Propagation, Forage Production and Forage Quality of Some Ghanaian Browse Plants

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1996-01

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University of Ghana

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Experiments were carried out to examine the ease of establishment of some native browse species through both seed and stem cuttings, the forage production from these browse species and the nutritive quality of the forage produced as livestock feed. Five experiments were therefore conducted to address the problem. Experiment I: The objective of this experiment was to test in vitro techniques for breaking the dormancy of the seed of some native browse plants. Germination tests were performed, after no treatment (control) soaking in warm water, immersion in hot water and mechanical scarification, on the seed of ten browse plants namely: Cajanus cajan, Dialium guineense, Afzelia africana, Khaya senegalensis, Grewia carpinifolia, Pithecellobium dulce, Albizia lebbek, Milettia thonningii, Baphia nitida and Griffonia simplicifolia. The experimental design was 10x4 factorial arranged in a completely randomised design with four replicates. The factors were the ten browse species and the four seed treatment methods. Percentage germination was high (54-98%) with mechanical scarification for all the species except Grewia carpinifolia and Khaya senegalensis (11-16%). The other treatments also gave high percentage germination (above 48%) with the exception of Grewia carpinifolia, Khaya senegalensis and Dialium guineense which were very low (5-41%). Number of days taken to germinate in the different browse species was significantly shorter (P<0.05) for the scarified seed than the other treatments. Regardless of the type of treatment adopted Cajanus cajan and Milettia thonningii took the same time to germinate for all the treatments (3 and 4 days respectively). Mechanical scarification reduced the number of days to germination from 13.8 to 2.3 and 12.7 to 6.3 in Albizia lebbek and Afzelia africana respectively. For Grewia carpinifolia and Dialium guinegm'4 B^tn warm and hot water treatments increased the number of days to germination. The control and mechanical scarification were similar. Species differed significantly (P<0.05) in the rate of germination. Mechanical scarification increased the rate of germination of the species more than the other treatments. Experiment II: The objective of this experiment was to study the changes in plant height with time, the relative growth rate (RGR), net assimilation rate (NAR) and Leaf area ratio (LAR) of the browse plants. The seed of the browse plants used in Experiment I were planted in polybags and their RGR, NAR, LAR and dry matter accumulation were noted. The experimental design was a completely randomised design with 8 replicates. The RGR was highest (0.052 g g'1 d'1) in Cajanus cajan and lowest (0.021 g g'1 d'1) in Afzelia africana. The NAR ranged between (153 and 491) x 10'6 g cm'2d‘' with Cajanus cajan and Albizia lebbek accounting for the lowest and highest values respectively. LAR values ranged between 60 and 339 cm2 g'1 being lowest and highest in Pithecellobium dulce and Cajanus cajan respectively. Dry matter accumulation was highest in Cajanus cajan (280g) and lowest in Afzelia africana (4g). The NAR value of Cajanus cajan suggests that it was very poor in putting on dry material contrary to actual observation. Thus care should be taken when comparing species using their NAR values. Experiment III: The objective of this experiment was to study the sprouting ability as well as the growth rate of these native browse plants, using hardwood stem cuttings treated with a rooting hormone. Cuttings of all the browse plants mentioned in experiment I in addition to those of Spondias mombin and Ficus exasperata were planted in polybags with the aid of a rooting hormone. It was observed that, the establishment of the browse plants studied. The percentage seedling emergence was over 80% for all the species while the percentage plant survival to 16 weeks was over 78% for all the species reaching 100% in Cajanus cajan. Experiment V: The objective of this experiment was to study the feed quality of the forage produced in Experiment IV in the laboratory. The dry matter content of the species ranged between 302-703 g/kg. The dry matter yield of Afzelia africana (0.08 t/ha) was so low that enough was not available for the determination of NDF, ADF cellulose, hemicellulose and lignin. Average crude protein (CP) content for the six, seven and eight months period were 21.52%, 19.67% and 19.36% respectively and ranged between 14.76 - 25.00%. The calcium (Ca) content of the species ranged between 2.2-5.6% while the phosphorus (P) content ranged between 0.15 and 0.23% for all the species over the three periods. The In vitro dry matter digestibility (iVDMD) ranged from 44-63% with Cajanus cajan, the lowest value and Afzelia africana having the highest. The in situ disappearance after 48 hours of incubation for both DM and CP was in the range of 40-70% and 29-68% respectively. The most promising species for dry season supplementary feeding of ruminants from these studies were Albizia lebbek, Cajanus cajan, Milettia thonningii and Pithecellobium dulce. These forages when supplemented to ruminants especially during the dry season could play a vital role in the improvement of animal production. It is therefore suggested that very efficient management practices should be adopted in the propagation agronomy of these browse species so that enough would be available for dry season supplementary feeding. The work done so far should be extended to include studies with animals so as to ascertain the voluntary intake and in vivo dry matter digestibility and animal preference.

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Thesis (MPhil)-University o Ghana

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