The effect of supplementation on the performance of free range local chickens in Tanzania

S K Mutayoba, A K Katule*, U Minga**, M M Mtambo*** and J E Olsen

* Department of Animal Science and Production, P.O. Box 3004, Sokoine University of Agriculture, Morogoro Tanzania
** Open University of Tanzania, P.O.Box 2409, Dar-es-Salaam, Tanzania
*** Faculty of Veterinary Medicine, Department of Medicine and Health, Sokoine University of Agriculture, Morogoro, Tanzania
smuta2004@yahoo.co.uk   ;   smuta@suanet.ac.tz

Abstract

A study to evaluate the effect supplementation on growth and egg production in free range chickens was carried out in Morogoro, Tanzania. The effect of location and household surroundings on performance of free range local chickens was also assessed. A total of 144 chickens were used. Birds were selected and sorted based on their body weight and age and then randomly allocated to three feeding regimes. The three feed types were; homemade and commercial supplement and the un-supplemented (those which were left to scavenge only). During the growing period, performance was measured in terms of body weight, shank length and growth rate. Total number of eggs laid, egg weight and shell thickness were recorded during the laying period. Gross margin analysis was done for the laying period. A digestibility trial was carried out to assess the nutritive value of feeds and their utilization by the birds.

Total dry matter digestibility differed significantly (P<0.05) between seasons and was 79 and 67% for the dry and wet season feed, respectively. Feed supplementation to free range local chickens led to improved performance in terms of growth rate and body weight. The mean mature body weight for the supplemented and un-supplemented chickens was 1484 g and 1282g, respectively. However no difference was observed between treatments on shank length. Significant (P< 0.05) differences for growth rate were observed between treatments during periods 1-3 and between locations. Performance for birds at the experimental station was lower for most parameters. An increase in egg number and shell thickness with supplementation was noted. The mean egg number for free range local chickens supplemented with homemade feed and commercial was 31.9 and 31.8, respectively whereas it was 20.4 for the un-supplemented free range chickens. The profit margin from eggs was increased by 11.2% and declined by 3.4% in birds under homemade and commercial supplementation, respectively. From these results it was therefore concluded that supplementation led to improved performance in terms of growth, egg production and quality but the profit margin was substantially reduced by feed cost. This means that cheap locally available feed ingredients should be used when supplementing rural chickens.  

Key words: Dry and wet season scavenged feed, feed supplementation, shank length

Introduction

Rural poultry production in most Sub Saharan and tropical countries is based on the traditional scavenging free-range which accounts for 70% of the total domesticated chickens in Africa (Sonaiya et al 1990 and Kitalyi 1998). Under this system birds are left to scavenge for their own food and water. The degree to which this system meets requirements for growth and production depend upon the nature of the land and the available foraging materials (Ologhobo 1989, Mwalusanya et al 2002). Failure to meet the nutrient requirements during scavenging consequently leads to low productivity. Sonaiya (2007) reported that birds perform poorly because during scavenging they fail to balance between energy and protein. It has been reported that the nutrition of the scavenging local chicken (SLC) is good during harvest time and during the rains due to the high levels of greens, earth worms, and insects (Kabatange and Katule 1989, Mwalusanya et al 2002). 

In the scavenging system, supplementation is rarely practiced but studies have shown that improvement in productivity may occur if it is properly done (Smith 1990). No authoritative information is available in Tanzania in relation to the supplementation benefits on performance and whether it would be economical to do it. The common practice is to give birds household leftovers which are in most cases convenient and inexpensive.

Therefore the present study was carried out with the aim of assessing the effect of supplementation on performance and economical aspects of rural scavenging birds kept under different ecological conditions. The digestibility trial was carried out so as to assess the availability and utilization of nutrients by the birds.

Materials and Methods

Digestibility trial

Twenty (20) growing local birds between the ages of 12 to 16 weeks were randomly allocated to the 4 dietary treatments shown in Table 1. The birds were individually allocated to wire battery cages measuring 72000cm³ (30 cm high, 40 cm wide 60cm long). The preliminary experiment to acquaint the birds with the experimental diets was done for 5 days during which birds were fed on an ad-libitum basis. It was established that a bird consumed about 60 to 70 grams per day. 

Feeding

Sixty (60) grams of each diet were offered to each bird at 8.00 am every day. Each morning before the birds were fed the remaining feed in the feeder (cup) was removed and was recorded as refusal. Fresh feed and water were placed in plastic cups tied to the front of the cages daily. 

