Farm Animal Metabolism and Nutrition

infrequently adapted rumen microbial
ecosystem that is capable of more efficient
microbial protein synthesis. It is speculated
that the more efficient ecosystem observed
by Ishaque et al.(1971) may have excluded

those bacterial species having a high affinity

for fermenting amino acids. That such a

more efficient microbial ecosystem may

occur frequently is suggested further by the

results of Dove and Milne (1994). Dove and

Feed Intake in Ruminants 357

Table 16.5.Mean responses to LY29a,cand DICbexpressed as fraction of control diet.

LY29 Trial DIC

Response variable Bermuda Ryegrass Mixed diet Rye Mean

Dietary OM intake 1.47 1.14 1.15 1.87 1.41
Duodenal flow
OM 1.31 1.33 1.42 1.51 1.39
Ammonia 0.77 1.25 1.43 ND 1.22
TCA-insoluble protein 1.62 2.05 1.26 1.58 1.32
TCA-soluble protein 1.62 1.13 1.65 1.50 1.48
Total protein 1.41 1.65 1.61 1.54 1.55

aResponse to LY29 = response to 500 mg/response to 0 mg of LY29.
bResponse to DIC = response to 80 mg of DIC/response to 0 mg of DIC.
cResponse to LY29 to dose, P= 0.07.

Table 16.6.Mean (n= 6) ruminal metabolic characteristics and digesta flow in two groups of lambs that,
based on the proportion of propionate in their rumen, appear to have adapted different microbial ecosystems
while receiving equal and limited amounts of an 83 g CP kg^1 diet (summarized from Ishaque et al., 1971).

Group
Group 2/
Item 1 2 Group 1

DM intake, g day^1900900
Rumen characteristics
pH 6.06 6.10 1.01
Ammonia, mg (100 ml)^1 27.9 11.3 0.40
Total volatile fatty acids, mEq (100 ml)^1 101.8 132.0 1.30
Propionate, molar % 14.9 33.2 2.23
Duodenal digesta
DM flow, g day^1 186.0 291.0 1.56
Nitrogen, fraction of DM 0.037 0.042 1.14
Nitrogen, g day^1 6.9 12.5 1.82
Cellulose, dig 0.76 0.54 0.71
DAPAa, g 100 g^1 DM 0.108 0.162 1.50
DAPAa, g day^1 0.201 0.472 2.35
Duodenal N flow/N intake 0.57 1.04 1.82

Ruminal digestion (recalculated from data)

Estimated truly fermented DMb, g day^1712629 0.46
Estimated g BCP g^1 TFDMc 0.03 0.075 0.40
Composition of ruminal efflux: g g^1 duodenal DM
Non-ammonia nitrogen 0.23 0.25 0.90
Microbial protein nitrogen 0.125 0.144 0.87

aDAPA = diaminopimelic acid.
bEstimated as ((DM intake apparent ruminal indigestibility of energy) (DAPA flow/0.005 g DAPA g 1

microbial DM)).

cEstimated as ((DAPA flow, g day (^1) /0.01 g DAPA g (^1) microbial crude protein)/(estimated truly digested
DM)).