Effects of graded levels of dietary pomegranate peel on methane and nitrogen losses, and metabolic and health indicators in dairy cows.

This study aimed to quantify the effects of dietary inclusion of tannin-rich pomegranate peel (PP) on intake, methane and nitrogen (N) losses, and metabolic and health indicators in dairy cows. Four multiparous, late-lactating Brown Swiss dairy cows (796 kg body weight; 29 kg/d of energy corrected milk yield) were randomly allocated to 3 treatments in a randomized cyclic change-over design with 3 periods, each comprising 14 d of adaptation, 7 d of milk, urine, and feces collection, and 2 d of methane measurements. Treatments were formulated using PP that replaced on a dry matter (DM) basis 0% (control), 5%, and 10% of the basal mixed ration (BMR) consisting of corn and grass silage, alfalfa, and concentrate. Gaseous exchange of the cows was determined in open-circuit respiration chambers. Blood samples were collected on d 15 of each period. Individual feed intake as well as feces and urine excretion were quantified, and representative samples were collected for analyses of nutrients and phenol composition. Milk was analyzed for concentrations of fat, protein, lactose, milk urea N, and fatty acids. Total phenols and antioxidant capacity in milk and plasma were determined. In serum, the concentrations of urea and bilirubin as well as the activities of alanine aminotransferase (ALT), aspartate aminotransferase, glutamate dehydrogenase, alkaline phosphatase, and γ-glutamyl transferase were measured. The data were subjected to ANOVA with the Mixed procedure of SAS, with treatment and period as fixed and animal as random effects. The PP and BMR contained 218 and 3.5 g of total extractable tannins per kg DM, respectively, and thereof 203 and 3.3 g of hydrolyzable tannins. Total DM intake, energy corrected milk, and methane emission (total, yield, and intensity) were not affected by PP supplementation. The proportions of C18:2n-6 and C18:3n-3 in milk increased linearly as the amount of PP was increased in the diet. Milk urea N, blood urea N, and urinary N excretion decreased linearly with the increase in dietary PP content. Total phenols and antioxidant capacity in milk and plasma were not affected by the inclusion of PP. The activity of ALT increased in a linear manner with the inclusion of PP. In conclusion, replacing up to 10% of BMR with PP improved milk fatty acid composition and alleviated metabolic and environmental N load. However, the elevated serum ALT activity indicates an onset of liver stress even at 5% PP, requiring the development of adaptation protocols for safe inclusion of PP in ruminant diets.

Nitrogen and energy losses and methane emissions from beef cattle fed diets with gradual replacement of maize silage and concentrate with grass silage and corn-cob mix.

Diets based on large proportions of grassland-based feed are uncommon in forage-based intensive beef production, thus contradicting governmental or commercial strategies to promote the use of grassland-based feed in ruminant production systems. Compared with typical maize silage/concentrate diets, grassland-based diets are associated with impaired nitrogen (N) and energy utilisation because of the comparably lower energy and higher CP content of these feeds. However, quantitative studies concerning the effects of increased dietary proportions of grassland-derived feeds on N and energy losses and utilisation and on methane emissions are missing and the compensation potential of using a limited proportion of an energy-rich forage is unknown. Therefore, we tested five diets with varying types and proportions of forage and concentrate. Three diets consisted of grass silage, maize silage, and concentrate in ratios of, g/kg DM, 100:600:300 (G100; control), 300:500:200 (G300), and 500:300:200 (G500), respectively. Two diets were composed of grass silage, corn-cob mix (CCM), and concentrate in ratios of, g/kg DM, 500:300:200 (G500CCM), and 750:150:100 (G750CCM), respectively. A high-protein concentrate (270 g CP/kg DM) was fed to G100, whereas a low-protein concentrate (140 g CP/kg DM) was used in the remaining diets. Diets were fed throughout the entire fattening period to groups of six Limousin-crossbred bulls each. When weighing 246 ± 18 kg, each animal underwent a 7-day total daily faeces and urine collection, which was followed by measuring methane emissions in respiration chambers for 48 h. Total DM intake was similar across all diets, whereas the N intake varied (P < 0.05). Urinary N loss (g/day) was the highest for G750CCM (28.2) and G100 (26.6) and lowest for G500CCM (15.2) and G300 (16.9) (P < 0.001). Energy utilisation was comparable among all groups. Metabolisable energy intake decreased numerically only with increasing proportions of grass silage in the diet. Substituting maize silage with CCM counteracted the loss in metabolisable energy intake. Absolute methane emissions were not different across the groups, but methane emission intensity (mg/g body protein retention) varied (P < 0.05), being numerically lower for G100 (349) and G500CCM (401) compared with the other groups (488 on average). In conclusion, the results show that the grass silage proportion in beef cattle diets can be substantially increased when strategically combined with energy-dense forages, such as CCM. This also limits the need for concentrate and additional protein sources; in addition, the associated urinary N emissions, which are potentially noxious to the environment, are avoided.

