Assessment of flock structure, preference in selection and traits of economic importance for domestic turkey (Meleagris gallopavo) genetic resources in Nasarawa State, Nigeria

A Yakubu, H K Abimiku*, I S Musa-Azara*, K O Idahor and O M Akinsola**

Department of Animal Science, Faculty of Agriculture, Nasarawa State University, Keffi, Shabu-Lafia Campus, P.M.B. 135, Lafia, Nasarawa State, Nigeria.
* Department of Animal Science, College of Agriculture, Lafia, Nasarawa State, Nigeria.
** Department of Animal Science, Faculty of Agriculture, Ahmadu Bello University, Zaria, Kaduna State, Nigeria.
abdul_mojeedy@yahoo.com

Abstract

Village poultry have been raised for thousands of years and the selection pressure present in the village environment has resulted in indigenous stock that are well adapted to local conditions. The present investigation examined the flock composition, preference in choice of breeding stock, production traits and culling criteria in indigenous turkeys of Nasarawa state, Nigeria. A semi-structured questionnaire was administered to 53 randomly selected households engaged in turkey farming in the study area.  

A low tom: hen ratio of 1: 2.75 was observed in the turkey population. Body size, egg number, hatchability, heat tolerance, body conformation and disease resistance were the preferred traits for selection of breeding stock. Higher rankings (P<0.01) were accorded economic traits such as high reproductive performance, increased egg production and large body size. Most of the households culled toms with low body size, low fertility and poor health while fertility, egg number, body size and mothering ability were highly ranked as culling criteria for hens. The rate of inbreeding (ΔF) calculated for the indigenous turkey flock considering the existing flock size and management practice was 0.0013 (0.13%), an indication that the population is not at the risk of extinction. It is concluded that community or village-based selective breeding schemes should consider farmers’ traits of preference as a good option to rational and sustainable way to improve and conserve turkey genetic resource in the study area.

Key words: breeding practice, improvement, inbreeding rate, performance, rural farmers

Introduction

The value of animal genetic resources conservation is generally underestimated, as the current indirect values are often neglected (Philipsson et al 2006). The concept of adaptability revolves around fitness describing relative ability of an individual to survive and reproduce next generation to ensure continued survival of the population and is the result of natural selection over many generations. Current trend in genetic selection has severely eroded the genetic base ignoring the diversity of the production milieu, importance of adaptation, production of multiple products and social value of the livestock (Naskar et al 2012). Indigenous birds are a vital reservoir of gene resources and their conservation has a technical role related to the future development of the productive system as well as a social-cultural role (Camacho-Escobar et al 2008; Ajayi et al 2012). In Nigeria, poultry production enjoyed a boom in the early 1980s due to the government subsidies on day-old chicks and feed. This was followed by a downward trend in the industry due to subsidies removal but in recent times, the industry is again experiencing growth due to the current regime’s effort at encouraging the citizenry to invest in the industry, several economic and agricultural policies reforms and removal of import duties on agricultural products (Fasina et al 2007, Anonymous, 2012). Turkey production is both an important and a profitable agricultural industry, with a rising global demand for its products (Case, Miller and Wood, 2010; Ironkwe and Akinola 2010; Anandh et al 2012). Local turkeys are about 1.05 million in Nigeria, being the smallest when compared with other poultry species (FAOSTAT 2011). Free range system of rearing is most popular for rearing the local stocks of turkey (Peters et al 1997). These birds are natural foragers and scavengers and always range farther. Indeed, they thrive best where they can rove about freely feeding on seeds, fresh grass, locusts, crickets; grasshoppers, worms, slugs and snails (Singh and Sharma 2012). 

