Chapter 8
CIRCULARLY INTEGRATED FARMS UTILIZING ANIMAL WASTES

The conflict for land and other natural resources increases sharply as populations and living standards grow. Integrated farming, which maximizes food production, optimizes land use and minimizes environmental pollution, is a concept which has become an imperative for developing countries with limited natural resources but unlimited demands.

There are many methods of farm integration, but a suitable model can be established only when all the segments of the eco-system are carefully considered. The examples set out here are therefore only indicative, and their economics are inevitably outlined very roughly. Nevertheless, most of these integrations exist as realities in various forms in Asia and elsewhere.

A typical example is Kamchai's (1978) farm (10,000 pigs) in Thailand. This integration involves a layer-pig-fish recycling principle; it is therefore applicable to a landless farmer, but it requires a fish pond. This type of livestock integration is usually applied on swampy or other lowland areas near urban centres, where cropping is less profitable while demand and animal product prices are high. Another Thai farm (Praves, 1978) applies successfully an integration involving starch waste from a rice-flour mill and bakery by-products which are fed to pigs (4,000 head/day), while all pig wastes are discarded to ponds as the sole feed for fish. One pig produces about 35 kg of fish biomass annually.

Another agro-industrial integration approach, using all possible segments of modern recycling technology, is applied at Maya Farms (23 hectares), in the Philippines. The schematic flow of this multi-recycling concept is illustrated in Figure 15.

The individual components of this complex are:

1. pig farm (about 4,000 pigs at any time)
2. biogas plant (24 digesters of different types - Germany, China, India)
3. flour and feed mill
4. abattoir
5. rendering plant
6. cannery
7. crops (rice, beans, vegetables, fruits and others)
8. mushroom production
9. algae/fish ponds

and related infrastructures as illustrated.

Figure 15 — Fuel, Feed and Fertilizer Production and Pollution Control Through Recycling Maya Farm

The pig farm produces annually about 10,000 pigs, which are slaughtered and processed at the abattoir and meat processing plant. Several other farms, integrated with Maya farms, also supply the abattoir and meat processing plant with pigs, buffaloes and cattle. Processed meat is partly marketed, partly canned in the cannery. Abattoir waste and by-products (including blood), processed in the rendering plant (run on methane gas) generate feed which is recycled via the feedmill to pigs. Manure from the pigs is washed with water into the biogas plant, which provides most of the electrical power required for lights, engines, deep-well pumps, dryers, smoke generators, burners, cooking and scalding tanks, refrigerators, etc. Digested liquor from the biogas plant is funnelled to the lagoon, where it yields algae, kang kong and fish. Sludge from the settling tanks is partially dried (using biogas and rice hulls). Most of it is utilized, via the feedmill, for pigs and other livestock, and the remainder as organic fertilizer. The paddy fields are fertilized by nutrient-rich liquid effluent. Rice straw as a by-product is used as a medium for mushroom production.

The main income from the recycling of wastes derives from feeding sludge to pigs, which provides more than five times the income derived from methane.

Some of the practically applicable, simple models involving recycling of animal wastes among livestock species are as follows:

These integrations are quite common in Thailand, the Philippines and several other countries in Asia. They are operating on both small and large (commercial) scales and there is naturally no limit to the number of possible modifications of the integrations designed above. All these systems are in reality a substitute for the common soil-plant-animal cycle, because they convert all waste resources into animal products more effectively than traditional disposal methods. In addition, they ensure a clean environment with a minimum labour requirement. Such operations would require about 4,000 m² (0.4 ha) of land if fish pond and cropping area are to be included, but they can also be modified for landless farmers or for farmers with very small plots. Under such conditions, fish and cropping would be excluded, and discarded animal wastes would be converted into biogas.

Most of the systems outlined above are suitable for lowland humid areas, and fish-ponds can be partially used for alternate cropping, rice in particular.

For these smallholding models, the following standard units would constitute the circular integration.

Layers

The flock would consist of 100 layers fed on a conventional layer mash with an annual production of 165 eggs per bird; approximately 80% of the birds would be sold ($1.50/each) at the end of the laying cycle.