Herbage utilisation method affects rumen fluid and milk fatty acid profile in Holstein and Montbéliarde cows.

Compared with maize silage- and concentrate-based diets, herbage-based diets were repeatedly shown to favourably influence the milk fatty acid (FA) profile. However, it is unclear how the herbage feeding mode (grazing vs indoor green-feeding) and conservation (fresh herbage vs hay vs silage) modify the milk FA profile. Therefore, the aim of the present experiment was to investigate the effect of different herbage utilisation methods (including herbage feeding mode and herbage conservation method) on the ruminal biohydrogenation of dietary FA and the consequences on the milk FA composition in cows of two breeds (Holstein and Montbéliarde). Concomitant effects of botanical composition and phenological stage of the herbage on milk FA profile were controlled for by harvesting barn-dried hay and silage simultaneously as first cut from the same ryegrass-dominated grassland in a semi-mountainous region. Seven weeks later, the first regrowth of the same plot was used as fresh herbage, either grazed or fed indoor (indoor green-feeding). Twenty-four Montbéliarde and 24 Holstein cows were randomly allocated to four groups of 12 cows balanced by breed, parity, and milk yield. In a free-stall barn, three groups were given ad libitum access to hay, silage, or fresh herbage, respectively. The fourth group was strip-grazing. All cows were supplemented with 3 kg DM/day of the same energy-rich concentrate. After 2 weeks of adaptation to the forage, samples of forage, concentrate, milk, blood, and rumen fluid were collected. Fatty acid composition of forages, rumen fluid, and milk was analysed by gas chromatography. Haymaking reduced total FA content of the herbage, in particular that of linoleic acid (LA) and α-linolenic acid (ALA). Still, rumen fluid lipids of hay-fed cows had the highest proportion of rumenic acid, LA, ALA, and total polyunsaturated fatty acids (PUFAs). Milk fat from hay-fed cows had the highest proportion of LA, and the apparent transfer rates from feed to milk of LA and ALA were higher in hay-fed cows than in silage-fed cows. The proportion of PUFAs was highest in milk fat from grazing and indoor green-fed Montbéliarde cows and lowest in silage-fed cows of both breeds. In conclusion, the herbage utilisation method affects the ruminal biohydrogenation of LA and ALA, whereby herbage drying particularly increases their transfer from herbage to milk.

LINTUL-Cassava-NPK: A simulation model for nutrient-limited cassava growth.

A solid understanding of the dynamics of plant nutrient requirements and uptake from the soil is needed to provide robust fertilizer recommendations, timing of applications and nutrient use efficiency. Our objective was to develop and test the ability of the crop model LINTUL-Cassava-NPK to simulate biomass growth and yield of cassava under nutrient-limited conditions. We used experimental data from six fields located in three different agro-ecologies in Nigeria: Rainforest Zone- Ogoja and Ikom (Cross River), Rainforest Transition Zone - Ekpoma (Edo) and Guinea Savanna Zone - Otukpo (Benue) over two consecutive growing seasons from 2016 to 2018. Nutrient stress in the model was implemented by combining N, P and K nutrition indices (NI) to account for the interaction of multiple nutrient limitations for crop growth. Nutrient uptake was determined by balancing demand and supply of nutrient equivalents. We parameterized and calibrated the model using observations from an experiment conducted under optimal growing conditions in Edo during the 2016 planting season. The model was then tested with data from experiments conducted in the 2017 season in Edo, Cross River and Benue. The model captured the uptake patterns of N, P and K well. Uptakes of N, P and K, and storage root yield were predicted with a small root mean squared error of 5.1 g N m-2, 0.8 g P m-2, 3.3 g K m-2 and 308 g DM roots m-2, with an R 2 of 0.7 - 0.8 for linear relationships between simulated and observed values. The time course of development of nutrient-limited yield of green leaves, stems and storage roots were simulated reasonably well. In general, the model responded aptly to both nutrient omissions and varying amounts of NPK. These findings increase our understanding of nutrient limitations and N, P and K interactions on cassava growth and yield. The model provided insight into surplus amounts of nutrients in the soil at the end of the season and, specifically, the need to balance the supply of N and K for cassava. To our knowledge, this is the first tested cassava process-based model that includes the three macro-nutrients.

Effects on performance, carcass and meat quality of replacing maize silage and concentrate by grass silage and corn-cob mix in the diet of growing bulls.

