Conservation of biomass for dairy rations via ensiling to optimize feed security in South Ethiopia

Feed conservation is a prerequisite for successful dairy production. The dairy sector plays a significant role in poverty alleviation for millions of smallholder farmers. In this regard, feed shortage was shown to be the major bottleneck for dairy development in Ethiopia. Based on their findings, researchers are making a lot of interventions to improve the dairy sector in the country. Yet, the interventions do not allow the dairy sector to fulfill the ever-increasing milk and milk product demand in the country. This is mainly due to the low attention given to feed production and conservation systems. Therefore, this PhD has considered feed conservation as the first priority for the dairy sector, aiming at improving feed security. Hence, as a first step, survey work was conducted with the objectives of assessing the existing dairy farming systems as well as the willingness of farmers to adopt new technologies. The survey work confirmed that feed shortage is the farmers' major problem in dairy production. More than 75% of the respondents are unaware of the technology of silage making, and feed conservation activities are limited mainly to dry crop residues. Smallholder farmers are showing interest in silages making from locally available crops. Therefore, in this dissertation, locally available biomass, being maize and banana crop by-products were selected for silage making. Hence, this dissertation tried to investigate the feasibility to apply silage technology on those crop by-products both at laboratory scale and in farm-scale studies. The second step in this research was to apply silage of fresh maize stover (FMS) and banana pseudostem (BPS) at laboratory scale under conditions prevailing in southern Ethiopia, and to monitor the dynamics of certain physical parameters and the microbial community. Laboratory scale fermentations were conducted in microsilos (4 kg capacity). FMS and BPS were included, both without and with the addition of molasses. All treatments, except for BPS without molasses, showed a significant reduction in pH. The BPS without molasses allowed the growth of Enterobacteriaceae longer than three other silage types, i.e. until 30 days. In all treatments, the yeasts and moulds and the Clostridium endospore counts were reduced within the early fermentation days and afterwards remained constant until day 90. Illumina MiSeq sequencing revealed that Leuconostoc, Buttiauxella species and Enterobacteriaceae were replaced by Lactobacillus, Weissella and Bifidobacterium species as the fermentation proceeded from day 0 to day 90. With these experiments, the feasibility of silage from two crop by-products was confirmed at laboratory scale. As a result, two candidate treatments, FMS without molasses and BPS with molasses were selected for the farm-scale study at farmers' level later in the work. A third objective of the PhD and the next step in the research was to ferment mixtures of the two crop by-products in different ratios. This was first implemented in the microsilos at laboratory scale. In this set-up, the FMS mixed with BPS resulted in a significant reduction of pH values. The lactic acid bacteria (LAB) counts reached a maximum in all treatments within 14 days. The Illumina MiSeq Sequencing also showed marked changes from the dominant aerobic bacteria species of Enterobactriaceae, Buttiauxella and Acinetobacter to anaerobic bacterial species of Lactobacillus and Bifidobacterium species. Different ratios of FMS and BPS showed a successful fermentation, and also a better aerobic stability than FMS without molasses. From this work, two specific mixtures (20% BPS plus 80% FMS, and 40% BPS plus 60% FMS) were selected for fermentation studies at local farms in the next chapter. Consequently, the fourth objective was to evaluate silage making at farm-scale. The selected treatments were T1 = 20% BPS plus 80 FMS, T2 = 40% BPS plus 60 % FMS, T3 = 100% FMS, and T4 = 95% BPS plus 5% molasses. The experiment was conducted using bags and drums with a capacity of 15 kg. During a period of 60 days, fermentation was conducted at two locations in the southern of Ethiopia, being Chano Dorga and Kolla Shelle, in the backyard of local farmers. In these experiments, the pH, microbial counts and nutritional value of mixed silages obtained using bags and drums were evaluated. The pH showed significant reduction in all treatments, fermentation conditions and locations. The effect of adding molasses may have contributed to the larger reduction in pH observed in T4 compared to the other treatments. In the microbial counts, T4 showed the lowest LAB as well as Clostridium spore counts after fermentation. The Enterobacteriaceae counts reached a level below the detection limit (1.00 log cfu/g) in all treatments fermented in drums, but not in bags. Though pH reduction was observed in the bags, damage of the bags was noticed during the silage period, making them less suitable than drums. The mixed treatments of T1 and T2 had a lower dry matter (DM) than T3. Though all the four treatments showed a significant increase in their crude protein (CP) content, the increases in the mixed treatments T1 and T2 were prominent as compared to T4 after fermentation. However, T2 revealed the lowest increase of 5.24%, 5.51% and 0.75 MJ/kg DM in the in vitro dry matter digestibility (IVDMD), the in vitro organic matter digestibility (IVOMD), and the metabolizable energy (ME), respectively. These results suggest that BPS and FMS can be fermented using drums rather than bags under the conditions prevailing for local farmers in the South of Ethiopia. The study provides possibilities for feed storage and contributes in this way to dairy feed security. Silage making needs continuous follow-up to result in a high-quality silage production. Therefore, for sustainable dairy development, the feed production and marketing systems should be inlined with the silage making. The silage making can also be commercialized by introducing chopping machines and ensilage material suppliers (such as drums). Moreover, affordable forage chopping machines should be designed and built. These technologies can be implemented with help of smallholder farmers, traders, youths of graduates from agricultural and technical colleges (to design and develop chopping machines). The silage making process should also be undertaken in collaboration with stakeholders working in feed production and processing in the area. Such collaborations will benefit both the dairy farmers and the market operators by providing machines for rent or sale. Further studies need to be undertaken in the first place on fermentation of other available forage crops, such as grasses and legumes (such as elephant grasses and alfalfa) grown under smallholder farmers, with a focus on the quality and safety of silages produced. These studies should include the quality parameters of microbial (Enterobacteriaceae, yeasts and moulds, Clostridium bacteria) and nutritional values of silage. Secondly, silage making should also be studied with respect to levels of yeasts and moulds and for the occurrence of mycotoxins. Thirdly, performance evaluation of different silage feeds with respect to milk production by dairy animals and milk quality is still a research field to be explored. Finally, the marketing and value chain development of milk and milk products in the area needs further exploration.

Publication year:2021

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