Morphometric variations of native chicken types in backyard farms of Bhutan

Jigme Dorji, Sonam Tamang, Tshewang and Tashi Y Dorji

Animal Genetic Resource Program, National Biodiversity Centre, Serbithang, P O Box 875, Thimphu, Bhutan
jigmedorjik@gmail.com

Abstract

This study assessed five morphometric and body weight variations among 10 native chicken types in backyard farms of Bhutan.

The results indicate a significant difference in body size and weights among the native chicken types and also between the sexes. Overall, the Baylaitey chicken was significantly smaller in all parameters compared to other chicken types. The body weight was highest in Kauray type (2. 36 kg) and least in Baylaitey (1.40 kg). The predominance of chicken types was the lowest for Baylaitey (dwarf) (2%) followed by Naam (Pure black (4%) and Pulom (frizzle) (6%). Overall, the study indicated a high morphometric variation of Bhutanese native chicken in terms of body sizes and weights in backyard farms catering to a varying production conditions and needs of the farmers. We recommend the conservation of Baylaitey native chicken since it’s a rare breed with unique phenotypic features.

Key words: indigenous, nutrition security, rural poverty, sustainable livelihoods

Introduction

Over two-third of Bhutanese population reside in rural areas (NSB 2005). Poverty in Bhutan (12%) is grossly a rural phenomenon and includes subsistence farmers (NSB 2012). Subsistence agriculture is characterized by backyard livestock farming and crops. The former has an important role in household food and nutrition security. The role of livestock in culture and traditional practices of the communities, replenishing soil fertility for crops and rural development are well recognized (Copland and Aurthur 2010). Indigenous livestock breeds are considered to have special nutritive and medicinal values (Dorji et al 2010).

About 66% of rural households in Bhutan rear chicken in backyard farms (NBC 2011). The backyard chicken farming is characterized by keeping of native chicken under minimal management input mainly under scavenging and free ranging conditions. Despite their low productivity, the population of native chicken in Bhutan continued to be more or less constant over the past decade (DoL 2006, 2010). However, native chicken population constitutes about 12% of chicken population of over 1 million (DoL 2016). Bhutanese native chicken are classified into 10 types and comprehensively described based on plumage, feather and body size (Nidup et al 2008). However, information gaps do exist on the morphometric parameters of native types in the country. A preliminary study with selected native chicken types indicated wide variations in morphometry (Needup and Sunwar 2014). Morphometrics is one of the standard parameters considered in phenotypic characterization of a species. In addition, morphometric parameters correlate to the production traits of chickens (Ojo et al 2014; Yahaya et al 2012).

This study aimed to assess and document the morphometric variations of native chicken in the country as a part of phenotypic characterization towards conservation and sustainable utilization for improved livelihoods in rural communities.

Materials and methods

Study sites

The study purposively sampled 16 sub-blocks with a native chickens population in the country (Figure 1) by considering the socioeconomic importance of the species to the community.

Figure 1. Sampling sites in Bhutan for morphometric data collection

Data collection

A total of 451 adult birds (Male 143, female 308) belonging to 10 native chicken types (Belochem, Baylaitey, Bobthra, Barred, Pulom, Kaap, Kauray, Naap, Naked neck and Shekheni) (Figure 2) were noted for feather characteristics (morphology, distribution, and color) and five body measurements (body length, chest circumference, shank length, wing span) and body weight using the standard guidelines of FAO (2012).

Figure 2. Ten native chicken types of Bhutan and their morphological characteristics

Data analysis

A descriptive statistics and multivariate analysis of body measurements with chicken type and sex as fixed factor, and age as covariate was analysed in Statistical Package for Social Science (SPSS) version 22. A multiple comparisons were performed using assuming Bonferreni equal variance for chicken types. A hierarchical cluster analysis of the means of the measurements of the aggregated sexes and a dendrogram was plotted employing within group linkage and squared Euclidean distances.

Results and discussion

The Baylaitey, Frizzle, Shekheni, Kauray and Naked neck chickens were specifically in southern districts of the country in addition to other chicken types indicating a rich diversity than other sites (Table 1). Based on the number of sampling of chicken types; some of the rarest types were Baylaitey (2%), Naap (4%) and Pulom (6%) in backyard farms of the country. The Baylaitey chickens are reported more susceptible to predators (Dorji et al 2013) and this in part explains the low preference of among the farmers and the low prevalence in farms.

The multivariate analysis of the body measurements indicated a significant difference across the type and sex (p< 0.05). Overall, Baylaitey chicken was the smallest of all native chicken types while Kauray was the largest in terms of body size and weight. The mean morphometric parameters of aggregated gender are presented in Table 1. The Baylaitey was significantly different from others in all morhphometric parameters. The small size of Baylaitey may be attributed to the dwarfing genes (Guillaume 2007). The small size of Baylaitey with short legs and body weight similar to Shekheni makes this chicken type appear stocky and small pace walker to not be able to escape from the predators.

The high body weight of Kauray compared to other the native chicken types present the potential for promotion as a meat type in backyard farms. However in addition to body weight, the assessment of quality aspect of meat needs to be considered.

As expected, sexual dimorphism was conspicuous in native chicken. The males were larger in body sizes and heavier compared to females. For example in Kauray; BL was 47.0±2.32 cm and 40.8±2.48, weighed 2.51±0.36 and 2.21±0.51 kg respectively for male and female (data not shown). Sexual dimorphism is widely reported in native chickens (Picardal et al 2015, Niguissie et al 2015). However, the body measurements and weights in current study were higher than reported for five native chicken types (Nidup and Sunar 2014).

The cluster analysis of the native chicken types based on the biometric measurements indicate five clusters; I. Frizzle group (including BOB, KAP, NAM), Shekheni-Naked neck group, Baylaitey, Barred-Belochem group and Kauray (Figure 2). This clearly differentiated Baylaitey, Kauray and Shekheni type as expected and are based on the classification based on body size by farmers. Most chicken types classified based on plumage colors were in same cluster except Barred type. Naked neck, Shekheni, Kauray and Baylaitey segregated from plumage type classification.

Figure 3. Cluster analysis of native chicken types breeds based on squared Euclidean distance of aggregated sexes body measurements (BOB Bobthra; FRZ Frizzle/Pulom; NN Naked neck; SKN Shekheni; BLT Baylaitey; BLC Belochem; BRD Barred; KRY Kauray)

Conclusions

• There is a huge variation in body size and weight of the native chicken types in backyard farms of Bhutan which may be used for selection and breed improvement.
  
  
• The Baylaitey was the smallest and the rarest chicken type and calls for conservation initiatives.
  
  
• The Kauray with largest body size and weight has potential for promotion as a meat type native chicken in backyard farms of Bhutan.

Acknowledgement

The authors would like to thank the District Livestock Officers, and Extension Officers of the sampling sites for coordinating visit to the sites and assisting in the data collection.

References

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Received 4 May 2017; Accepted 21 June 2017; Published 1 September 2017

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