Rr. Grummer et al., LACTATIONAL PERFORMANCE OF DAIRY-COWS FED RAW SOYBEANS, WITH OR WITHOUT ANIMAL BY-PRODUCT PROTEINS, OR ROASTED SOYBEANS, Journal of dairy science, 77(5), 1994, pp. 1354-1359
Twelve multiparous Holstein cows averaged 10 wk postpartum and were us
ed in a replicated 3 x 3 Latin square design to compare two feeding st
rategies for increasing the ratio of dietary undegradable to degradabl
e protein. Treatments were raw soybeans, with or without meat and bone
meal plus blood meal, and roasted soybeans as the primary protein sup
plements. Meat and bone meal and blood meal were fed at 4.0 and .9% of
dietary DM, respectively. Basal diets were 30% alfalfa silage, 18% co
rn silage, and 52% corn-based concentrate mix. Diets were formulated t
o be isonitrogenous and isocaloric. Estimated undegradable protein con
tents, as a percentage of total CP, were 32.2, 36.2, and 34.3 for diet
s containing raw soybeans, raw soybeans plus animal by-product protein
s, and roasted soybeans, respectively. The undegradable protein estima
tes were calculated from NRC values for basal feeds and from results o
f in vitro analysis of test protein supplements. Yields of milk and 3.
5% FCM of cows receiving raw soybeans plus animal by-product proteins
(45.5 and 43.4 kg/d) and roasted soybeans (44.7 and 42.7 kg/d) were gr
eater than those of cows receiving raw soybeans alone (43.2 and 41.3 k
g/d). Increasing the ratio of undegradable to degradable dietary prote
in also increased yields of milk protein and fat. No differences occur
red in lactation performance among cows fed the two diets containing h
igher undegradable protein. The DMI was not influenced by treatment. I
ncreasing the ratio of undegradable to degradable dietary protein by f
eeding animal by-product proteins or heated soybeans enhanced lactatio
n performance.