Growth performance and gum arabic production of Acacia senegal in northwest lowlands of Ethiopia

Despite the wide distribution of natural stands of Acacia senegal in Ethiopia, commercial exploitation of gum arabic is constrained by lack of tapping and development techniques. We evaluated the gum arabic yield from natural stands of A. senegal and the growth of 6 provenances in different parts of the country. For the gum yield evaluation from natural stands, four tapping positions and three tapping seasons were tested in a factorial RCB design. The second experiment in Metema evaluated survival and growth of six provenances. A. senegal trees in natural stands respond well to tapping if tapped during the appropriate season and at the correct position on the tree. The mean gum yield did not vary significantly by tapping season (p=0.63). Higher mean yield was, however, collected from trees tapped in October (96 g·tree^?1 per two harvests). The mean yield differed significantly (p=0.009) between the tapping positions. Mean separation (α=0.05) shows that trees tapped at mid stem gave higher yield (160 g·tree^?1 per two harvests). The interaction effect of tapping season and position was not significant. Higher mean yield ((70 ± 112) g·tree^?1) was recorded in mid October-mid stem in two harvests. The second experiment indicated statistically significant difference in mean survival (p=0.0298), height (p=0.000) and root collar diameter (RCD), (p=0.012) between the six provenances. Highest survival, height and root collar diameter growth was observed from Abderafi provenance (100%, (148±11) cm, (38±11) mm, respectively). We recommend October and mid-stem and branches as appropriate tapping season and position. We recommend planting of the Abderafi provenance for the study area due to its superior growth and survival. Our study contributes to the proper selection of provenances for plantation development and improved tapping technology for better production of gum arabic in the country.     

Diversified Investments of Wealthy Ethiopian Pastoralists Include Livestock and Urban Assets That Better Manage Risk

The Borana pastoral system has long been regarded as a model for sustainable resource use in eastern Africa. Recent growth in human and livestock populations, however, has contributed to a marked decline in rangeland condition, as well as increasing poverty. Another trend is fewer pastoralists controlling more resources. Today, for example, only 10% of households own 60% of all livestock. This wealthy minority has become increasingly important but has received little research attention. We wanted to learn how such elites perceive system change and how they innovate when accumulating or managing their assets. Twelve wealthy men were interviewed. They noted that the pastoral system is in sharp decline, with the most serious livestock-production constraints including chronic shortages of forage and labor. The average value of the physical and financial assets held by these men was estimated as at least USD $164,000, about 62-times that held by poor households. The average investment portfolio was composed of livestock (two-thirds of total value), while savings accounts in local banks and urban real estate (largely housing) made up the remainder. Livestock in general—and cattle in particular—were the riskiest physical assets given recurrent effects of drought and forage scarcity on animal productivity and mortality. When asked to identify future investment priorities, the men said that investing in urban real estate and their children was now preferred to investing in more livestock; their tradition of steady livestock reinvestment has thus changed. Recent urban growth in the rangelands has given the wealthy elite new investment options that offset heightened risks of animal losses. Urban investments are important because they could facilitate town development and provide incentives to improve range management via destocking. Outreach programs focused on the diversification of pastoral assets could include wealthy pastoralists as opinion leaders and accelerate positive change here.     

Moisture-dependent physical properties of niger (Guizotia abyssinica Cass.) seed

Moisture-dependent physical properties of niger (Guizotia abyssinica Cass.) seed were studied at 5.60, 12.99, 19.77, 27.08 and 31.65% moisture content (wet basis). The length, width, thickness and geometric mean diameter increased significantly (p < 0.05) from 3.86 to 4.06 mm, 0.96 to 1.02 mm, 0.86 to 0.96 mm and 1.47 to 1.59 mm, respectively with increase in moisture content from 5.60 to 31.65% whereas the increase in sphericity from 38.10 to 39.01% was not significant. Similarly, thousand seed mass, porosity and angle of repose increased (p < 0.05) linearly from 2.50 to 3.69 g, 41.76 to 47.65% and 29.86° to 39.12°, respectively with increase in moisture content under the experimental condition. The bulk density decreased significantly (p < 0.05) from 635.23 to 561.06 kg m^?3 with increase in the moisture content range considered in the study, whereas the true density showed a slight increase from 1090.71 to 1098.42 kg m^?3 with increase in moisture content from 5.60 to 27.08% followed by a drop from 1098.42 to 1071.75 kg m^?3 as moisture content increased from 27.08 to 31.65%. Coefficient of static friction increased (p < 0.05) logarithmically from 0.34 to 0.51, 0.38 to 0.56 and 0.13 to 0.53 on mild steel, plywood and glass surfaces, respectively with increase in moisture content from 5.60 to 31.65%.     

