Allometric equations for estimating aboveground biomass of Coffea arabica L. grown in the Rift Valley escarpment of Ethiopia

Coffee, Coffea arabica L., which is native to Ethiopia, is the world’s most widely traded tropical agricultural commodity. While much is known about the productivity and management of coffee for coffee beans little attention has been given to the plants overall biomass production and carbon sequestration. The objective of this study was to develop and evaluate allometric equations for estimating the aboveground biomass of C. arabica plants growing in indigenous agroforestry system in the Rift Valley escarpment of south-eastern Ethiopia. Coffee plays an important role in providing income and in sustaining these productive systems. Biomass harvesting of 31 plants with 54 stems was carried out in a 40 km² area varying in elevation from 1,500 to 1,900 m. The stem accounted for most (56 %) of plant biomass, followed by branches (39 %) and twigs plus foliage (5 %). Plant mean biomass was 22.9 ± 15.8 kg. Power equations using stem diameter measured at either 40 cm (d ₄₀) or at breast height (d, 1.3 m) with and without stem height (h) were evaluated. The square power equation, $ Y \; = \; b_{ 1} d_{ 40}^{ 2} $ , was found to be the best (highest ranked using goodness-of-fit statistics) for predicting total and component biomass. The reliability of the prediction decreased in the order: stem > branches > twigs plus foliage. A cross-validation procedure showed that equation parameterization was stable and coefficients reliable. Our parameterized square power equation for total aboveground biomass was also found to be better than the equations parameterized by Hairiah et al. (Carbon stocks of tropical land use systems as part of the global C balance: effects of forest conversion and options for clean development activities, International Centre for Research in Agroforestry, Bogor, 2001) and Segura et al. (Agroforest Syst 68:143–150, 2006) for C. arabica grown in agroforestry systems, confirming the importance of parameterization of allometric equations with site specific data when possible.     

Abattoir survey on cattle hydatidosis in Tigray Region of Ethiopia

A cross-sectional epidemiological study was conducted from November 2006 to October 2007 to determine the epidemiology of bovine hydatidosis in cattle slaughtered at Mekelle Municipal abattoir in Tigray Region of Ethiopia. A one-year long ante and post mortem examination of 4481 cattle slaughtered at the abattoir showed a prevalence of 32.1% (1,439) for hydatidosis. The percentage of hydatid cysts in different internal organs was observed as 25.62% in the lung, 12.56% in the liver, 0.47% in the heart, 0.17% in the kidney and 0.42% in the spleen, respectively. In this study, the lung was found to be the most predominantly affected organ (63.0%) followed by the liver (36.4%). As regards size of the cyst, the small sized cysts had the highest percentage (80.39%), followed by medium sized cysts (10.90%) and large sized cysts (8.69%). The monthly prevalence of hydatidosis was highest (36.44%) in July and lowest (25.11%) in April indicating that different seasons significantly affect its prevalence (χ² = 30.3013, d.f. = 11, and p = 0.003). Age, sex, breed and origin of animal didn’t have significant effect (p > 0.05) on prevalence of the disease; however, body condition score had statistically significant effect on the disease prevalence (χ² = 17.8481, d.f. = 2, p < 0.001). Of the 7,315 cysts examined for fertility and viability, 2349 (32.11%) were sterile, 3979 (54.39%) calcified, 782 (10.66%) fertile and viable while 205 (2.80%) were fertile but nonviable. It was observed that hepatic and pulmonary cysts had fertility rate of 11.75% and 13.83%, respectively. Out of the total cysts examined, the proportion of viable protoscoleces was 10.69%. The present study provides baseline data on the current status of the disease in the area.     

Effect of litterbags on rate of organic substrate decomposition along soil depth and geomorphic gradients

Purpose

The effect of litterbags on rate of organic substrate decomposition and how the magnitude of this effect varies depending on different soil and environmental variables remains poorly quantified. In this work, I determine the effect of mesh litterbags on decomposition of organic substrate at different landform positions and soil depths in a small, naturally eroding watershed.

Materials and methods

Results presented here are derived from an 18-month field decomposition experiment using a common substrate, wood. I monitored the rate of mass loss of wood as is and the same type of wood enclosed in litterbags constructed from nylon mesh material with 1-mm wide openings. The study was carried out in three to four depths each at four geomorphologically distinct landform positions along an undisturbed hillslope in Northern California.

