Growth, composition and eating quality of Longissimus dorsi from young bulls fed the β-agonist cimaterol at consecutive developmental stages.

The objective was to investigate the effect of the β-adrenergic agonist, cimaterol, on gain, composition and meat quality of primerib (M. longissimus dorsi) from Friesian young bulls slaughtered at different developmental stages. Twelve pairs of monozygotic twins were allocated to three liveweight (LW) groups (162, 299 and 407 kg, respectively). Within each pair, one animal was given 0·056 mg cimaterol per kg LW for 90 days, while the other served as a control. Cimaterol treatment increased the estimated gain and the weight of primerib by 55 and 20%, respectively (both P < 0·001), and lean and protein content of the longissimus dorsi muscle by 26 and 25%, respectively (both P < 0·001), and concomitantly reduced fat content of primerib by 16% (P < 0·01) and intramuscular fat in longissimus dorsi by 36% (P < 0·001). Cimaterol treatment reduced total collagen content (P < 0·02), but not collagen solubility (P > 0·55). Meat colour was slightly lighter (lightness, P < 0·06), but pH(24) and pH(final) was not affected by cimaterol. Cimaterol increased Volodkevich shear force values (P < 0·001). In general, the effect of cimaterol on meat quality characteristics was evident in all three LW groups, and LW only affected percent fat in primerib, intramuscular fat content in longissimus dorsi, meat colour and absolute contents of protein, fat and bone.