Grass silage is barely used in intensive beef production, but it is unclear if its lower energy supply compared to maize-silage feeding really impairs growth performance. Diets with 100, 300, 500 or 750 g grass silage/kg dry matter replacing maize silage and concentrate were tested with or without dried corn-cob mix (CCM). Performance, carcass and meat quality were studied in 30 Limousin-sired bulls. Feeding grass silage, CCM, and concentrate in a ratio of 500:300:200 allowed to maintain a similar animal performance, carcass and meat quality compared to a conventional maize silage/concentrate diet. Increasing the dietary grass silage proportion to 750 g/kg decreased the shear force of the meat. The proportion of n-3 fatty acids in intramuscular fat increased with dietary grass silage proportion. Consequently, a strategic combination of grass silage with energy-rich forages may facilitate grassland-based feeding strategies in intensive beef production with favourable meat fatty acid profiles and a performance comparable to that with maize-silage based diets.

Effects of maternal high-energy diet and spirulina supplementation in pregnant and lactating sows on performance, quality of carcass and meat, and its fatty acid profile in male and female offspring.

The concept of developmental programming suggests that maternal excessive energy intake during intrauterine development could permanently affect the offspring's performance. Spirulina might alleviate adverse programming effects, but currently has only been shown to affect productivity and product quality of livestock when fed directly. Therefore, we investigated effects of supplementing 20 g spirulina/day to 20 gestating and lactating sows fed either a commercial or a high energy diet (HED), on performance and meat quality of their piglets fattened for 4 months. Control and HED offspring did not differ in growth and slaughter performance. Maternal spirulina supplementation impaired growth performance in male but not in female offspring. Physicochemical meat quality was not affected by any treatment. Maternal spirulina intake tended to improve the polyunsaturated fatty acids (FA)/saturated FA ratio without affecting n-6/n-3 FA ratio in offspring meat. The present findings indicate a sex-specific programming effect for offspring growth in response to maternal spirulina but not high energy intake in pigs.

Maternal and direct dietary polyphenol supplementation affect growth, carcass and meat quality of sheep and goats.

The beneficial effects of polyphenol intake such as improved nitrogen retention make them interesting feed supplements for ruminants. In contrast, dietary polyphenols may have adverse effects on the bioavailability of nutrients and palatability of the feed which might impair growth performance. The beneficial and adverse effects might differ between different ruminant species as well as between direct intake and intake of polyphenol metabolites via suckling when supplemented to lactating dams. This study investigated the effects of maternal and direct polyphenol supplementation via grape seed extract in sheep and goats on growth, slaughter performance, meat quality and fatty acid profile. The diet of lactating East Friesian Dairy sheep (n = 11) and Saanen goats (n = 9) and of their lambs (n = 16) and kids (n = 13), respectively, was supplemented either with grape seed extract (dams: 7.4% and offspring: 5.6%, P) or without (C). This resulted in four groups per species, namely maternalC/offspringC, maternalC/offspringP, maternalP/offspringC, and maternalP/offspringP. In lambs but not in goats, maternalP increased average daily gain and improved slaughter performance whereas offspringP had no effect. Maternal and offspring diet did not affect physicochemical meat quality in lambs, but direct intake of grape seed extract increased rancid aroma of burger patties. In goat kids, both maternal and offspring diets slightly affected meat colour. While groups of meat fatty acids (FAs) were not affected by diet in both species, maternalP in lambs as well as maternalP and offspringP in goat kids increased the meat n-6 to n-3 FA ratio compared to the respective control groups. In goat kid but not in lamb meat, direct intake of polyphenols affected the proportions of several rumen biohydrogenation intermediates. In conclusion, grape seed extract can be applied in both the maternal and offspring diets in sheep and goats while maintaining or even improving offspring growth performance and carcass quality. Only few species-specific effects of grape seed extract supplementation were observed, and additive effects were scarce. Larger studies are required to confirm the observed species-specific growth response to maternalP during lactation. The underlying reasons for this differential response need to be further evaluated.

Basket of options: Unpacking the concept.

How to stimulate technological change to enhance agricultural productivity and reduce poverty remains an area of vigorous debate. In the face of heterogeneity among farm households and rural areas, one proposition is to offer potential users a 'basket of options' - a range of agricultural technologies from which potential users may select the ones that are best suited to their specific circumstances. While the idea of a basket of options is now generally accepted, it has attracted little critical attention. In this paper, we reflect on outstanding questions: the appropriate dimensions of a basket, its contents and how they are identified, and how a basket might be presented. We conceive a basket of options in terms of its depth (number of options related to a problem or opportunity) and breadth (the number of different problems or opportunities addressed). The dimensions of a basket should reflect the framing of the problem or opportunity at hand and the objective in offering the basket. We recognise that increasing the number of options leads to a trade-off by decreasing the fraction of those options that are relevant to an individual user. Farmers might try out, adapt or use one or more of the options in a basket, possibly leading to a process of technological change. We emphasise that the selection (or not) of specific options from the basket, and potential adaptation of the options, provide important opportunities for learning. Baskets of options can therefore be understood as important boundary concepts that invite critical engagement, comparison and discussion. Significant knowledge gaps remain, however, about the best ways to present the basket and to guide potential users to select the options that are most relevant to them.

