No abstract

Nineteen tanniferous browse plants were collected from South Africa to investigate their digestibility, gas production (GP) characteristics and methane production. Fresh samples were collected, dried in forced oven, and ground and analyzed for nutrient composition. In vitro GP and in vitro organic matter digestibility (IVOMD) were determined using rumen fluid collected, strained and anaerobically prepared. A semi- automated system was used to measure GP by incubating the sample in a shaking incubator at 39°C. There was significant (p<0.05) variation in chemical composition of studied browses. Crude protein (CP) content of the species ranged from 86.9 to 305.0 g/kg dry matter (DM). The neutral detergent fiber (NDF) ranged from 292.8 to 517.5 g/kg DM while acid detergent fiber (ADF) ranged from 273.3 to 495.1 g/kg DM. The ash, ether extract, non-fibrous carbohydrate, neutral detergent insoluble nitrogen, and acid detergent insoluble nitrogen and CP were negatively correlated with methane production. Methane production was positively correlated with NDF, ADF, cellulose and hemi-cellulose. Tannin decreased GP, IVOMD, total volatile fatty acid and methane production. The observed low methanogenic potential and substantial ammonia generation of some of the browses might be potentially useful as rumen manipulating agents. However, a systematic evaluation is needed to determine optimum levels of supplementation in a mixed diet in order to attain a maximal depressing effect on enteric CH4 production with a minimal detrimental effect on rumen fermentation of poor quality roughage based diet.

Some medicinal plants have the tendency to manipulate the rumen microbial ecosystem, which in turn might reduce methane (CH4) emissions. The anti-methanogenic activities of leaf fraction of Piper betle, Aloe vera, Carica papaya, Azadirachta indica, Moringa oleifera, Tithonia diversifolia, Jatropha curcas and Moringa oleifera pods were studied at different doses. The plant materials were extracted with pure methanol and subsequently reconstituted at the rate of 25, 50, 75 and 100 mg in 1000 mL distilled water. Four mL of each plant extracts preparation was anaerobically incubated with 400 mg Eragrostis curvula hay in four replicates and the experiment was repeated five times. Plant extracts of P. betle and A. vera significantly increased total gas produced whereas other extracts recorded lesser or similar values to the control group. Leaf extracts of A. indica, C. papaya, J. curcas, M. oleifera, T. diversifolia and M. oleifera pods all significantly reduced CH4 volume at dosages of 25 and 50 mg/L due to the activities of their phytochemicals. Total volatile fatty acids and in vitro organic matter digestibility values recorded for all extracts were generally superior when compared with the control. Methane yield per unit of total gas were significantly lower in extracts of T. diversifolia, M. oleifera, A. indica, M. oleifera pods whereas it is higher in P. betle and A. vera. It can be concluded from the study that methanolic extracts of A. indica, C. papaya, J. curcas, M. oleifera, M. oleifera pods and T. diversifolia resulted in reduced CH4 production, and thus can be used potentially to manipulate rumen condition, improve feed digestibility and reduce enteric CH4 emission from ruminants. However, the in vitro results needs to be verified using in vivo studies by administering concentrated crude extracts at a rate of 25 mg or 50 mg per kg of roughage feed for small ruminants.

This paper summarizes effects of forage-legume intercropping on grain and fodder yield, land equivalent ratio, residual soil fertility, disease and insect pest reduction in mixed crop-livestock systems in Africa. In particular, it discusses the potential benefit of forage-legume intercropping in improving productivity, resource use efficiency and resilience of the system under climate change, which enhances adaptation to climate change and possibly provides the co-benefit of reducing greenhouse gases in sub-Saharan Africa. Research undertaken in Africa demonstrates that intercropping forage legumes with cereals improves overall yield and soil fertility, and reduces the risk of crop failure owing to rainfall variability, diseases, weeds and pests. When the forage from intercropped legumes is provided to animals it improves the digestibility of poor-quality feed, animal performance and efficiency of roughage feed utilization by ruminants. Additional role that legumes may play include lowering erosion and the loss of organic matter, reducing nitrogen leaching and carbon losses, and promoting carbon sequestration. Nitrogen fixed by legumes is safer than nitrogen from inorganic fertilizers. Despite the many benefits of forage legume intercropping the current adoption rate in sub-Saharan Africa is very low. Future research aimed at selection of compatible varieties, appropriate plant geometry and temporal arrangement of the various intercrops under different locations and management scenarios, as well as minimizing the confounding effects of water, soil, light, microclimate, and seeds could enhance adoption of the technology in Africa.

Objective The use of tannin extract and other phytochemicals as dietary additives in ruminants is becoming more popular due to their wide biological actions such as in methane mitigation, bypass of dietary protein, intestinal nematode control, among other uses. Unfortunately, some have strong astringency, low stability and bioavailability, and negatively affecting dry matter intake and digestibility. To circumvent these drawbacks, an effective delivery system may offer a promising approach to administer these extracts to the site where they are required. The objectives of this study were to encapsulate acacia tannin extract (ATE) with native starch and maltodextrin-gum arabic and to test the effect of encapsulation parameters on encapsulation efficiency, yield and morphology of the microparticles obtained as well as the effect on rumen in vitro gas production. Methods The ATE was encapsulated with the wall materials, and the morphological features of freeze-dried microparticles were evaluated by scanning electron microscopy. The in vitro release pattern of microparticles in acetate buffer, simulating the rumen, and its effect on in vitro gas production was evaluated. Results The morphological features revealed that maltodextrin/gum-arabic microparticles were irregular shaped, glossy and smaller, compared with those encapsulated with native starch, which were bigger, and more homogenous. Maltodextrin-gum arabic could be used up to 30% loading concentration compared with starch, which could not hold the core material beyond 15% loading capacity. Encapsulation efficiency ranged from 27.7%±6.4% to 48.8%±5.5% in starch and 56.1%±4.9% to 64.8%±2.8% in maltodextrin-gum arabic microparticles. Only a slight reduction in methane emission was recorded in encapsulated microparticles when compared with the samples containing only wall materials. Conclusion Both encapsulated products exhibited the burst release pattern under the pH conditions and methane reduction associated with tannin was marginal. This is attributable to small loading percentages and therefore, other wall materials or encapsulation methods should be investigated.

