Improving rumen effciency
Rumendegradable protein is eventually broken
down into ammonia or incorporated intomicrobial
protein thatwill be available in the intestine.
Ammonia ends up in the bloodstreamand is
converted into urea in the liver. This urea is excreted
inmilk or urine, or recycled through the saliva or the
rumenwall. Itmay also serve as a nitrogen source
for rumenmicrobes. Recycling ofmicrobial protein
results in considerable loss of protein in the rumen
(Figure 1).
This leads not only to increased ammonia inmilk and
urea, but also to unnecessary energy losses.
Awell-knownmethod to optimise rumen effciency
is by balancing protein and energy in the rationusing
Provimi’s ration calculationprogram, PFOS. Another
method is to remove the protozoa fromthe rumen.
This is calleddefaunation. Theoretically, up to
40%moremicrobial proteinmay become available
for the ruminant by suppressionof protozoa.
Studies in sheephave shown that a substantial
improvement in effciency is obtainedwhere
rumenprotozoa are reduced as shown in Table 1.
Maximumrumen fermentation for optimal production
Figure 1. Protein metabolism in the rumen
Feed
Protein
Peptides
Aminoacids
Ammonia
Ammonia Urea
= Microbial protein
Undegradedprotein& starch
+Microbial protein +VFA
A
B
C
Many complex processes occur in the rumenof the dairy cow including the release of
protein and energy that canbe usedby the animal. Volatile fatty acids (acetic acid,
propionic acid, butyric acid) are formed andmicrobial protein is produced. Rumen
fermentation, however, alsoproduceswaste products. Some of thesewaste products
disappear in the formof gases like carbondioxide (CO
2
) andmethane (CH
4
). These
greenhouse gases harmthe environment and also represent losses of dietary energy.
Ineffciencies
Loss of nitrogen
Microbial proteinbreakdown
Imbalance in amino acids
A
B
C