Table 6.

Meta-regression estimates for the effects of length of time that beef was aged before evaluation, length of time that cattle were fed, use of multiple HGP implants (yes or no), treatment comparisons using TBA (yes or no), breed of cattle, sex of cattle, and electrical stimulation of the carcass on tenderness responses

Variable	SMD	SE	95% CI	P-value	R 2	I 2, %	τ2
Aging of the beef, d	0.011	0.014	−0.167 to 0.038	0.435	0.10	78.11	0.273
Length of feeding, d	−0.001	0.002	−0.005 to 0.005	0.872	−18.6	65.3	0.277
Multiple implants, % of studies	0.468	0.182	0.104 to 0.832	0.013	41.46	71.34	0.16
TBA, % of studies	0.364	0.246	−0.129 to 0.858	0.145	7.06	78.43	0.254
Breed (reference British, British cross, European, and Holstein)
Brahman and Brahman crosses	−0.211	0.182	−0.576 to 0.154	0.252	68.21	73.03	0.087
Crossbred (undescribed)	0.537	0.177	0.181 to 0.892	0.004
Not stated	−1.167	0.547	−2.083 to −0.251	0.014
Sex (reference steers)
Bull	0.974	0.493	−0.013 to 1.962	0.053	0.55	76.0	0.272
Heifer	0.068	0.349	−0.630 to 0.767	0.845
Mixed	−0.390	0.447	−1.29 to 0.505	0.386
Stimulation (reference not stimulated)
Stimulated	−0.341	0.235	−0.812 to 0.129	0.151	55.02	72.25	0.123
Not stated	0.371	0.192	−0.141 to 0.756	0.059

The estimates are based on Knapp–Hartung methods and provide a SMD, SE, and 95% CI of the SMD, significance (P-value), model fit (R²), and measures of heterogeneity I² and τ². There were 59 treatment comparisons and 15 experiments.