In the case of layer-pig integration, layer cages would be fixed above the pig pen, and all falling layer manure would be consumed instantly by pigs. The layer manure contribution as a direct benefit on feed saving per pig/year is estimated to be $6.00 to $14.00.

Where layer-dairy cow integration is foreseen, layer waste would serve as a protein feed for the dairy herd; it would be collected daily, chemically treated and substitute for most of the protein requirement (60 to 90%) of the herd. Another option would be to ensile wet, freshly collected, layer waste with forages, feeds or other wastes (grass, tubers, leaves, fruit waste and other resources), giving enough soluble carbohydrates to ensure proper fermentation and to maintain the moisture content of the silage in the range of 40–65%. Ensiling would require 10–21 days and could be carried out in re-usable plastic bags. The farmer would prepare and use (10–21 days later) one bag (about 35–50 kg) of the silage daily.

Broilers

Broiler-dairy cattle integration would require about 500 broilers kept on wood shavings or any other ligno-cellulosic bedding material. Broilers would supply about 25 to 30% of the total DM requirement and most of the protein requirement (70 to 90%) of the cow. Broiler litter would be either chemically treated or ensiled together with forages, feed or wastes as indicated above.

Pigs

A simple wooden slatted house divided into 2 or 4 pens, for housing 20 pigs, would be constructed by the farmer at a cost of $300. The estimates assume the purchase of 20 piglets at 15 kg liveweight; they reach 100 kg (85 kg weight gain) within 170 to 180 days (feed efficiency 3.5); with a mortality allowance of 5%, 19 porkers will be sold.

In pig-fish integration, all faecal waste generated by pigs will be directly discharged through slats into the fish-pond. In pig-dairy integration, the pig pens would require a concrete flooring which would facilitate the collection of waste for further handling. In this case, freshly collected pig waste will be ensiled for 14–21 days with suitable forages, feeds or wastes.

Dairy Herd

The herd would comprise 2 milking cows of a value of US$500 each, with a 520-day calving interval. The herd would generate 10 litres of milk daily (5 litres per cow/day). Milk is to be sold at an estimated $0.22 per litre.

The feed input would consist of broiler litter or layer manure (20 to 35% of DM requirement of dairy rations), 1 kg of feed concentrate per cow/day during 300 days only, forage (leaves, fruit and vegetables) or its substitutes (grass growing within the premises of the farm and higher aquatic plants recoverable from the pond).

Sheep

The sheep herd would consist of 20 head of sheep yielding wool and meat. Dairy cattle-sheep integration would be applicable in arid areas where all cattle waste would be recycled to sheep. It is estimated that about 35% of the DM feed requirement of sheep would be met by cattle waste in the form of silage with other available forages, feeds or wastes.

Fish

There are several suitable species of tropical fish, of which the best appear to be Tilapia (particularly Tilapia mossambica) and catfish. A small multiplication pond for sexing of fingerlings is necessary to control the number of fish in the pond because Tilapia and some other tropical species have an enormous reproductuve capacity which could cause overcrowding of the pond. Although most of these species can survive under a low oxygen supply and poor water management, the yields of fish biomass can be significantly increased with good water management on one hand and control of the waste flow on the other.

Water hyacinth and other higher plants usually growing in the pond can cover about 10–15% of the DM forage requirement of dairy cows, and in pig-fish integraton about 5–10% of the DM requirement of the pigs. In addition, higher aquatic plants, where available in excess, can be chopped finely and returned to the pond as a feed for fish.

Biogas

The biogas installation would consist of one or two underground digesters with tanks, resettling ponds and the necessary infrastructure including feed funnels and piping for gas distribution.

Cropping

In lowland areas rice (2 crops/year) will be the main crop, with some intercropping of forage for cattle and vegetable/fruit for family use; the required area would be about 4,000 m² = 0.4 ha. The smaller the land area the more intensive cropping programme could be applicable.

In all these recycling systems the first limiting dietary factor in ruminant feeding would be feed energy. Therefore the choice of ingredients in humid tropics would be centered on root crops, cassava in particular; in arid areas the feed energy requirement could be balanced by dates and their waste products.

