Ma. Messman et Wp. Weiss, USE OF ELECTROPHORESIS TO QUANTIFY RUMINAL DEGRADABILITY OF PROTEIN FROM CONCENTRATE FEEDS, Animal feed science and technology, 49(1-2), 1994, pp. 25-35
Proteins in soyabean meal, spray-dried and ring-dried blood meals, mai
ze grain, and maize dried distillers grains were extracted before and
after ruminal fermentation in vitro. Extracts were subjected to sodium
dodecyl sulfate-polyacrylamide gel electrophoresis, and stain intensi
ty of the bands was quantified by densitometry. Undegradability values
(proportion of total protein) for soyabean meal, spray-dried blood me
al, ring-dried blood meal, maize grain, and distillers grains were 0.4
0, 0.99, 0.97, 0.56, and 0.82, respectively, after 2 h of fermentation
in vitro and 0.09, 0.79, 0.82, 0.49, and 0.59, respectively, after 20
h of fermentation. Soyabean meal and spray-dried blood meal contained
slowly degradable, soluble proteins. Individual proteins within feeds
tuffs showed different degrees of degradation. The basic subunit of gl
ycinin was degraded much slower than were other proteins in soyabean m
eal. Zein proteins in maize grain and distillers grains were much less
degradable than were the glutelin proteins. Electrophoresis has poten
tial as a method for measuring degradability of both particle and flui
d associated proteins and to account for bacterial protein contaminati
on.