Integrating interventions against village chicken diseases to reduce mortalities of chicks and growers in southern zone, Tanzania

A O Mbyuzi, E V G Komba* and R C T Mulangila**

Veterinary Investigation Centre, Southern zone, P.O.Box 186, Mtwara. Tanzania
* Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, P.O. Box 3021, Morogoro, Tanzania
** Livestock Research Centre Naliendele, P.O.Box 509, Mtwara, Tanzania
babagrid@yahoo.com   ;   ekomba@suanet.ac.tz

Abstract

Despite the efforts to control the devastating Newcastle disease (ND) through vaccination programs, chicken mortalities of especially chicks and growers in the free range husbandry system continue to exist at significantly higher levels, implying the existence of other causes of such mortalities. We conducted an intervention study to evaluate the impact of integrating the control of other important chicken diseases into ND control programs in southern zone of Tanzania. A total of ten villages were selected from Mtwara Rural, Mtwara Urban and Lindi Rural Districts and divided into test and control groups each comprising of five villages. Chickens in the control and test villages received ND vaccination on quarterly basis. In addition to vaccinating the chickens against ND, integrated disease control in the test villages included vitamin A supplementation and control of endo- and ecto-parasites. In both groups of villages the disease management processes were conducted by trained community vaccinators and recorders (CVRs).

 The results of the present study indicate that good proportions of the vaccinated birds in both control group (70.1%) and test group (69.4%) were protected against challenge with virulent ND virus. However there were significantly more losses of chick (p< 0.0001) and grower (p=0.0171) chickens in the control villages than the test villages. Majority of the losses in the control group were due to the intervened diseases in the test group. The results highlight the importance of these other diseases in contributing to chicken losses. We recommend integration of control of these diseases in ND control programs so as to significantly reduce losses of especially chick and grower chickens.

Key words: free range, HI test, scavenging, vaccination

Introduction

Village chickens have a big socioeconomic contribution and their market is gaining popularity in towns. Their products particularly meat and eggs are even tastier (Muhairwa et al 2008).  They are further considered important genetic resources that should be conserved against production threats and replacement with commercial hybrids (Muchadeyi et al 2007). Unlike other birds and mammals, chicken farming is neither suppressed, challenged, frustrated nor influenced by taboos (Ministry of Agriculture and Food Security, MAFS 2003). In Tanzania, over 94% of chickens are comprised of indigenous birds, predominantly kept by village farmers under scavenging production system (MAFS 2003). Further quantification on the contribution of indigenous chickens to human welfare in rural areas has been documented by Alders and Pym (2008) and MAFS (2003).

A major weakness in village chicken farming is on disease control measures. Losses caused by mortalities due to diseases alone have been overshadowed by devastating pressure of Newcastle disease (ND). This has led to underestimation of other factors whose contribution to chicken losses is huge (Alders et al 2002 and Muhairwa et al 2008). Endoparasites (worms) and ectoparasites are equally economically important in village chicken farming. They reduce weight gain, egg production and hatchability and are responsible for significant deaths in young birds (Muhairwa et al 2008). Chicken losses are further inflated by challenges of poor husbandry practices, especially poor nutrition and housing that predispose chicken to diseases and other causes of losses. Malnutrition in terms of avitaminosis A is a serious killer particularly in young chicks and growers during prolonged dry season and at the beginning of rain season due to lack of green vegetation which serve as important sources of vitamin A to the scavenging birds. During that period hens lay eggs with severe deficiency of vitamin A and consequently new hatches are also deficient of the vitamin. The contribution to chicken losses; of predation, theft and accidents associated with poor housing has always been significant.

 In 2007 the chicken population in Southern zone (SZ) was estimated at 2,577,819; contributing significantly to rural household welfare (Veterinary Investigation Centre (VIC), Mtwara 2008). Ninety nine percent of the chickens were indigenous (local) kept by 90% of the households. Apart from keeping chickens as a source of delicacy and income, farmers enjoy chicken farming as it is articulated to various socio-economic functions such as prestige and dignity, dowry payments, traditional healing, sports, presents during festivals and manure for farm crops and gardens (Alders et al 2002). On the other hand, since 1994, more efforts to reduce chicken losses have been put on the control of Newcastle disease (ND) in all the districts of SZ (Salum et al 1997), the success of which has been minimal. Chicken losses involving chicks and growers have constantly featured in the industry. This has led to slow growth of the industry despite high demand of its products. Nevertheless attempts to investigate on the contribution of other important diseases, most of which have been documented, to these chicken losses in an ND controlled environment have never been made in the country and therefore information is lacking. Consequently, the present study was conducted with an objective of evaluating the impact of integrating, into ND control, interventions against other diseases of indigenous chickens in reducing high mortalities of chicks and growers. Specifically it was to evaluate the impact of controlling Avitaminosis A, worms and ectoparasites in stemming the mortalities.

