Fibre Sources

Fibre is essential to achieving good rumen health in dairy cows, which is the key to happy and productive animals.

Many fibre sources can be fed to dairy cows if they are supplemented with high-energy feeds and protein sources as part of a balanced diet. When pasture is limited and supplies of fodder reduced, farmers may be forced to consider using alternative fibre options they have not used before. These options vary widely in nutritive value, digestibility, and effective fibre value. They also may present risks such as rumen acidosis, mycotoxins, and chemical residues, so it is important to be cautious. Nutritional values of high-fibre by-products are particularly variable and feed analysis tests should be done before buying alternative fibre sources.

Some alternative fibre sources which may be available depending on seasonal circumstances and location include:

1. Cereal straws (barley, oat, triticale, wheat): Cereal straws are poor nutritional quality forages (very low in energy and protein) but are highly effective fibre sources. Their sole purpose in a cow’s diet is to help stimulate chewing and saliva production and maintain a fibre mat in the rumen. If fed at substantial levels, they will reduce performance due to very low energy content and low fibre digestibility.

2. Almond hulls: Almond hulls are a good forage extender, with medium effective fibre value when fed whole. They are a reasonable energy source with very good palatability but are low in protein. Almond hulls are available whole and milled, and whole hulls have a higher effective fibre value but a lower bulk density. Milled almond hulls provide no effective fibre. 

3. Rice straw: Like cereal straws, rice straw is a poor nutritional quality forage (very low in energy and protein) but a highly effective fibre source. Its sole purpose is to help stimulate chewing and saliva production and maintain a fibre mat in the rumen. Rice straw is high in silica and low in lignin compared to other straws and palatability and intake issues should be considered.

4. Sugarcane products: There are two main by-products of sugar production sourced from cane growers in NSW and Queensland: whole plant sugar cane forage (silage or hay), and sugar cane tops (hay). Both are low nutritional quality forages, but high in effective fibre values. They can vary widely in nutritive value depending on the age, variety and amount of frosting of the cane. Products are high in iron, magnesium, potassium, manganese, cobalt, and aluminum (which may interfere with phosphorus absorption) and silage may contain some significant residual alcohol (6-17 per cent).

5. Grape marc: Grape marc raw meal is a by-product of red and white wine production sourced from winemakers throughout Australia. It is a forage extender, not a grain replacer and varies widely in nutritive value. Whole seeds are largely indigestible and grape marc is high in tannins, low in pH, and may contain some residual alcohol. Buying grape marc in pelleted form may be an option. Potential advantages over raw grape marc are higher digestibility because grape seeds and skins are dried and hammer-milled before pelleting, less prone to mould growth, given dry matter content is much higher (approx. 90 per cent), and can be stored in a silo, rather than on the ground.

Fibre during heat stress

With daily feed intake reduced and more grain or concentrates being fed to maintain energy intake in hot weather, the quality and amount of fibre sources fed is critical. High-quality fibre is the best tool farmers have to maintain rumen stability and increase nutrient density without producing excessive metabolic heat.