Effects of hydroxy methyl-thio buanoic acid (Alimet) on performance and carcass characteristics of finishing beef cattle and on fermendation in a contiuous culture system

Three experiments were conducted to evaluate the effects of feeding graded levels of hydroxy methyl-thio butanoic acid (HMB); (Alimet; Novus Int., Inc., St. Louis, MO) on feedlot performance and carcass characteristics of finishing beef steers and on fermentation in a continuous-culture system.

In Exp. 1, 160 steers (average BW; 384.9 kg; SD = 26.9 kg ) were blocked by body weight (BW) into eight blocks and assigned to four dietary treatments in a randomized complete block experimental design. The following four diets were fed, 1) Control, (0% Alimet); 2) 0.069% Alimet; 3) 0.137% Alimet and 4) 0.204% Alimet. Final BW decreased linearly (P = 0.069), adjusted final BW decreased linearly (P = 0.063) and average daily gain decreased linearly (P = 0.099) as the percentage of Alimet in the diet increased. No significant (P > 0.10) linear or quadratic effects of Alimet dose were noted for any of the carcass measurements collected in this study

In Exp. 2, 80 steers (average BW 431.5 kg; SD = 42.2 kg) were blocked by BW into eight blocks and assigned to two dietary treatments in a randomized complete block design. Treatment diets were a Control (0 % Alimet) and an Alimet diet, with increasing concentrations of Alimet until 15 g/steer daily was achieved. Dry matter intake in the Alimet group tended (P = 0.132) to differ from intake than Controls. Gain:feed ratio was less (P = 0.046) with Alimet added to the diet than for Control for the d 0 to 56 period. No differences were detected in carcass measurements between the two treatments.

A continuous culture system was used to determine the effects of Alimet on ruminal fermentation in Exp. 3 in two dietary treatments: Control (0% Alimet) and Alimet (0.24% Alimet). No ruminal digestibility, pH, ammonia, or fatty acid differences where were detected in Exp. 3; however, the molar proportion of valerate was greater (P = 0.05) for Control vs. Alimet. There also was a trend (P = 0.12) for a greater acetate:propionate ratio for the Control cultures.

Results suggest that Alimet has the potential to be used as an intake limiting/control agent for use with finishing beef cattle fed high-concentrate diets based on steam-flaked corn. However, a better understanding of the cause for decreased DMI by finishing beef cattle fed Alimet is needed.