Materials and Methods

 Ethics Statement

 This project was approved by the Institutional Review Board at Livestock Research Centre Naliendele, Mtwara, Tanzania. Permissions to carry out the studies in the Districts were sought from the District council offices. Farmers provided verbal consents. Blood collection from birds was effected by qualified, registered veterinarians using standard procedures.

 Study area

 The present study was conducted in the southern zone of Tanzania. The zone covering 103,478 km², comprises Mtwara and Lindi regions and Tunduru District of Ruvuma region.  Southern Zone has two main seasons: a humid and hotter wet season (November-May) and a cooler, less humid dry season (June-October). Mean annual rainfall ranges from about 800 mm in inland and central areas to 1,200 mm in the hills and plateaux near the coast. The zone is characterized by mixed farming systems whose elements change with variations in climate and environment. The most important crops grown in this zone are starchy staples (sorghum, maize, rice, cassava, and millet), leguminous food crops (pigeon peas, cowpeas, fiwi beans, green gram, and bambara nuts), vegetables and oilseeds (groundnuts, sesame, soybeans, sweet potato, onion, and tobacco) and tree crops (cashews, coconuts, oranges, bananas). Livestock keeping involves raising poultry (especially village chickens), goats, sheep and cattle. The present study was conducted between September 2009 and August 2010. Study villages were selected from three district councils i.e. Lindi rural, Mtwara rural and Mtwara Municipality.

 Selection of study villages

Inclusion of any village in this study considered the following criteria: 1) relatively higher chicken population in the district, 2) willingness of farmers to cooperate with researchers and livestock experts/extension staff during and after the project, 3) willingness of leaders to address to their farmers on promotion of the project towards alleviation of poverty and food insecurity and 4) support of leaders and villagers on preferential involvement of women and youths in the project. Extension staff from the District Agriculture and Livestock Development Officers’ (DALDOs) offices facilitated the selection process.

 Selection of project farmers

Meetings with chicken keepers were organized in selected villages with involvement of the village leaders and extension staff. Farmers were introduced to the project objectives and principles and village leaders assigned a task to take a lead in the selection of farmers and community vaccinators and recorders (CVRs) for each village. Eligibility criteria for both farmers and CVRs were high-lighted to the leaders and farmers to facilitate acquisition of intended sample. Farmers criteria included possession of at least seven breeding birds (five pullets and two cockerels) being an initial flock, willingness to participate in the project and abide by the project principles. The criteria for CVRs included: background in chicken keeping, gender balance, possession of formal education (ability to read, write and count) and willingness to collaborate and abide  by research ethics and principles.

 Farmer training

Following receipt of names of selected farmers and CVRs in each village, training seminars were organized. A one day seminar was conducted in each village; attended by the selected farmers, CVRs, village leaders and any other willing villager. The delivered content in test villages covered aspects of poultry health, nutrition, husbandry; and keeping production, reproduction and health records.  Farmers in control villages were only exposed to the epidemiology and control of ND; and record keeping.

 Disease management in the study villages

Chickens in both control and test villages were vaccinated against ND on quarterly basis using Thermotorelant Newcastle disease vaccine (ND I₂).  Additional treatments for chickens in test villages included the following: 1) Strategic vitamin A supplementation to hens, chicks and growers using OXYVIT PLUS^® (NUTEC Ltd, Lichfield, Staffordshire, UK), a water soluble product rich in vitamins and a small amount of antibiotic (Oxytetracycline), 2) Deworming using PIPERAZINE CITRATE (Biotec Laboratories Ltd,  Dar es salaam, Tanzania) and 3) Control of ectoparasites using commercially available products; namely AKHERI POWDER^® containing a combination of Carbaryl 5% and Lambdacyhalothrin 0.1% W/W as active ingredients (FARMBASE LTD, Dar es salaam, Tanzania) and SEVIN DUDU-DUST^® containing Carbaryl 7.5% W/W as an active ingredient (BAYER Environmental Science, Nairobi, Kenya). The farmers were supported to design chicken houses and urged to use the locally available materials to construct them. Routine vaccination; and drug and vitamin administration in the study villages were effected by CVRs.