Feeding cows with hay, silage, or fresh herbage on pasture or indoors affects sensory properties and chemical composition of milk and cheese.

In European countries, silage-free feeding is an ancient tradition and has a particularly positive reputation among consumers. In the present study, we compared grass-based forages from the same plot conserved as hay or silage or fed fresh either on pasture or indoors, and we evaluated the differences in sensory properties of milk and uncooked pressed cheese. All herbage from the first cut of a grassland dominated by perennial ryegrass was harvested on the same day and preserved either as hay or silage. The first regrowth of the same plot was used for strip grazing or green feeding indoors. Balanced by breed, 24 Montbéliarde and 24 Holstein cows were allocated to the 4 treatments. Apart from the forages, the late-lactation cows received 3 kg/d of dry matter from concentrate. After 2 wk of dietary adaptation, the bulk milk of 3 subgroups, each with 4 cows, was collected. Part of the milk was pasteurized, and part was left raw and partly transformed to small-sized Cantal-type cheese ripened for 9 wk. Milk and cheese underwent descriptive sensory analysis by a trained sensory panel, as well as analyses of physicochemical traits. Volatile organic compounds of the cheeses were also analyzed. Raw and pasteurized milk from hay-fed cows had less intense odors of cooked milk, cream, and barnyard than milk from grazing cows, whereby the effect of pasteurization did not differ between herbage utilization methods. Cheeses obtained from cows fed fresh herbage (grazing and indoors) were clearly yellower than cheeses from silage- and hay-fed cows, which coincided with the color intensity perceived by the panelists. Moreover, cheeses from cows fed fresh herbage had more intense barnyard and dry fruit flavors, were perceived as creamier and having less lactic odor, and exhibited more fat exudation than those from cows fed conserved herbage. Only a few differences were observed in milk and cheeses from hay-fed compared with silage-fed cows, and those differences were far less pronounced than those of milk and cheeses from cows fed fresh herbage. In conclusion, the present study did not substantiate assumptions of clear sensory differences of milk and uncooked pressed cheese from hay-fed compared with silage-fed cows. For the first time, this study reports that the global flavor intensity of cheeses from indoor green-fed cows is similar to that of cheeses derived from cows fed conserved forages, whereas cheeses from grazing cows have the greatest global flavor intensity.

Phylogeography and Symbiotic Effectiveness of Rhizobia Nodulating Chickpea (Cicer arietinum L.) in Ethiopia.

Chickpea (Cicer arietinum L.) used to be considered a restrictive host that nodulated and fixed nitrogen only with Mesorhizobium ciceri and M. mediterraneum. Recent analysis revealed that chickpea can also establish effective symbioses with strains of several other Mesorhizobium species such as M. loti, M. haukuii, M. amorphae, M. muleiense, etc. These strains vary in their nitrogen fixation potential inviting further exploration. We characterized newly collected mesorhizobial strains isolated from various locations in Ethiopia to evaluate genetic diversity, biogeographic structure and symbiotic effectiveness. Symbiotic effectiveness was evaluated in Leonard Jars using a locally released chickpea cultivar "Nattoli". Most of the new isolates belonged to a clade related to M. plurifarium, with very few sequence differences, while the total collection of strains contained three additional mesorhizobial genospecies associated with M. ciceri, M. abyssinicae and an unidentified Mesorhizobium species isolated from a wild host in Eritrea. The four genospecies identified represented a subset of the eight major Mesorhizobium clades recently reported for Ethiopia based on metagenomic data. All Ethiopian strains had nearly identical symbiotic genes that grouped them in a single cluster with M. ciceri, M. mediterraneum and M. muleiense, but not with M. plurifarium. Some phylogeographic structure was observed, with elevation and geography explaining some of the genetic differences among strains, but the relation between genetic identity and symbiotic effectiveness was observed to be weak.

Effects of the substitution of soybean meal by spirulina in a hay-based diet for dairy cows on milk composition and sensory perception.

