Cowpea and Groundnut Haulms Fodder Trading and Its Lessons for Multidimensional Cowpea Improvement for Mixed Crop Livestock Systems in West Africa

Cowpea is an important legume crop in Africa, valued highly for its grain and also haulms, which are a tradable commodity in fodder markets. Fodder market surveys in Northern Nigeria showed that groundnut haulms were priced higher than cowpea haulms, probably because of their superior nutritive value. The economic value of haulms has prompted cowpea breeders and livestock nutritionists to explore haulm fodder traits as additional selection and breeding criteria. Fifty cowpea genotypes cultivated across five locations in Nigeria in 2013 and 2014 were evaluated for food fodder traits. Significant (P < 0.05) genotypic dependent variations were observed in yields (kg/ha) of grains (537-1082) and haulms (1173-3368), though significant (P < 0.05) effects of location and year were observed. Grain and fodder yield had a tendency to be positively correlated (r = 0.26, P = 0.07). Haulms were analyzed for nitrogen (N), fiber fractions, in vitro digestibility, and metabolizable energy content. Highly significant variations were observed in all genotypic and livestock nutrition traits, although location and year had significant effects. Trade-offs between grain yield and haulm fodder quality traits were largely absent and haulm acid detergent lignin and grain yield were even inversely correlated (r = -0.28, P = 0.05), that is high grain yielders had decreased haulm lignin. However, haulm N and grain yield also tended to be negatively associated (r = -0.26, P = 0.07). Haulm fodder quality traits and haulm yield were mostly positively correlated (P < 0.05). Broad sense heritabilities for grain and fodder yield were 0.50 and 0.29, respectively, while heritability for haulm fodder quality traits ranged from 0.61 to 0.67, providing opportunities for concomitant increase in grain yield and haulm fodder quality traits. Selection of the 10 highest ranking genotypes for grain yield, haulm yield, haulm N, and haulm in vitro organic matter digestibility showed selection groups overlapping, suggesting that multi-trait selection is feasible. Economical evaluation showed that choice of primary traits is context specific, highlighting the need for identifying and targeting appropriate genotypes to fit different production systems. Considering haulm quantity and quality as traits of economic value can increase overall plant value in mixed crop-livestock systems.

Livestock water productivity: feed resourcing, feeding and coupled feed-water resource data bases

While water requirement for livestock is widely perceived as daily drinking water consumption, ~100 times more water is required for daily feed production than for drinking water. Increasing livestock water productivity can be achieved through increasing the water-use efficiency (WUE) of feed production and utilisation. The current paper briefly reviews water requirements for meat and milk production and the extent of, and reason for, variations therein. Life-cycle analysis (LCA) can reveal these variations in WUE but LCA are not tools that can be employed routinely in designing and implementing water-use-efficient feed resourcing and feeding strategies. This can be achieved by (1) choosing agricultural by-products and crop residues where water applications are partitioned over several products for example grain and straw (or food and fodder) contrary to planted forage production where water and land have to be exclusively allocated to fodder production, (2) select and breed WUE crops and forages and exploit cultivar variations, (3) increase crop productivity by closing yield gaps; and (4) increase per animal productivity to reduce the proportion of feed (and therefore water) allocated for maintenance requirement rather than productive purposes. Feed-mediated WUE of dairy buffalo production on almost completely (94%) by-product-based feeding systems could be reduced from 2350 to 548 L of water per kg of milk by the combined effect of increasing basal ration quality in a total mixed ration, which resulted in increased milk yield of ~30%, and by increasing crop productivity from 1 t (actual crop yield) to 3 t (potential crop yield). Exemplary, multi-dimensional sorghum improvement using staygreen quantitative trait loci (QTL) introgression for concomitant improvement of WUE of grain and stover production and stover fodder quality showed opportunities for further linked improvement in WUE of crop and livestock production. Metabolisable energy (ME) yield under water stress conditions measured in lysimeters, (which measure crop water transpired) ranged QTL dependent from 16.47 to 23.93 MJ ME per m3 H2O. This can be extrapolated to 8.23–11.97 MJ ME per m3 H2O evapotranspired under field conditions. To mainstream improvement in WUE of feed resourcing and feeding, the paper suggests the combination of feed resource databases with crop–soil–meteorological data to calculate how much water is required to produce the feed at the available smallest spatial scale of crop–soil–meteorological data available. A framework is presented of how such a tool can be constructed from secondary datasets on land use, cropping patterns and spatially explicit crop–soil–meteorological datasets.