 Serological evaluation of flocks’ responses to vaccination

A convenient and most commonly used serologic procedure for determining the response of the flocks to ND vaccine, the hemagglutination-inhibition (HI) test, was adopted. Blood samples were collected from randomly picked vaccinated chicken and sera harvested. The collected sera samples were stored at -20°C till when transported on ice to Sokoine University of Agriculture for HI test.

 Diagnosis of chicken diseases

The diagnosis of chicken diseases both ante mortem (AM) and post-mortem (PM) was carried out by ward resident livestock field officers, District Veterinary officers and researchers. The diagnosis was either conducted in the field (study villages), District Agriculture offices or Veterinary investigation centre (Mtwara). Livestock field officers holding diploma in Animal health and animal production were given refresher course on how to diagnose various chicken diseases with emphasis on diagnosis of avitaminosis A, Fowl Pox, ND, Worms and bacterial infections. They were shown on how to conduct PM in chickens to identify some common disease problems including lesions typical of ND. Intestinal lesions with no specific signs suggestive of a given condition were regarded as enteritis whose lab confirmation was not performed because of limited financial resources. Birds dying with no well defined clinical and post-mortem picture fell into undiagnosed cases. Same training was conducted to CVRs at a lower depth, sufficient to predict likely disease. Alarming chicken deaths were communicated to researchers by CVRs and these were responded by urgent visits by researchers. During diagnostic procedures disease signs and postmortem lesions were recorded.

 Record keeping

Project farmers were required to keep daily records on various health, reproduction and production parameters in both the control and test villages. CVRs compiled the records on monthly basis. Collaboration was extended to DALDOs office staff (extension officers) to increase efficiency in recording the required information from farmers. Finally the records were collected by principal and co-investigators (PI & CIs) during monitoring and evaluation which was done quarterly, an activity which was accompanied by on site training. Often researchers cross checked between farmers’ and CVRs’ records.

 Data analysis

Gathered data were entered into Microsoft Excel spreadsheet and analyzed using StatView^® software. Descriptive statistics were computed for different parameters of interest. Chi square and t-test were computed in Medcalc® software to determine significance of differences in parameters between the test and control villages at P=0.05.

Results

 Project villages and farmers

 A total of ten villages (5 control and 5 test) were selected from the three district councils based on the set criteria. The village names and their bearing groups are as shown in table 1. Ten farmers and two community vaccinators and recorders (CVRs) were selected from among the chicken keepers in each village to participate in the project. The majority of the farmers in both control and test villages couldn’t meet the criterion of having 5 breeding hens and 2 cockerels. Additionally majority of the farmers in the test villages could not meet a criterion of building chicken houses. The reasons raised were lack of funds to buy raw materials and fear of exposing their birds to thieves. They therefore continued to shelter their chicken in the human dwelling units.   

 Training of farmers

A total of 179 villagers were trained in the present study, 83 in the control group and 96 in the treatment group. Though the study was to involve 60 farmers in each group, a need, observed during training, of many farmers to take part in the study resulted into elevating the number to 67 farmers per group.  

 Chicken population in the study villages before and after intervention

The study started with a total of 384 and 328 chickens in the control and test groups respectively; owned by 67 households in each group. The difference in mean household chicken flock sizes between the two study groups (Control=5.73; Test=4.91) was not statistically significant (p=0.287) as shown in table 2.  After twelve months of the study a total of 1907 and 2603 chicken were recorded in the control and test villages respectively. The mean household chicken flock size at this point was significantly higher in the test group than control group (p< 0.007) as shown in table 2. The mean household numbers of chicken of each age group were also significantly higher in the test group than control group (p= 0.048 for chicks, p= 0.036 for growers and p= 0.042 for adults) as shown in table 3.

