Deon Schlechter
WINDHOEK – Bush feed has become the most popular word in the vocabulary of drought-stricken Namibian farmers and communal, emerging and commercial producers are actively busy producing forage for suffering animals now that the drought has reached devastating proportions.
The use of bush fodder creates many new opportunities, but it also has many challenges. According to the Namibia Agricultural Union, there are many opinions and there are also different results in the field.
A project, under the auspices of the Livestock Producers’ Organisation (LPO), will soon kick off to investigate the interaction between raw materials and to look at different chemical additions.
The project will be done in collaboration with the University of Pretoria, under the Faculty of Natural and Agricultural Sciences.
“Success in the livestock industry starts with the quality of your forages,” says Feedmaster’s corporate brand specialist, Dawid Krause.
He says one measure of quality in forages is the percentages of acid detergent fiber (ADF) and neutral detergent fiber (NDF) they contain. The levels of ADF and NDF are critical because they impact animal productivity and digestion
An expert committee has been set up to oversee the LPO project and it is planned that the first part of the project (pilot project) will be launched this month with the initial analysis of various types of bush, cut in various ways (thicknesses and degrees of fineness). The main part of the project is planned for January/February 2020 and will involve the physical feeding of herds of cattle with bush feed and an analysis of the rumen material under different conditions.
“The fibrous component represents the least digestible fiber portion of forage or other roughage. This highly indigestible part of forage includes lignin, cellulose, silica and insoluble forms of nitrogen but not hemicellulose,” Krause explained to Farmers Forum.
Krause says NDF is the most common measure of fiber used for animal feed analysis, but it does not represent a unique class of chemical compounds. NDF measures most of the structural components in plant cells (i.e. lignin, hemicellulose and cellulose), but not pectin.
“Total digestible nutrients (TDN): The sum of the digestible fiber, protein, lipid, and carbohydrate components of a feedstuff or diet. TDN is directly related to digestible energy and is often calculated based on ADF. Fat is an energy source with 2.25 times the energy density of carbohydrates.
“Lignin fills the spaces in the cell wall between cellulose, hemicellulose, and pectin components, especially in vascular and support tissues: xylem tracheids, vessel elements and sclereid cells. The crosslinking of polysaccharides by lignin is an obstacle for water absorption to the cell wall,” he explains.
“Lignin has a digestibility value of near zero, provides little nutrient value and takes up space in the rumen. This is the most common problem in bush feed.
“Beef cattle can digest cellulose and hemicelluloses through rumen microbial action but cannot digest lignin. High ambient temperatures tend to increase plant lignification (production of the indigestible compound lignin), thus lowering digestibility in forages,” he says.