Processed Crop Residues To Improve Ruminant Performance

This study by Ramana Reddy and G Reddy, from the College of Veterinary Science, India, looks at enhancing ruminant diets through processing crop residues.
calendar icon 30 July 2011
clock icon 8 minute read


Due to the highly fibrous nature and low nutrient content of crop residues, several physical processing methods were employed to improve their utilisation in ruminants. Among the physical processing methods, grinding and blending crop residues and concentrate (in a given ratio) into mash or pellet was found to be a useful technology for efficient utilisation of crop residues in ruminants.

Feeding different crop-residue-based complete feed in mash or pellet form, on average increased milk production by 15.4 per cent and supported daily weight-gain up to 108 g in lambs and kids. Feed wastage and cost/kg milk or weight-gain in lactating and meat-producing animals were decreased by 23.3, 23.4 per cent and 17.5, 20 per cent, respectively, in on-farm trials. However the quality of crop residue used in the complete diet influenced the performance of ruminants.

A complete-feed processing unit suitable for rural areas was developed and distributed to research institutions and farmers for transfer of technology to improve nutrient use efficiency in the animal food chains. Cost of machinery, infrastructure required and lack of extension are the main constraints for transfer of this technology. The technology, if transferred for use on a community or on cooperative basis, could play a key role in enhancing livestock-based rural economy in India.


The efficient utilisation of crop residues and agro-industrial by-products as animal feed has assumed importance in India due to shortages of dry roughages, concentrates and green fodder which were estimated to be 19, 62 and 45 per cent respectively (Anonymous, 2008). Due to cultivation of food and commercial crops, enormous quantities of different types of crop residues are produced as a renewable resource every year. Most of them are being wasted or used as fuel in some villages.

Crop residues are rich in fibre and low in nitrogen, minerals and vitamins. Hence, their palatability is low and therefore crop residues cannot form a sole ration for livestock. Any processing method that improves the nutrient availability from crop residues will assist in bridging the gap between availability and requirement of roughages.

The concept of complete feeds for ruminants is relatively recent in India. In this system, all feed ingredients inclusive of roughages are proportioned, processed and mixed into a uniform blend. The product is fed as a sole source of nutrients. This system ensures an adequate supply of balanced nutrients to the animal, controls the ratio of concentrate to roughage, helps in improving utilisation of low-grade fibrous crop residues and reduces feed wastage and feeding cost. The system also promotes feed intake and avoids refusal of the unpalatable portions of feedstuffs. Such rations also reduce eating and rumination time and increase resting time.

An even intake of feed is associated with less fluctuation in rumen-release of ammonia so that non-protein nitrogen may be more efficiently utilised. This system gives good scope for increasing the use of home-grown fibrous crop residues and by-products. The level of inclusion of different crop residues in complete diets of ruminants is shown in Table 1.

The roughage portion varies from 30 to 70 per cent depending upon the physiological status of animals to be fed. The roughage content of complete diets is 30–40 per cent for high-yielding animals, 40–50 per cent for growing animals and 60–70 per cent for dry animals, whereas the protein content varies from 11 to 13 per cent. The proportion of other ingredients varies accordingly. These diets can be processed into mash or pellets. For pelleting of mash feed, traditional steam pelleting or recently developed expander-extruder technology can be adopted.

Processing of Complete dIets

Mash. The different ingredients of the diet are proportioned as per formula into 100 kg batches using appropriate scales. A hammer mill with 8 mm sieve is used for grinding the ingredients. Through screw conveyor and bucket elevator the ground ingredients are discharged into the hopper fixed on top of the mixer. The ingredients that do not require mixing are directly added to the mixer. Molasses is pumped from the storage tank to a heating tank, where it is heated to 70 °C.

The heated molasses is sent to the mixer through a dosage tank, as per formula. The micro-ingredients (vitamins and minerals) are made into a premix by mixing them with ground grain or bran and the required quantity of premix is added to the mixer directly. Later, all ingredients are mixed for about 10 minutes and then collected in sacks and stored.

Pelleting. For pelleting, the mash from the mixer is dropped into bucket elevator and lifted and conveyed into a hopper over the pellet mill. The feed, in mash form, is conveyed from the hopper into the conditioning chamber of the pellet-mill through a screw conveyor. A wheel-valve controls the rate of flow of the feed into the conditioning chamber.

The steam produced from a boiler attached to the pellet-mill is supplied into the conditioning chamber of the pellet-mill. The required quantity of steam at 97–98 °C is supplied into the conditioning chamber through a control valve. Conditioned mash at 90–92 °C and 16–17 per cent moisture is conveyed to the pellet mill and extruded through a ring die with 9 mm holes. The pellets of 9 mm diameter at 83–85 °C and 14–15 per cent moisture are dropped from the pellet mill into a vertical cooler, fixed below the pellet mill. The cooled pellets are collected into sacs.