Flocks’ responses to vaccination

Following hemagglutination-inhibition (HI) test; 70.1% and 69.4% of the chicken had protective Newcastle disease virus (NDV) antibodies in the control and test group respectively. The difference in proportions of birds with protective antibodies between control and test groups was not statistically significant.

 Chicken losses in the study villages

 Overall losses

The overall chicken losses in the control and test villages are as shown in table 4. The mean household losses were higher in the control group (34) than test group (9.18). The differences in the mean losses were statistically significant (p< 0.0001) as seen in table 4.

Chicken losses by age categories

Presented in table 5 are the mean household values for chick, grower and adult chicken losses. The losses were significantly higher in the control group than test group for chicks (p < 0.0001) and growers (p= 0.0171). Differences in mean losses in adult chickens were not statistically significant between the two groups (P = 0.181).

Causes of chicken losses in the study villages

General

Chicken losses in the study villages were due to disease and non disease causes. The disease causes had significantly higher contribution to the total losses in the control villages as shown on figure 1.

Figure 1: The proportion of disease and non disease causes to chicken losses

Figure 2: The numbers of birds lost due to disease and non disease causes

Disease causes of chicken losses

 Diseases involved in chicken losses in the two groups of villages are presented in table 6. The numbers of households and birds affected is indicated for each disease. The intervention of Avitaminosis A, worms and ectoparasites in the test villages made the diseases occur less frequently. The same diseases however occurred at significantly higher levels in the control villages where they were not controlled. Avitaminosis A affected more than 70% of the households in the control villages. The same disease affected only 3% of the households in the test villages. Worms were detected in 40% of the control group villages affecting 16% of the households. In the test villages worms affected only 3% of the households. Around 4% of the households in the control villages were affected by ectoparasites killing 36 birds, where as 6% of the households in the test villages had such an incidence but no bird loss occurred.  

Non disease causes of chicken losses

Predation, accidents and theft were recorded to be non-disease causes of chicken losses in both control and test villages. There were significantly more incidences of predation in the test villages than control villages (P< 0.0001). Control villages were however featured by significantly higher incidences of accidents (P < 0.0001). There were no significant differences in theft incidences between the two groups (P = 0.273).

Discussion

We are reporting preliminary results of integrating control of other important poultry diseases into ND control program in the rural chickens in southern Tanzania. We aimed at reducing mortalities of chicks and growers in the study area through a community-based approach.

In developing countries access to poultry meat and eggs depends on village-level poultry production. The system provides valuable protein through a low input system, representing 30% or more of the protein consumed (FAO 1998). It further plays an important role in supplying villagers with additional income. Sale of eggs and live birds in urban and rural markets is perhaps the only source of cash earnings available to rural families (Kperegbeyi et al 2009). Chickens are also used in traditional caring rituals, means of knowing the time, offered as gifts and in cementing marriages and friendship.

For a long time Newcastle has been known to be the most important disease in free range chicken production systems (Msoffe et al 2010). Control of the disease is achieved through vaccination of health birds. ND vaccination projects have reported early success, but later reported the emergence of other causes of poultry mortality as birds live longer (Yongolo et al 1998). Similarly, a recent observation in Mtwara, Tanzania (Mbyuzi 2009; personal communication) has revealed that in ND-immunised birds mortality is still high in chicks and growers. Alders et al (2002) and Muhairwa et al (2008) proposed that in order to reduce heavy chicken losses, the control of ND must go along with improved husbandry practices and control of avitaminosis A, parasites, bacterial infections and fowl pox (only where pox is a problem).

Avitaminosis A is known to be a common nutritional disease in chicks and grower chickens (Jordan and Pattison 1996; Calnek et al 1997).  The disease has emerged to be a threat to both intensive and extensive chicken production systems in various parts of the country especially during the dry spell (Komba 2009; personal communication). In the present study, supplementation of chickens in the test villages with commercially available vitamin combination containing substantial levels of vitamin A resulted into fewer incidences of the disease as compared to control villages. This approach can serve as a way of combating the problem in village chicken during dry spell when naturally available sources of vitamin A are scarce.

