Crossbred heifers (683 lb; n = 175; 30
pens) were used to evaluate alfalfa and cooked
molasses block supplementation to prairie hay.
Treatments were arranged in a 2×3 factorial
with the factors being 0 or 5 lbs of alfalfa
supplementation, and supplementation with no
block or with low or high protein blocks (analyzed
to contain 14.4 and 27.5% crude protein,
respectively). Heifers had ad libitum access to
prairie hay and salt. The experiment was 89
days, with heifers fed blocks for 84 days. During
days 5 to 19, heifers had ad libitum access
to blocks. Thereafter, access was restricted to
4 hours daily. No significant interactions occurred
between alfalfa and blocks for intake or
gain. Supplementation with alfalfa increased
total forage intake by 49% (18.4 vs. 12.3
lb/day), and gains from –.39 lb/day to +.95
lb/day. Intake of the blocks was lower when
alfalfa was supplemented (.76 vs. .98 lb/day).
Heifers fed the high-protein block gained more
weight (.46 lb/day) than those fed the lowprotein
block (.25 lb/day) or no block (.12
lb/day). Heifers fed the high-protein block ate
more forage (16.1 lb/day) than those fed the
low-protein block (14.8 lb/day), with heifers fed
no block (15.3 lb/day) being intermediate.
Intake of block was greater for the high-protein
(.93 lb/day) than for the low-protein block (.81
lb/day). Differences in forage intake accounted
for much of the differences in performance
among treatments.