Improvement in performance of indigenous stock or populations’ overtime can arise through improvement in management and feeding conditions and through genetic improvement by use of genetically superior animals (Yakubu et al 2012). The traits traditionally considered as criteria for selecting breeding stock are important in describing the adaptive attributes and genetic merits of the indigenous birds and in identifying farmers’ choice of genetic stock used (Dana et al 2010; Ilori et al 2012). An issue that has received little attention in the tropics is the development of relevant breeding objectives for smallholder production circumstances. Design of sustainable genetic improvement schemes under smallholder situations requires indigenous knowledge on traditional breeding practices which is structured differently from scientific knowledge (Duguma et al 2010). Lack of such knowledge leads to the setting up of unrealistic breeding goals and the consequence of which can put in danger the conservation of indigenous animal genetic resources (Gizaw et al 2011) 

In Nigeria, sub-saharan Africa, limited information exists on the criteria used by rural dwellers in the selection of their breeding flocks. Such information would better inform breed conservation and improvement programmes. This study was therefore undertaken to determine the breeding practices and criteria preferred by village turkey producers for the production, selection and culling of their birds in Nasarawa State, north central Nigeria. 

Materials and Methods

A cross sectional survey was carried out in six villages of close proximity within Nasarawa Eggon Local Government Area of Nasarawa State, north central Nigeria. A semi-structured questionnaire was administered to 53 randomly selected households. This was complemented with participatory farmers’ group discussions. All the selected households owned turkeys that were reared through the extensive system of production. Although farmers did not control breeding or keep records of their turkeys due to scavenging nature of production, they selected them at household level using their own indigenous knowledge, experience and performance history of the birds. Farmers that practiced selection of breeding stock were asked to rank the criteria (body size, body conformation, plumage colour,  mothering ability, hatchability, disease resistance, egg number, egg size and heat tolerance) used in stock selection in order of importance. All farmers were also asked to rank production traits such as body size, growth rate, survivability, disease susceptibility, reproductive performance, cultural suitability, egg number and egg size in order of importance. Lastly, farmers were asked to which extent they practice culling and the criteria they use. All ratings were carried out by assigning different weights, ranging from 1 being the most important criterion to 4 the least important following the description of  Muchadeyi et al (2009). 

Statistical analysis

Data on flock composition were estimated using the mean procedure of SPSS (2010). The non-parametric Kruskal Wallis test (using a Chi square test) was used to test whether median ranks attached to each criterion used in choosing breeding stock, production traits and culling turkeys varied. Furthermore, rate of inbreeding was calculated in the population. Effective population size for a randomly mated population was calculated as Ne= (4NmNf) / (Nm+Nf) where Ne=effective population size, Nm=number of breeding males in the flock and Nf=number of breeding females in the flock. The rate of inbreeding (ΔF) was calculated from Ne as ΔF=1/2Ne (Falconer and Mackay 1996). 

Results and discussion

The mean flock composition per household in the study area is shown in Table 1. The present value on tom: hen ratio (1: 2.75) fell within the range of 1.69 to 3.69 reported for native turkey in the State of Michoacan, Mexico (Lopez-Zavala et al 2008). Flock structure and dynamics help in the identification of the age and number of animals to be maintained within the breeding population (Okeno et al 2012). The proportion of mature hens in a flock is used to estimate egg and poultry production (Yakubu 2010). The low sex ratio on the farms studied is an indication that the breeding system is not controlled by the farmers (Zahraddeen et al 2011). This could lead to decline in reproductive success, and impact negatively on the profitability of the turkey enterprise. It has been reported that for high fertility rate to be achieved, one tom is to serve 20-25 hens in a flock of turkeys (Farmer 2008). Therefore, there is an urgent need for the restructuring of the flock composition by encouraging the indigenous turkey producers to keep more hens to increase the productivity and profitability of their farms.

Farmers’ decisions on choice of breeding stock are shown in Table 2. Body size, egg number, hatchability, heat tolerance, body conformation and disease resistance were the traits of utmost importance for selection purpose; while mothering ability, plumage colour and egg size were ranked low. The present findings are consistent with the report of Desta and Wakeyo (2012) in chickens that selection of birds was mainly dependent on physically observed traits like body size. Similarly, Duguma et al (2010) reported that conformation traits are important criteria of selection under traditional livestock breeding practices. This is because size/conformation heavily determines live birds prices in traditional poultry markets. However, the low rating of plumage colour in the present study is contrary to the report of Dana et al (2010) where this trait was used as a selection criterion. The difference might be as a result of the socio-cultural role of plumage colour in chickens, whereas less emphasis is laid on this in indigenous turkeys. Development of a breeding goal for improvement of indigenous birds should focus on the traits perceived important by stakeholders (Okeno et al 2011). This is because breeding goals developed without considering the needs of all the stakeholders have high chances of rejection by end users.

