Transition of Ethiopian highland forests to agriculture-dominated landscapes shifts the soil microbial community composition

Background

Land use changes and related land management practices significantly alter soil physicochemical properties; however, their effects on the soil microbial community structure are still unclear. In this study, we used automated ribosomal intergenic spacer analysis to determine the fungal and bacterial community composition in soils from different land use areas in the Ethiopian highlands. Soil samples were collected from five areas with different land uses, natural forest, eucalyptus plantation, exclosure, grassland and cropland, which had all historically been natural forest.

Results

Our results showed a significant shift in the soil bacterial and fungal community composition in response to land use change. We also identified soil physicochemical factors corresponding to the changes in bacterial and fungal communities. Although most soil attributes, including soil organic carbon, total soil nitrogen, labile P, soil pH and soil aggregate stability, were related to the change in bacterial community composition, the total soil nitrogen and soil organic carbon had the strongest relationships. The change in fungal community composition was correlated with soil nutrients, organic carbon, soil nitrogen and particularly the labile P concentration.

Conclusions

The fungal community composition was likely affected by the alteration of vegetation cover in response to land use change, whereas the bacterial communities were mainly sensitive to changes in soil attributes. The study highlights the higher sensitivity of fungal communities than bacterial communities to land use changes.

     

Concurrent comparison of energy intake and expenditure among adults in Butajira District, Ethiopia

OBJECTIVE: To estimate and compare dietary energy intake (DEI) and total energy expenditure (TEE) among adults, using questionnaires. DESIGN: Comparative, cross-sectional study. SETTING: Community-based, at the demographic surveillance site (DSS) in Butajira District of Ethiopia. SUBJECTS: A total of 619 adults, 18-64 years of age, were randomly selected from among the urban and rural population of Butajira using the DSS sampling frame. Habitual dietary intake and physical activity were assessed using questionnaires. BMR was estimated using a regression equation, and TEE was calculated from BMR and the metabolic energy equivalent task (MET) and duration of reported activities. Physical activity level (PAL) was calculated as TEE/BMR, while food intake level (FIL) was calculated as DEI/BMR. The mean DEI:TEE ratio was used to evaluate reported DEI at the population level, while individual misreporters were identified by applying the Goldberg cut-off points at three levels of PAL. RESULTS: Based on the Goldberg method, 57% of the study participants were identified as acceptable reporters of DEI, among whom mean TEE was 8.21 (95% CI 8.01, 8.42) MJ (1963 (95% CI 1914, 2012) kcal), mean DEI was 8.13 (95% CI 7.93, 8.34) MJ (1944 (95% CI 1895, 1993) kcal) and mean DEI:TEE was 1.01 (95% CI 0.99, 1.04). CONCLUSION: The dietary history and physical activity questionnaires provide comparable estimates of mean energy intake and expenditure at a population level. Acceptable reporters have to be identified in order to obtain better estimates. Questionnaire-based estimates of energy intake should not be interpreted without an inherent system of comparison or validation.     

Influence of variety and nitrogen fertilizer on productivity and trait association of malting barley

Poor soil fertility is a major constraint to crop productivity in the highlands of Ethiopia. This study was conducted to evaluate the effects of nitrogen (N) fertilization, variety and growing season on grain yield and yield related traits, and determine relationships among agronomic traits of malting barley. The treatments studied were five N levels (0, 23, 46, 69 and 92?kg ha^?1) and two malting barley varieties (Miscal-21 and Holker) over three growing seasons (2012, 2013 and 2014) at Bekoji, south eastern Ethiopia. The results revealed that as N rates increased, grain yield, number of tillers and spikes per square meter, biomass yield at harvest, days to physiological maturity, spike length and number of kernels per spike increased, but harvest index decreased. Grain yield, harvest index, number of tillers and spikes per square meter, spike length and biomass yield at harvest were greater in Miscal-21, whilst days to maturity and number of kernels per spike were greater in Holker. Grain yield, harvest index, number of tillers and spikes per square meter, spike length, biomass yield at harvest and days to maturity were significantly affected by seasonal conditions, but spike length and kernels per spike were not affected. Grain yield was positively influenced by the number of tillers per square meter, biomass yield at harvest, spikes per square meter, spike length, kernels per spike and harvest index. However, the number of tillers per square meter followed by biomass yield and spikes per square meter largely determined grain yield. The results of the current study suggest that genetic improvement of those yield related traits is the likely basis of increasing grain yield in barley.     

