Food and agricultural innovation pathways for prosperity

This introduction to the special issue deploys a framework, inspired by realist synthesis and introduced in Section 1, that aims to untangle the contexts, mechanisms, and outcomes associated with investments that link poverty reduction and rural prosperity within a broad agri-food systems perspective. Section 2 considers changes in contexts: Where are agricultural research investments most likely to be an engine of poverty reduction? Over the past 25 years, there have been profound changes in the development context of most countries, necessitating an update on strategic insights for research investment priorities relevant for the economic, political, social, environmental, and structural realities of the early 21st Century. Section 2 briefly surveys changes in these structural aspects of poverty and development processes in low-income countries, with particular attention to new drivers (e.g., urbanization, climate change) that will be of increasing salience in the coming decades. In Section 3, we turn to mechanisms: What are the plausible impact pathways and what evidence exists to test their plausibility? Poor farmers in the developing world are often the stated focus of public sector agricultural research. However, farmers are not the only potential beneficiaries of agricultural research; rural landless laborers, stakeholders along food value chains, and the urban poor can also be major beneficiaries of such research. Thus, there are multiple, interacting pathways through which agricultural research can contribute to reductions in poverty and associated livelihood vulnerabilities. This paper introduces an ex ante set of 18 plausible impact pathways from agricultural research to rural prosperity outcomes, employing bibliometric methods to assess the evidence underpinning causal links. In Section 4, we revisit the concept of desired impacts: When we seek poverty reduction, what does that mean and what measures are needed to demonstrate impact? The papers in this special issue are intended to yield insights to inform improvements in agricultural research that seeks to reduce poverty. History indicates that equity of distribution of gains matters hugely, and thus the questions of “who wins?” and “who loses?” must be addressed. Moreover, our understanding(s) of “poverty” and the intended outcomes of development investments have become much richer over the past 25 years, incorporating more nuance regarding gender, community differences, and fundamental reconsideration of the meaning of poverty and prosperity that are not captured by simple head count income or even living standard measures

Investigating soil and gut microbial communities and connections with child health in rural Kenya

Soils contain diverse and dynamic communities of microbes that interact with, and influence, microbiota in and on plants, animals, and humans. These exchanges, such as between soil and human microbiota, are part of a vast, integrated microbial ecosystem that underpins much of terrestrial life on Earth. This dissertation addresses relationships between soil microbiota and human microbiota, and their connections with human health. I approached these investigations by collecting and compiling a range of data spanning soil microbiota, child gut microbiota, health and disease factors, household characteristics, and biophysical landscape characteristics among 144 households across three rural counties in western Kenya. Using these data I first investigated the variation in gut microbial communities between children living in different rural environments, including agriculture, rural settlements, and uncultivated forest and shrubland landscapes. Although we did not find differences in child gut microbial diversity between children from these different landscapes, we found (1) significant differences in abundances of specific gut microbial taxa that are associated with health and disease, and (2) landscape-level differences in the taxa that discriminate children with a recent diarrheal episode from those without. These findings are initial evidence of a potential landscape association with the child gut microbiota, with implications for understanding childhood diarrheal disease burden. Next I investigated the relationship between the child gut microbial community and the soil microbiota in children’s households using a microbial source tracking approach. I found that the proportion of the gut microbiota attributed to soils (S2F proportion) varied among households, and in some was greater than a third, indicating a significant relationship between soil and gut microbiota at the household level. Furthermore I observed that S2F proportions were notably higher in households where I collected data later in the region’s seasonal rainy-dry cycle. Using three complementary regression modeling approaches, I examined potential correlates of S2F proportion from among the household and landscape biophysical data. I found stronger associations among soil and climate characteristics than among household and social factors, and soil pH and seasonal precipitation had the greatest association with S2F proportion. These results demonstrate the potential involvement of seasonal climate and soil properties in the relationship between the child gut microbiota and soil microbiota. Finally, I evaluated the capability of the soil and fecal microbiota to predict child and household characteristics using a series of machine-learning based classifier models. Utilizing only the fecal microbial data, the classifier successfully identified household-level landscape classes. With soil microbial data, the model successfully classified households by their landscape classes, soil classes, drinking water source, and season of sampling. A relatively small number of soil taxa were more important in the model’s performance, including taxa commonly found in the human gut. These findings indicate that a seasonal change in soil microbiota may influence the composition of the child gut microbiota in rural households. Altogether, this research presents novel evidence that household- and landscape-level exposures, including to soil microbiota, are strongly associated with the human gut microbial community, and that these associations hold potential implications for health and disease

Towards Sustainable Aquafeeds: Complete Substitution of Fish Oil with Marine Microalga Schizochytrium sp Improves Growth and Fatty Acid Deposition in Juvenile Nile Tilapia (Oreochromis niloticus)