The farmers’ preferences for production traits in the flock are shown in Table 3. It illustrates that given a choice, farmers would prefer (P<0.01) birds that produced more offspring (high reproductive performance), more eggs (for procreation and sale) and large body size (for meat production). Growth rate, survivability and egg size, came fourth, fifth and sixth in ranking, while disease resistance and cultural significance were the least ranked. The present findings are congruous to the submission of Okeno et al (2011) in chickens where some of the traits of economic significance that were highly rated were egg number, body size and fertility Favourable correlation suggests that if major importance is placed on performance traits in stressful environments, adaptability traits would not be compromised and thus the most productive and adapted animals for each environment need to be identified for breeding purposes (Naskar et al 2012). It should be stressed that genetic improvement for performance traits tends to be cumulative and permanent and that response of even a few per cent in gross efficiency often means a several fold increase in income (Assan 2011).

The culling criteria for breeding toms and hens are shown in Table 4. Body size, fertility and health were highly ranked as culling criteria for toms while fertility, egg number, body size and mothering ability were accorded more importance in hens. Birds that were not retained for breeding purposes were culled through sales, consumption and gift. The culling criteria used give an indication of the implicit farmers’ breeding goals (Muchadeyi et al 2009). The present trend indicates that farmers cull birds for productive rather than morphological traits (plumage colour) implying that the village turkeys are kept mainly for economic and food security reasons. The high ranking of mothering ability indicates that farmers are also concerned with the number of chicks reaching adulthood (Muchadeyi et al 2009).  

The effective population size (Ne) and the rate of inbreeding (ΔF) calculated for the indigenous turkey flock considering the existing flock size and management practice were 396  and 0.0013 (0.13%) , respectively (Table not shown). Effective population size is a measure of genetic variability within a population with large values of Ne indicating more variability and small values indicating less genetic variability (Maiwashe et al 2006; Cervantes et al 2008). Inbreeding is the probability that two alleles at any locus in an individual are identical by descent relative to a base population (Falconer and Mackay 1996). The rate of inbreeding in the free-range turkey population was low, although a direct opposite of what is obtained in commercial turkey production where care is taken to preserve genetic variation by avoiding inbreeding in the populations (Swalander, 2012). The low value of ΔF is an indication that the turkey population is not at the risk of extinction. However, a balanced breeding programme through the introduction of blood from more superior indigenous turkey birds from neighbouring communities or other ecotypes in the country may be a step in the right direction in attenuating inbreeding rate. This should be executed with caution because of fanciers who have precise selection criteria and who will not choose a male from a neighbour (Lariviere et al 2011). 

Farmers’ breeding objectives may not be fully addressed by breeding objectives and selection criteria defined by project experts in nucleus centers. This has great implications in the success of livestock projects, as breeding strategies that are based on farmers’ indigenous knowledge and preferences are more suitable and sustainable than exotic technologies (Gizaw et al 2011).  

Conclusion

• Body size, egg number, hatchability, heat tolerance, body conformation and disease resistance were the preferred traits for selection of breeding stock.
  
  
• Farmers accorded higher rankings to production traits such as high reproductive performance, increased egg production and large body size.
  
  
• Most of the households culled toms with low body size, low fertility and poor health while fertility, egg number, body size and mothering ability were highly ranked as culling criteria for hens.
  
  
• The low rate of inbreeding in the indigenous turkey flock is an indication that the population is not at the risk of extinction.
  
  
• Therefore, any breed improvement strategies that are intended to be implemented in the study area should consider farmers traits of preference, the traditional breeding practices and breeding objectives of the community.

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Received 7 December 2012; Accepted 22 December 2012; Published 4 January 2013

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