Influence of dietary supplementation of guanidinoacetic acid on growth performance and blood chemistry profile of growing steers

Guanidinoacetic acid (GAA, Cas no. 352-97-6) is a feed additive that positively influences the energy and protein metabolism of animals, so it has the potential to improve the productivity of animals without affecting their health. The objective of the present study was to evaluate the influence of dietary supplementation with GAA on growth performance and blood chemistry profile of growing steers for 60 d. Forty growing crossbred male steers (Bos taurus × Bos indicus; 146.0 ± 0.5 kg body weight (BW)) were randomly divided into two experimental groups (n = 20): the first, consisted of a total mixed ration (TMR) without; and the second, substituted the 0.1 % of the TMR with GAA. Dietary supplementation of GAA decreased (P < 0.0001) dry matter intake (DMI) by 12.8 % compared to the steers that were fed the TMR without GAA. Although these changes did not influence (P = 0.4180) BW and average daily gain (ADG), they improved (P < 0.0490) feed conversion efficiency (FCE) by decreasing DMI per kilogram of ADG by 10.4 %. Furthermore, the inclusion of GAA in the TMR reduced (P < 0.0050) triglycerides by 23.2 % and increased the urea nitrogen (BUN) in the steers by 22.4 % (P < 0.0002). However, sampling time influenced (P ≤ 0.0042) all blood chemistry parameters except calcium, and the interaction between GAA supplementation and time did not significantly influence (P ≥ 0.0750) any parameter. In conclusion, dietary supplementation of 1 g GAA kg⁻¹ of TMR, decreased the DMI and improved FCE without negative effects on blood chemistry profiles.