Excreta collection

Total collection method was used whereby a plastic sheet was laid beneath each cage for excreta collection. Excreta from each hen was collected quantitatively every 24 hrs and spilled feed and feathers were carefully removed. At the end of the 5 day collection period the excreta from each was weighed, thoroughly mixed using a mortar and pestle and was stored in a deep freezer at -20⁰C to await further analyses.

Chemical analyses

Proximate analyses for the diet samples and freeze dried excreta were done according to Association of Agricultural Chemists Official Methods of analyses (AOAC)  1990). Uric acid in the excreta samples was determined according to (Marquadt 1983).

Digestibility coefficients calculations

Digestibility coefficients were calculated according to the methods described by Castrolli and Rigoni (1980).

Statistical analysis

Data on digestibility were analyzed using the General Linear Model (GLM) of SAS (2001)

Y_ij = µ ₊ T ₊ e_ij

Where_:

Y_ij = record on the j^th bird from the i^th dietary treatment

µ = general mean common to all observations

T_i = Effect of the ith dietary treatment

e_ij = Random effect perculiar to each treatment

Supplementation study

Three feeding regimes designated as Scavenging only; Scavenging + homemade feed and Scavenging + commercial feed were used in the supplementation study. The main objective was to assess the effect of supplementation using diets containing locally available ingredients on the bird’s performance. The supplementation study was carried out for 7 months (May –December) covering the cool/dry season and the short rain season.

Management of birds

Indigenous free range chickens female chicks aged between 7 to 9 weeks were purchased from villages within 20 to 30 km from the experimental station and were kept at the station for 7 days. During this 7 day period the birds were vaccinated against Newcastle disease, dewormed using piperazine and dusted for external parasites. The birds were then wing banded, weighed to obtain the initial weight and were distributed to the villages thereafter.

Experimental design and treatment allocation

A complete randomized block design was employed in this study. The treatments were blocked by village where all the three feeding regimes were represented. Six farmers were selected per village basing on their experience in rearing chickens making a total of 24 farmers for the study. The birds kept on station for seven days were distributed to the villages on the same day. Each farmer was randomly allocated 12 chickens of mixed sexes making a total of 288 birds for the study. To facilitate supplementation the experimental birds were housed differently at night and were given 60 gm of feed at around 4.00 pm and remained there until morning. The villages were different in their agro-ecological conditions. Mkuyuni and Changa from a high altitude area with good vegetation and Kauzeni and Mkundi on a low altitude were in a drier climate (semi arid). Apart from wing banding the birds were color coded so as to differentiate the different diets.

On station study

The objective of this study was to assess the contribution of household surroundings towards the nutrition and performance of free range local chickens by comparing the performance of birds in the villages with those at the station. An open ground with some shrubs and natural grass and vegetation with a total area of 5122.44 m² was selected for the study. Twelve houses each measuring 1.65x2.25 m and 22.5m apart were constructed using burnt bricks as the wall, palm leaves and a plastic sheet on the roof. Each house was designed to keep 12 birds giving a total of 144 birds for the experiment thus providing a free range stocking density of 35.6m² per bird. A one meter high chicken wire fence was constructed along the peripheral of the study area so as to keep the chickens in and to prevent crawling predators. The experimental design and diets were similar to those used under farm conditions.

Parameters

Body weight, body weight gain and shank length

During the growing period body weight and shank length were recorded weekly until the birds were sexually mature i,e. laid their first egg. On a weighing day farmers were asked to confine the birds until they were weighed. Body weights were measured using a Silvano kitchen scale on weekly between 7.00 and 8.00 a.m. Shank length used a measure of skeletal development was measured from the hock joint end of the tibia to the beginning of the foot pad using a ruler graduated in centimeters and was recorded to the nearest 0.5 cm (Yakub et al 2009). The body parameters were recorded for 7 months and each month was designated as a period.

Egg production

Egg production parameters were recorded for 3 months (October-December). Time taken for each treatment group to reach sexual maturity and egg production was also recorded.

Number of eggs in each household was recorded daily. Hen day egg production was calculated as the number of eggs laid within a clutch divided by the number of days it took to lay the clutch and was expressed in percentage. Pause period was calculated as the number of days between the last egg within a clutch and the day the same chicken started laying the next clutch.

Shell quality

Shell thickness was used as a measure of shell quality. The eggs were first boiled air dried and the shell removed. Shell thickness including the membranes was measured on four places of the shell, the broad end, the pointed end and two middle parts from each side of the egg. The mean of the four measurements per egg was taken as the shell thickness of that egg. Shell thickness was obtained from shell with the membrane intact and measured to the nearest 0.1mm using an Ames No 25M micrometer.

Statistical analysis

The collected data were analyzed using the General Linear Model (GLM) according to SAS (2001).