The demand for protein sources alternative to soybean meal for supplementing forages low in metabolizable protein is large. The suitability of spirulina (Arthrospira platensis), a fast growing and resource-efficient blue-green microalga, as a source of metabolizable protein for dairy cows is known, but its effects on milk antioxidants and sensory properties were never investigated. Twelve cows were allocated to 2 groups and fed hay-based diets complemented with sugar beet pulp and wheat flakes in individual feeding troughs. The N content per kilogram of DM was equivalent between the 2 diets. Diet of 1 group was supplemented with 5% spirulina; the second group was supplemented with 6% soybean meal (control). After an adaptation period of 15 d, data were collected, and feed, milk, blood, and rumen fluid were sampled. Feeds were analyzed for proximate contents, and blood plasma was analyzed for total antioxidant capacity and antioxidant contents (tocopherol, phenols). Milk samples were analyzed for fatty acid profile, coagulation properties, color, and contents of fat, protein, lactose, total phenols, lipophilic vitamins, and provitamins (e.g., ß-carotene). Triangle tests were performed by a trained sensory panel on 6 homogenized and pasteurized bulk milk samples per treatment. The substitution of soybean meal by spirulina in the diet did not affect feed intake, milk yield, milk fat, protein, or lactose contents compared with the control group. However, the milk from the spirulina-fed cows had a higher content of ß-carotene (0.207 vs. 0.135 µg/mL) and was more yellow (b* index: 14.9 vs. 13.8). Similar to the spirulina lipids but far less pronounced, the milk fat from the spirulina-fed cows had a higher proportion of γ-linolenic acid (0.057 vs. 0.038% of fatty acid methyl esters) compared with milk fat from soybean meal-fed cows. Also trans-11 C18:1 (vaccenic acid) and other C18:1 trans isomers were elevated, but otherwise the fatty acid profile resembled that of cows fed the control diet. No sensory difference was found between milk from the 2 experimental groups. Furthermore, we observed no effects of substituting soybean meal by spirulina on total antioxidant capacity, α-tocopherol and total phenols in blood and milk. Effects on rumen fluid characteristics were minor. In conclusion, spirulina seems to be a promising protein source for dairy cows with certain improvements in nutritionally favorable constituents in milk and without side-effects on animal performance in the short term.

Evaluating the effects of storage conditions on dry matter loss and nutritional quality of grain legume fodders in West Africa.

Feed scarcity is a major challenge for livestock production in West Africa, especially during the dry season when grass quality and quantity on grazing lands are inadequate. In the dry season, crop residues are a key source of livestock feed. The residues of grain legumes, also known as grain legume fodders (GLFs), are stored and traded for feeding in the dry season. The objectives of our experiment were to evaluate the effects of storage conditions and duration on dry matter (DM) and nutritional quality of GLFs, and to assess the risk of aflatoxin in stored groundnut fodder. The experiment was designed as a factorial trial with 18 treatment combinations with four replicates (4 farms). The treatments included: 3 types of GLFs (cowpea, groundnut and soybean fodder), 3 types of storage locations (rooftop, room and tree-fork) and 2 types of packaging (packed in polythene sacks and unpacked but tied with rope). Over a 120 day storage period, DM quantity reduced by an average of 24 % across all storage conditions, showing a range from 14 % in the best condition (sacks and rooms) to 35 % in the worst condition (bundles tied with rope and stored on rooftops or tree-forks). Soybean fodder had no leaves, the lowest crude protein content (CP) and organic matter digestibility (OMD), and the highest content of cell wall components compared to cowpea and groundnut fodder. These nutritional quality parameters in soybean fodder hardly changed during storage. Cowpea and groundnut fodder showed a decrease in leaf-to-stem ratio (LSR), CP and OMD, and an increase in the content of cell wall components during storage, but their nutritional value remained better than that of soybean fodder. Storage in sacks resulted in less DM loss, in less reduction of LSR and in a smaller increase of the content of cell wall components than storage of bundles tied with rope. Our study shows that the DM loss, the decrease in LSR, and the increase in the content of cell wall components can be prevented partly by storing GLFs in sacks instead of tying bundles with rope, and to a minor extent by storing in rooms instead of in the open air. Aflatoxin was not detectable in the groundnut fodder samples. Our results highlight that attention to storage conditions can improve the feeding value of GLFs which are key for livestock nutrition during the dry season.

Co-design of improved climbing bean production practices for smallholder farmers in the highlands of Uganda.

We evaluated the usefulness of a co-design process to generate a relevant basket of options for climbing bean cultivation in the context of a large-scale project. The aim was to identify a range of options sufficiently diverse to be of interest for farmers of widely-different resource endowment. The co-design process consisted of three cycles of demonstration, evaluation and re-design in the eastern and southwestern highlands of Uganda in 2014-2015. Evaluations aimed to distinguish preferences of farmers between the two areas, and among farmers of different gender and socio-economic backgrounds. Farmers, researchers, extension officers and NGO staff re-designed treatments for demonstrations in the next season. Climbing bean yields and evaluation scores varied between seasons and sites. Evaluation scores were not always in line with yields, revealing that farmers used multiple evaluation criteria next to yield, such as marketability of varieties, availability of inputs and ease of staking methods. The co-design process enriched the basket of options, improved the relevance of options demonstrated and enhanced the understanding of preferences of a diversity of users. Developing options for resource-poor farmers was difficult, however, because they face multiple constraints. The basket of options developed in this study can be applied across the East-African highlands, with an 'option-by-context' matrix as a starting point for out-scaling. The study also showed, however, that consistent recommendations about the suitability of technologies for different types of farmers were hard to identify. This highlights the importance of a basket of options with flexible combinations of practices rather than developing narrowly specified technology packages for static farm types.

