Brief introduction to the project
Smallholder livestock production is the mainstay of large parts of India’s rural population but the benefits derived from it are mainly constrained by the availability of affordable, good quality feeds. Feed costs relative to farm gate prices of livestock production are increasing, reducing farmers’ income and resulting in a higher cost of animal-sourced food (ASF) for consumers. The improvement of feed resources is severely constrained by bio-physical factors such as the availability of arable land and water but increasingly also by competition for, and shortages of, on-farm labour. Crop residues, that is straws, stover and haulms which are the by-products from seed/grain production of ligno-cellulosic nature, contribute the overwhelming (>70%) bulk to feed resources for livestock production in India (Ramachandra et al., 2007). At the same time, there is a substantial deficit in terms of total digestible nutrients which will need to be addressed to close yield gaps in livestock production. This nutrient deficit is due to the generally poor fodder quality of cereal crop residues. On the other hand, a significant improvement of fodder quality of crop residues would result in a transformative event in the quality of Indian feed resources. This project aims to improve feed quantity and quality without compromising grain yield, which also increases land and water use using a two-pronged approach: 1) collaborations of livestock nutritionists and crop scientists to identify, select and breed crop cultivars that provide superior grain yields and improved fodder quantity and quality in their crop residues than currently available cultivars; and 2) explore technologies that can increase the fodder quality of crop residues post-harvest.
Process
In collaboration with the National Rice Research Institute (NRRI), Cuttack, straw of approximately 800 rice varieties/lines (500 varieties, 100 landraces and 200 advanced breeding lines) in different ecologies were phenotyped for 10 feed quality parameters at the ILRI feed technology research platform (https://hdl.handle.net/10568/108032) in Hyderabad. All straw samples provided by the NRRI were scanned with a Near Infrared Reflectance Spectroscopy (NIRS) instrument, FOSS Forage Analyzer XDS, installed with the WinISI II software package and using specifically developed calibration equations. Predictions for feed quality parameters were made for straw nitrogen content (N), neutral (NDF) and acid (ADF) detergent fibre, acid detergent lignin (ADL), silica, in vitro organic matter digestibility (IVOMD) and metabolizable energy (ME). The generalized linear model in SAS (2012) was used to analyse the effects of variety and year.
The analysis revealed that considerable genotypic variation exists in different varieties/lines in key straw fodder quality traits, such as nitrogen (crude protein) and organic matter digestibility, that are of high livestock nutritional significance. While the observed cultivar-dependent variations in straw quality are very promising, they should not come at the expense of grain yield. However, in most cases trade-offs between grain yield and straw quality appear to be largely absent (Padmakumar et al., in preparation). Both high grain yield and high straw quality can be combined in one rice cultivar and therefore targeted for rice improvement. Consequently, we suggest that crop improvement programs and new rice variety releasing agencies should include information about straw fodder quality traits when promoting new varieties in areas where rice straw contributes significantly to livestock feeding.
The price quality relation study conducted by ILRI in rice straw traded in Kolkata (Teufel et al., 2012) showed that a difference of 1% unit increase in digestibility fetched almost an addition of Rs. 1.00 per kg of rice straw traded, which is 33% more than the base price. The variation among NRRI rice cultivars is therefore offering tremendous opportunities. Out of all cultivars analysed ‘Jalamani’ shows maximum digestibility (45.6%) compared to average digestibility of 40-42% without a significant yield penalty since the cultivar was among the 10 highest grain yielders.
Currently, we are developing the association of genomic information of lines (already available with NRRI) in relation to straw quality, although this requires more time. This will give additional information of the lines to target straw quality in rice breeding. By this, breeding for straw quality can be accelerated (field breeding for varietal development requires 3-4 years, more funds and human resources than are required for the application of genomic selection).
