Bronwen Pihlwret, nutritional advisor at Quality Liquid Feeds (QLF), explains that grazed grass is naturally high in sugars, providing cows with a sufficient dietary supply. However, this isn’t the case once cows are brought indoors and fed a forage based diet.
“Compared to grazed grass, fermented silage is naturally lower in sugar. For example, average UK dietary sugar levels at housing are around 2% of dry matter (DM) and therefore supplementation is vital to maximise performance and push milk yields, particularly milk from forage,” she explains.
Research has shown that 5 to 7% of the overall DM should be provided as fermentable six carbon sugars in order to maximise dry matter intakes (DMI) and fibre digestibility.
“This level of sugar improves the rumen microbes’ ability to break down fibre and digest it more effectively, meaning producers should get more from their forage,” says Bronwen.
“However, it’s important to synchronise quickly available ERDP (Effective Rumen Degradable Protein) with quickly available FME (Fermentable Metabolisable Energy), found in sugar. If this isn’t achieved, it can cause huge inefficiencies.”
She points out that when grazing, the nitrogen and sugars in grass match closely.
“This changes once cows are housed and fed a grass silage with a much lower sugar content and the FME therefore needs to be replaced to help balance the ration.
“Sucrose, a six-carbon sugar found in molasses, is an ideal replacement due to its close synchronisation of degradability with the protein content of the grass silage,” explains Bronwen.
“Studies have found that six carbon sugars increase dry matter intakes (DMI), and fibre digestibility, much more effectively than five-carbon sugars, found in fermentation products such as wheat syrup,” she adds.
Supplementation will be particularly important this year as many farmers took the opportunity to take a later cut of silage this year due to the varied season.
“Silage produced later in the season has the potential to be wetter and lower in sugar content because of factors such as reduced daylight and lower temperatures. This will mean that most, if not all, of the sugar in the grass will be used up in the fermentation.
“Therefore, this forage will be naturally even lower in sugar than good quality first cut silages, and supplementation of sugar is therefore vital.”