Improving forage and making bought-in feed savings

22 March 2011

Dairy farmers will be able to improve their forage value and make subsequent savings on bought-in feed of up to £4,000 for a 1,000 tonne clamp of grass silage, if they treat with an inoculant this season, according to IBERS trial findings. Those savings are attributed to significantly reduced silage dry matter losses from fermentation within the clamp and subsequent improved feed-out value.

Grass silage was made in mini silos by IBERS using two treatments under controlled laboratory conditions; four replicates were treated with the additive Lactobacillus plantarum NCIMB 30094, (strain specific to Volac) applied at the recommended rate of one million lactic acid producing bacteria per gram of grass and a further four left untreated. On analysis, there were statistically significant differences in the key values between the samples, due to the fermentation which, for the untreated silage contributed to a loss of over 14% dry matter (DM) compared with only 6% for the treated. See table 1.

Table 1. Analysis of treated v untreated silages

Source: IBERS 2008

“The analysis shows the pH is statistically significantly lower in the sample treated with Lactobacillus plantarum compared to the untreated silage, due to the treated silage’s higher lactic acid levels. In addition, the untreated silage has undergone a secondary fermentation by Clostridia bacteria resulting in production of butyric acid and ammonia. Furthermore the treated silage has retained more residual sugar (WSC),” explains Volac’s Dr Phil Jones. 

“Consequently the untreated silage has undergone a far less efficient fermentation; the DM losses in terms of CO₂ and NH₃ are 8% higher in the untreated forage, 14.33% compared with 6.25% for the treated forage.

“Translated into farm terms, a 1,000 tonne clamp of silage having a DM of 30% would contain 300 tonnes of DM.  A fermentation loss of 8% DM is the equivalent of 24t DM. The cost of replacing this amount of DM with concentrate at £200/tonne works out at £4,800. Treating 1,000 tonnes of silage with quality additive costs £1,000, consequently the cost benefits are significant at £3,800.”

Assuming fermentation losses of 8% and ignoring potential additional losses from effluent or aerobic spoilage, potential DM replacement costs can be estimated as in Table 2.

Table 2:  Cost of replacing silage dry matter with concentrate

Source: Volac

“IBERS states that in general, clamp DM losses average 25%, however, they can stretch up to a massive 70%.”

So when and where do these do losses occur? “They can happen at any stage throughout the process: in the field at harvesting through spillages, respiration, heating; during storage due to poor fermentation, effluent, heating and also at feed out, due to heating from aerobic spoilage and spillage.

“However, using a quality additive to deliver that vital one million lactic acid producing bacteria per gram of grass will encourage a fast and controlled fermentation with little protein breakdown, resulting in a silage that is not only nutritionally improved and more palatable, but also encourages increased intakes and better performance.”

He adds: “In view of the fact there is unlikely to be a reversal in bought in feed price trends in the coming year, then any opportunity to improve and exploit the value of farmers’ own resources has to be grasped. Investing in a quality inoculant is a sure safe way to improve returns, whatever the weather this season.”

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