Expander-extruder processing. This is a system which combines the features of expanding (application of moisture, pressure and temperature to gelatinise the starch portion) and extruding (pressing the feed through constrictions under pressure). The mash containing 12–13 per cent moisture and at room temperature is reconstituted with the required quantity of water to get 17–18 per cent moisture in the mixer and then sent to the hopper above the expander-extruder from which it passes through a screw in which it attains 90–95 °C by the time it comes out of the die openings. Otherwise, the mash without reconstitution can be sent to hopper and steam is added to get the required moisture while the feed is passing through the screw of expander-extruder. The pellets coming out of the expander- extruder are cooled and collected into sacks.

ExperIences of applyIng Technology In the fIeld

To demonstrate the advantages of the complete diet for economical milk and meat production, three complete diets containing a) cotton stalks (Reddy and Reddy, 2003), b) maize cobs, and c) sunflower heads as sole roughage sources (28.5 per cent in dairy ration and 40 per cent in sheep and goat ration) were fed to Murrah buffalo/sheep and goats owned by farmers in the state of Andhra Pradesh, India.

Milk production studies. The diets maintained 6–8 litres/day of milk yield in lactating Murrah buffalo. Dry matter intake was 28.2, 26.7 and 15.0 per cent less on complete diets containing cotton stalks, maize cobs and sunflower heads, respectively, compared with the conventional diet. Average milk yield increased by 11.3, 11.5, 23.5 per cent and cost of feed/kg milk yield reduced by 21.5, 23.4 and 25.2 per cent on feeding complete diets containing cotton stalks, maize cobs and sunflower heads respectively, compared with the conventional diets. The results indicated that cotton stalks, maize cobs and sunflower heads can be incorporated in complete diets as sole sources of roughage without any adverse effect on milk production in lactating Murrah buffalo. The milk yield was 16.7 and 11.4 litres/day on feed blocks produced from premium and lower-quality sorghum stover, respectively (Anandan et al., 2010) indicating the feasibility of medium levels of milk production on crop-residue-based complete feeds.

Meat production studies. The diets supported 87–108 g average daily gains (ADG) in Nellore ram lambs and 71 to 81 g ADG in local male kids in intensive-feeding system. The ADG was significantly (P<0.05) higher on complete diets compared with the respective conventional diet in both species. The dry matter intake/kg gain decreased by about 20 per cent in sheep and 15 per cent in goats while the cost of feed/kg gain decreased by 13 to 32 per cent in lambs and 13–22 per cent in kids compared with the conventional diet. Dressing per centage and meat: bone ratio were optimum and almost similar for complete and conventional diets in sheep and goats.

These results indicate that complete diets containing cotton stalks, maize cobs and sunflower heads can sustain optimum growth in lambs and kids under intensive system of feeding without any adverse effect on meat characteristics. In addition, enteric methane production can be reduced considerably by formulating a balanced complete-diet with different concentrate ingredients and crop residues. Gross energy lost as methane reduced (P<0.01) from 5.64 to 4.90 per cent and from 5.85 to 5.14 per cent in buffalo and cows, respectively (Kannan and Garg, 2009).

Further, with this system of feeding, migration of sheep and goats during scarcity periods can be avoided.

Status of ApplIcatIon of Technology/practIce by farmers

Based on the response of farmers in on-farm evaluations, a small-scale complete-feed processing unit (Photo 1) capable of grinding all crop residues including cotton stalks, was developed under National Agricultural Technology Project (NATP) for use at village level.

Twenty four units of small-scale complete-feed processing units were distributed to different research institutions and farmers in India. Two farmers established the same units on their own farms for feeding dairy animals and sheep in the state of Andhra Pradesh, India. This enabled the farmers to utilise their crop residues effectively. However, the technology developed is not being extensively used due to the prevailing smallholder livestock-system, the high cost of the machinery (US$11 000/unit), the infrastructure required and the lack of extension.

Lessons Learnt

Crop residues hitherto wasted can be effectively, efficiently and economically utilised in the form of complete diets. The technology has the potential to create wealth from waste in an environmentally friendly manner – crop residues when fed in the form of complete diets reduce greenhouse gas emission from ruminants whilst at the same time improving milk and meat production.

Future of the Technology

Owing to human population-growth, increasing urbanisation and rising incomes, the demand for milk and meat is projected to double by 2020 in India. At the same time there will be increased requirement for food grains (cereals, pulses and oilseeds) which will result in decreased land for cultivation of fodders and in increased availability of crop residues.

Ruminant livestock in developing countries, including India, will have to depend increasingly on crop residues to meet their nutrient requirements. To make the ruminant production system efficient, the crop residues will have to be processed. The technology described in this paper will play a key role in enhancing the livestock-dependent rural economy in India in the near future provided the technology is adopted on a community and cooperative basis.

August 2011
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