SLU news

Silage additives improve the protein quality

Published: 09 April 2013

Silage additives enable better protein utilization from the forage and thereby reduces the need for concentrates in the feeding plans. A large proportion of the dairy cattle protein requirements can be obtained from forage containing high levels of crude protein. Giving cows much forage is also good for the their health, the environment and the farmer's economy.

A large proportion of the crude protein in forages is easily degradable in the rumen, which make the protein less utilized than if it were more stable in the rumen. What percentage of crude protein in silage that can be utilized by the cow depends on how the ensiling process was carried out. This was shown in an experiment in two parts with both a silages study and a production study conducted at SLU in Skara and at Lantmännen's experimental farm “Nötcenter Viken”.

Protein quality was analysed
By using a new protein fractionation method, not tested in Sweden before, the researchers could calculate from chemical analyses the percentage of the crude protein in the different silages that was stable in the rumen. In the study it was seen that the bacterial preparation “Kofasil Life” (equivalent to the bacterial preparation “Kofasil Lac”, approved in organic production) and the salted preparation “Kofasil Ultra” C (Addcon Europe GmbH) gave an increase in rumen stable proteins from 210 to 232 grams per kg crude protein. This increase means that more of the cow's protein needs can be met by forage and leads to about 0.5 kg of concentrate savings per cow and day.

The cows gained weight and had lower cell concentration in milk
The cows, which received silage treated with additives, increased 5 kg in weight on 20 days compared to when they ate untreated silage.

– The energy of this weight increase can be released when needed and used to produce nearly 2 kg of milk per cow and day. We saw no difference in consumption or milk yield but the cows milked already very good and had perhaps difficulties to produce additional quantities of milk, says Elisabet Nadeau, research leader at SLU.

- The cows getting treated silage also had a lower urea content in milk and urine as well as a lower cell concentration in milk compared with those who received the untreated silage. The lower level of urea can be explained by a better protein utilization, but why the cows had a better udder health is more difficult to explain but an exciting question to proceed with, says Elizabeth.

The project was funded by Agroväst’s milk program, Addcon Europe GmbH, Lantmännen /AIC Holland, VL Foundation and SLU.

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