A total of 397 crossbred heifers were used to evaluate the effects of two levels of feeding during the post-weaning period on growth, gain/feed, and ultrasound carcass measurements as well as the associations among these traits. The heifers were assigned to a control diet (fed to appetite) or a restricted diet (80% of that consumed by controls) during a 140-day postweaning period. Heifers were individually fed a diet of 68% corn silage, 18% alfalfa, 8% barley, and 6% protein-mineral supplement (dry matter basis). Ultrasound measurements of loin muscle area (LMA), intramuscular fat (IMF), and subcutaneous fat (SQF) thickness over the LM were made on day 140.

Feed restriction significantly decreased (P<0.01) body wt. (644 vs. 692 lb), avg. daily gain (1.15 vs. 1.43 lb/day), LMA (8.8 vs. 9.4 sq. in.), IMF (3.2 vs. 3.5%), and SQF (0.12 vs. 0.15 in.), but increased gain/feed (0.12 vs. 0.11). The magnitude of correlations of dry matter intake with avg. daily gain, body wt., LMA, and body condition score were greater in restricted than control heifers. Pregnancy rate tended to be reduced in restricted heifers (86.3 vs. 91.5%). However, avg. daily gain was significantly greater (P<0.001) in restricted than control heifers while grazing native range in the 7 mos. after restriction (1.12 vs. 1.01 lb/day). The authors summarized by noting that restricted heifers consumed 22% less feed on a per-pregnant-heifer basis during the development period and had a greater magnitude of association between dry matter intake and several growth-related traits at the end of the 140-day postweaning period, which is indicative of improved feed efficiency (Roberts et al. 2007. J. Anim. Sci. 85:2740).