Genetic Interaction Studies Reveal Superior Performance of Rhizobium tropici CIAT899 on a Range of Diverse East African Common Bean (Phaseolus vulgaris L.) Genotypes.

We studied symbiotic performance of factorial combinations of diverse rhizobial genotypes (GR) and East African common bean varieties (GL) that comprise Andean and Mesoamerican genetic groups. An initial wide screening in modified Leonard jars (LJ) was followed by evaluation of a subset of strains and genotypes in pots (contained the same, sterile medium) in which fixed nitrogen was also quantified. An additive main effect and multiplicative interaction (AMMI) model was used to identify the contribution of individual strains and plant genotypes to the GL × GR interaction. Strong and highly significant GL × GR interaction was found in the LJ experiment but with little evidence of a relation to genetic background or growth habits. The interaction was much weaker in the pot experiment, with all bean genotypes and Rhizobium strains having relatively stable performance. We found that R. etli strain CFN42 and R. tropici strains CIAT899 and NAK91 were effective across bean genotypes but with the latter showing evidence of positive interaction with two specific bean genotypes. This suggests that selection of bean varieties based on their response to inoculation is possible. On the other hand, we show that symbiotic performance is not predicted by any a priori grouping, limiting the scope for more general recommendations. The fact that the strength and pattern of GL × GR depended on growing conditions provides an important cautionary message for future studies.IMPORTANCE The existence of genotype-by-strain (GL × GR) interaction has implications for the expected stability of performance of legume inoculants and could represent both challenges and opportunities for improvement of nitrogen fixation. We find that significant genotype-by-strain interaction exists in common bean (Phaseolus vulgaris L.) but that the strength and direction of this interaction depends on the growing environment used to evaluate biomass. Strong genotype and strain main effects, combined with a lack of predictable patterns in GL × GR, suggests that at best individual bean genotypes and strains can be selected for superior additive performance. The observation that the screening environment may affect experimental outcome of GL × GR means that identified patterns should be corroborated under more realistic conditions.

Replacing sunflower oil by rumen-protected fish oil has only minor effects on the physico-chemical and sensory quality of Angus beef and beef patties.

In the present study, the effects of feeding 450 g/day of rumen-protected fish oil (FO) compared to sunflower oil (SO) to Angus heifers (60 g/kg total intake) were quantified. Animal performance was not affected whereas the physico-chemical meat quality, assessed in three muscles, was slightly affected by diet. The oxidative shelf life of the perirenal fat declined with FO compared to SO. Despite the formerly shown increased n-3 fatty acid proportions of meat due to FO supplementation, a trained sensory panel identified an only slightly more intense fishy flavour in grilled steaks and beef patties from the FO compared to the SO group. In FO compared to SO patties, flavour intensity was more pronounced. The perception of off-flavours was negligible and differences between muscles were larger than between diets. In conclusion, supplementing ruminants with FO containing nutritionally beneficial n-3 fatty acids results in few side-effects on meat quality, restricted to quite faint off-flavours and a shorter fat shelf life.

LEGUME-MAIZE ROTATION OR RELAY? OPTIONS FOR ECOLOGICAL INTENSIFICATION OF SMALLHOLDER FARMS IN THE GUINEA SAVANNA OF NORTHERN GHANA.

Soil nutrient constraints coupled with erratic rainfall have led to poor crop yields and occasionally to crop failure in sole cropping in the Guinea savanna of West Africa. We explored different maize-grain legume diversification and intensification options that can contribute to mitigating risks of crop failure, increase crop productivity under different soil fertility levels, while improving soil fertility due to biological N2-fixation by the legume. There were four relay patterns with cowpea sown first and maize sown at least 2 weeks after sowing (WAS) cowpea; two relay patterns with maize sown first and cowpea sown at least 3 WAS maize in different spatial arrangements. These were compared with groundnut-maize, soybean-maize, fallow-maize and continuous maize rotations in fields high, medium and poor in fertility at a site each in the southern (SGS) and northern (NGS) Guinea savanna of northern Ghana. Legumes grown in the poorly fertile fields relied more on N2-fixation for growth leading to generally larger net N inputs to the soil. Crop yields declined with decreasing soil fertility and were larger in the SGS than in the NGS due to more favourable rainfall and soil fertility. Spatial arrangements of relay intercrops did not have any significant impact on maize and legume grain yields. Sowing maize first followed by a cowpea relay resulted in 0.18-0.26 t ha-1 reduction in cowpea grain yield relative to cowpea sown from the onset. Relaying maize into cowpea led to a 0.29-0.64 t ha-1 reduction in maize grain yield relative to maize sown from the onset in the SGS. In the NGS, a decline of 0.66 and 0.82 t ha-1 in maize grain yield relative to maize sown from the onset was observed due to less rainfall received by the relay maize. Groundnut and soybean induced 0.38-1.01 t ha-1 more grain yield of a subsequent maize relative to continuous maize, and 1.17-1.71 t ha-1 more yield relative to relay maize across both sites. Accumulated crop yields over both years suggest that sowing maize first followed by cowpea relay is a promising ecological intensification option besides the more common legume-maize rotation in the Guinea savanna, as it was comparable with soybean-maize rotation and more productive than the other treatments.