The use of crop modeling as a decision tool by farmers and other decision-makers in the agricultural sector to improve production efficiency has been on the increase. In this study, artificial neural network (ANN) models were used for predicting maize in the major maize producing provinces of South Africa. The maize production prediction and projection analysis were carried out using the following climate variables: precipitation (PRE), maximum temperature (TMX), minimum temperature (TMN), potential evapotranspiration (PET), soil moisture (SM) and land cultivated (Land) for maize. The analyzed datasets spanned from 1990 to 2017 and were divided into two segments with 80% used for model training and the remaining 20% for testing. The results indicated that PET, PRE, TMN, TMX, Land, and SM with two hidden neurons of vector (5,8) were the best combination to predict maize production in the Free State province, whereas the TMN, TMX, PET, PRE, SM and Land with vector (7,8) were the best combination for predicting maize in KwaZulu-Natal province. In addition, the TMN, SM and Land and TMN, TMX, SM and Land with vector (3,4) were the best combination for maize predicting in the North West and Mpumalanga provinces, respectively. The comparison between the actual and predicted maize production using the testing data indicated performance accuracy adjusted R2 of 0.75 for Free State, 0.67 for North West, 0.86 for Mpumalanga and 0.82 for KwaZulu-Natal. Furthermore, a decline in the projected maize production was observed across all the selected provinces (except the Free State province) from 2018 to 2019. Thus, the developed model can help to enhance the decision making process of the farmers and policymakers.

Tannin extracts have wide biological activity in ruminant nutrition. The possibility of masking their bitter taste and enhancing sustained release in the rumen can be achieved through encapsulation. The objectives of this study were to prepare an encapsulated Acacia tannin extract (ATE) suitable for ruminants using the solid-in-oil-in-water (S/O/W) method, and to evaluate the microparticles in terms of morphology, encapsulation efficiency and in vitro release under varying pH. Subsequently, the effect of the microparticles on rumen in vitro gas and methane production would be evaluated. Lipid microparticles were prepared using the double emulsion process with palm oil and lard, dichloromethane, and Tween80/Span80 emulsifiers. The microparticles produced by S/O/W emulsion tended to be smaller (P = 0.06), and had greater encapsulation efficiency compared with those produced by the melt dispersion method. Scanning electron micrographs showed microparticles had stable cylindrical and spherical shapes, with mean size of 34± 10.2 μm. Maximum encapsulation efficiencies of 78.6% and 80.1% were obtained with lard and palm oil as lipid wall materials, respectively, even under high core material loading percentage of 80%. Wall material type did not affect the characteristics of microparticles. In acetate buffer, only about 20% of tannin was released from the lipid-encapsulated microparticles into buffer media after 24 hours. In contrast, about 90% of the tannin had been released into solution before eight hours in the crude extract. Lipid-encapsulated ATE reduced rumen gas and methane production in vitro (P ˂0.05) in both Eragrostis and total mixed ration (TMR) diet substrates, but the magnitude of reduction was lower than that obtained when unencapsulated ATE was the additive (10% vs 20% for total gas and 17% vs 24% for methane). Crude ATE and palm oil encapsulated ATE reduced the concentration of methane in sampled gas (P = 0.054) when fermenting the TMR substrate, but this effect was not observed in the Eragrostis substrate. Ammonia nitrogen concentration was greater in encapsulated ATE compared with the crude ATE (P ˂0.001). These results show that the lipid-encapsulated ATE produced small-sized and more uniform microparticles, with high encapsulation efficiency compared with microparticles prepared by melt dispersion. Encapsulation of ATE enhanced the sustained release of tannin in the rumen, and with the potential to improve gas production and reduce methane production.

The study was conducted in Chifra district in Awsi-Resu zone of Afar Regional State to explore production objectives and strategies of sheep and goats in pastoral and agro-pastoral production systems. Cross-sectional survey with systematic random selection of 180 households (90 households from each production system was conducted. Descriptive statistics, t test, chi-square test, analysis of variance, and ranking method were employed in analyzing data using JMP-5 software. In pastoral production system, sheep and goat were primarily reared for household milk consumption, followed by live animal savings and income, while in agro-pastoral production system, sheep and goat are primarily reared for income, followed by household milk consumption and manure supply, as live animal savings. Overall mortality rates of sheep and goats (4 to >12 months of age) were 9 and 9.5 % in pastoral production systems while 7 and 6 % in agro-pastoral production system. Average age at first mating, kidding interval, days of mating after birth, weaning age, lactation length, litter size, slaughtering age, and marketable age of sheep and goats in pastoral production system were 7.4 months, 358 days, 29 days, 4.2 months, 3.1 months, 1.5 lambs, 7.4 months, and 14 months, respectively, while in agro-pastoral production system, they are 6.9 months, 353.3 days, 28 days, 3.2 months, 1.6 lambs, 6.4 months, and 14.5 months, respectively. It was concluded that production system-based development interventions could help to increase the productivity of sheep and goats and thereby enhance the livelihood of smallholders.