S. P. Gunaratne

Feed is the most important item in modern commercial (intensive) poultry production, in terms of its contribution to the costs of production. In many situations, feed costs account for about 60 to 90 % of the production costs, depending on the availability of raw materials. These costs can be considered zero or negligible in scavenging chicken production. However, the importance of feed in scavenging chicken production cannot be underestimated due to its direct and indirect effects on many aspects of the production.

As the term "scavenging" implies, scavenging village chickens find their feed from surrounding environment. However, in some countries supplementation of these birds with kitchen refuse, household waste, agricultural by-products is not uncommon. Supplementation is sometimes essential during certain periods of the year, where the availability of feed resources is limited. It is understood that compounded commercial feed or purchased feed is generally not used in this system.

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Importance of Scavenging Feed Resource Base (SFRB) for village chicken production is clearly demonstrated by Roberts and Gunaratne (1992) and Gunaratne et al. (1993). Total biomass of the flock is determined by SFRB. If the biomass of the flock exceeded carrying capacity of SFRB, some birds in the population, especially the weaker birds (young chicks) will die. Similarly survival will be more when SFRB is more than the requirement of the flocks. A natural balance is seen between SFRB and biomass of the flock in a given environment unless some intervention is made. SFRB is comprised of household waste, crop by-products, cleaning of gardens, fields and wastelands. In some environments SFRB is relatively constant through out the year and in some others SFRB will fluctuate with factors such as seasonal rainfall, agricultural activities, etc. It should also be noted that in some environments rapid urbanization, development projects and environmental changes are causing restrictions on availability and access to the SFRB. Land area available for scavenging and a distance a flock can travel to scavenge will depend on many factors such as flock size, feed availability, population density, agricultural activities, predators, etc. In addition, behavioral studies have shown that some birds (e.g. unselected) have better scavenging ability compared to others (e.g. crossbred). When crossbred birds were released to scavenging environment, they tend to restrict their scavenging area close to the household.

If the capacity of the SFRB and the seasonal variations are known, more efficient strategies for production by flocks of scavenging village chickens can be developed. Roberts and Gunaratne (1992) described two methods for estimating the capacity of the SFRB for chicken in villages and discussed application to utilize the information obtained. In one method, the following formula was proposed for the calculation of SFRB. For this calculation, measurement and identification of different components in household waste and crop content are required.

	H		N
SFRB =	----	x	---------	where;
	P		N - X

H = amount of household waste/family/day (kg dry weight),
P = proportion of the crop content which is household waste as determined by visual inspection,
N = number of families in the community.
X = number of families in the community which do not keep chickens.

In the study of Gunaratne et al. (1993) the figures are:
0.200/ 0.720 x 1/0.5 x 365 = 203 kg dry weight/family/year.

The amount of protein in the SFRB can be determined from an analysis of crop content, and the ME can be determined by analysis of the crop content or by reasonable estimation. On this basis of 11.2 % protein and 3,000 Kcal/kg, the SFRB has 23 kg protein and 609 Mcal metabolizable energy per year.

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Alternatively, the SFRB can be calculated if the weight profile and constitution of the average flock is known, together with the growth rate and hen day production %. To the extent that there is available feed, the amount of feed consumed by the birds is determined by their energy requirement. The protein consumption and availability for maintenance, growth and egg laying, is determined by the percentage protein in the diet. The daily consumption of the flock is the SFRB, so it can be calculated using the formula,

SFRB = ∑Ej / Es where;

j = the average number of birds in the family flock,
Ej = the ME requirement for the daily maintenance and production of each bird per day (kcal/kg dry weight),
Es = the ME in the scavenging feed (kcal/kg dry weight),
'j' can be determined from a census of the family flocks.
'Es' can be measured or reasonable estimated from the crop content.
'Ej' can be calculated for each bird from the production data of growth rate and egg production, using a formula such as that of the National Research Council (1984), below,

ME/bird daily = W^0.75 (173-1.95T) + 5.5 ΔW + 2.07 EE

Where;
W = body weight (kg),
T= ambient temperature (°C),
ΔW = change in body weight (g/day),
EE= daily egg mass (g).

An ambient temperature of 26 °C is assumed throughout.

The values for the SFRB calculated from published data from developing countries are;

475 kg/year in Indonesia (Kingston and Creswell, 1982),
390 kg/year in Thailand (Janviriyasopak et al., 1988),
195 kg/year in Sri Lanka (Gunaratne et al., 1993 ), which can be compared with the measured value of 203 kg, above.