Contribution of roots and hyphae to phosphorus uptake of mycorrhizal onion (Allium cepa L.)—A mechanistic modeling approach

Phosphorus uptake by plant roots and arbuscular mycorrhizae (AM) hyphae can be described based on morphological and physiological uptake characteristics and parameters affecting P transport in the soil to the uptake surface. The current study aimed to quantify the relative contribution of hyphae and roots to P uptake of onion and to investigate the associated mechanisms using a mechanistic simulation model. Onion was grown in a growth chamber under controlled conditions at five levels of P supply with (M) or without (NM) AM. Uptake by onion roots and AM hyphae was simulated separately using a nutrient‐uptake model, which was developed for roots. Model parameters describing P transport in the soil, as well as morphological and physiological uptake characteristics of roots and hyphae were derived from soil and nutrient‐solution experiments. The model fairly described P uptake of M and NM plants at the highest level of P supply (28 µM P in soil solution) where roots and hyphae contributed nearly equally to P uptake of M plants. However, at lower P levels (≤0.41 µM P), hyphae accounted for nearly the whole P uptake whereas roots hardly explained any uptake. The effectiveness of AM hyphae at low P supply was well explained by their favorable morphological and physiological uptake properties. Hyphae were characterized by a diameter of 3 × 10^–4 cm, a K_m of 0.25 µM, and a C_min of 0.04 µM, values that are about 200, 40, and 10 times lower, respectively, compared to those of roots. Not more than 60% of the uptake at lower levels of P supply could be explained by the sum of predicted uptake of roots and hyphae suggesting that hyphae and roots may have used mechanisms additional to those described by the model to mobilize P. This work demonstrated that mechanistic models can be useful tools to study the role of AM in P uptake of plants, although reliable estimation of model parameters, especially physiological uptake properties of AM, is still limiting this approach.     

Technology transfer pathways and livelihood impact indicators in central Ethiopia

A survey was conducted in central Ethiopia to elicit information on existing and potential dissemination pathways for technical information on donkey husbandry. A detailed socio-economic survey was also conducted to provide background information on the people and the region, and livelihood indicators were drawn out at the same time. The results showed that there are many opportunities for group dissemination by making use of existing social networks. There are also opportunities for dissemination through extension agents, farmer groups and radio broadcasting.     

Performance of Arsi-Bale sheep fed urea treated maize cob as basal diet and supplemented with graded levels of concentrate mixture

The experiment was conducted using 20 yearling intact male Arsi-Bale sheep with a mean body weight of 20.56?±?0.45 (mean?±?SD) to investigate the performance and economic benefit of graded levels of concentrate supplementation to urea-treated maize cob (UTMC)-based diet. The experiment consisted of 7 days of digestibility trial and subsequent 90 days of feeding trial. Before the commencement of the experiment, sheep were vaccinated against common infectious diseases, dewormed, and disinfected against internal and external parasites, respectively. The experimental design was randomized complete block design. The sheep were grouped into five blocks of four animals based on their initial body weight, and one animal from each block was randomly assigned to one of the four treatments. The treatments included ad libitum feeding of UTMC (T1) and supplementation with a concentrate mixture composed of wheat bran (WB) and noug seed cake (NSC) in 2:1 ratio, which were offered at 150 g (T2), 250 g (T3), and 350 g (T4) DM/head/day. The CP content of the UTMC was 9.3% on DM basis. The daily DM intake of UTMC was higher (P?<?0.001) for T4 (614.6 g) compared to T1 (505.1 g), T2 (538.9 g), and T3 (590.3 g). Total DM intake was higher (P?<?0.001) for supplemented treatments T2 (688.4 g), T3 (844.1 g), and T4 (966.9 g). Supplementation did not improve (P?>?0.05) digestibility of DM, OM, NDF, and ADF, except CP digestibility which was significant (P?<?0.001) across treatments. Supplementation increased (P?<?0.001) final body weight (FBWT), feed conversion efficiency (FCE), and average daily weight gain (ADG). The average daily gain (ADG) was highest (P?<?0.001) in T4 (80.8?±?7.74 g/day) followed by T3 (33.3?±?7.74 g/day) and T2 (23.1?±?0.95 kg) whereas the un-supplemented animals lost about 9.2 g/day. The highest total return, net income, and marginal rate of return were observed in higher level supplemented sheep than the control. Therefore, T4 improved biological performance and marginal rate of return than the other treatments and can be considered as better alternative feed supplement in UTMC-based feeding of Arsi-Bale sheep in Ethiopia.     