Y_ij =μ + F_i + Sj +L_{k +} (FL)_{ik +} β(X_{ijkl) -} µ) e_ijkl

Y_ij =                 Record of j^th bird from i^th treatment

μ =                   Overall mean

F_i  =                 Effect of i^th feeding regime

Sj =                  Effect of j^th sex of the bird

L_{k =}                        Effect of k^th location

FL_ik =              Interaction of feeding regime and location

μ  =                  Overall mean for initial body weight, shank length and relative shank length

e_{ijkl =}                      random effect

Results

Digestibility

The chemical composition of the dietary treatments for the digestibility experiments is shown in Table 2. Variations for the chemical components were observed with season, where CP and ash were highest in the wet season.  

The effect of feed type on apparent digestibility of feed components is presented in Table 3. Total feed dry matter digestibility differed significantly (P<0.001), between feeding regimes. The homemade and scavenged feed in the dry season were more digested than the commercial and scavenged feed during the wet season. Apparent DM digestibility for homemade, commercial, dry and wet season feeds was 81, 71, 79 and 67, respectively. Significant differences were also observed for CP, EE and Ash and were higher for the dry season scavenged feeds; CF digestibility was slightly higher for the homemade feed.

The digestibility of Calcium and phosphorus was influenced significantly (P<0.001) by diet type, and was highest for the wet season scavenged feed followed by the commercial feed. The lowest digestibility for both calcium and phosphorus was observed in the dry season scavenged feed. 

Body weight, growth rate and shank length

The effect of feeding regimes on body weight is presented in Table 4. Scavenging only birds had smaller body weights than supplemented birds throughout the experimental period. On average the homemade and commercial supplemented birds were heavier by 18.1% and 14.2%, respectively than scavenging only birds. Increasing difference between scavenging only and supplemented birds with time was noted and was 48g at period 1 to 173g at period 7. Mean final body weights for homemade, commercial and scavenging only birds were 1486g, 1437g and 1259g, respectively. 

The effect of location on body weight is shown in Table 5.The body weights were lowest for birds kept on station throughout the experimental period and were followed by Mkundi a more drier area compared to the other locations but the differences were insignificant. 

Growth rate

The effect of location on growth rate is shown in Table 6. Significant differences between locations were noted during periods 1, 2, 3, 4, and 5 whereas no significant differences were observed in periods 6 and 7. Growth rate was lowest in birds kept at the station and the birds at Mkundi during the 1^st 3 sampling periods. Growth rate reached a peak during the 3^rd period after which a decline in all locations was noted.  

Figure 1 shows the effect of feeding regime on growth rate of rural chickens. Differences in growth rate between the homemade and commercial feeding regimes were insignificant during sampling periods 1, 2, and 3 but slight differences were noted after the 4^th period and were slightly higher in birds supplemented with the commercial diet. Throughout the experimental period growth rate was lower in birds under the scavenging only regime although differences were narrower after the 4^th period.

Shank Length

The effect of feeding regimes and location on shank length during the growing period is shown in Figures 2 and 3. The differences in shank length were not significant (P>0.05) between the feeding regimes but slight differences were observed between locations. In both feeding regimes shank length was lower at Kauzeni a village located in the drier area.

Egg Production

The effect of feeding regimes and location on egg production parameters is shown in Table 7 and 8. The mean no of eggs (31.7) during the experimental period was similar between the supplemented birds and was higher than the scavenging only birds (20.5). This was an increase in mean egg production of 54%, however when feed cost was taken into account an increase in profit over the scavenging only regime was only 11.6% for the homemade feed whereas a decrease in profit of 3.4% for the commercial feed was noted. The effect of treatment on egg weight was significant (P<0.01). Scavenging only birds laid lighter eggs than supplemented birds in all locations. Mean egg weight was 39.3g, 39.0g and 34g for mixed, commercial and scavenging feeds respectively being 15.6% and 14.3% heavier than scavenging only feeds. Shell thickness was influenced by both diets and location.

Number of eggs per clutch was not affected by treatment although the number of days per clutch and pause days were longer in the scavenging only birds. The mean for pause days was 17.5±1.2, 18.5±2.0 and 31.8±1.8 for scavenging with homemade, commercial and scavenging only feeding regimes. 

