Making the most of your forage

As everyone is all too aware, the current milk price to concentrate price ratio is extremely unfavourable - so it will be absolutely vital to extract as much production from forage as possible this winter.

For the majority of milk producers plenty of scope remains for improvement. Benchmarking shows that, overall, little progress has been made in the last ten years in the amount of milk produced from forage. However, the gap in performance between the average and the best performing herds is wide - about 1700 litres per cow. In the long term, one of the keys to survivability and profit is milk per forage hectare. However, this winter, the aim is to get more milk out of the silage that has already been made, and to improve feed efficiency – the amount of milk produced per kilogram of feed eaten.

The first step is to have the forage analysed  to ascertain its potential. Frequent and accurate dry matter (DM) assessments of the silage being fed should also be carried out, in order to ensure the proportions in the diet are correct.

There are three interlinking factors that will then determine how much milk any silage will produce; the nutritional content, the forage intake, and, how much of the potential feed value can be extracted by the fibre-degrading bugs in the rumen. The nutritional potential is set - so the focus must be on intake and maximising digestibility.

To maximise intake it is vital to avoid any contamination of the feed offered to cows. It is now possible to have zero visible waste silage, using a combination of an effective inoculant, such as Axphast Gold, and a sheeting system which incorporates an effective oxygen barrier. This is very important, as just 5% of spoiled silage in the diet can reduce neutral detergent fibre (NDF) digestibility by up to 10%, as well as significantly reducing intake. If there is any spoiled silage on the shoulders or top of the pit, then remove it - do not try and feed it.

Surface spoilage on the open feed face must also be minimised. If a block cutter is used - maintain it and keep it sharp. The aim is to prevent air penetrating the silage as this can trigger aerobic spoilage or heating. As silage DM increases, so does the risk of heating, unless an effective inoculant has been used. An increase in temperature from 30°C to 50°C will reduce the “D” value by up to 10%.  

The level of the silage potential realised when it is fermented in the rumen largely depends on rumen pH. Fibre degrading microbes all work best at a higher pH. However, when concentrate is added to the diet, the microbial profile changes in response, and reduces rumen pH. This in turn reduces the effectiveness of the fibre degrading microbes. Each additional 1% of rumen degradable starch in the diet will reduce the rumen pH by 0.1%. This may not sound like much, but it is associated with a 3% reduction in NDF digestibility which will reduce efficiency.

Cows can buffer drops in rumen pH by producing large amounts of saliva - between 200 – 300 litres a day. For each hour a cow cuds, the buffering capacity of the saliva produced is equivalent to adding about 100g of sodium bicarbonate to the feed. However, the response to supplying additional sodium bicarbonate in the feed is variable. Its mode of action is indirect, as it stimulates water intake which in turn helps to dilute the fermentation acids in the rumen. It is important, therefore, to ensure every cow has unrestricted access to clean water - keep the water troughs spotlessly clean, add more troughs if necessary and ensure there is an adequate water flow.

Feeding a rumen specific live yeast is a proven method of raising rumen pH – which increases the level and activity of fibre digesting microbe and thereby increases fibre digestion. In a recent trial, the yeast component in Biotal SC Toxisorb was compared to 170g of sodium bicarbonate in high yielding dairy cows. The time spent below the rumen pH 5.8 threshold was reduced by 60% when the yeast was added, leading to a 6.5% increase in feed efficiency.

Maintaining a higher rumen pH is also the first defence against mycotoxins that may be present in the forage. There is a range of rumen microbes available which detoxify mycotoxins, but they work most efficiently at a higher pH. Several of the most common mycotoxins can reduce feed intake, rumen microbial efficiency and nutrient absorption.

With feed and forage costs typically making up 30 - 40% of the total cost of production, it pays dividends to closely examine all aspects of the winter feeding system to identify where savings and efficiency improvements can be made. 

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