Analysis of milk-derived isolates of E. coli indicating drug resistance in central Ethiopia

Mastitis is one of the most important diseases in dairy cows throughout the world and is responsible for significant economic losses to the dairy industry. This study was performed to characterize the genetic basis of drug resistance in Escherichia coli isolated from cases of clinical and sub-clinical bovine mastitis. A total of 224 California mastitis test (CMT)-positive milk samples were collected from December 2015 to April 2016 to characterize the phenotypic and genetic basis of antimicrobial resistance in E. coli isolated from raw milk from dairy farms found in Burayu, Sebeta, and Holeta areas of Ethiopia. The prevalence of E. coli was 7.1% (16) and both phenotypic and molecular techniques were used to identify E. coli antimicrobial susceptibility trait. The most commonly observed phenotypic resistance was against ampicillin (68.7%), sulphamethazole-trimethoprim (50%), and streptomycin (25%). Multidrug resistance phenotypes were found in 11 of 16 (68.7%) of E. coli isolates. Tetracycline (tet (A)) and chloramphenicol (cml (A)) genes were the most predominant encoding resistance genes identified (50%) each, followed by gentamycin resistance encoding gene (aac (3)-IV) (37.5%). Overall, 11 (68.7%) of the isolates had multidrug resistance genes responsible to two or more classes of antibiotics. The most common pattern detected was cml (A) and tet (A) together 37.5% followed by aac (3)-IV and tet (A) 25%. The current study indicated that raw milk could be regarded as critical source of antibiotic-resistant pathogenic E. coli.

     

Effect of Embryo Density on In vitro Developmental Characteristics of Bovine Preimplantative Embryos with Respect to Micro and Macroenvironments

To overcome developmental problems as a consequence of single embryo culture, the Well of the Well (WOW) culture system has been developed. In this study, we aimed to examine the effect of embryo densities with respect to both microenvironment and macroenvironment on developmental rates and embryo quality to get a deeper insight into developmentally important mechanisms. WOW diameter and depth significantly affected developmental rates (p < 0.05). WOWs with diameter of 500 μm reached significantly higher blastocyst rates (32.5 vs 21.1% vs 20.3%) compared to embryos cultured in WOWs of 300 μm diameter or plain cultured controls. Embryos cultured in WOWs with 700 μm depth reached significant higher developmental rates compared with embryos cultured in WOWs of 300 μm depth and control embryos (30.6 vs 22.6% vs 20.3%). Correlation of the embryo per WOW volume with developmental rates was higher (r² = 0.92, p = 0.0004) than correlation of WOW diameter or WOW depth with developmental rates. However, the embryo per WOW volume did not affect differential cell counts. An embryo per culture dish volume of 1 : 30 μl was identified to be optimal when the embryo per WOW volume was 1 : 0.27 μl increasing developmental rates up to the level of mass embryo production. Giving the opportunity to track each embryo over the complete culture period while keeping high developmental rates with normal mitotic dynamics, the results of this work will provide benefit for the single culture of embryos in human assisted reproduction, mammalian embryos with high economic interest as well as for scientific purpose.