Results and discussion

Enclosure of wood inside mesh litterbags significantly changed its rate of decomposition overall and the percent C and C/N ratio of the decomposing substrate, at an inconsistent rate at the different depths and landform positions. The highest change in mass loss due to bagging was observed on the surface of the soil, on the summit part of the hillslope where there was up to 80-times more difference in decay rate of bagged vs. not-bagged substrate. At depth, the effect of bagging on rate of mass loss reached a maximum of 10 times at 50 cm depth in the alluvial/colluvial plain at the base of the study hillslope.

Conclusions

Results from this study underscore the need to exercise caution when inferring rates of organic substrate decomposition in dynamic hillslope environments from litterbag decomposition experiments conducted on the surface of soil or flat landscapes.     

Prevalence of antibodies to peste des petits ruminants virus before and during outbreaks of the disease in Awash Fentale district, Afar, Ethiopia

The present study was conducted to assess the seroprevalence of peste des petits ruminants (PPR) in sheep and goats in Awash Fentale district, Afar, Ethiopia. Small ruminants in the district had poor herd immunity at the first visit and succumb to the disease then after. The seroprevalence during the time of an outbreak was much higher compared with the initial levels: 7.3% and 42.6% in sheep and goats, respectively. The higher seroprevalence figure in goats was suggestive of their relative susceptibility to PPR compared with sheep.     

Effect of replacing concentrate feed with leaves of Oldman saltbush (<Emphasis Type="Italic">Atriplex nummularia</Emphasis>) on feed intake,weight gain,and carcass parameters of highland sheep fed on wheat straw in northern Ethiopia

Atriplex nummularia (oldman saltbush) is widely planted on salt-affected land to provide a vegetative cover, which can be used as an alternative feed resource. The study was conducted to evaluate the replacement of commercial concentrate with oldman saltbush (SB) leaf on the feed intake, live weight gain, and carcass parameters of local sheep. Twenty-five sheep with an age of 6 months and weighting 14.60?±?2.47 kg were used in randomized complete block design and distributed into five equal groups, with five animals each. The selected sheep were fed with the dietary treatments for 2 weeks for adaptation and continued until the end of the study, which lasted for 90 days. In the control treatment (SB-0), sheep were fed 100% concentrate mix, while in SB-5, SB-10, SB-15, and SB-20, 5, 10, 15, and 20% of the concentrate mix was replaced by SB, respectively. Wheat straw and water were given at ad libitum throughout the experiment period. Data on feed intake and live weight gain were recorded daily and weekly, respectively, for 90 days. Three animals from each treatment were slaughtered for carcass analysis. Atriplex nummularia leaf (Oldman saltbush) contained 92.02% dry matter (DM), 21.99% crude protein (CP), 24.77% ash, 58.27% neutral detergent fiber (NDF), and 26.56% acid detergent fiber (ADF). Dry matter intake, live weight gain, and carcass parameter were not statistically different among the treatments. Result indicated that concentrate feed can be replaced with Atriplex nummularia leaf up to 20% in sheep diet without negative effect on growth performance and carcass characteristics.     

Seroprevalence and sero-conversion after vaccination against Peste des Petits Ruminants in sheep and goats from Awash Fentale District, Afar, Ethiopia

A cross-sectional epidemiological study followed by vaccination and postvaccinal serum antibody assessment against Peste des Petits Ruminants (PPR) in small ruminant population of Awash Fentale District, Afar, Ethiopia, was conducted from September 2006 to June 2007 with the aim of investigating seroprevalence and post-vaccination sero-conversion rate. A total of 1239 sera collected from sheep and goats which were not vaccinated, were screened by using nucleoprotein-based competitive enzyme-linked immunosorbent assay (c-ELISA). Only 21 (1.70%) animals were found to be positive. Following the base-line seroprevalence study, small ruminants in the area were vaccinated using the attenuated homologous PPR virus (Nigeria 75/1) strain vaccine, produced at National Veterinary Institute (NVI) in Debre-Zeit, Ethiopia. A total of 1096 small ruminants were resampled from the vaccinated population fourteen days after vaccination. The postvaccination sero-conversion rate in the population was found to be 61.13%, indicating a relatively weak herd immunity. The main reason for the low sero-conversion could be the thermolabile nature of the vaccine, since no statistically significant difference was observed between small ruminants vaccinated by Veterinary Professionals and Community Animal Health Workers (CAHWs), using Chi-squared test at 95% CI (P>0.05). This signifies the need for thermostable vaccine that could potentially increase the herd immunity in addition to that being administered by CAHWs independently. The current finding indicated that CAHWs could participate in vaccination campaigns in such areas as Afar, where there are few veterinarians despite of the huge livestock populations, as means of pastoralists' livelihood.