Effects of zilpaterol hydrochloride on growth performance, blood metabolites, and fatty acid profiles of plasma and adipose tissue in finishing steers1

Abstract

The effects of zilpaterol hydrochloride (ZH) on blood metabolites and fatty acid profiles of plasma and adipose tissue were evaluated in crossbred finishing steers (n = 18, BW 639 ± 12.69 kg) that were stratified by BW and randomly assigned, within strata (block), to receive 0 (control) or 8.33 mg/kg diet DM ZH. Cattle were fed once daily ad libitum in individual feeding pens (9 pens/treatment). Zilpaterol hydrochloride was fed for 23 d and withdrawn 3 d before harvest. Blood samples and measures of BW were taken on d 0, 7, 14, and 21. Concentrations of β-hydroxybutyrate (BHB), glucose, and lactate were determined from whole blood. Nonesterified fatty acids, urea nitrogen (PUN), glucose, lactate, and long-chain fatty acid (LCFA) concentrations were analyzed from plasma. Postharvest, adipose tissue samples (approximately 20 g) from subcutaneous fat covering the lumbar vertebrae were collected after 48 h of refrigeration and analyzed for LCFA profiles. Feeding ZH decreased DMI by 8% (P = 0.03) but did not affect BW gain or efficiency (P = 0.83 and P = 0.56, respectively). Addition of ZH resulted in greater HCW, dressing percentage, and LM area ( P = 0.02, P = 0.08, and P = 0.07, respectively) but did not influence other carcass traits (P > 0.10). A ZH × d interaction was observed for PUN and whole-blood glucose concentrations (P = 0.06), in which concentrations decreased in cattle receiving ZH. Nonesterified fatty acids, BHB, plasma glucose, whole-blood, and plasma lactate concentrations were unaffected by ZH (P > 0.10). Zilpaterol hydrochloride increased plasma concentrations of elaidic (P = 0.03), vaccenic (P = 0.006), and docosapentaenoic acids ( P= 0.08), but LCFA concentrations of adipose tissue were unaffected ( P> 0.10), suggesting no preferential oxidation of specific fatty acids. In conclusion, ZH supplementation decreased PUN concentration possibly due to decreased muscle catabolism, but components of blood related to lipid oxidation were unaffected.

Skeletal muscle and liver gene expression profiles in finishing steers supplemented with Amaize

“…The marked increase in serum BHBA by day 130, and the elevated glucose concentration on days 90 and 130 regardless of treatment may be indicative of an age‐dependent mechanism to secure more readily available energy substrates for body tissues. In accordance with our results, Van Bibber‐Krueger, Miller, Parsons, Thompson, and Drouillard () showed that blood BHBA increased in finishing steers from day 0 to day 21, while another study observed that plasma glucose was higher in finishing steers on day 94 compared with day 49 (Van Bibber‐Krueger, Axman, Gonzalez, Vahl, & Drouillard, ). The increase in BHBA might have been associated with increased epithelial ketogenesis and ruminal volatile fatty acid (VFA) biosynthesis (Naeem, Drackley, Stamey, & Loor, ; Penner, Steele, Aschenbach, & McBride, ).…”

The effects of zilpaterol hydrochloride and shade on blood metabolites of finishing beef steers1

“…These results using clen buterol are in contrast to the present experiment where wholeblood glucose was decreased by feeding ZH and it was less after vs. before feeding ZH. However, the current data are similar to other data from an experi ment using ZH (Van BibberKrueger et al, 2015).…”

“…The increase was temporary as after 9 d of clenbuterol feeding, glucose concentrations were not different (Eisemann et al, 1988). It was hypothe sized by the authors that the initial spike in glucose was caused by elevated liver gluconeogensis or glycoge nolysis (Eisemann et al, 1988), but then cells become desensitized and the glucose response disappears (Van BibberKrueger et al, 2015). These results using clen buterol are in contrast to the present experiment where wholeblood glucose was decreased by feeding ZH and it was less after vs. before feeding ZH.…”

“…In a previous experiment, a ZH × time interaction was detected for wholeblood glucose, where glucose decreased over time in cattle fed ZH but glucose con centrations in control cattle were not different across sampling days (Van BibberKrueger et al, 2015). In the current experiment, there was not a ZH × time interac tion for wholeblood glucose, but it was less for cattle fed ZH for 21 d and less after vs. before feeding ZH.…”

“…The lack of difference in PUN with β-agonist is inconsistent with other studies in the literature. Van BibberKrueger et al (2015) reported that ZH supple mentation caused PUN to decrease and was likely be cause of decreased protein catabolism in skeletal mus cle. Ricks et al (1984) reported that blood urea nitrogen decreased with clenbuterol administration in steers, and Eisemann et al (1988) noted decreased PUN concen trations after clenbuterol feeding.…”