Comparative evaluation of eggs from three selected species of indigenous laying hens

S Garba, E D Assam¹, R O Yusuf, A Sa'adu and M Jibir

Department of Animal Science, Usmanu Danfodiyo University, PMB 2346, Sokoto, Nigeria.
sanigarba2003@yahoo.com
¹ Department of Animal Science, University of Uyo, P.M.B. 1017, Uyo, Nigeria

Abstract

The study was conducted to compare quality parameters of eggs from three selected species of indigenous laying hens. The treatments were regarded as LF, DU and GF which represent eggs from local fowl, ducks and guinea fowl respectively. Each treatment had 3 replicates with 40 eggs per replicate (n=360). Eggs were sourced from village market in Wamakko, Kware and Dange Shuni local government areas of Sokoto State. The parameters assessed were egg quality parameters (external and internal).

The results of the study showed that there were significant differences (P<0.05) between treatments in all the external egg quality parameters evaluated except shell thickness. However, the eggs indicated no significant differences (P>0.05) in albumen height, yolk height, yolk colour, yolk index and albumen index while albumen width, yolk width, yolk weight, albumen weight and Haugh unit were significantly different between treatments (P<0.05). It may be concluded that indigenous species of laying hens possessed good egg quality characteristics comparable to exotic or improved laying hens. Egg from village market which is considered fresh and natural could be recommended for consumers and food processing industries.

Keywords: food, local, poultry species, village market

Introduction

One of the major developmental challenges facing most developing countries is their inability to adequately feed their ever-increasing population with the right proportion of calories and protein (Apantaku 2006). Most Africas' diets (including Nigeria) are deficient is animal protein which results in poor and stunted growth as well as increase in spread of diseases and consequently death (Apantaku et al 1998). The state of nutrition in Nigeria is characterized by inadequate protein intake. The poultry industry serves as a major source of animal protein in form of meat and eggs and has the potential of solving this problem. Local chickens are among the many local resources of the poor, living in the rural areas, which could be harnessed and utilized for poverty alleviation (Njue et al 2002). The existing scavenging system of indigenous poultry allows the chickens  and other species to utilize scavengeable materials from  the environment such materials are either directly  from the household or from other sources in  environment such as refuse heaps, crawling insects, vegetation cover and household left over (Sonaiya and Olukosi 2002). It was emphasized that eggs produced by laying birds should be suitable for the purpose which they are produced. The suitability is determined by the quality of the egg. Therefore the economic importance and the success of the layer enterprise depend on the total number of quality eggs produced (Ojedapo et al 2009). Local eggs are perceived as natural food. Food products from villages, which are particular advertised as natural and fresh, are in the focus of consumer’s preferences. However, there was less or no studies conducted in order to examine differences in egg quality among different species of indigenous laying hens other than commercial eggs.

Materials and Methods

The study area

The study was conducted in the physical laboratory of the Faculty of Agriculture, Usmanu Danfodiyo University, Sokoto main campus. Sokoto state is located (lat. 12^o 00’ – 13^o 05’N and Long. 4^o 08’ – 6^o 04’E) in the North West zone of Nigeria. The extreme northern part of the state falls within the Sahel Savanna while the remaining southern part falls within the Sudan Savanna vegetation zones (Mamman et al 2000). The entire state experiences two alternating seasons: the short wet (rainy) season; which start in May/June and ends in September, and the long dry season; which complete the remaining parts of the year. The mean annual rainfall vary from 500 to 700 mm. Mean monthly temperature varies from 13.2^oC to 41^oC recorded in January and April respectively (SEPP 1996). The open Savanna vegetation pattern in the state provided opportunity for extensive livestock rearing and cultivation of short duration arable crops. Thus, most of the people in the state are agro-pastoralists (rearing livestock alongside arable crop production).

General Experimental Layout      

A total of 360 eggs were sourced from village market in Wamakko, Kware and Dange Shuni local government areas of Sokoto State. The treatments were regarded as LF, DU and GF which represent eggs from local fowl, ducks and guinea fowl respectively. Each treatment was replicated 3 times and each replication comprises of 40 eggs.