Discussion

The results of the present study are discussed in relation to findings reported elsewhere. The differences in feed digestibility between seasons were a reflection of the different feed components. Studies have shown that the digestibility of nutrients is normally influenced many factors which include age of animal, type of feed ingredients and feed composition especially protein (Iyayi and Fayayon  2005; Applegate  2008). The high amount of green plant materials in the wet season feed may have been the probable reasons for the low digestibility particularly protein for the wet season scavenged feed. The wet season feed is made of a large component of green materials which may contain anti-nutritional factors and are fibrous. This means that although protein content is very high in the wet season feed, a greater proportion may not be available to the bird due to the low digestibility of this fraction. The high differences in fat digestibility between the dry and wet was attributed to seasonal differences in the type of lipids present in the scavenged feeds in these seasons. In the dry season much of the fat normally comes from grains and legume seeds whereas in the wet season the fat is mainly from insects, maggots and larvae. Fats of animal origin are more saturated than those from plants and therefore they are not easily digested (Harper et al 1977; Klasing 2000). The higher calcium and phosphorus digestibility in the wet season was probably due to the low level of cereal grains, since their presence increase levels of phytic acid and oxalates which binds these minerals (Reddy et al 1982). 

The low body weight and growth rate for birds on the scavenging only feeding regimen in all periods was a reflection of the low nutrient availability from scavenging as reported in other studies (Mwalusanya et al 2002; Rashid et al 2004). Differences observed between locations whereby the on farm birds outperformed the on station birds on most parameters was an indication that the scavenging feed resource base (SFRB), on farm was better quantitatively and qualitatively than on station. This was probably due to human contribution to the SFRB and the unlimited scavenging area which was not the case at the on station location. This concurs with the findings of Goromela et al (2006) who showed that the differences in SFRB were mainly due to season, agroecological climate, land area and population density. The contribution of human activities to the nutrition of scavenging chickens is advantageous to the birds and it varies within households and ecological areas.  

The results on growth rate showed that free range chickens responded to supplementation during the early stages probably due to high nutrient demands. The trend was similar between on farm and on station where the response to supplementation was observed more in the early days of growth but declined in later stages. This suggests that feed availability might not be limiting growth in the latter stages of the chicken's life. In the early stages, growth is mainly due to accretion of lean tissue (protein) therefore the availability of proteins (amino acids), is critical at this time Griminger and Scanes (1986). As the bird grows there is more accumulation of lipids than protein thus the requirement of the bird changes accordingly and as a result energy becomes more limiting factor to growth (Harper et al 1971). These results indicate that probably during the early stages of growth, the SFRB was inadequate in proteins to meet the bird’s requirement for growth hence the observed response to supplementation. As the birds grew protein and amino acids requirement declined thus the available protein on the range was adequate to meet the bird’s requirement resulting in low response to supplementation. The mean shank length of about 6.5–7 cm was similar to values reported by Yakub et al (2009) and it seems the length is constant and less affected by diet. The lack of response to supplementation suggests that calcium and phosphorus availability are not limiting on range. Previous studies by Mwalusanya et al (2002) showed that Calcium content of the scavenged feed was close and sometimes above the chicken’s requirement levels in the study areas during the dry and wet seasons respectively.

The higher number of eggs in supplemented chickens compared to the un-supplemented birds observed in the present study was similar to findings reported by (Rashid et al 2004). The wider energy to protein ratio for the scavenged observed in other studies may have been responsible for low egg production of the un-supplemented free ranging chickens since they eat to meet their energy requirements and as such they become deficient in other nutrients needed for egg production (Mwalusanya et al 2002). The increase in egg production led to higher total egg income although the net gain income was lower. The net gain of 11.2% and a deficit of 3.4% for the homemade and commercial birds respectively over the scavenging only birds observed in the present study were in agreement with findings from other researchers that native chickens do not give good economic returns when they are given expensive commercial balanced feed Huque and Ukil (1993) and Demeke (1996). Therefore it seems improvement in performance of scavenging birds is influenced not only by feed but also probably by the genetic potential. The longer pause days observed in birds under the scavenging only regime might have been due to inadequate nutrients needed to be deposited into the yolk so as to initiate ovulation since egg laying poses a big drain on nutrient reserve (Johnson  1986, Elharidy  2002). Improvement in egg quality i.e. egg weight and shell quality due to supplementation obtained in the present study is in agreement with the fact that, egg quality is highly influenced by nutrition whereas some factors such as number of eggs per clutch are mainly influenced by genetic factors (Rashid et al 2004, Thuy and Ogle  2007).

Conclusion

• Supplementation of rural chickens led to improvement in performance but cheaper feed ingredients are needed in order to get high economic gains. The effects of supplementation were high during the early part of the growth stage. Scavenging feed resource base around the homestead has a great influence on performance of chickens.

Acknowledgments

The authors would like to thank DANIDA (Danish International Development Agency) for the financial support and the late F. Kampeni for his tireless efforts in this work.

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Received 9 February 2011; Accepted 18 April 2012; Published 7 May 2012

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