Table 1.

Descriptive statistics (mean and standard deviation, SD) and least square means (confidence interval) of productivity traits by developmental stage of the heifers and feed efficiency group.

Stage/Variable (Unit)	Mean ± SD	Efficient	Inefficient	p-Value
Heifer calves		(n = 54)	(n = 53)
Residual feed intake (kg DMI/day)	0.00 ± 1.07	−0.83 (−1.01, −0.66)	0.85 (0.67, 1.03)	<0.01
Average daily gain (kg/day)	0.73 ± 0.16	0.71 (0.67, 0.76)	0.74 (0.70, 0.79)	0.35
Dry matter intake (DMI; kg/day)	6.22 ± 1.29	5.45 (5.17, 5.73)	7.01 (6.73, 7.30)	<0.01
Feed to gain ratio	8.80 ± 2.18	7.92 (7.38, 8.46)	9.70 (9.15, 10.2)	<0.01
Average body weight (kg)	303 ± 40.4	300 (289, 311)	308 (297, 319)	0.33
Average rib eye area (cm2)	40.7 ± 5.67	40.2 (38.7, 41.7)	41.1 (39.6, 42.7)	0.58
Average back fat thickness (mm)	1.41 ± 0.85	1.43 (1.20, 1.66)	1.87 (1.30, 1.62)	0.66
Average rump fat thickness (mm)	1.62 ± 1.25	1.52 (1.18, 1.35)	1.72 (1.38, 1.52)	0.71
Average marbling score A (1–11)	4.00 ± 0.31	4.00 (3.84, 4.12)	4.09 (3.88, 4.14)	0.80
Pregnant heifers		(n = 16)	(n = 15)
Residual feed intake (kg DMI/day)	0.00 ± 1.24	−1.02 (−1.45, −0.59)	1.06 (0.61, 1.50)	<0.01
Average daily gain (kg/day)	0.99 ± 0.17	1.01 (0.93, 1.10)	1.02 (0.94, 1.11)	0.86
Dry matter intake (DMI; kg/day)	9.68 ± 1.73	8.64 (7.89, 9.39)	10.93 (10.2, 11.7)	<0.01
Feed to gain ratio	9.78 ± 2.02	8.57 (7.69, 9.45)	10.56 (9.65, 11.47)	<0.01
Average body weight (kg)	480 ± 49.6	480 (455, 505)	496 (470, 522)	0.35
Average rib eye area (cm2)	51.1 ± 7.52	50.3 (46.3, 54.3)	53.2 (49.1, 57.3)	0.32
Average back fat thickness (mm)	1.98 ± 1.11	1.82 (1.23, 2.41)	2.27 (1.67, 2.88)	0.30
Average rump fat thickness (mm)	3.20 ± 2.12	3.04 (1.65, 3.67)	3.36 (1.79, 4.03)	0.71
Average marbling score A (1–11)	4.91 ± 0.58	4.96 (3.68, 4.24)	4.90 (3.61, 4.19)	0.79

^A 1: devoid; 11: prime according to Canadian beef quality grade.