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1. The effects of Progut™ in dairy cows - practical
experiences in Finland 2006-2007
A. Efficacy and consistency of the results
The feeding of dairy cows in Finland is primarily based on grass silage, barley
and oats being the most typical energy sources. In normal feeding situations
Progut™ has consistently improved milk production and helped cows to utilise
home produced feeds better. Typically the rolling average of milk production
for the whole herd has increased by 50 to 100 kg / cow / month, after Progut™
containing feeds have been taken into use. This would mean from 600 to 1200
kg more milk per cow on yearly basis. Worth of mentioning is perhaps also an
unofficial Finnish record, 93.1 kg of milk per day, by a cow fed with Progut™
containing feed. Results have been particularly good with high feeding of good
quality silage and barley based concentrates (enough starch/energy). In these
cases the silage intake has often increased so that it has been possible to
lower the amount of the concentrate. The efficacy of Progut™ addition has
been variable in feeding situations with very unbalanced diets, like very low
starch content in feeding, especially low protein in the diet or extremely
high/low fibre content of the silage.
In early lactation the effects of Progut™ have usually been seen as an
increased milk amount already from the first or second week of usage. Protein
and fat content of milk have increased or remained the same. Cows in late
lactation (> 100 days from calving) have kept their production level better than
earlier (usually the daily milk production in this phase decreases 2-3 kg in
month). The addition of Progut™ has slowed down the normal decrease in
milk production during late lactation, improved the protein and fat content and
improved feed utilisation. It seems that feeding Progut™ in late lactation
changes the use of nutrients between milk production and tissue deposition,
thus decreasing the risk of fattening. In late lactation, the effects of Progut™
on daily milk yield and composition may sometimes slip unnoticed on the farm,
but a more exact follow-up of the results has shown to have a remarkable
effect on milk and component yield. This has been seen in individual followups of late lactation cows by monthly milk recordings.
B. Dose
Last autumn, Suomen Rehu added Progut™ into a compound feed and a halfconcentrate feed. In the compound feed the dose is 0.1 % (max. daily
allowance of the feed is 15 kg / cow / day, average daily allowance has been
lower) and in the half-concentrate feed the dose is 0.18 % (max. daily
allowance 8 kg). On average the used doses have varied between 10 and 15
grams per cow and day. Good responses have been obtained in normal
feeding systems and lower responses in feeding systems in which the daily
concentrate intake (and Progut intake) is lower than normal (e.g. milking robot
systems). This indicates that the dose of Progut should not be much lower
than 10 grams per cow and day.
2. Hydrolysed brewery yeast (Progut™) vs. other yeast
products for ruminants
A. The main differences - composition and modes of action
Hydrolysed whole yeast (Progut™) is a mixture of mannans, β-glucans,
nucleotides, amino acids and peptides. Unlike cell wall products, Progut™ also
contains the extract part of the yeast. This is why it contains remarkably more
oligosaccharides than the cell wall products. In the processing of cell wall
products most of the oligosaccharides are removed together with the extract.
Due to hydrolysation Progut™ also contains more oligosaccharide particles
than standard inactivated yeast (e.g. feed yeast).
Live yeast products for ruminants have been in the market for a long time and
the common belief among feed manufacturers is that yeasts have to be of the
“live” type for ruminants. One reason for this opinion is that there has not been
any good alternative dead yeast product for ruminants so far. Diamond V is
considered to be a dead yeast product. However, it's actually more a growth
substrate (in which yeast has been grown) than a yeast and it contains very
few yeast cells. It seems to have only limited effects on rumen fermentation as
we have shown in rumen simulation studies ("Progut application for
ruminants"). Typical dead yeast products (e.g. feed yeast) have also limited
effects in the rumen because those are not hydrolysed.
Research by Oezturk et al 2005 showed that the addition of live and
autoclaved (inactivated) Saccharomyces cerevisiae boulardii yeasts both
stimulated microbial metabolism, but no major differences were seen
between the live and dead form. However, it should be noticed, that the
inactivation of the yeast was done by autoclave (high moisture, temperature
and pressure), which not only inactivates the yeast but also breaks its cell wall
structures. It was concluded that yeast is utilised as a prebiotic rather than
probiotic agent (see a separate article).
However, our opinion is that the effect of yeast in the rumen is only partly due
to its prebiotic effect. The so called "quorum sensing" effect between yeast
and microbes is most likely more important. Yeast and microbes have always
been in competitive situation in the nature and microbes in the rumen are
"sensing" yeast or particles of yeast either dead or alive as "hostile strangers"
and start to grow and to produce VFA to survive. More information about the
topic can be found from PubMed at www.ncbi.nlm.nih.gov.
B. The special effect of Progut™ in the rumen is due to its
patented production process
The patented hydrolysis process of Progut™ breaks the yeast cell wall into
small pieces and thus there are more "hostile strangers" for rumen microbes.
This was actually seen in the trial at Hannover Veterinary High School. In this
trial (see Progut application for ruminants) the effects of Progut and less
hydrolysed brewery yeast (same raw material but about 3 times weaker
hydrolysis than in Progut) were studied. It was clearly shown that the addition
of Progut™ increased the production of total SCFA, acetic acid and
propionate. The effect of the less hydrolyzed brewery yeast on rumen
microbial metabolism was negligible.
C. The benefits of Progut™ compared with live yeast products
The effects of both Progut™ and live yeast products include increased rumen
microbial biomass and volatile fatty acid production. According to rumen
simulation studies at Alimetrics Ltd. 2006 ("Progut application for ruminants")
the effect of Progut™ on rumen fermentation was at least as good as the
studied live yeast product (YeaSacc).
As hydrolysed yeast Progut™ is stable in feed processing and storing. A live
yeast product should stay viable through variable storage times before and
after feed production. It should be stable in high feed processing temperatures
or should be added after pelleting. Potential problems in viability and stability
may reduce the efficacy of live yeasts in practice.
Live yeast cells may cause problems in cheese production with unpasteurised milk (like parmesan and emmenthal). For the potential
contamination risk the use of live yeast products is forbidden in the milk
production for parmesan cheese. The same risk exists also in milk production
for other special cheeses, in which the raw material is not pasteurised.