The role of legumes in the sustainable intensification of African smallholder agriculture: Lessons learnt and challenges for the future.

Grain legumes play a key role in smallholder farming systems in sub-Saharan Africa (SSA), in relation to food and nutrition security and income generation. Moreover, because of their N2-fixation capacity, such legumes can also have a positive influence on soil fertility. Notwithstanding many decades of research on the agronomy of grain legumes, their N2-fixation capacity, and their contribution to overall system productivity, several issues remain to be resolved to realize fully the benefits of grain legumes. In this paper we highlight major lessons learnt and expose key knowledge gaps in relation to grain legumes and their contributions to farming system productivity. The symbiosis between legumes and rhizobia forms the basis for its benefits and biological N2-fixation (BNF) relies as much on the legume genotype as on the rhizobial strains. As such, breeding grain legumes for BNF deserves considerably more attention. Even promiscuous varieties usually respond to inoculation, and as African soils contain a huge pool of unexploited biodiversity with potential to contribute elite rhizobial strains, strain selection should go hand-in-hand with legume breeding for N2-fixation. Although inoculated strains can outcompete indigenous strains, our understanding of what constitutes a good competitor is rudimentary, as well as which factors affect the persistence of inoculated rhizobia, which in its turn determines whether a farmer needs to re-inoculate each and every season. Although it is commonly assumed that indigenous rhizobia are better adapted to local conditions than elite strains used in inoculants, there is little evidence that this is the case. The problems of delivering inoculants to smallholders through poorly-developed supply chains in Africa necessitates inoculants based on sterile carriers with long shelf life. Other factors critical for a well-functioning symbiosis are also central to the overall productivity of grain legumes. Good agronomic practices, including the use of phosphorus (P)-containing fertilizer, improve legume yields though responses to inputs are usually very variable. In some situations, a considerable proportion of soils show no response of legumes to applied inputs, often referred to as non-responsive soils. Understanding the causes underlying this phenomenon is limited and hinders the uptake of legume agronomy practices. Grain legumes also contribute to the productivity of farming systems, although such effects are commonly greater in rotational than in intercropping systems. While most cropping systems allow for the integration of legumes, intercropped legumes provide only marginal benefits to associated crops. Important rotational benefits have been shown for most grain legumes though those with the highest N accumulation and lowest N harvest index appear to demonstrate higher residual benefits. N balance estimates often results in contradictory observations, mostly caused by the lack of understanding of belowground contributions of legumes to the N balance. Lastly, the ultimate condition for increased uptake of grain legumes by smallholder farmers lies in the understanding of how legume technologies and management practices can be tailored to the enormous diversity of agroecologies, farming systems, and smallholder farms in SSA. In conclusion, while research on grain legumes has revealed a number of important insights that will guide realization of the full potential of such legumes to the sustainable intensification of smallholder farming systems in SSA, many research challenges remain to be addressed to realize the full potential of BNF in these systems.

Sustainable intensification through rotations with grain legumes in Sub-Saharan Africa: A review.

We conducted a systematic review of literature on the residual effects of grain legumes in cereal-based systems of sub-Saharan Africa (SSA) to quantify the magnitude and variability of rotational effects, to explore the importance of environmental and management factors in determining variability and to evaluate the evidence of the different mechanisms that explain rotational effects. We retrieved 44 unique publications providing 199 observations comparing continuous cereal performance with that of a grain legume-cereal rotation. The overall mean yield increase of 0.49 t grain ha-1, equal to an increase of 41% of the continuous cereal yield, is highly significant, but the variability in residual effects is large. Effects were more pronounced in southern Africa, the highlands of East Africa and the Guinea savannah, and less in the humid forest/derived savannah of West Africa and the Sudano-Sahelian zone. Maize showed stronger yield responses after a legume than millet and sorghum. Agro-ecological zone and cereal type were however confounded. All grain legume types significantly improved cereal yields, with stronger residual effects observed after soybean and groundnut than after cowpea. Fertiliser N application to cereals reduces the residual effects of legumes, but the response at 60-120 kg N ha-1 still equalled 0.32 t ha-1 or 59% of the response when no N is applied. The sustained benefits with large N applications indicate the importance of non-N effects. While mechanisms for improved soil P availability after grain legumes have been studied in some detail, it remains uncertain how important these are in farmers' fields. Grain legumes are unlikely to have a major influence on the availability of nutrients other than N and P, or on soil pH. Beneficial impacts of grain legumes on soil organic matter content can occur if legumes contribute to a greater overall cropping productivity, but studies generally report no such impacts. Evidence of impacts of grain legumes on weeds is limited to striga. Studies on the impacts on nematode pressure in cereals are inconclusive, probably because legumes act as a host for some of the key nematode genera that harm maize. The impact on the pressure of other pests and diseases in cereals is probably important, but evidence on this from SSA is lacking. Future research on N2-fixation by grain legumes and residual N benefits should focus on explaining the wide variability observed among sites. There is a clear need for more detailed mechanistic studies to assess the occurrence and relevance of non-N effects of grain legumes, particularly in relation to common pests and diseases in cereals.