We conducted a 84-day nutritional feeding experiment with dried whole cells of DHA-rich marine microalga Schizochytrium sp. (Sc) to determine the optimum level of fish-oil substitution (partial or complete) for maximum growth of Nile tilapia. When we fully replaced fish oil with Schizochytrium (Sc100 diet), we found significantly higher weight gain and protein efficiency ratio (PER), and lower (improved) feed conversion ratio (FCR) and feed intake compared to a control diet containing fish oil (Sc0); and no significant change in SGR and survival rate among all diets. The Sc100 diet had the highest contents of 22:6n3 DHA, led to the highest DHA content in fillets, and consequently led to the highest DHA: EPA ratios in tilapia fillets. Schizochytrium sp. is a high quality candidate for complete substitution of fish oil in juvenile Nile tilapia feeds, providing an innovative means to formulate and optimize the composition of tilapia juvenile feed while simultaneously raising feed efficiency of tilapia aquaculture and to further develop environmentally and socially sustainable aquafeeds. Results show that replacing fish oil with DHA-rich marine Sc improves the deposition of n3 LC PUFA levels in tilapia fillet. These results support further studies to lower Schizochytrium production costs and to combine different marine microalgae to replace fish oil and fishmeal into aquafeeds

Initial weight, final weight, weight gain, percentage weight gain, feed conversion ratio (FCR), specific growth rate (SGR), protein efficiency ratio (PER), feed intake, and survival rate of tilapia fed experimental diets.

<p>Initial weight, final weight, weight gain, percentage weight gain, feed conversion ratio (FCR), specific growth rate (SGR), protein efficiency ratio (PER), feed intake, and survival rate of tilapia fed experimental diets.</p

Formulation (g/100g diet) and proximate composition (%) and essential amino acids (% in the weight of diet as is) of five experimental diets for juvenile tilapia.

<p>Formulation (g/100g diet) and proximate composition (%) and essential amino acids (% in the weight of diet as is) of five experimental diets for juvenile tilapia.</p

Fatty acid (% of total fatty acids) content of fillets from Nile tilapia fed experimental diets for 84 days and 42 days sampling events; average ± SE for 15 fish per diet (5 fish/replicate with 3 replicates/diet)^§.

<p>Fatty acid (% of total fatty acids) content of fillets from Nile tilapia fed experimental diets for 84 days and 42 days sampling events; average ± SE for 15 fish per diet (5 fish/replicate with 3 replicates/diet)<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0156684#t006fn002" target="_blank">^§</a>.</p

Fatty acid content (% of total fatty acids) of experimental diets.

<p>Fatty acid content (% of total fatty acids) of experimental diets.</p

Linear correlation between the Sc inclusion levels in diet and DHA (mg/100g fillet) deposition in fish fillet.

<p>Each point represents the average value (±SE) of three tanks per diet. The amount of DHA is described by the function of y = 7.1423x + 155.8. The correlation coefficient (r) was 0.9459 (<i>p</i><0.01).</p

Fatty acid content (% of total fatty acids) of lipid sources (menhaden fish oil and whole cell dried <i>Schizochytrium</i> sp) used in the experimental diets.

<p>Fatty acid content (% of total fatty acids) of lipid sources (menhaden fish oil and whole cell dried <i>Schizochytrium</i> sp) used in the experimental diets.</p

Towards Sustainable Aquafeeds: Complete Substitution of Fish Oil with Marine Microalga Schizochytrium sp. Improves Growth and Fatty Acid Deposition in Juvenile Nile Tilapia (Oreochromis niloticus)

We conducted a 84-day nutritional feeding experiment with dried whole cells of DHA-rich marine microalga Schizochytrium sp. (Sc) to determine the optimum level of fish-oil substitution (partial or complete) for maximum growth of Nile tilapia. When we fully replaced fish oil with Schizochytrium (Sc100 diet), we found significantly higher weight gain and protein efficiency ratio (PER), and lower (improved) feed conversion ratio (FCR) and feed intake compared to a control diet containing fish oil (Sc0); and no significant change in SGR and survival rate among all diets. The Sc100 diet had the highest contents of 22:6n3 DHA, led to the highest DHA content in fillets, and consequently led to the highest DHA:EPA ratios in tilapia fillets. Schizochytrium sp. is a high quality candidate for complete substitution of fish oil in juvenile Nile tilapia feeds, providing an innovative means to formulate and optimize the composition of tilapia juvenile feed while simultaneously raising feed efficiency of tilapia aquaculture and to further develop environmentally and socially sustainable aquafeeds. Results show that replacing fish oil with DHA-rich marine Sc improves the deposition of n3 LC PUFA levels in tilapia fillet. These results support further studies to lower Schizochytrium production costs and to combine different marine microalgae to replace fish oil and fishmeal into aquafeeds