Stockfarm asked three experts in the field of animal feed to share their knowledge regarding the role that particle length plays in feed rations.
The long and the short of it
For Dr Ockert Einkamerer of the Faculty of Natural and Agricultural Sciences at the University of the Free State, ruminants’ feed requirements are first on the list.
“In terms of ruminant nutrition, fibre has certain nutritional and physiological properties, and it is important that its quality denotes its digestibility as well as its capacity to maintain rumen health. The right amount and correct length therefore support rumen health and milk fat, by stimulating adequate rumination.”
He says metabolic disorders can occur when rumen health is not maintained. “This means that while the diet may contain enough fibre, its physical form in the feed may not be adequate to stimulate rumination. Rumination is then reduced and the rumen pH can decrease. Ruminants therefore need enough coarse or long roughage to promote effective rumination. The total diet must also be balanced.”
The influence that particle length and the quality of roughage have on microbial fermentation and rumen health, also varies between fibre sources. Dr Einkamerer compares the influence of high-quality roughage (prime grade lucerne) on rumen function to that of lower-quality roughage (wheat straw/crop residues) with the same particle length.
“The latter is more effective in stimulating rumination than the former, although the lucerne fed to animals is cut very roughly with a particle length of more than 12,5mm. This type of roughage is almost ‘too good’, and it is quickly and efficiently fermented in the rumen. In order to stimulate rumination, the rumen requires longer or larger particles, usually of lower-quality roughage.”
If particles are not fine enough, they will not be able to move to the lower intestinal tract of cattle (4,5mm) and sheep (1,8mm). The reason for this, he explains, is that any particle exceeding 1mm has a low probability of moving from the rumen or reticulum of sheep and goats, to the lower intestinal tract. This may have a negative effect on intake and production; too much coarse material impairs intake and bypass through the intestinal tract, and a balance must therefore be maintained.
Differences in species
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