Determination of egg quality parameters

Twenty eggs were randomly collected from each replication of the treatments (n=180) and labelled. Each egg was weighed and broken into a Petri-dish and the yolk was separated from the albumen using a yolk separator. Yolk weights were measured using a sensitive electronic scale (Mettler Toledo, XS precision Lab balance) to the nearest 0.01g. The albumen weight was obtained after subtracting the weights of the yolk and shell from the egg weight. Shell thickness was measured with the aid of micro-meter screw gauge (Panda et al 2003). Yolk and albumen heights were measured using Vernier calliper. Haugh unit was calculated by taking the average values of albumen height and weight of the eggs using the formula below (Oluyemi and Roberts 2000): HU = 100 log (H7.57 – 1.7W^0.37). Where, HU =   Haugh unit

H =   albumen height in millimetres

W =  observed weight of eggs in grams

The shell interior was cleaned with a tissue paper and allowed to dry. Thereafter, the weight was taken using electronic sensitive scale to the nearest 0.01g. The color of the yolk was scored visually with the aid of the Roche yolk colour fan (Hoffmann-La Roche, Switzerland). The Roche yolk colour fan numbered from 1-15, indicating very light to orange coloration. The colour fan was placed near the yolk to determine the color that matches the yolk. The color number was then noted.

Data analysis

The data generated from the experiment was subjected to analysis of variance (ANOVA) using the statview statistical package (SAS 2002).      

Results and Discussion

External quality parameters

Table 1 shows external egg quality parameters. There were significant differences (P< 0.05) among the species mean egg weight. It is an established fact that the weight of an egg is a direct proportion of albumen, yolk and shell that it contains and this varies significantly between strains of hen (Pandey et al 1986).

 The egg length differed significantly (P<0.05) between treatments. Egg width in this study indicated higher significant differences between the treatments.  There were no significant differences (P> 0.05) in respect to the shell thickness among all the treatments. The shell thickness values reported in this study (0.34 – 0.36mm) is close to the values (0.35 – 0.36 mm) reported by (Oluyemi and Roberts 2000). Good shell thickness is an important bio-economic trait in commercial egg production as it may help to reduce the percentage of cracked eggs (Fayeye et al 2005). Mean egg shape index differ significantly between the three species of laying hens. The shape egg index reported in this study has showed that LF and GF are similar while DU differ significantly (P< 0.05). Eggs have elongated and rounded shape and still account for a significant percentage of all eggs laid. However, they differed according to bird species and race. According to (Romanoff and Romanoff 1949), the standard eggs from hens had a shape index of 74% with blunt and pointed ends. Elongated eggs have lower shape index while rounded eggs have higher value. This could be the reason why DU eggs had lower (52.25%) shape index.

Internal Quality Parameters 

Table 2 shows internal egg quality parameters. Albumen height in this study indicates lack of significant differences between the three species of laying hens. It is accepted that the lesser the surface of egg white dense and the more its height, the better is the egg. The height of egg white (albumen) in fresh egg should not be less than 0.5cm ((Maria and Dmowski 2005).

The values reported in this study (0.32 – 0.37cm) were lower than the recommended value of 0.5cm in fresh egg. This may not be unconnected with the local egg sourced from village markets where freshness of an egg is not guaranteed. Yolk height means showed no significant difference (P< 0.05) between all treatments in this study. Another parameter describing the quality of egg is flattening of yolk. The height of yolk over 1.6cm and its spherical shape characteristics indicates a freshness of an egg (Maria and Dmowski 2005). This study reported yolk height values (1.71-1.86cm) greater than 1.6cm, therefore likely confirmed freshness of the egg samples used during the research. Albumen weight and yolk weight recorded in this study signifies significant differences between treatments. Duck eggs (DU) recorded the highest albumen weight compared to the other treatments (Table 2). According to Pandey et al (1986), the weight of an egg is a direct proportion of albumen, yolk and shell that it contains and this varies significantly between strains of hen. There were no significant differences in yolk colour for all the treatments according to Roche yolk colour fan assessment. The colour of the yolk scores indicated very light (Pale) colouration. This could be attributed to the nature of management of the laying hens. Previous researches have indicated that yolk colour of an egg depends on the type of diets (Garba et al 2010), system of production and housing system (Hasin et al 2006). There were significant differences between the treatments in Haugh unit evaluation. A Haugh Unit value of 79 and above is an indication of good quality. Brandt et al (1991) reported that eggs of inferior quality have Haugh Unit of less than 40%. There was no statistical significance in albumen index and yolk indices in all the treatments measured. Yolk index values range from 0.36 to 0.46 further indicated freshness characteristics of eggs from species of the laying hens. Since, according to Maria and Dmowski (2005) yolk index not lower than 0.30 characterize a fresh egg.

Conclusion

• Egg quality parameters of indigenous species of laying hens evaluated have indicated higher quality in comparison with egg quality parameters of commercial laying hens.

Recommendation

Egg from village market which is considered fresh could be recommended for consumers and food processing industries.

Acknowledgement

We sincerely thank Prof. W.A. Hassan who provided helpful comments and Dr. Nasiru Muhammad of the Department of Animal science, Usmanu Danfodiyo University, Sokoto, Nigeria for data analysis work.

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Received 12 December 2015; Accepted 12 March 2016; Published 1 May 2016

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