Approximate financial estimates of some of these integrations at the small-farm level are given in Tables 103–110.

Table 103
LAYER-PIG-FISH INTEGRATION: ECONOMIC CHARACTERISTICS*

Assumption: Immediate start-up of all segments of the integrated farm because the time component cannot be judged.
¹ Cost and construction (including labour) of cages above pigpen for 100 layers.
² Simple pens with wooden slats for 20 pigs.
³ Some adjustment in earthwork assuming the fish-pond already exists.
⁴ 150 day-old female chicks.
⁵ 20 piglets (15 kg live weight) at US$40/head.
⁶ Fingerlings are produced by the farmer.
⁷ Working capital for feed is estimated to be 3 months' requirements for poultry and 6 months' for pigs;no provision is made for other species.
⁸ 165 eggs/bird/year, 6.5¢/egg, salvage value $1.50/bird, 20% mortality and condmnation.
⁹ 5% mortality; 38 pigs sold at $100/head.
¹⁰ 950 kg fish biomass at US$0.60/kg.
¹¹ 1 tonne feed consumption during replacement period, 35 kg feed/layer/yr; total 4,5 t at $150/t.
¹² Feed conversion: 3.5 per 85 kg of live weight gain for 39 pigs = 11.6 t feed at $140/t.
¹³ Layers 1 hour, pigs 3 hours, fish 1 hour/day at $2.00/man/day.
^* Instant Development Return (Preliminary estimates).

Table 104
BROILER-DAIRY COW-FISH INTEGRATION: ECONOMIC CHARACTERISTICS*

¹ Poultry shed with equipment for 500 broilers.
² Simple cattle shed.
³ As in Table 103.
⁴ 500 × 4 batches at $0.30/bird.
⁵ 2 dairy cows at $500/each.
⁶ 1.8 kg/bird × 2,000 birds at $1.00/kg.
⁷ 5 litres/cow/day at $0.22/1; calves income at $70.00/yr based on 0.7 calf/yr.
⁸ 2.5 kg conversion = 9t at $250/t.
⁹ Feed concentrate 600 kg/yr/herd at $140/t; forage collected without cost.
¹⁰ 4 hours/day at $2.00/man/day.
* Instant Development Return (Preliminary estimates).

Table 105
LAYER-DAIRY-FISH INTEGRATION: ECONOMIC CHARACTERISTICS*

¹ For assumptions see Tables 103 and 104.

* Instant Development Return (Preliminary estimates).

Table 106
LAYER-PIG-DAIRY-FISH-CROP INTEGRATION: ECONOMIC CHARACTERISTICS*

¹ For assumptions see Tables 103 and 104.
² Seedlings (rice + vegetables).
³ 4,000 m², 2 rice crops/year and forage with vegetables between rice crops.
⁴ 140 man/days at $2.00.
* Instant Development Return (Preliminary estimates).

Table 107
BROILER-DAIRY-BIOGAS-FISH-CROP INTEGRATION: ECONOMIC CHARACTERISTICS

¹ For assumptions see Tables 103, 104 and 106.
² Digester including piping.
³ 1.000/kWh/yr at $0.05/kWh.
⁴ 12 man-days at $2.00.

^* Instant Development Return (preliminary estimates).

Table 108
PIG-BIOGAS-FISH-CROP INTEGRATION: ECONOMIC CHARACTERISTICS*

¹ For assumptions see Tables 103, 106 and 107.
* Instant Development Return (Preliminary estimates).

Table 109
PIG-DAIRY-BIOGAS-FISH-CROP INTEGRATION: ECONOMIC CHARACTERISTICS*

¹ For assumptions see Tables 103, 104, 106 and 107.
² 1.2 t feed concentrate/yr/herd @ $140.00 because only about 60–70% pig faeces would be fed, the rest being used for biogas.
* Instant Development Return (Preliminary estimates).

Table 110
LAYER-PIG, BROILER-DAIRY, BIOGAS-FISH-CROP INTEGRATION:
ECONOMIC CHARACTERISTICS*

¹ For assumptions see Tables 103, 104 and 106.
² Larger, but simple, type of digester.
* Instant Development Return (Preliminary estimates).