Nf. Makoni et al., DEGRADABILITY OF FROZEN AND ENSILED ALFALFA PROTEINS BY SHEEP AND ASSESSMENT OF DUODENAL DIGESTA PROTEIN, Animal feed science and technology, 53(3-4), 1995, pp. 221-231
Six adult ewes equipped with ruminal and duodenal cannulae were used i
n a crossover experiment to determine the effect of ensiling alfalfa o
n protein degradation in vivo. Frozen alfalfa and wilted silage prepar
ed from the same crop were fed twice a day (08:00 and 16:00 h) with a
mineral supplement. Water was available free choice. Rumen digesta out
-flow rate and duodenal microbial nitrogen (N) were estimated using ch
romium mordanted alfalfa and RNA respectively. Animals fed frozen alfa
lfa had significantly higher (P<0.05) duodenal non-ammonia N (g day(-1
)), Ensiling alfalfa did not alter ruminal degradation of forage N, th
e passage of duodenal microbial N (g day(-1)) and the apparent efficie
ncy of microbial N synthesis in the rumen (g kg(-1) organic matter app
arently digested in the rumen). Plasma levels of branched chain amino
acids in ewes fed frozen alfalfa were significantly higher (P<0.05) th
an in ewes fed silage. There were no treatment differences (P>0.05) in
the composition of amino acids flowing to the duodenum. Attempts to i
dentify proteins entering the duodenum indicated the presence of only
low molecular weight proteins below 40 kDa for sheep fed frozen alfalf
a and largely below 18 kDa for sheep fed silage. The results obtained
indicate that alfalfa protein is a source of highly degradable protein
with 13% and 10% undegradable protein in frozen and ensiled alfalfa r
espectively, and sheep fed alfalfa silage diets had less intestinal am
ino acid absorption compared with those fed frozen alfalfa.