Rhizobia nodulating African Acacia spp. and Sesbania sesban trees in southern Ethiopian soils are metabolically and genomically diverse

The diversity of 110 rhizobial strains isolated from Acacia abyssinica, A. seyal, A. tortilis, Faidherbia albida, Sesbania sesban, Phaseolus vulgaris, and Vigna unguiculata grown in soils across diverse agro-ecological zones in southern Ethiopia was assessed using the Biolog™ system and amplified fragment length polymorphism (AFLP) fingerprinting technique. By cluster analysis of the metabolic and genomic fingerprints, the test strains were grouped into 13 Biolog and 11 AFLP clusters. Twenty-two strains in the Biolog method and 15 strains in the AFLP analysis were linked to eight and four reference species, respectively, out of the 28 included in the study. Most of the test strains (more than 80% of 110) were not related to any of the reference species by both methods. Forty-six test strains (42% of 110) were grouped into seven corresponding Biolog and AFLP clusters, suggesting that these groups represented the same strains, or in some cases clonal descendants of the same organisms. In contrast to the strains from S. sesban, isolates from Acacia spp. were represented in several Biolog and AFLP clusters indicating the promiscuous nature of the latter and widespread occurrence of compatible rhizobia in most of the soil sampling locations. The results showed that indigenous rhizobia nodulating native woody species in Ethiopian soils constituted metabolically and genomically diverse groups that are not linked to reference species.     

Prevalence of ovine and caprine oestrosis in Ambo,Ethiopia

A study was carried out to estimate the prevalence, larval burden and risk factors of ovine and caprine oestrosis from December 2007 to May 2008 on 554 heads of randomly selected sheep and goat slaughtered at Ambo town, Western Shoa, Ethiopia. The results show an overall prevalence of 59.9% with infection rate of 69.8% and 47.3% in sheep and goats respectively. No statistically significant difference in the prevalence was noted with regard to the assumed risk factors like sex, nose color, face color, horned versus polled, origin, and months (p > 0.05). Sheep were nearly twice more likely to be infected as compared to goats (p = 0.0001, odds ratio (OR) = 1.975). Age of the animals was found to be protective (OR = 0.579; 95% confidence interval = 0.393, 0.853; p = 0.006). As compared to very fat animals, poor (p = 0.040, OR = 4.834), medium (p = 0.049, OR = 4.198), and fat (p = 0.022, OR = 5.795) body condition animals are more likely to be infected by Oestrus ovis larvae. Nasal and sinus cavity pathology is positively correlated with the total larval count (r = 0.56, p < 0.0001). Out of a total of 3,770 larvae collected, 57.5% were L1, 30.8% L2, and 11.7% L3 larvae. All the three larval instars were seen throughout the study months. It is concluded that oestrosis is a common problem in the study area and more prevalent in sheep than goats, in adult than young, and in animals with poor body condition.     

Evaluating spawning performance among captive Florida pompano Trachinotus carolinus broodstock using microsatellite‐based parentage assignment

Florida pompano has been identified as a promising candidate for commercial‐scale aquaculture production, but to date, little information is available regarding captive broodstock spawning characteristics. Genetic markers were tested for their power in monitoring mating outcomes and potential in analysing heritability of rapid growth trait in Trachinotus carolinus. A total of 20 unrelated adults (10 females and 10 males) were chosen for a hormone‐induced mass spawning event. The 515 fastest growing and 485 slowest growing fish of the total 4852 offspring were considered a selected progeny stock, and fish were collected at 45 days post hatch based on their growth traits. Parentage analyses based on the 20 breeders and 1,000 selected progeny were performed using a total of nine microsatellite markers, a 100% assignment rate was achieved, and a four‐marker set was the minimum number for the parentage assignment. The effective breeding number for the selected progeny was 11 (six females and five males), among which three females and two males were predominant contributors with the total contribution of 95.8% and 94.7% respectively. The proportion of fast‐growing offspring from broodfish and each mating cross (sire/dam) was used for detecting whether variation in growth of the offspring was related to parental stocks. Results showed that three adults and their mated combination exhibited the greatest fast‐growing offspring proportion (69.73% and 55.95%). This research provided new information regarding spawning performance and parental contribution during mass spawning events; both important first steps towards developing improved management strategies for captive Florida pompano broodstock.