Farmers' use and adaptation of improved climbing bean production practices in the highlands of Uganda.

Climbing beans offer potential for sustainable intensification of agriculture, but their cultivation constitutes a relatively complex technology consisting of multiple components or practices. We studied uptake of improved climbing bean production practices (improved variety, input use and management practices) through co-designed demonstrations and farmer-managed adaptation trials with 374 smallholder farmers in eastern and southwestern Uganda. A sub-set of these farmers was monitored one to three seasons after introduction. About 70% of the farmers re-planted climbing beans one season after the adaptation trial, with significant differences between eastern (50%) and southwestern Uganda (80-90%). Only 1% of the farmers used all of the improved practices and 99% adapted the technology. On average, farmers used half of the practices in different combinations, and all farmers used at least one of the practices. Yield variability of the trials was large and on average, trial plots did not yield more than farmers' own climbing bean plots. Yet, achieved yields did not influence whether farmers continued to cultivate climbing bean in the subsequent season. Uptake of climbing beans varied with household characteristics: poorer farmers cultivated climbing beans more often but used fewer of the best-bet practices; male farmers generally used more practices than female farmers. Planting by poorer farmers resulted in adaptations such as growing climbing beans without fertilizer and with fewer and shorter stakes. Other relationships were often inconsistent and farmers changed practices from season to season. The diversity of farmer responses complicates the development of recommendation domains and warrants the development of a basket of options from which farmers can choose. Our study shows how adoption of technologies consisting of multiple components is a complicated process that is hard to capture through the measurement of an adoption rate at a single point in time.

N2-fixation and N contribution by grain legumes under different soil fertility status and cropping systems in the Guinea savanna of northern Ghana.

Continuous cereal-based cropping has led to a rapid decline in soil fertility in the Guinea savanna agro-ecological zone of northern Ghana with corresponding low crop yields. We evaluated the effects of cropping system and soil fertility status on grain yields and N2-fixation by grain legumes and net N contribution to soil fertility improvement in contrasting sites in this agro-ecological zone. Maize was intercropped with cowpea, soybean and groundnut within a row, with a maize stand alternated with two equally spaced cowpea or groundnut stands and in the maize-soybean system, four equally spaced soybean stands. These intercrops were compared with sole crops of maize, cowpea, soybean and groundnut in fertile and poorly fertile fields at sites in the southern (SGS) and the northern (NGS) Guinea savanna. The proportion of N derived from N2-fixation (%Ndfa) was comparable between intercrops and sole crops. However, the amount of N2-fixed was significantly larger in sole crops due to a greater biomass accumulation. Legumes in poorly fertile fields had significantly smaller shoot δ15N enrichment (-2.8 to +0.7‰) and a larger %Ndfa (55-94%) than those in fertile fields (-0.8 to +2.2‰; 23-85%). The N2-fixed however was larger in fertile fields (16-145 kg N ha-1) than in poorly fertile fields (15-123 kg N ha-1) due to greater shoot dry matter and N yields. The legumes grown in the NGS obtained more of their N requirements from atmospheric N2-fixation (73-88%) than legumes grown in the SGS (41-69%). The partial soil N balance (in kg ha-1) was comparable between intercrops (-14 to 21) and sole legumes (-8 to 23) but smaller than that of sole maize receiving N fertiliser (+7 to +34). With other N inputs (aerial deposition) and outputs (leaching and gaseous losses) unaccounted for, there is uncertainty surrounding the actual amount of soil N balances of the cropping systems, indicating that partial N balances are not reliable indicators of the sustainability of cropping systems. Nevertheless, the systems with legumes seem more attractive due to several non-N benefits. Our results suggest that soybean could be targeted in the SGS and cowpea in the NGS for greater productivity while groundnut is suited to both environments. Grain legumes grown in poorly fertile fields contributed more net N to the soil but growing legumes in fertile fields seems more lucrative due to greater grain and stover yields and non-N benefits.