Importance of crop residues as animal feed source
Crop residues, such as straw, stovers or haulm from cereal or grain legume crops, are already an important source of fodder in India, providing more than 40 per cent of the available dry matter for feeding livestock. Some experts estimate this could rise to 70 per cent by 2020. A survey conducted in 9 countries across SSA and South Asia, showed that crop residues account for up to 60% of the total livestock diet in mixed systems (Valbuena et al).
Crop residues however, especially from cereals, are often of low nutritional quality which affects the productivity of cattle and buffalo. Farmers may reject new sorghum and pearl millet varieties that had been improved only for grain yields, because of low stover quantity and quality (Kelley et al., 1996).
Increasing fodder quality of crop residues
In the 1980's and 1990's livestock nutritionists focused on post harvest interventions trying to promote technologies for improving the nutritive quality of crop residues by chemical, physical or biological treatments. However, except for chopping, farmers did not adopt these innovations because of the labour and input costs of chemical treatments. Breeding crops that yield more crop residues which give higher fodder quality is more promising.
Dual-purpose crops, which produce high grain yields and nutritionally-rich residues, allow crop breeders to address the problem of poor fodder quality while also reducing land and water competition, and fit well in India where many smallholder farmers run a mixed livestock-crop system.
Studies on various key crops such as sorghum (R.Reddy and Blummel, 2010) and groundnut (Nigam and Blummel,2010) show important variation of crop residues yields, up to 2 or 3 tons per hectare, and of fodder quality. For sorghum stover, a difference of 5 to 10% in vitro organic matter digestibility units was noted among best grain yielding sorghum varieties.
Better feed quality means greater livestock productivity. ICGV 91114 groundnut variety, introduced in Andhra Pradesh, India, is an early maturing, high yielding and drought-tolerant groundnut variety, which produced 15 % higher pod yields, 17 % more haulm and better quality fodder compared to the locally grown variety. After giving their cows and buffalo the improved fodder, dairy farmers noticed an immediate impact as their milk production increased by 11%. The combination of increase of grain yield, crop residue yield and better crop residue fodder quality, even if relatively small, as in the case ICGV 91114, facilitate adoption of these cultivars by farmers.
Indicators of stover quality have now been incorporated into the sorghum and millet breeding programmes. Together with the International Livestock Research Institute (ILRI), ICRISAT is for instance looking at introducing dual purpose crop breeding especially for sorghum in African and Asian countries.
The increasing importance and demand for crop residues as fodder is reflected in three major trends:
- Farmers’ preferences for crop varieties with crop residues of high fodder quality;
- Higher market price for crop residues with a higher feed quality. For example in India sorghum stover is now sold for up to 50 to 60% of the grain price on an equal dry matter weight basis.; and
- Higher livestock productivity with crop residues with a higher feed quality.