High mortalities are recorded in young chickens in villages, but if measures such as creep feeding or feed supplementation are undertaken to increase the survival of the chicks, then the mortality will only be transferred to an another age group, unless the number of eggs incubated is planned to match the capacity of the SFRB. If such plans are made, then the extra eggs which are surplus to requirements for incubation, are available for sale or for consumption.

If the capacity of the SFRB varies seasonally then periods when it is high can be selected for activities such as hatching and rearing, and culling for consumption and sale can be undertaken in anticipation of a reduction in the capacity of the SFRB. On the other hand if it is desirable to maintain the population trough a lean period, then the appropriate feed supplement can be provided.

Alternative production systems can be compared e.g. Comparisons between egg and meat production, in order to optimize the nutritional return, and /or the cash return, from a SFRB of known capacity.

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Nutritional value of SFRB may vary with the environment. In the study of Gunaratne et al. (1993), analysis of crop content similar to that quoted by Prawirokusumo (1988), but the higher ether extract and lower crude fibre of 5.4 % allows more scope in choice of supplements. The proximate analysis of feed and crop content and the presence of substantial abdominal fat in all hens indicated that the availability of protein was a constraint on production in that environment. Protein rich materials such as earthworms, snails and insects were of minor proportion in the field diet, but young grass shoots, the larger constituent, could have helped to redress the protein imbalance. The levels of calcium (Ca) and phosphorus (P) in the diets were very low, as were their levels in the plasma of scavenging chickens. The plasma levels of both Ca and P increased when village chickens were maintained under intensive system on a balance diet, but the Ca levels still did not reach that of commercial chickens under the same conditions (Table 1).

Table 1: Plasma Ca and P levels in groups of 15 village and commercial chickens

If the low levels were constraints on production, then Ca and P could be easily and cheaply provided in the form of shell grit and bone meal. Additional supplementation with a balanced ration would increase production further, but would be less efficient than if applied to commercial layers (Creswell and Gunawan, 1982),which can be successful in the scavenging system (Huchzermeyer, 1973). In view of the high energy requirement of scavenging activities, the final step to optimize the utilization of the SFRB could be to have a small number of hybrid layers in a pen, fed with a household waste supplemented appropriately and immunized as necessary. Such a system is unlikely to be culturally acceptable, and in any case it deprives the household of the benefit of the waste from those households which do not keep chickens.

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Survival, growth and production in village chickens under four feeding conditions as listed below were studied in Sri Lanka.

1. Control - Normal scavenging system
2. Creep feeder - Household refuse disposed to creep feeder
3. Low supplementation - As 2 above + 35 g of supplement per flock/day
4. High supplementation - As 2 above + 25 g of supplement/bird unit (adult bird equivalent)/day.

(composition of the supplement: equal weight of fishmeal and expeller coconut meal with 2 % DCP, in addition shell grit ad libitum to supply calcium)

Survival
The survival of the chicks and growers shown significant improvement by introducing the creep feeder (P≤0.05) compared to control. Addition of supplementary feed to the household refuse had further increased the chick survival. High levels of supplementation had positive impact on chick survival compared to the low level of supplementation, although the difference was not significant (P≥0.05). There was a high correlation between supplementation and chick survival. The high rate of chick survival may be due to the preferential access to household waste for young birds and reduction in predator attacks as chicks remained near creep feeder.

Growth rate
Provision of household waste in creep feeder showed negative impact on growth rate of chicks up to eight week in this study, suggesting qualitative and quantitative deficiencies in household refuse. When household refuse was supplemented at low level, growth rate significantly improved with creep feeder. Further supplementation at higher level had not shown any positive improvement.

Egg production
There was no improvement in egg production in this study with any supplementation. The point-of-lay was also not affected by the treatments. This suggests that feed resource base is not limiting egg production in the study environment. Genetic improvement may be the option available under these circumstances to improve the production. The situation may be different in some other environments as Hugue and Ukil (1993) reported increased in egg production with supplementation.

Although results of this study is location specific, some general conclusions could be drawn to suit any scavenging situation. There is positive response to supplementation as seen in improvement of survival and growth rates. However, quality and quantity of SFRB determines the degree of response. Any intervention in the form of feeding needs therefore careful consideration of SFRB. The fact that the egg production is not responding to supplementation indicates that SFRB is not a limiting factor in this environment, and production improvement needs consideration of other management aspects. Genetic improvement may be one possible option.

