation, primiparous Holstein cows were assigned to a sequential elimination trial with access to 0, 10, 20, 40, or 80 g/d of activated carbon in a cafeteria-style feeder to determine taste preference. Cows were fed a diet similar to that in Exp. 2. As activated carbon increased, preference for that particular feed decreased. Results indicated that activated carbon improves apparent total-tract nutrient digestibilities when cows are fed poor-quality (mycotoxin-laden) silage, but activated carbon should not be used when good-quality forage is fed