The interactions of nutrition and infection with regard to individual infections and defined nutrients are now better known. The importance of interactions between vitamin A deficiency and a number of infectious diseases are now becoming clear. For instance, Vitamin A functions to maintain epithelial tissues (Uni et al., 1998), a lack of this vitamin reduces the integrity of the epithelial barrier and eventually leads to easier penetration of a pathogen into the epithelium, its proliferation site. This has been observed in the present study in which Avian pox has featured in most of the households where Avitaminosis A was prominent suggesting a positive correlation. As observed elsewhere (Gerlach 1999), the disease was most commonly characterized by cutaneous proliferative lesions that hardened to thick scabs. According to Tripathy and Reed 2008 those types of lesions are suggestive of mechanical transmission of the virus. It was previously pointed out by Sentíes-Cué et al 2010 that the typical distribution of cutaneous fowl pox, along with the encrusted proliferative type of skin lesion, is an important characteristic for clinical diagnosis.

Extensive management systems where chickens have access to outdoor areas, and not confined, predispose them to a greater diversity of parasite infestations (Muchadeyi et al 2007). Meanwhile parasitism has been known to be a big constraint to chicken productivity (Mungube et al 2008). Helminths are among the important internal parasites in free range chickens affecting all ages (Jordan and Pattison 1996; Calnek et al 1997). On the other hand fleas, lice and mites feature in most of the ectoparasitic infestations, chicks and growers being commonly affected. Control of these parasites in the test villages in the present study led to fewer losses as compared to control villages. The differences in the numbers of lost birds between the two groups of villages were however not statistically significant. This may have been attributable to the existing control practices in both the groups using traditional methods including the use of herbs.

The main features of the local chicken production systems are improper housing and inadequate hygiene (Abdelqader et al 2007). In the present project, a criterion of building chicken houses could not  be met by majority of the farmers in the intervention villages due to lack of funds to buy raw materials as the season was characterized by food insecurity in most of the households such that small earnings obtained were directed to food purchase. However, some farmers mentioned fear of exposing their birds to thieves as among the reasons for not accepting the idea of constructing separate houses for their birds. They therefore continued to shelter their chicken in the human dwelling units.

Free ranging predisposes birds to some non disease causes of flock losses such as predation, accidents and theft as observed in the study area. In the present study predation had a huge contribution to the chicken losses in both control and test villages. Abdelqader et al (2007) also revealed predators to be the main non disease cause of flock losses.

The present investigation considered chicken flock size dynamics and chicken losses as among the parameters for comparison between control and test villages. At the beginning of the study majority of the farmers couldn’t meet the criterion of having 5 breeding hens and 2 cockerels since the project took off just at the end of ND strike leaving many households with small stocks due to mortalities or sales to avoid losses. The mean household flock size, and the within group proportions of chicks, growers and adults didn’t differ between the two groups at this stage. After 12 months of intervention, however, the mean household chicken flock size was significantly higher in the test group indicating a positive impact of intervention. The control group on the other hand experienced significantly higher bird losses of particularly chicks and growers as compared to the test group. Many of the losses were due to the diseases which were controlled in the test villages. This indicates that the diseases had substantial contribution to chicken losses. 

The present study strived to enhance performance through involvement of local leaders and extension staff from the very beginning. This imparted the community a sense of ownership of the project. The use of local trained persons (CVRs) to conduct various disease control procedures further created community trust. The training of CVRs contributed to technical capacity building that will remain in the local community after the life of the project (Msoffe et al 2010).

The present study revealed that diseases other than Newcastle contribute significantly to local chicken losses in the free range production systems. With resource constraint, however, our study had a limited coverage both in terms of study area and diseases to work on. We recommend similar studies at a large scale so as to come up with recommendations whose implementation will make local chicken production a sustainable enterprise that will improve rural communities’ livelihoods. The present study is currently assessing the cost effectiveness of the tried intervention and also investigates on the socio-economic implications attributable to increased chicken populations in test villages as a result of the intervention.

Acknowledgments

This research project was funded by Zonal Agricultural and Livestock Research and Development Fund (Southern zone). We highly appreciate and value their financial support. The authors wish to acknowledge DALDOs in the three district councils for being very instrumental in ensuring that the project activities are implemented well. Managements and staff of VIC Mtwara and Sokoine University of Agriculture (Morogoro) also had valuable contributions to the success of this research. The cooperation of village leaders and project farmers is highly appreciated.

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Received 15 April 2011; Accepted 6 December 2011; Published 4 January 2012

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