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The studies carried out in Sri Lanka to compare the performances of village chickens, their crosses (village x commercial hybrid) and hybrid layers under deep litter intensive system using commercial compounded feed and choice feeding system (Choice feeding; energy supplement, protein supplement and shell grit after point-of-lay, supplied in separate feeders). Energy supplement in this study was the crushed maize, and protein supplement was a mixture of soya bean meal + coconut meal + vitamins / mineral premixes in different proportion to suit various age groups). Performances of village chickens under choice feeding and commercial feed are given in Table 2, together with those of scavenging system for comparison.

Table 2: Performance of village chicken under intensive deep litter system with choice feeding and commercial feeds

There was an improvement in growth rate and egg production when village chickens reared under intensive feeding system. However, this improvement needs to be matched against the additional inputs supplied under intensive system, Mortality was significantly reduced as there was no predation, which was the main cause for high chick mortality under scavenging situation.

Improvement in growth rate and egg production in village chickens under intensive feeding can be considered marginal when compared to massive increase in egg production when village chickens were crossed with hybrid layers (Table 3).

Table 3: Performances of village chickens, village x hybrid crosses and hybrid layers in deep litter intensive system under choice feeding conditions

These results clearly confirm the results of supplementation studies and studies of village chickens under intensive feeding, where marginal response was seen with regard to egg production, suggesting that village chickens under scavenging system performed closer to optimum in this environment. Cross breeding of village chickens with hybrid layers is a one option to improve production, but its application under field conditions needs further studies.

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1. Scavenging is one of the most economical and sustainable feeding system to utilize feed resources in the villages for production of high quality animal proteins, i.e. meat and eggs.

2. Measurement of SFRB is important to plan the production cycle and to optimize the utilization of SFRB for better returns.

3. Any attempt to intervene the existing scavenging system by way of supplementation needs careful consideration of quality and quantity of SFRB. Suitable supplements for a given environment will depend on nutritional value of SFRB and availability of low-cost feed materials. Investigations to find out cheap nutritional supplements is desirable.

Feeding village chickens under intensive system can be recommended if village chicken products are paid premium price to justify low nutritional utilization of these birds.

Cross breeding has improved the production performances of village chickens under intensive system, but whether these crosses survive and produce under scavenging system warrant further studies.

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Creswell, D.C and Gunawan, B. (1982): Indigenous chickens in Indonesia: Production characteristics in an improved environment. Research Institute for Animal Production, Bogor, Indonesia, Report no 2, pp. 9-14.

Gunaratne, S.P., Chandrasiri, A.D.N., Hemalatha, W.A.P.M. and Roberts, J.A. (1993): The feed resource base for scavenging village chickens in Sri Lanka. Tropical Animal Health and Production 26: 249-257.

Haque, Q.M.E. and Ukil, M.A. (1993): The effect of supplementary feeding on the growth performance of local chicks under village conditions. Egg. Bangladesh J. Scientific Research, cited by Ahmed, N. (1994). Backyard poultry system in Bangladesh. Proceedings, 7th Animal Science Congress, Indonesia.

Huchzermeyer, F.W.(1973): Free ranging hybrid chickens under African tribal conditions. Rhodesian Agricultural Journal 70: 73-75.

Janviriyasopak, O., Thitisak, W., Thepkraiwan, L., Jongsathlen, K., Mekapratheep, M., Kruedener, R.V. and Morris, R.S. (1989): A health and productivity study of village poultry. In: Proceedings of the international Seminar on Animal Health and Production Service for Village Livestock, Khon Kaen, Thailand, pp. 161-171.

Kingston, D.J. and Cresswell, D.C.(1982): Indigenous chickens in Indonesia: Population and production characteristics in five villages in West Java. Research Institute for Animal Production, Bogor, Indonesia, Report no 2, pp 3-8.

National Research Council (1984): Effect of environment on Nutrient requirement of domestic animals. Committee on animal nutrition, National academy press, Washington D.C., USA

Prawirokusumo, S.(1988): Problems to improve small scale native chickens management in South-east Asian countries. Proceedings, 18th World's Poultry Congress, Japan, pp. 113-117.

Roberts, J.A. and Gunaratne, S.P. (1992): The scavenging feed resource base for village chickens in a developing country. Proceedings, 19th World's Poultry Congress, Vol. 1, pp. 822-825.

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