Table 1. Effects of zilpaterol on feedlot performance and carcase characteristics.

Outcome	Number of studies (n)	Raw mean difference 95% CI	Effect Size and 95% CI	Weighted mean difference and 95% CI	I2 estimated hetero-geneity	Significant meta-regression effects
Final Body weight (kg)	31	6.562	0.449	8.150	0.0
		4.229 to 8.895	0.277 to 0.621	5.627 to 10.674
Dry Matter Intake (kg/d)	26	−0.160	−0.470	−0.118	0.0
		−0.243 to −0.077	−0.676 to −0.264	−0.167 to −0.070
Average Daily Gain (kg/d)	29	0.210	0.884	0.153	29.1
					(0.0)1
		0.141 to 0.278	0.656 to 1.113	0.111 to 0.194
Gain:feed (kg/kg ratio)	28	0.024	1.336	0.024	54.1
		0.017 to 0.031	1.002 to 1.671	0.018 to 0.030
Hot Carcase Weight (kg)	35	15.383	1.323	15.179	55.9
		12.937 to 17.829	1.034 to 1.611	13.615 to 16.743
Ultimate pH	5	0.022	0.102	−0.002	0.0	NA
		−0.033 to 0.077	−0.411 to 0.616	−0.017 to 0.013
Longissimus muscle area (cm2)	35	8.147	2.302	8.006	70.8	Unit (0.022) period (0.165) Multivariate2
		7.115 to 9.180	1.898 to 2.705	7.052 to 8.959
Objective measurement of ‘redness’ (Colour)	18	0.012	0.098	0.03	15.0
		−0.122 to 0.098	−0.174 to 0.371	−0.004 to 0.066
Fat thickness at the 12th rib (cm)	35	−0.106	−0.697	−0.11	47.8	Fat of control(0.120) and period (0.186) Multivariate2
		−0.139 to −0.073	−0.940 to −0.453	−0.158 to −0.080
Standardised USDA marbling score	34 (28)*	−23.004	−0.861	−22.947	37.3	Unit (0.030) period (0.050) Multivariate2
		−31.245 to −14.763	−1.100 to −0.621	−30.330 to −15.564
Dressing Percentage (%)	27	1.657	2.205	1.706	71.5
		1.319 to 1.996	1.669 to 2.741	1.510 to 1.902
Warner-Bratzler Shear Force (kg)	47	1.022	1.212	0.840	61	Age (0.001) unit (0.001) Multivariate2
		0.854 to 1.191	1.024 to 1.401	0.720 to 0.960

CI – Confidence interval.

¹Sensitivity with removal of Avendano-Reyes et al.

NA – insufficient studies to attempt.

²Higgins and Thompson (2004) method.

*6 trials removed with different units for Raw mean and weighted mean differences.