Kamati, Magdalena Ilongeni2020-02-042020-02-042019http://hdl.handle.net/11070/2653A thesis submitted in fulfillment of the requirements for the Degree of Master of Science in Agriculture (Animal Science)Feed shortage, especially during dry seasons, is a critical threat to livestock production in Namibia. Innovative feed production from encroacher bush species has benefits of increasing fodder availability and controlling bush encroachment. Bush-based feed is characterized by high fiber and low protein content which makes it less palatable and digestible to livestock; hence often requires supplementation with commercial feed ingredients which increase bush feed production costs. This study was undertaken to identify, quantify and characterize the nutritive values of agro-industrial by-products (AIBPs) in Namibia as potential supplements for the bush-based feed. A survey conducted for a period of six months in 2018 (from March to September) targeting agricultural processing companies across Namibia identified a total of ten cereal by-products (sorghum brew residue, pearl millet bran, hominy chop, malt dust coarse, malt dust fine, malted barley, maize chop, wheat bran, traditional spent grains, and industrial spent grains), six oil seed-by-products (marula oil seed cake, olive oil press cake, jojoba oil press cake, !Nara oil press cake, press cake) and four horticultural by-products (potato peels, herb wastes, cull vegetables, and winery and spirits by-products). Cereal by-products can be available throughout the year and majority is sold at a price range of N$0.20-N$2.90/kg. Pearl millet bran and hominy chop had the highest yearly production volumes of about 60 000kg/year. The highest yearly production volume for oil seeds was 2000 kg. Majority of the oil seeds are mainly used as fertilizer and available from April to December. Most of the horticultural by-products are seasonally available, except for potato peels mainly from restaurants which have a year-round production. Chemical compositions, in vitro gas production, organic matter digestibility and metabolizable energy of some of the agro-industrial by-products identified were determined. The chemical compositions differed significantly (p≤0.05) among the cereal and oil seeds by-products categories. The Crude Protein (CP) contents (DM %) of the cereal by-products were in the range of 9 ±0.00 (Sorghum spent grains) to 21.95±0.29 (Brewer’s spent grains), while oil seed by-products CP were in the range of 7.55 (Olive (Olea europaea ) oil cake) to 37.30 ±0.20 (Marula (Sclerocarya birrea) oil press) and potato peels had 12.78±0.06% CP. Ether extract for the cereal by-products ranged from 1.37±0.06 (in Malt dust fine) to 9.29±0.06 (Pearl millet bran), 8.11±0.08 (in Manketti (Schinziophyton rautaneni) oil cake) to 53.59±0.08 (Marula oil cake) in oil seed by-products while potato peels (the only horticultural by-product analyzed) had 2.06±0.07% EE. Ash content (%DM) of cereal by-products ranged from 2.64±0.04 (Sorghum brew residue) to 5.39±0.02% (in Malt dust coarse) while for the oil seed by-product, the ash content ranged from 2.75±0.05 (Jojoba oil cake) to 5.31±0.00 (in Olive oil cake).The in vitro gas production, OMD and metabolizable energy also differed significantly (p≤0.05) among AIBPs. The organic matter digestibility (OMD) (% in dry matter (DM) basis) of the cereal by-products ranged from 55.55±0.50 (Brewer’s spent grains) to 83.50±0.50 (White maize chop) and in oil seed by-products OMD ranged from 38.95±0.15 (Marula oil press) to 59.35±0.15 (Jojoba oil cake). The metabolizable energy (ME) for the cereal by-products ranged from 9.30±0 MJ/Kg (Brewer’s spent grains) to 14.00±0.00 MJ/Kg (White maize chop) while for the oil seeds by-products ranged from 7.75±05 MJ/Kg (Manketti oil cake) to 15.95±05 MJ/Kg (Marula oil press) and potato peels had 11.05±0.05 MJ/Kg content of ME. Production volumes and high nutritive qualities of the agro-industrial by-products indicated their potential for utilization as energy and protein supplements for fibrous feeds low in crude protein and energy such as bush based feed in Namibia.enAgro-industrial productsSupplementsBush encroachmentBush-based feedThesis